Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week of 6 June – 12 June 2018

Agung | Bali (Indonesia) : PVMBG reported that during 1 May-7 June activity at Agung remained at a relatively high level. Emissions were mostly water vapor, occasionally with ash. In general, tiltmeter and GPS showed long-term deflation since December 2017, though inflation began to be detected the second week of May; deformation analysis indicated that magma continued to accumulate about 3-4 km below the crater. Low- and high-frequency earthquakes also suggested rising magma. Sulfur dioxide flux was 190-203 tons/day, and thermal anomalies in the crater were identified in satellite data. The erupted volume of lava was estimated to be 23 million cubic meters, equivalent to about a third of the total crater volume. At 2214 on 10 June an event generated an ash plume that drifted W at an unspecified altitude. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone was stable at a 4-km radius.

Aira | Kyushu (Japan) : JMA reported that there were eight events and five explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 4-11 June. Crater incandescence was occasionally visible at night. Ash plumes rose up to 2 km above the crater rim, except an event at 1135 on 10 June produced a plume that rose 3.5 km. Tephra was ejected as far as 1.3 km from the crater during 8-11 June. The Alert Level remained at 3 (on a 5-level scale).

Ambae | Vanuatu : The Vanuatu Meteorology and Geo-hazards Department reported that activity at Ambae’s Lake Voui decreased in May, and by 7 June had ceased; the Alert Level was lowered to 2 (on a scale of 0-5) and a 2-km-radius exclusion zone was emplaced. Steam and volcanic gas emissions continued, and were reportedly smelled by local residents near the volcano.

Ambrym | Vanuatu : On 7 June the Vanuatu Geohazards Observatory (VGO) reported that the lava lakes in Ambrym’s Benbow and Marum craters continued to be active, and produced sustained and substantial gas-and-steam emissions. The Alert Level remained at 2 (on a scale of 0-5); the report reminded the public to stay outside of the Permanent Danger Zone defined as a 1-km radius from Benbow Crater and a 2.7-km radius from Marum Crater.

Cleveland | Chuginadak Island (USA) : AVO reported that low-level unrest at Cleveland continued during 6-12 June. Elevated surface temperatures were identified using satellite data on most days, during times of cloud-free observations. Nothing unusual was observed in seismic or pressure sensor data. Steam emissions were observed during 11-12 June. The Aviation colour Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Dukono | Halmahera (Indonesia) : Based on PVMBG observations and satellite data, the Darwin VAAC reported that during 6-12 June ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted W, NW, N, NE, and E.

Ebeko | Paramushir Island (Russia) : KVERT reported that a diffuse ash plume drifting 8 km E of Ebeko was identified in satellite images on 5 June. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kadovar | Papua New Guinea : According to the Darwin VAAC a pilot observed an ash plume from Kadovar rising to an altitude of 1.2 km (4,000 ft) a.s.l. on 10 June. The ash plume was not identified in satellite data.

Kilauea | Hawaiian Islands (USA) : HVO reported that the eruption at Kilauea’s Lower East Rift Zone (LERZ) and at Overlook Crater within Halema`uma`u Crater continued during 7-12 June. Lava fountaining and spatter was concentrated at Fissure 8, feeding lava flows that spread through Leilani Estates and Lanipuna Gardens subdivisions, and built out the coastline where the fast-moving flow entered the ocean in the Kapoho Bay area. Minor lava activity at Fissures 16/18 was occasionally noted.

Inward slumping of the crater rim and walls of Halema`uma`u continued, adjusting from the withdrawal of magma and subsidence of the summit area; the floor had subsided at least 100 m during the previous few weeks, and by 12 June the lowest point was 300 m below the crater rim. Steam plumes rose from areas in the crater as well as from circumferential cracks adjacent to the crater.

Summit explosions occurred almost daily. Explosions at 1607 and 0244 on 6 and 8 June, respectively, each produced an ash plume that rose 3 km (10,000 ft) a.s.l. An explosion was recorded at 0448 on 9 June. Two explosions, the second larger than the first, were recorded at 0046 and 0443 on 11 June. An ash-poor explosion occurred at 0152 on 12 June. A pattern of an increasing number of earthquakes, an explosion, and then a drop-off of seismicity immediately afterwards had emerged during the past few weeks and continued.

A total of 12 rockfalls in Pu’u ‘O’o Crater were recorded between 1031 and 1056 on 8 June, following a M 3.2 earthquake at the summit. A red dust plume was visible around 1050 but dissipated quickly.

Fountaining at Fissue 8 was stable, though by 10 June three closely spaced fountains were active within the 35-m-high spatter cone. The heights of the fountains varied, but rose no higher than 70 m. Pele’s hair and other volcanic glass from the fountaining fell within Leilani Estates. The fountains continued to feed the fast-moving lava flow that traveled NE, and then SE around Kapoho Crater, and into the ocean. The width of the channel varied from 100-300 m along its length. Periodic overflows sometimes sent small flows down the sides of the channel. Lava entered the ocean at Kapoho Bay, building a lava delta that by 11 June was just over 100 hectares in area. A plume of laze rose from the entry points. An area of strong thermal upwelling in the ocean around 920 m out from the visible lava-delta front was visible beginning on 7 June, suggesting lava flowing on the ocean floor. According to a news report, the Hawaii County Mayor noted that by 8 June lava flows had destroyed over 600 homes.

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Klyuchevskoy and a diffuse ash plume drifting 12 km W were identified in satellite images on 6 June. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Langila | New Britain (Papua New Guinea) : Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 7 June a minor ash emission from Langila rose to an altitude of 3.4 km (11,000 ft) a.s.l., slowly drifted SW, and detached form the summit. On 10 June a discrete event produced an ash plume that rose to 2.1 km (7,000 ft) a.s.l. and dissipated.

Pacaya | Guatemala : INSIVUMEH and CONRED reported that on 6 June a lava flow emerged from a vent on La Meseta (the Mesa) on Pacaya’s NW flank and traveled 200 m over a period of six hours. Strombolian explosions ejected material as high as 50 m above the crater rim during 7-10 June.

Popocatepetl | Mexico : CENAPRED reported that each day during 6-12 June there were 19-34 steam-and-gas emissions from Popocatépetl, and nightly crater incandescence. Explosions were detected almost every day: at 2026 on 7 June; 0130 on 8 June; 1756, 1931, and 2358 on 9 June; 1724 on 10 June. An explosion at 0220 on 11 June ejected incandescent fragments. The Alert Level remained at Yellow, Phase Two.

Sangay | Ecuador : The Washington VAAC reported that on 8 June a possible discrete ash emission from Sangay rose to an altitude of 5.8 km (19,000 ft) a.s.l. and drifted 28 km WSW before dissipating.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images during 5-6 June. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

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Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 6 June – 12 June 2018

Fuego | Guatemala : During 6-12 June INSIVUMEH and CONRED reported that strong lahars at Fuego were often hot, steaming, and had a sulfur odor, and were generated from heavy rains and the recent accumulation of pyroclastic-flow deposits from the 3 June events. On 6 June lahars descended the Santa Teresa, Mineral, and Taniluyá drainages (tributaries of the Pantaleón river) and possibly the Honda drainage, halting search-and-rescue efforts. The lahars were 30-40 m wide, 2-5 m deep, and carried blocks (2-3 m in diameter) and tree parts. CONRED noted on 9 June that deposits on roads were being cleaned at a rate of 150 m per day, and that exposed deposits were as hot as 150 degrees Celsius. Significant hot lahars, 40 m wide and 5 m deep, traveled down the Seca, Mineral, Niágara, and Taniluyá drainages, carrying rocks and tree branches. On 10 June a strong lahar traveled down the Seca, Mineral, Niagara, Taniluyá, and Ceniza drainages. It was 35 m wide, 3 m deep, and carried blocks up to 1 m in diameter, tree trunks, and branches. Lahars that traveled down the Seca and Mineral drainages on 11 June were 40 m wide and 3 m deep. Lahars on 12 June were 20-45 m wide and 2-5 m deep, and flowed down the Ceniza and Mineral rivers. During 6-11 June as many as nine weak explosions per hour produced ash plumes that rose as high as 1.1 km above the crater and drifted 8-15 km W, SW, and S. Avalanches of material descended the Las Lajas and Santa Teresa ravines. Some explosions vibrated local structures. At 0820 on 8 June a pyroclastic flow descended the Las Lajas and El Jute drainages, producing an ash plume that rose as high as 6 km and drifted W and SW. Explosive activity increased during 11-12 June, with dense ash plumes rising 1.3 km and drifting as far as 25 km N and NE. Pyroclastic flows traveled down the Seca drainage. According to CONRED, as of 12 June, the number of people that had died due to the 3 June pyroclastic flows was 110, and 197 more were missing. In addition, 12,578 people had been evacuated.

Great Sitkin | Andreanof Islands (USA) : Seismicity at Great Sitkin was elevated during the previous five days, though at 1139 on 10 June a seismic signal indicating a possible short-lived steam explosion prompted AVO to raise the Aviation colour Code to Yellow and the Volcano Alert Level to Advisory. No infrasound signal associated with the event was detected, and no volcanic clouds rose about the meteorological cloud deck at 2.4 km (8,000 ft) a.s.l.

Ibu | Halmahera (Indonesia) : PVMBG reported that at 1206 on 6 June an eruption at Ibu generated an ash plume that rose at least 500 m above the crater rim and drifted N. An event at 1750 on 12 June produced an ash plume that rose 600 m and drifted N. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side.

Kerinci | Indonesia : Based on satellite data, the Darwin VAAC reported that on 10 June an ash plume from Kerinci rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted W.

Manam | Papua New Guinea : Based on a pilot observation, the Darwin VAAC reported that on 10 June an ash plume from Manam rose to an altitude of 1.8 km (6,000 ft) a.s.l. The ash plume was not identifiable in satellite images.

Ruapehu | North Island (New Zealand) : On 5 June GeoNet reported that a new heating cycle at Ruapehu’s summit Crater Lake began, as indicated by a recent rise in the water temperature. The increasing lake temperature began 29 May, at a rate of about 1°C per day. Volcanic tremor also increased, representing a greater flow of hydrothermal fluids into the lake. Many heating and cooling cycles have occurred in the past; the current cycle does not indicate an unusual sign of unrest. The Volcanic Alert Level remained at 1 (minor volcanic unrest) and the Aviation colour Code remained at Green.

Sierra Negra | Isla Isabela (Ecuador) : On 8 June IG reported a continuing high level of seismicity at Sierra Negra, characterized by a larger number and magnitude of earthquakes, indicating magma movement. The number of events per day had been significantly increasing since mid-2016. In the previous 10 days there was an average of 42 local events/day; on 25 May there were 104 events, the largest number of earthquakes per day recorded since 2015. In addition, in a 24-hour period during 7-8 June there were a total of 48 volcano-tectonic events, two long-period events, and three hybrid earthquakes; a M 4.8 long-period earthquake was recorded at 0715 on 8 June. The earthquake epicenters were mainly located on the edges of the crater, in two NE-SW trending lineaments; the first covered the N and W edges of the crater and the second went from the NE part around to the S edge. Data showed very large deformation at the caldera’s center, compared with lower levels of deformation outside of the caldera.

Ulawun | New Britain (Papua New Guinea) : According to the Darwin VACC, a NOTAM (Notice to Airmen) stated that on 8 June an ash plume from Ulawun rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted W.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week of 30 May – 5 June 2018

Aira | Kyushu (Japan) : JMA reported that there were 12 events and four explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 28 May-4 June. Tephra was ejected as far as 1.1 km from the crater, and ash plumes rose as high as 2.5 km above the crater rim. Crater incandescence was occasionally visible at night. The Alert Level remained at 3 (on a 5-level scale).

Dukono | Halmahera (Indonesia) : Based on ground observations and satellite data, PVMBG and the Darwin VAAC reported that during 30 May-June ash plumes from Dukono rose to altitudes of 1.4-2.1 km (4,500-7,000 ft) a.s.l. and drifted NE and E.

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Klyuchevskoy was identified in satellite images on 25 and 28 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Piton de la Fournaise | Reunion Island (France) : OVPF reported that during an overflight of Piton de la Fournaise on 29 May scientists noted that the vent atop the main cone (about 22-25 m high) was about 5 m in diameter. Slumping and small collapses on the flanks were visible, and gas emissions rose from the vent. Based on seismicity, OVPF stated that at 1430 on 1 June the eruption that began on 27 April was over.

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was comparable to the previous week; explosions averaged 28 per day during 28 May-3 June. Seismicity was dominated by long-period events and signals indicating emissions. Gas-and-ash plumes rose as high as 4.3 km above the crater rim and drifted 40 km NE, E, and SE. The MIROVA system detected six thermal anomalies, and on 30 May the sulfur dioxide gas flux was high at 5,571 tons/day. The report noted that the public should not approach the crater within a 12-km radius.

San Miguel | El Salvador : SNET reported a significant increase in the number of low- and high-frequency earthquakes beneath San Miguel’s crater beginning on 22 May. RSAM values fluctuated between 142 and 176 units (normal values are 50-150 units) during 30 May-1 June. Webcam images on 30 May showed a small gray gas emission.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images on 31 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Suwanosejima | Ryukyu Islands (Japan) : Based on JMA notices and satellite data, the Tokyo VAAC reported an explosion at Suwanosejima on 2 June.

Yasur | Vanuatu : Based on webcam images and model data, the Wellington VAAC reported that during 5-6 June intermittent, low-level ash plumes from Yasur rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW. Ash was not identified on satellite imagery.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 30 May – 5 June 2018

Fuego | Guatemala : In a special bulletin from 0600 on 3 June INSIVUMEH noted increased activity at Fuego. Strong explosions were accompanied by rumbling sounds, and shock waves that vibrated local structures. Dense ash plumes rose 2.3 km above the crater and drifted SW, W, NW, and N. Pyroclastic flows descended the Seca (Santa Teresa) drainage on the W flank, and possibly other drainages, though poor weather conditions prevented clear views of the summit area. Ash plumes drifted in westerly directions, causing ashfall (on roofs and cars) in Sangre de Cristo (8 km WSW) and San Pedro Yepocapa (8 km NW). By 1000 pyroclastic flows were descending the Cenizas (SSW) drainage. Ashfall was reported in additional areas including La Soledad (10 km ESE), Quisache, and the municipality of Acatenango (8 km E).

Based on information from multiple agencies, the Washington VAAC reported an ash plume rising to 9 km (30,000 ft) a.s.l. at 1130 from an explosive eruption. In a report from 1340, INSIVUMEH described large pyroclastic flows traveling down the Seca, Cenizas, Mineral, Taniluya (SW), Las Lajas (SE), and Honda (E) drainages, producing dense ash plumes that rose 6.2 km above the summit (or 32,800 ft a.s.l.). A news article stated that the pyroclastic flows traveled at least 8 km and reached temperatures of 700 degrees Celsius. Tephra and lapilli fell in areas more than 25 km away, including in La Soledad, San Miguel Dueñas (10 km NE), Alotenango, Antigua Guatemala (18 km NE), and Chimaltenango (21 km NNE). Ashfall was reported as far away as Guatemala City, 70 km E. Explosions rattled structures within 20 km of Fuego. The La Aurora International Airport closed at 1415. Eyewitness accounts described the fast-moving pyroclastic flows inundating fields people were working in, overtaking bridges, and burying homes up to their roof lines in some areas. San Miguel Los Lotes, Alotenango, and El Rodeo (10 km SSE) were the worst affected.

According to Simon Carn, satellite data analysis showed that the event produced the highest SO2 loading measured from a Fuego eruption in the satellite era (since 1978), and therefore most likely the highest since the major 1974 eruption. He went on to note that the SO2 mass was about ~2 orders of magnitude than the 1974 eruption, which had a significant stratospheric impact.

At 1650 INSIVUMEH noted reports of lahars descending the Pantaleón drainage (fed by the Santa Teresa and El Mineral rivers) and other drainages. CONRED had evacuated communities near Fuego, including Sangre de Cristo, finca Palo Verde, and Panimache. At 2200 (~16.5 hours after the increased activity began), the eruption waned, with activity characterized by weak-to-moderate explosions, crater incandescence, and ash plumes that rose almost 800 m. The seismic station (FG3) recorded the last pyroclastic flow at 1845. By 0725 on 4 June seismicity had returned to normal levels. Explosions occurring at a rate of 5-7 per hour produced ash-rich plumes that rose as high as 900 m and drifted 15 km SW, W, NW, and N. Avalanches of material descended the flanks. The La Aurora International Airport reopened and flights resumed at 0930.

On 5 June INSIVUMEH reported that activity again increased. Explosions occurring at a rate of 8-10/hour, some strong, generated ash plumes that rose 5 km and drifted E and NE. At 1928 a pyroclastic flow traveled down the Las Lajas drainage. News articles noted that authorities called for another evacuation.

CONRED reported that by 0630 on 6 June a total of 12,089 people had been evacuated, with 3,319 people dispersed in 13 shelters. One bridge and two power networks had been destroyed. According to news sources on 6 June, Guatemala’s National Institute of Forensic Sciences stated that 75 people were confirmed to have died and 192 were still missing. Many, possibly thousands, received burns and other injuries. Weather conditions, continuing activity at Fuego, poor air quality, hot pyroclastic flow deposits, and rain made rescue efforts difficult.

Kerinci | Indonesia : Based on satellite data, the Darwin VAAC reported that on 5 June a minor ash emission from Kerinci rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted W.

Kilauea | Hawaiian Islands (USA) : HVO reported that the eruption at Kilauea’s Lower East Rift Zone (LERZ) and at Overlook Crater within Halema`uma`u Crater continued during 30 May-6 June. Lava fountaining and spatter was concentrated at Fissure 8, feeding lava flows that spread through Leilani Estates and Lanipuna Gardens subdivisions, and reached the ocean at Kapoho Bay. Fissures 22, 6, and 13 were periodically active on 30 May, and fissures 6/13 spattered on 4 June. Sluggish lava flows were present around Fissure 18.

Inward slumping of the crater rim and walls of Halema`uma`u continued, and earthquake activity beneath the caldera was mostly high, as the summit area adjusted to the withdrawal of magma from Overlook Crater. Passive degassing of SO2 from the summit decreased, but emission rates were high enough to impact air quality downwind. Ash emissions were intermittent and low, though around 1100 on 30 May an ash plume rose to 3.6 km (12,000 ft) a.s.l. A small explosion was detected at 1339 on 1 June. A preliminary M 5.5 earthquake was recorded at 1550 on 3 June, producing an ash plume that rose to 2.4 km (8,000 ft) a.s.l. A small explosion and accompanying M 5.5 earthquake was detected at 0432 on 5 June; an ash plume rose to 1.6 km (5,100 ft) a.s.l.

During the beginning of the reporting period Fissure 8 generated tall lava fountains, rising 80 m, and some secondary fountains that rose 18 m. Pele’s hair and other volcanic glass from the high fountaining fell in areas W of the fissure and within Leilani Estates. A small (30 m high) spatter cone formed at the downwind side of the fountain. Volcanic gas emissions from the fissures were very high; trade winds blew vog to the S and W parts of the island.

The lava flow fed by Fissure 8 advanced NE at a rate of 550 m/hour during 29-30 May, but then slowed to 90 m/hour on 31 May. High eruption rates led to the formation of a leveed channel along the W edge of the lava flow; small overflows from the channel occurred along its length. On 2 June lava flowed around the N part of Kapoho Crater and then turned S, entering the Vacationland neighborhood. At 0700 the flow front had entered Kapoho Beach Lots, moving about 75 m/hour. Lava entered Green Lake (70 m x 120 m in dimension, and 60 m deep) at 1000, creating a large steam plume. By 1500 lava had completely filled the lake and boiled off the water. Locals reported that lava (with a flow front 800 m wide) entered the ocean at Kapoho Bay around 2230. By late afternoon on 4 June lava had built a delta extending almost 700 m into the bay.

Overnight during 4-5 June lava fountaining at Fissure 8 was less vigorous, with a maximum height of 55 m. By 0630 on 5 June lava had completely filled Kapoho Bay, creating a new coastline 1.1 km away from the former coastline. To the S lava had overtaken most of the Vacationland subdivision and was entering the tidepools. All but the northern part of Kapoho Beach Lots had been covered.

Merapi | Central Java (Indonesia) : PVMBG reported that at 0820 on 1 June an event at Merapi generated an ash plume that rose at least 6 km above the crater rim and drifted NW, but then winds changed to the SW. Ashfall was reported at the Selo observation post. Observers noted white smoke rising from a forested area 1.5 km NW, possibly indicating burning vegetation. The report noted that volcano-tectonic events were occurring at about 3 km below the crater. Later that day at 2024 an ash plume from a 1.5-minute-long event rose 2.5 km above the crater rim and drifted NE and W. At 2100 an ash plume rose 1 km and drifted NW. The Alert Level remained at 2 (on a scale of 1-4), and PVMBG noted that all people within 3 km of the summit should be evacuated.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week of 23 May – 29 May 2018

Agung | Bali (Indonesia) : PVMBG reported that although there were some periods of foggy conditions during 23-29 May, white plumes were occasionally observed rising as high as 400 m above Agung’s crater rim. At 0539 on 29 May an event generated an ash plume that rose 500 m above the crater rim and drifted SW. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone continued at a 4-km radius.

Aira | Kyushu (Japan) : JMA reported that there were 21 events and 19 explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 21-28 May. Tephra was ejected as far as 1.3 km from the crater, and ash plumes rose as high as 3.2 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Ambae | Vanuatu : On 18 May a news article noted that the eruption from a cone in Ambae’s Lake Voui continued with minor activity at the vent. The article noted that widespread ashfall had significantly impacted food and water supplies, shelter, and the health of island residents. The Alert Level remained at 3 (on a scale of 0-5), and the report reminded residents to stay at least 3 km away from the active crater.

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 23-29 May ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted W, WNW, and NW. Ash plumes drifted as far as 225 km NW on 28 May.

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that during 19-20 May a thermal anomaly over Karymsky was identified in satellite images. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Langila | New Britain (Papua New Guinea) : Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 23 and 26-28 May ash plumes from Langila rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifted WSW, W, and NW.

Mayon | Luzon (Philippines) : PHIVOLCS reported that during 23-29 May white steam plumes from Mayon drifted WNW, WSW, and SW, sometimes rising 250-300 m above the crater rim. Crater incandescence was visible each night. The Alert Level remained at 2 (on a 0-5 scale) and PHIVOLCS reminded residents to stay away from the 6-km-radius Permanent Danger Zone and the 7-km Extended Danger Zone on the SSW and ENE flanks.

Reventador | Ecuador : During 23-28 May IG reported a high level of seismic activity including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions at Reventador. Steam, gas, and ash plumes rose 1.5 km above the crater rim and drifted NW on 23 May, and a plume of gas, water vapor, and ash rose 300 m on 26 May; cloudy weather prevented views of emissions on most days. A lava flow had advanced to 900 m on the NE flank. On 27 May incandescent blocks were observed rolling as far as 800 m down the flanks in multiple directions. An ash plume rose 3 km above the crater rim and quickly drifted W, causing ashfall in Papallacta (62 km SW), San Antonio de Pichincha (90 km W), Tabacundo (63 km WNW), Cayambe (57 km WNW), Puellaro (85 km WNW), and Puembo (80 km W).

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was comparable to the previous week; explosions averaged 35 per day during 21-27 May. Seismicity was dominated by long-period events and signals indicating emissions. Gas-and-ash plumes rose as high as 3.3 km above the crater rim and drifted 30 km NE, E, and SE. The MIROVA system detected nine thermal anomalies, and on 24 May the sulfur dioxide gas flux was high at 3,950 tons/day. The report noted that the public should not approach the crater within a 12-km radius.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images on 19-20 and 23-24 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Turrialba | Costa Rica : OVSICORI-UNA reported that an event at Turrialba at 0930 on 28 May generated a plume that rose 300 m above the crater rim and drifted SE.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 23 May – 29 May 2018

Kilauea | Hawaiian Islands (USA) : HVO reported that the eruption at Kilauea’s Lower East Rift Zone (LERZ) and at Overlook Crater within Halema`uma`u Crater continued during 23-29 May. Lava fountaining and spatter was concentrated in the middle portion of the fissure system, feeding lava flows that spread through Leilani Estates and Lanipuna Gardens subdivisions, and also traveled to the ocean.

Earthquakes beneath the summit and ash emissions from Overlook Crater continued as the summit area subsided and adjusted to the withdrawal of magma. Ash emissions were small and frequent, punctuated by larger plumes. The Overlook crater vent continued to widen to the W, and by 25 May the vent area was about 36 hectares. At 1244 on 25 May a M 4 earthquake was located in the summit region. That same day a new pit opened on the N part of Halema`uma`u Crater floor. Three explosions (at 0042, 0144, and 0500) on 26 May generated ash plumes that rose 3-3.3 km (10,000-10,800 ft) a.s.l. A small explosion at 0156 on 29 May sent an ash plume vertically to 4.6 km (15,000 ft) a.s.l. and drifted slightly NW. The explosion was felt by residents in Volcano, and ejected incandescent blocks within Halema`uma`u Crater. On 28 May a M 4.1 earthquake occurred at 1739 along the Koa’e fault zone, S of the caldera.

Lava fountains from Fissure 22 continued to form a channelized lava flow that entered the ocean NE of MacKenzie State Park, causing explosions and generating a plume of hazardous laze (lava haze, a mixture of condensed acidic steam, hydrochloric acid gas, and tiny shards of volcanic glass). On 23 May relatively tall lava fountains at fissures 6 and 13 fed another channelized flow that created a second ocean entry. Observers noted that a perched lava pond/channel was 11 m above ground level, and that methane was seen overnight that burned blue in road cracks. On 24 May lava was entering the ocean at three points between Pohoiki Bay and MacKenzie State Park, though by the next day only two were active.

Overnight during 25-26 May vigorous spatter was observed from a cone on Fissure 8, and multiple booming gas emissions occurred at Fissure 17. By the morning of 26 May an estimated 9.6 square kilometers had been covered by new lava. Fissures 7 and 21 fed a perched lava pond and sent flows NE; the lava-flow fronts became ‘a’a. A perched pond on the W side of Fissure 7 was breached, sending short flows W. Later that day the flows turned S, and by dusk were cascading into Pawaii crater, adjacent to the W margin of the Fissure 6 flow that fed one of the ocean entries. Lava from Fissure 21 flowed onto Puna Geothermal Venture (PGV) property.

During 26-27 May activity at Fissure 7 increased; lava from fountains 45-60 m tall built a large, 30-m-high spatter rampart. Large cracks were observed overnight on Kupono St., near Fissure 9. Three vents active at Fissure 8 spattered and flamed, and doubled in size in one day. On 27 May lava flows from fissures 7 and 8 advanced NE on PGV property; at about 1900 a flow broke out in this area and advanced rapidly to the N and W, through the E portion of Leilani Estates, prompting several residents to evacuate. Three minor ocean entries were again active. Fissure 24 opened in Leilani Estates.

On 28 May the vents that fed the ocean entries stopped erupting, leading to only residual lava in the channel to occasionally enter the ocean. During 28-29 May fountains, lava flows, and spattering from multiple fissures persisted. Pele’s hair from vigorous fountaining (60 m high) at Fissure 8 drifted downwind, with some strands falling in Pahoa. According to a news article, the LERZ eruption had destroyed at least 94 structures, including 53 homes, by 29 May. The flows also cut off road access to PGV, which had been evacuated.

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Klyuchevskoy was identified in satellite images during 19-20 and 24 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Merapi | Central Java (Indonesia) : PVMBG reported that a two-minute-long phreatic eruption at Merapi which began at 1349 on 23 May was heard from the Babadan observation post. A plume was not visible due to inclement weather, though minor ashfall was reported in Ngepos post. On 24 May an event at 0256 generated an ash plume that rose 6 km above the crater rim and drifted W. Roaring was heard from all of the Merapi observation posts. A two-minute-long event at 1048 produced an ash plume that rose 1.5 km and drifted W. The Alert Level remained at 2 (on a scale of 1-4), and PVMBG noted that all people within 3 km of the summit should be evacuated.

Piton de la Fournaise | Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise which began on 27 April from fissures at Rivals Crater continued through 29 May. Tremor levels continued to decrease slightly, though were mostly stable at low levels. Observations on 24 May indicated flowing lava was mostly confined to tubes, though a small area of incandescence was visible at the main crater.

Volcanos

Roundup of Global Volcanic Activity – Obgoing Activity for the week of 16 May – 22 May 2018

Aira | Kyushu (Japan) : JMA reported that there were 13 events and 20 explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 14-21 May. Tephra was ejected as far as 1.1 km from the crater, and ash plumes rose as high as 2.7 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 16-22 May ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NW, W, and SW.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 12-14 May that sent ash plumes as high as 2.8 km (9,200 ft) a.s.l. Ash plumes drifted about 20 km SW on 13 May. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Fuego | Guatemala : INSIVUMEH reported that beginning at 1400 on 17 May a lahar descended the Seca (Santa Teresa) drainage on Fuego’s W flank. The lahar was 25 m wide, 1 m deep, and carried trees and blocks 1.5 m in diameter. During 19-21 May explosions occurred at a rate of 5-8 per hour, and generated ash plumes that rose almost 1 km and drifted 10-20 km S, SW, and W. Some explosions were accompanied by rumbling audible more than 30 km away, and shock waves that vibrated structures in Morelia (9 km SW) and Panimaché (8 km SW). Incandescent material was ejected 200-300 m above the crater rim, and generated avalanches of material within the Seca, Ceniza (SSW), and Las Lajas (SE) drainages that reached vegetated areas. Ash fell in areas downwind including in Santa Sofía (12 km SW), Morelia, Panimaché I and II, and Finca Palo Verde. A lava flow 700-800 m long was active in the Ceniza drainage.

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that during 13-15 May a thermal anomaly over Karymsky was identified in satellite images, as well as ash plumes drifting about 150 km SW on 14 May. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Kirishimayama | Kyushu (Japan) : The Tokyo VAAC reported that on 15 May ash plumes from Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, were identified in satellite images drifting S at an altitude of 7.6 km (25,000 ft) a.s.l. JMA noted that white plumes rose 100 m above the crater rim during 18-21 May. The Alert Level remained at 3 (on a scale of 1-5).

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Klyuchevskoy was identified in satellite images during 13-14 May. Strong explosions began at 0315 on 15 May, and generated ash plumes that rose as high as 10.5 km (34,400 ft) a.s.l. The ash clouds lingered around Klyuchevskoy and surrounding volcanoes for about eight hours before gradually dissipating. Nighttime summit incandescence and a hot avalanche were noted. The Aviation Color Code was raised to Orange.

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was comparable to the previous week; explosions averaged 30 per day during 14-20 May. Seismicity was dominated by long-period events and signals indicating emissions. Gas-and-ash plumes rose as high as 1.9 km above the crater rim and drifted N and NW. The MIROVA system detected nine thermal anomalies, and on 19 May the sulfur dioxide gas flux was high at 3,147 tons/day. The report noted that the public should not approach the crater within a 12-km radius.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images on 28 and 11-16 May. The Aviation Color Code remained at Orange.

Sinabung | Indonesia : PVMBG reported that during 16-21 May gray-to-white plumes from Sinabung rose as high as 700 m above the crater rim and drifted in multiple directions. At 0900 on 20 May an event produced an ash plume that rose 700 m and drifted NW. An ash plume from an event later that day at 2122 rose 2.5 km and drifted W and NW. The Alert Level remained at 4 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions of 7 km on the SSE sector, 6 km in the ESE sector, and 4 km in the NNE sector.

Turrialba | Costa Rica : OVSICORI-UNA reported that an event at Turrialba at 0900 on 21 May generated a plume that rose to an unknown height due to poor visibility.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 16 May – 22 May 2018

Kilauea | Hawaiian Islands (USA) : On 16 May HVO reported ongoing deflation at Kilauea’s summit, where the lava lake continued to recede in the Overlook Crater; by the afternoon the caldera floor had dropped a total of almost 1 m since the onset of the lake drainage. The drop of the floor stressed faults around the caldera causing earthquakes as strong at M 4.4. HVO and National Park staff reported frequent ground shaking, and damage to roads and buildings. Phreatic explosions had ejected blocks up to 60 cm in diameter that were found in the parking lot a few hundred meters from Halema’uma’u Crater. Ash plume heights varied, but generally rose no higher than 1.2 km and drifted N. Lava continued to erupt from multiple vents at the NE end of the active fissure system at the Lower East Rift Zone (LERZ). Lava from fissure 17 advanced about 90 m. Weak spattering arose from fissure 18, and fissure 20 was again active.

At about 0415 on 17 May an explosive event (or a series of explosions) at Overlook Crater generated an ash plume that, according to the Washington VAAC, rose as high as 9.1 km (30,000 ft) a.s.l. and drifted NE. Ash fell in areas downwind, including in the Volcano Golf Course and Volcano Village. Subsequent gas, steam, and ash emissions rose to 3.7 km (12,000 ft) a.s.l. and drifted SW. Fissure 17 actively spattered, though its lava flow had nearly stalled. Fissures 18, 19, and 20 reactivated, and a new fissure (21) opened between fissures 7 and 3. A 50-100-m-wide depression with cracks formed parallel to the fissures between Highway 130 and Lanipuna Gardens, into which pahoehoe lava flowed from fissures 20 and 21. Fissure 22 opened just downrift of fissure 19.

On 18 May a robust gas-and-steam plume rose from Overlook Crater, punctuated by several minor ash emissions. At 2358 a short-lived explosion generated an ash plume that rose up to 3 km (10,000 ft) a.s.l. and drifted SW. Spattering continued from fissures 15, 17, 18, 20, 21, and 22, with pahoehoe lava flows being erupted from fissures 17, 18, and 20. Large fountains at fissure 17 ejected bits of spatter 100 m high. Lava flows from fissure 18 traveled almost 1 km SE, and a flow from fissure 15 crossed Pohoiki Road. A fast-moving lava flow (275-365 m per hour) emerged from fissure 20 and traveled SE, across Pohoiki Road. Gas emissions remained elevated in areas downwind of the fissure system; air quality was poor from gas emissions as well as smoke from burning vegetation. Earthquake locations had not moved farther downrift in the previous few days.

Small ash emissions from Overlook Crater occurred intermittently on 19 May. The eruption of lava and ground cracking in the area of Leilani Estates subdivision continued. Fissure 17 was weakly active after fountaining earlier in the day. Fissures 16-20 merged into a continuous line of spatter and fountaining; flows from this fissure 20 complex flowed 275 m/hour S. Two of the flows joined less than a 1.6 km from the ocean and continued to flow S between Pohoiki and Opihikao roads.

During 19-20 May there were two explosive eruptions from Overlook Crater, and several smaller ash emissions. Lava flows reached the ocean overnight (late on 19 May) along the SE Puna coast. On 20 May spatter was ejected from fissures 6 and 17, and fissure 20 produced significant lava flows. A ground crack opened under the E lava channel diverting lava into underground voids. Gas emissions tripled as a result of the voluminous eruptions from fissure 20. Photos take in the afternoon showed two ocean entries along approximately 1 km of coastline.

A small explosion at Overlook Crater at 0055 on 21 May produced an ash plume that rose around 2.1 km (7,000 ft) a.s.l. and drifted SW. Several smaller emissions throughout the day ejected abundant ash. Robust steam-and-gas plumes also rose from the crater. Lava fountains from fissure 22 fed a channelized lava flow that entered the ocean N of MacKenzie State Park. Spattering occurred at fissures 6, 17, and 19. Small ash emissions from Overlook Crater continued on 22 May. Lava continued to enter the ocean, though by the afternoon only one entry was active. Most of the LERZ activity shifted to the middle part of the fissure system. The Aviation colour Code remained at Red and the Volcano Alert Level remained at Warning.

Langila | New Britain (Papua New Guinea) : Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 17-18 and 21-22 May ash plumes from Langila rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted WSW, W, and WNW.

Merapi | Central Java (Indonesia) : PVMBG reported that a phreatic eruption at Merapi began at 0125 on 21 May and lasted for 19 minutes, generating an ash plume that rose 700 m above the crater and drifted W. A six-minute-long phreatic eruption began at 0938 and produced an ash plume that rose 1.2 km above the crater. Ashfall from both events was reported in areas 15 km downwind. A third event, detected at 1750, lasted three minutes and produced a plume of unknown height. After the events one volcano-tectonic earthquake and one tremor event were recorded. The seismicity along with increased phreatic events prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4).

Piton de la Fournaise | Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise which began on 27 April from fissures at Rivals Crater continued through 22 May. Flowing lava was mostly confined to tubes, though spatter was ejected 20-30 m above the highest-elevation (and most active) vent of the three. Lava was weakly ejected from the lowest-elevation vent. CO2 concentrations at the summit were high. Inflation continued to be detected. Tremor levels had increased around 15 May but then began to steadily decrease on 18 May. Observers noted a significant decrease in activity on 19 May at the highest-elevation vent, and by 22 May was quiet; the main cone continued to spatter.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week of 9 May – 15 May 2018

Aira | Kyushu (Japan) : JMA reported that during 7-11 May there were 12 events, three of which were explosions, at Minamidake crater (at Aira caldera’s Sakurajima volcano). Tephra was ejected as far as 700 m from the crater, and ash plumes rose as high as 2.8 km (9,200 ft) above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Bagana | Bougainville (Papua New Guinea) : Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 11 May at 0900 an ash plume from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SW. The plume dispersed within six hours.

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 9-15 May ash plumes from Dukono rose to altitudes of 1.5-2 km (4,500-6,000 ft) a.s.l. and drifted E and S.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions at Ebeko on 4 May and during 6-10 May that sent ash plumes as high as 2.4 km (7,875 ft) a.s.l. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Fuego | Guatemala : Small ash explosions at Fuego on 11 and 12 May rose to 5 km (15,000 ft) a.s.l., or approximately 1 km (3,280 ft) above the summit. The ash dispersed quickly to the southwest and was visible on webcams.

Karymsky | Eastern Kamchatka (Russia) : Based on satellite data, KVERT reported that during 11-14 May explosions at Karymsky generated ash plumes that rose as high as 3.5 km (11,500 ft) and drifted 145 km SW. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kirishimayama | Kyushu (Japan) : JMA reported that at Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, an eruption occurred between 1444 and 1610 on 14 May. The plume rose to 4.5 km (15,000 ft) above the crater and drifted SE. A pyroclastic flow travelled 2 km down the flank. Volcanic earthquake rates under the crater increased after the eruption. Shallow, low-frequency earthquakes and tremor were also reported. The Alert Level remained at 3 (on a scale of 1-5).

Langila | New Britain (Papua New Guinea) : Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 13 May at 0709 an ash plume from Langila rose to an altitude of 5.5 km (17,000 ft) a.s.l. and drifted W. An image acquired around six hours later indicated that the ash from the event had dissipated.

Popocatepetl | Mexico : CENAPRED reported that each day during 9-15 May there were 51-137 steam and gas emissions from Popocatépetl as well as ongoing incandescence from the summit. Additionally, three explosions were recorded: at 1834 on 11 May, at 0912 on 11 May, and at 1452 on 14 May. These explosions dispersed ash to the S and SW. Volcano-tectonic earthquakes with magnitudes up to M 2.8 also occurred throughout the time period.

Reventador | Ecuador : During 9-15 May, IG reported ongoing high levels of eruptive activity at Reventador. Steam, gas, and ash emissions continued, with plumes moving to the N and W. On 12 and 13 May, a small lava flow was observed on the E flank 700 m below the summit.

Sabancaya | Peru : Intermittent ash and gas emissions at Sabancaya during 9-15 May were reported by the Buenos Aires VAAC, with plume altitudes reaching 7-9 km (2,300-3,000 ft) a.s.l.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images during 10-14 May. The Aviation colour Code remained at Orange.

Stromboli | Aeolian Islands (Italy) : INGV reported typical activity at Stromboli from 7 to 13 May, with 2-4 hourly low-intensity explosions to heights of less than 80 m (300 ft) above the crater, in the North crater area. Fine ash as well as lapilli and bombs were ejected. The South Central crater area vents produced between 5-12 hourly, low-intensity explosions, also to heights of less than 80 m above the crater. Continuous degassing was also observed from these vents. On 13 May there was an increased frequency of explosions, with 16 events/hour. No significant variations were reported in seismological, deformation, or geochemical parameters.

Suwanosejima | Ryukyu Islands (Japan) : The Tokyo VAAC reported that explosions occurred at Suwanosejima on 15 May, based on information from JMA.

Turrialba | Costa Rica : OVSICORI reported that there were strong emissions of SO2 from Turrialba, accompanied by vigorous fumarolic activity and jetting noises. An ash plume was reported on 10 May, with ashfall in La Pastora de Santa Cruz de Turrialba and Pacayas. A weak water vapor and gas plume was detected at 0920 on 13 May, rising 300-500 m (1000-1600 ft) above the summit. Seismicity was low, with low-amplitude long-period earthquakes and some low-amplitude tremor. Continuous low-amplitude tremor was report on 13 May.

Kilauea Spews Boulders in 5-Mile-High Eruption

An explosion at Kilauea volcano’s summit spawned chunky boulders and a tremendous volcanic cloud that reached as high as commercial airplanes fly — about 30,000 feet (5.6 miles, or 9.1 kilometers) above sea level — early yesterday morning (May 17) local time.

The explosion began as the volcano spewed out boulders hundreds of feet into the air at 4:15 a.m. Hawaii Standard Time, according to the U.S. Geological Survey (USGS). The earth-shattering event happened at the Overlook Vent, which holds a lava lake known as Halema’uma’u. On May 10, geologists with the Hawaiian Volcano Observatory (HVO) said that as Halema’uma’u drained further, there was a risk it could intersect with the water table underground, and heat that groundwater. If the crater’s conduit became plugged by infalling boulders, the trapped steam could erupt dramatically, spewing boulders.

The new explosion sent Kilauea into code red, the highest-level warning for the volcano on Hawaii’s Big Island.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 9 May – 15 May 2018

Kilauea | Hawaiian Islands (USA) : On 9 May the intermittent eruption of lava in Leilani Estates in the lower East Rift Zone (ERZ) of Kilauea continued. In the northeast part of the area, fissure 15 extended across Poihiki Road, generating a pahoehoe flow about 20 m (66 ft) long. In the summit caldera, steady lowering of the Overlook Crater lava lake within Halema`uma`u crater raised the potential for steam-driven explosions if the lava column dropped to the groundwater level and allowed water into the conduit. On 10 and 11 May, little new extrusive activity was noted from the ERZ fissures, though there were continued earthquakes, ground deformation, and considerable gas discharge. Tiltmeters recorded ongoing deflation and the Overlook crater lava level continued to drop.

Fissure 16 opened at 0645 on 12 May near the end of Hinalo Road. It produced a lava flow that traveled about 230 m before stalling around 1430. An area that had been actively steaming developed into fissure 17, reported at 1800 just east of fissure 16, and was actively spattering and degassing. At the summit, rockfalls from the steep walls into Overlook crater generated intermittent small steam-and-ash clouds throughout the day.

Lava eruptions continued on 13 May along the lower ERZ. Aerial observations showed that a new outbreak in the early morning about 900 m NE of the end of Hinalo Street and 900 m S of Highway 132 was several hundred yards long and ejected spatter along with a slow-moving lava flow. By late in the day this activity from fissure 17 was dominated by lava fountaining, explosions that sent spatter bombs to 100 m into the air, and several advancing lava flow lobes moving generally NE; as of 1900 one lobe was 2 m thick and advancing roughly parallel to Highway 132. Steady, vigorous plumes of steam and occasionally minor amounts of ash rose from the Overlook vent and drifted downwind to the SW. Later in the day, ash clouds rose up to 650 m (2,000 ft) above the vent. Several strong earthquakes shook the Hawaiian Volcano Observatory and the surrounding area overnight.

Activity on the morning of 14 May in the lower ERZ was dominated by lava fountaining, explosions of spatter more than 30 m (100 ft) into the air, and an advancing flow from fissure 17 at the NE end of the fissure system. As of 0630, the fissure 17 flow had traveled about 1.6 km roughly ESE parallel to the rift zone. Fissure 18 was weakly active. A 19th fissure spotted around 0800 just NE of Pohoiki Road and N of Hinalo Street produced a sluggish lava flow. Volcanic gas emissions remained elevated throughout the area downwind of the vents. Deflationary tilt at the summit continued and seismicity remained elevated.

On the morning of 15 May activity remained concentrated at fissure 17. The lava flow had advanced about 380 m since 1430 on 14 May. At 0645 the flow was nearly 2.5 km long. However, the advance of the flow had slowed significantly since that afternoon. Also in the morning a new fissure (20) located near fissure 18 produced two small pads of lava. Ash emission from the Overlook crater increased compared to previous days. Although varying in intensity, at times the plume contained enough ash to be gray in colour. Variable pulses sent the cloud to an estimated 1-1.3 km (3-4,000 ft) above the ground. The ash cloud drifted generally W and SW from the summit and ash fell in the Ka’u Desert. On 15 May the Aviation colour Code was raised from Orange to Red and the Volcano Alert Level remained at Warning.

Merapi | Central Java (Indonesia) : PVMBG reported that an explosive eruption occurred at 0740 on 11 May. The eruption began with a small roar and vibrations that were felt at the observation post for 10 minutes. The eruption plume rose to 5.5 km (18,000 ft) above the peak. There was no seismic precursor and no seismic activity continued after the event. PVMBG did not change the alert level from Green/Normal; they interpreted the event as a minor eruption triggered by the accumulation of volcanic gases unlikely to be followed by further eruptions.

Oraefajokull | Iceland : On 4 May, the Icelandic Met Office reduced the Aviation colour Code at Öræfajökull from Yellow to Green due to signs of reduced activity. Since September 2017 there has been less earthquake activity, stable hydrological and geochemical measurements, and reduced geothermal heat output. There has been possible minor ongoing inflation, but no signs of an imminent eruption.

Piton de la Fournaise | Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise, which began on 27 April from fissures at Rivals Crater, continued through 15 May. Field reconnaissance on 10 May revealed that activity was focused on the main cone, with some activity from a second cone that was ejecting material 10-20 m high. Over the next two days the crater of the main cone narrowed and lava projections at both cones became rare. Lava flows during this time were often confined to tubes, with some breakouts at the change in slope below Piton de Bert, about 3 km from the active cone. Burning vegetation as a result of the breakouts was visible on and at the foot of the rampart. Based on satellite data when surface flows were visible, lava emission rates were estimated to be about 1-2 cubic meters/second. Tremor intensity fluctuated over the week, with a sharp increase during 0500 and 0900 on 15 May.

Sangeang Api | Indonesia : Based on a VONA from PVMBG, on 9 May a gas emission was observed at 1807 from Sangeang Api that rose to 4,150 m (13,000 ft) a.s.l. and drifted west. On 9 May the Aviation colour Code was changed from unassigned to Yellow.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week of 2 May – 8 May 2018

Aira | Kyushu (Japan) : JMA reported that there were seven events and 15 explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 1-7 May. Tephra was ejected as far as 1.3 km from the crater, and ash plumes rose as high as 2.8 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Bagana | Bougainville (Papua New Guinea) : Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 8 May a possible ash plume from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted W.

Cleveland | Chuginadak Island (USA) : AVO reported that a small explosion at Cleveland was detected in seismic and infrasound data at 2149 on 4 May. The event produced a small ash cloud that rose as high as 6.7 km (22,000 ft) a.s.l. and drifted SE. The Aviation colour Code and the Volcano Alert Level were raised to Orange/Watch. No additional significant activity led AVO to the lower the levels back to Yellow/Advisory on 6 May.

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 2-8 May ash plumes from Dukono rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted NE and E.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 1-3 May that sent ash plumes as high as 2.8 km (9,200 ft) a.s.l. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Klyuchevskoy | Central Kamchatka (Russia) : Based on webcam and satellite observations KVERT reported that at 1150 on 8 May an ash plume from Klyuchevskoy rose to altitudes of 5-5.5 km (16,400-18,000 ft) a.s.l. and drifted 105 km SSE. The Aviation colour Code was raised to Orange.

Pacaya | Guatemala : INSIVUMEH reported that during 1-2 May Strombolian explosions at Pacaya’s Mackenney Crater ejected material as high as 50 m above the crater rim. A 500-m-long lava flow advanced NW towards Cerro Chino. Nighttime crater incandescence was visible, and rumbling was heard in areas within 2-3 km. Activity increased on 4 May, with explosions ejecting tephra as high as 80 m. The lava flow continued to advance and by 6 May was 600 m long. Strombolian explosions ejected material 15 m above the crater rim, and nighttime incandescence continued to be present.

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya increased compared to the previous week; explosions averaged 25 per day during 30 April-6 May. The number of long-period events and signals indicating emissions increased. Gas-and-ash plumes rose as high as 2 km above the crater rim and drifted 40 km N, NE, and E. The MIROVA system detected four thermal anomalies, and on 6 May the sulfur dioxide gas flux was high at 2,662 tons/day. The report noted that the public should not approach the crater within a 12-km radius.

Santa Maria | Guatemala : INSIVUMEH reported that explosions at Santa María’s Santiaguito lava-dome complex, detected by the seismic network during 1-2 and 5-6 May, generated ash plumes that rose 600-700 m and drifted SW. Avalanches of material descended the SE flank of the lava dome.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images on 28 and 30 April and 2 May. The Aviation colour Code remained at Orange.

Suwanosejima | Ryukyu Islands (Japan) : The Tokyo VAAC reported explosions at Suwanosejima on 2 and 4 May, based on JMA notices and satellite data.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 2 May – 8 May 2018

Ibu | Halmahera (Indonesia) : At 0622 on 5 May an eruption at Ibu generated an ash plume that rose at least 600 m above the crater rim and drifted N and NE, based on information from the Darwin VAAC and PVMBG. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side.

Karymsky | Eastern Kamchatka (Russia) : Based on satellite data, KVERT reported that during 28 April and 2-3 May explosions at Karymsky generated ash plumes that rose as high as 5.5 km (18,000 ft) and drifted 150 km NE and SE. A weak thermal anomaly over the volcano was visible on 3 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kilauea | Hawaiian Islands (USA) : On 2 May HVO noted that the intrusion of magma into Kilauea’s lower East Rift Zone (ERZ) continued, with deformation and frequent earthquakes (many felt by residents). Small cracks formed on some of the roads in and adjacent to Leilani Estates. Seismicity at Pu’u ‘O’o Crater remained elevated after floor collapses which began on 30 April. Short-lived ash plumes periodically rose from the crater. The lava flows on the pali near the Royal Gardens subdivision were sluggish. Deflation at the summit accelerated around midday, accompanied by a drop in the level of the lava lake.

On 3 May the intensity of the ERZ seismicity decreased slightly, and the eastward migration of hypocenters slowed or ceased; deformation continued. The lava level in Overlook crater dropped over 30 m, though spattering in the lake continued. At 1030 ground shaking from a M 5 earthquake S of Pu’u ‘O’o caused rockfalls and possibly a collapse in the crater; an ash plume rose from the crater and drifted SW. More ground cracks in the E part of Leilani Estates formed that afternoon; hot white and blue fumes rose from the cracks. Lava spatter and gas bursts began erupting from 150-m-long fissures just after 1700 and ended around 1830. Lava flows spread less than 10 m, and strong sulfur dioxide odors were noted. The lava lake in the Overlook Crater dropped an additional 37 m.

By the morning of 4 May three fissures were active; fissure 2 opened at 0100 and fissure 3 opened around 0600. Spatter was ejected as high as 30 m and lava flows were traveling short distances. Large, loud bubble bursts occurred at fissure 3. Ash plumes from intermittent collapses at Pu’u ‘O’o continued to rise above the crater, and the 61 G lava flow was no longer being fed. A M 6.9 earthquake occurred at 1233, centered on the S flank. Fissures 4 and 5 opened at 1039 and 1200, respectively, and by 1600 there were six, each several hundred meters long. The sixth fissure was on the E edge of the subdivision. The Hawaii Emergency Management Agency stated that multiple agencies were assisting with the mandatory evacuation of residents (about 1,700) in the Leilani Estates and Lanipuna Gardens subdivisions. A temporary flight restriction was declared for most of lower Puna. The report noted dangerously high concentrations of sulfur dioxide.

Based on satellite InSAR data, the summit caldera floor subsided about 10 cm during 23 April-5 May. Corresponding to this deflationary trend, the summit lava lake in Overlook crater had dropped to about 128 m below the crater rim since 30 April. Summit seismicity increased during 4-5 May coincident with the M 6.9 earthquake; about 152 events (M 2-3) were recorded. Rockfalls from the inner crater walls produced ash plumes that rose above the Halema’uma’u crater rim on 5 May. New ground cracks on Highway 130 opened on 5 May, and at dawn fissure 7 formed. By mid-afternoon fissure 7 stopped erupting, and the 8th fissure opened at 2044 near fissures 2 and 7. Lava fountains from fissure 8 rose as high as 70 m, and in other areas were as high as 100 m. A lava flow from fissure 7 traveled 260 m NE. The lava lake in Overlook Crater continued to drop.

The eruption from one or two fissures was continuous during 5-7 May, and ‘a’a lava flows from fissure 8 advanced 0.9 km NNE by 1000 on 6 May. HVO warned that poor air quality from sulfur dioxide gas emissions, and smoke plumes from burning asphalt and houses was a health concern. Strong gas emissions rose from the fissures during 6-7 May, though lava effusion was minimal overnight. New cracks crossed Highway 130 west of the eruption site, and some others widened. The level of the summit lava lake continued to drop, and by 7 May was 220 m below the crater rim. Two new fissures emerged on 7 May. The first (fissure 11) opened at about 0930 in a forested area SW of Leilani Estates, and was active for about three hours. The second (fissure 12) opened at about 1220 between fissures 10 and 11. By 1515 both new fissures were active, and the W end of fissure 10 was robustly steaming. According to a news article, lava had covered an area about 36,000 square meters.

Lava effusion at night during 7-8 May was minimal, and by around 0700 on 8 May the ERZ eruption had paused. The fissure system was about 4 km long and continued to strongly emit gas. Ash plumes generated by falling rocks in Overlook crater continued to produced ash plumes. On 8 May the Office of the Mayor stated that 35 structures had been destroyed, and lava covered. HVO maps show the locations and numbers of the fissures.

Marapi | Indonesia : On 2 May at 0703 an eruption at Marapi produced a dense, gray ash plume that rose 4 km above the crater rim and drifted SE. The Alert Level remained at 2 (on a scale of 1-4). Residents and visitors were advised not to enter an area within 3 km of the summit.

Osorno | Chile : Servicio Nacional de Geología and Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS) raised the Alert Level for Osorno to Yellow (the second lowest level on a four-colour scale) on 8 May, due to a gradual increase in the number and magnitude of seismic events recorded during 1-30 April. Earthquakes were concentrated on the NNW flank. The largest of the 294 total events was a M 3, located 2 km NW of the crater at a depth of 3.3 km.

Piton de la Fournaise | Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise which began on 27 April from fissures at Rivals Crater continued through 8 May. Spattering was weak at the highest-elevation vent of the three. During fieldwork on 3 May scientists observed spattering from the central vent. Lava breakouts frequently occurred from a well-developed lava tube originating at the central vent. During 5-7 May activity was mainly confined to the lava tube, though the lava-flow front had not significantly advanced. The central vent had completely closed over by 6 May. Fires on and at the foot of the rampart were reported on 7 May. Tremor intensity had decreased during the previous few days but stabilized on 8 May.

Volcanos

Hawaii’s Kilauea Volcano Erupts Dramatically After a 5.1-Magnitude Quake

After authorities had warned for several days of an impending eruption, Hawaii’s Kilauea volcano delivered Thursday. White clouds of steam and volcanic gases rose high in the sky above the southeastern part of Hawaii Island.

A river of destructive lava flowing underground was released around 4:30 p.m. local time into a residential subdivision, prompting people in the area to pack their belongings and abandon their homes.

On some streets the bright red-orange lava could be seen spurting out of cracks in the ground. The deafening sound of grinding rocks filled the air and “white, hot vapor and blue fumes emanated” from the cracking.

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Roundup of Global Volcanic Activity – Ongoing Activity for the week of 25 April – 1 May 2018

Agung | Bali (Indonesia) : PVMBG reported that at 2245 on 30 April an event at Agung generated an ash plume that rose 1.5 km above the crater rim and drifted SW. Seismicity was dominated by low-frequency earthquakes related to gas-and-steam emissions. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone continued at a 4-km radius.

Aira | Kyushu (Japan) : JMA reported that there were nine events and 30 explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 20 April-1 May. Tephra was ejected as far as 1.3 km from the crater, and ash plumes rose as high as 3.3 km above the crater rim. Crater incandescence was visible at night on 20, 23, 26, and 30 April. The Alert Level remained at 3 (on a 5-level scale).

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 25 April-1 May ash plumes from Dukono rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted NE, E, and SE.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 21 and 25 April that sent ash plumes as high as 2.5 km (8,200 ft) a.s.l. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Kikai | Japan : JMA reported that the number of volcanic earthquakes at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was low during 20-26 April. White plumes rose as high as 700 m above the Iwo-dake lava dome; incandescence from the crater had not been visible since 12 April. During field surveys on 25 and 26 April observers noted a slight expansion of a thermally anomalous area compared to 24-25 March observations, and a decrease in sulfur dioxide flux from 600 tons/day on 24 March to 300 tons/day. The Alert Level was reduced to 1 (on a 5-level scale) on 27 April.

Pacaya | Guatemala : INSIVUMEH and CONRED reported that during 27-28 April seismicity at Pacaya had increased, and moderate-to-strong explosions ejected material as high as 150 m above the crater rim. Lava originating from the 2010 fissure traveled about 500 m NW, towards Cerro Chino. The report noted that ejected material has filled the crater.

Popocatepetl | Mexico : CENAPRED reported that each day during 25 April-1 May there were 63-114 steam and gas emissions from Popocatépetl, often containing ash. Incandescence from the crater was visible at night. As many as five explosions per day were recorded during 25-29 April, with resulting eruption plumes rising around 1 km above the crater rim. The Alert Level remained at Yellow, Phase Two.

Reventador | Ecuador : During 24 April-1 May IG reported a high level of seismic activity including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions at Reventador. Steam, gas, and ash plumes sometimes rose higher than 1 km above the crater rim and drifted NE, NW, and W. On 27 April incandescent blocks rolled as far as 800 m down the flanks, and a small pyroclastic flow traveled down the E flank.

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was similar to the previous week; explosions averaged 22 per day during 23-29 April. Seismicity was dominated by long-period events and signals indicating emissions. Gas-and-ash plumes rose as high as 2 km above the crater rim and drifted 30 km NE and SE. The report noted that the public should not to approach the crater within a 12-km radius.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images during 21 and 23-25 April. The Aviation Color Code remained at Orange.

Stromboli | Aeolian Islands (Italy) : INGV reported that on 24 April an intense explosive sequence occurred at vents on Stromboli’s south-central crater terrace area. The first explosion, recorded at 1105, ejected an abundant amount of ash, incandescent material, and large blocks to a height of 250 m that fell onto the summit area and along the Sciara del Fuoco. An explosive event at 1106 was characterized by modest lava fountaining. The last event, recorded at 1110, ejected pyroclastic material, though it was less intense than the first. An ash plume from the sequence quickly dispersed SE.

Suwanosejima | Ryukyu Islands (Japan) : Based on JMA notices and satellite data, the Tokyo VAAC reported an explosion at Suwanosejima on 24 April, and that events during 27-29 April produced plumes that rose 1.2-2.1 km (4,000-7,000 ft) a.s.l. and drifted in multiple directions.

Turrialba | Costa Rica : OVSICORI-UNA reported that an event at Turrialba at 0700 on 26 April generated a small ash plume that rose 300 m above the crater rim and drifted W.

Yasur | Vanuatu : On 25 April the Vanuatu Meteorology and Geo-hazards Department (VMGD) reported that ongoing explosive activity at Yasur was confined to the crater. The Alert Level remained at 2 (on a scale of 0-4). VGO reminded residents and tourists that hazardous areas were near and around the volcanic crater, within a 395-m-radius permanent exclusion zone, and that volcanic ash and gas could reach areas impacted by trade winds.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 25 April – 1 May 2018

Ibu | Halmahera (Indonesia) : PVMBG reported that at 1822 on 30 April an eruption at Ibu generated a dark gray ash plume that rose at least 500 m above the crater rim and drifted E. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side.

Karymsky | Eastern Kamchatka (Russia) : On 26 April KVERT reported that the last explosive event at Karymsky occurred on 27 January, and the last thermal anomaly was detected on 26 March; activity remained at a low level. The Aviation colour Code was lowered to Green (the lowest level on a four-colour scale). Explosive activity was identified in satellite images beginning at 1825 on 28 April, prompting KVERT to raise the Alert Level to Orange. Ash plumes rose as high as 5.5 km (18,000 ft) a.s.l. and drifted 150 km NE.

Kilauea | Hawaiian Islands (USA) : During 25 April-1 May HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. The lake level was high enough to produce lava flows onto the Halema’uma’u crater floor through 27 April, but afterwards fell to about 15-16 m below the new elevated rim. The lake level rose again, to just below the rim of the Overlook crater vent. Since 21 April about 2/3 of the crater floor had been covered by new lava flows. Episode 61g lava flows were active above Pulama pali, within 2 km of the active vent. A marked increase in seismicity and ground deformation at Pu’u ‘O’o Crater was detected just after 1400 on 30 April, following weeks of uplift and increasing lava levels within the cone. Within a few minutes a webcam on the crater rim recorded the first of two crater floor collapses; the second collapse began at 1520 and lasted about an hour. Thought poor weather conditions inhibited views at times, a webcam recorded what were likely small explosions from the W side of the crater as the floor collapsed. At 1800 seismicity remained elevated, though ground deformation had significantly slowed. A large amount of red ash was produced from the collapses, and deposited around the crater as well as in areas up-rift as far as Mauna Ulu. Following the collapses of Pu’u ‘O’o’s crater floor, seismicity and deformation increased along a large section of the East Rift Zone, in an area 9-16 km down-rift (with seismicity occurring as far E as highway 130), indicating an intrusion of magma. By 0830 on 1 May activity had significantly decreased. During an overflight that day a new, nearly continuous, 1-km-long crack was found on the W (up-rift) side of Pu’u ‘O’o. The crack was steaming, and aligned in a segment with small pads of newly-erupted lava and spatter. Thermal images of Pu’u ‘O’o Crater suggested that smaller drops of the crater floor likely continued on 1 May.

Kirishimayama | Kyushu (Japan) : JMA reported that a very small explosion at Iwo-yama (also called Ioyama, NW flank of Karakuni-dake), a stratovolcano of the Kirishimayama volcano group, occurred at 1815 on 26 April and produced a milky white plume that rose over 200 m. The event continued until around 1826. The event occurred from a fumarole in the vicinity of the highway, on the W side of Iwo-yama, first observed on 20 April. During a field survey on 30 April observers noted muddy water flowing as far as 500 m W. The Alert Level remained at 3 (on a scale of 1-5).

Kusatsu-Shiranesan | Honshu (Japan) : JMA reported that on 21 April the number of volcanic earthquakes at Yugama crater (Kusatsu-Shiranesan complex) increased and deformation was also recorded. The Alert Level for the crater area was raised to 2 (on a 5-level scale) the next day. Deformation slowed on 23 April. Seismicity decreased on 23 April though continued to be somewhat elevated, and low-frequency events were recorded on 24 April. No surficial changes were noted during an overflight on 26 April.

Marapi | Indonesia : On 27 April a phreatic eruption at Marapi produced an ash plumes that rose 300 m above the crater rim. The Alert Level remained at 2 (on a scale of 1-4). Residents and visitors were advised not to enter an area within 3 km of the summit.

Piton de la Fournaise | Reunion Island (France) : OVPF reported that seismicity at Piton de la Fournaise increased on 21 April, and then significantly on 23 April. A seismic crisis which began at 2015 on 27 April was accompanied by rapid deformation, indicating magma migrating towards the surface. The onset of tremor at 2350 heralded the beginning of the eruption, though the first visual confirmation of the eruption was recorded by the webcams at 0015 on 28 April. The eruption took place from fissures at Rivals Crater, and the SW flank of Dolomieu crater. During an overflight around 0830, scientists noted that four fissures had opened, one of which intersected the crater. Lava fountains less than 30 m high rose from the entire length of the fourth fissure, which was 300 m long and at a lower elevation that Rival Crater. Several small lava flows formed a larger flow which traveled 200-300 m S towards the Enclos Fouqué. Tremor steadily decreased throughout the day, and by the end of the day the lava flow had slowed in an area around 300 m away from the rampart. During 29-30 April tremor levels were relatively stable, with a few fluctuations related to morphological changes at the eruptive site such as cone building. During an overflight around 1020 on 30 April scientists observed three active vents (S of Rival Crater). The third vent, in a 5-m-high cone, was mostly closed over, though it continued to produced lava flows. The middle and most active cone was about 30-40 m long and 10-15 m high, and had a vent with a lava lake. Large bubbles of lava rose from the lake and exploded into lava fountains. Lava fountains from the northernmost vent rose no more than 15 m high. Lava flows had traveled 150 m and 1.2 km; the longer lava flow had reached the S rampart and traveled an additional 400 m E along it.

San Cristobal | Nicaragua : INETER reported that at 1320 on 22 April a small explosion at San Cristóbal generated a gas-and-ash plume that rose 800 m and drifted SW, causing ashfall in the La Bolsa region and Hacienda Las Rojas.

Semeru | Eastern Java (Indonesia) : Based on analysis of satellite images, the Darwin VAAC reported that on April a short-lived, discreet eruption at Semeru generated an ash plume that rose to an altitude of 3.4 km (11,000 ft) a.s.l. and drifted NW.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week of 18 April – 24 April 2018

Agung | Bali (Indonesia) : PVMBG reported that although there were often foggy conditions during 18-24 April, white plumes were observed rising as high as 300 m above Agung’s crater rim and drifting E. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone continued at a 4-km radius.

Aira | Kyushu (Japan) : JMA reported that there were eight events and 13 explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 16-23 April. Tephra was ejected as far as 1.1 km from the crater, and plumes rose as high as 2.5 km above the crater rim. At 0038 on 22 April an explosion produced an ash plume that rose 3.3 km and ejected tephra as far as 1.3 km. Crater incandescence was visible on most nights. The Alert Level remained at 3 (on a 5-level scale).

Ambae | Vanuatu : Vanuatu Geohazards Observatory (VGO) reported that during April the eruption from a cone in Ambae’s Lake Voui continued through 23 April, with ash emissions and some lava fountaining. Ash, scoria, and acid rain fell on the island. Observations on 21 April confirmed that the cone had grown, and that the crater in the center of the cone was larger; a small lake was present in the crater. The Alert Level remained at 3 (on a scale of 0-5), and the report reminded residents to stay at least 3 km away from the active crater.

Ambrym | Vanuatu : On 25 April the Vanuatu Geohazards Observatory (VGO) reported that the lava lakes in Ambrym’s Benbow and Marum craters continued to be active, and produced gas-and-steam emissions. The Alert Level remained at 2 (on a scale of 0-5); the report reminded the public to stay outside of the Permanent Danger Zone defined as a 1-km radius from Benbow Crater and a 2.7-km radius from Marum Crater.

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 19-24 April ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted in multiple directions.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 15 and 17-19 April that sent ash plumes as high as 2.6 km (8,500 ft) a.s.l. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that the last explosive event at Karymsky occurred on 27 January, and the last thermal anomaly was detected on 26 March. The Aviation colour Code was lowered to Yellow (the second lowest level on a four-colour scale).

Kuchinoerabujima | Ryukyu Islands (Japan) : JMA reported that a low-temperature thermal anomaly persisted near the W fracture in Kuchinoerabujima Shindake crater. In addition, both the number of volcanic earthquakes (generally occurring in a large quantity) and sulfur dioxide flux remained above baselines levels in August 2014. No eruptions have occurred since 19 June 2015, and deflation had been recorded since January 2016; the Alert Level was lowered to 3 (on a scale of 1-5).

Mayon | Luzon (Philippines) : PHIVOLCS reported that during 18-24 April white steam plumes from Mayon drifted NW, W, SW, and NE. Crater incandescence was visible at night. The sulfur dioxide flux was 796 tonnes/day on 17 April. The Alert Level remained at 2 (on a 0-5 scale) and PHIVOLCS reminded residents to stay away from the 6-km-radius Permanent Danger Zone and the 7-km Extended Danger Zone on the SSW and ENE flanks.

Pacaya | Guatemala : INSIVUMEH reported increased activity at Pacaya’s Mackenney Crater during 18-19 April. Strombolian explosions ejected material as high as 50 m above the crater rim, and four lava flows traveled 200-500 m down the SW, W, and NW flanks. Strombolian explosions continued to be detected during 21-23 April.

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya increased compared to the previous week; explosions averaged 19 per day during 16-22 April. Seismicity was dominated by long-period events, with a rise in signals indicating emissions. Gas-and-ash plumes rose as high as 2.2 km above the crater rim and drifted 40 km NW, W, and SW. The MIROVA system detected five thermal anomalies, and on 17 April the sulfur dioxide gas flux was high at 3,421 tons/day. The report noted that the public should not approach the crater within a 12-km radius.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images during 14-18 April. The Aviation colour Code remained at Orange.