Volcanos

Global Volcanic Activity – Ongoing Activity for the week of 4 September – 10 September 2019

Aira | Kyushu (Japan) : JMA reported that at 1549 on 3 September an explosion at Minamidake crater (at Aira Caldera’s Sakurajima volcano) generated an ash plume that rose 1.9 km above the crater rim and ejected material as far as 900 m from the vent. Very small eruptive events were detected during 6-9 September. The Alert Level remained at 3 (on a 5-level scale).

Asosan | Kyushu (Japan) : JMA reported that during 2-9 September ash plumes rose from Asosan and drifted N and NW. The sulfur dioxide emission rate was 800, 2,500, and 2,000 tons per day on 2, 6, and 9 September, respectively. The Alert Level remained at 2 (on a scale of 1-5).

Copahue | Central Chile-Argentina border : OVDAS-SERNAGEOMIN reported that seismicity at Copahue increased at 1250 on 9 September, characterized by increased amplitude of continuous tremor. Anomalies in the seismic signals suggested elevated surface activity, though cloudy weather prevented visual observations. According to the Buenos Aires VAAC diffuse steam emissions recorded by the webcam on 10 September rose to 3.5 km (11,000 ft) a.s.l. and possibly contained minor amounts of ash. The Alert Level remained at Yellow (second lowest level on a four-colour scale); SERNAGEOMIN recommended no entry into a restricted area within 500 m of the crater. ONEMI maintained the Alert Level at Yellow (the middle level on a three-colour scale) for the municipality of Alto Biobío.

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, and information from PVMBG, the Darwin VAAC reported that during 4-10 September ash plumes from Dukono rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko | Paramushir Island (Russia) : KVERT reported that a thermal anomaly over Ebeko was identified in satellite images during 30-31 August. Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E, observed explosions during 30 August and 3-5 September that sent ash plumes up to 3 km (10,000 ft) a.s.l. Ash plumes drifted E and SE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Etna | Sicily (Italy) : INGV reported that the mean amplitude of volcanic tremor at Etna had been increasing. Notably, the increase since mid-August had reached significant values by 6 September and were comparable to those values recorded just before the December 2018 eruption, and higher than those observed before the eruptive episodes during May-July 2019. Inclement weather prevented visual observations of the summit craters, though mountain guides reported characteristic sounds of Strombolian activity at the Bocca Nuova crater on 6 September. A sudden increase in volcanic tremor amplitude was recorded at 0449 on 9 September, and by 0536 Strombolian activity at Northeast Crater (NEC) was visible. At 1050 volcanic tremor amplitude again increased, with signals localized beneath NEC. Diffuse ash plumes rose from the crater and dissipated near the summit.

Ibu | Halmahera (Indonesia) : PVMBG reported that at 0936 on 4 September a gray ash plume from Ibu rose at least 300 m above the summit and drifted S. 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.

Karangetang | Siau Island (Indonesia) : PVMBG reported that during 2-8 September lava continued to effuse from Karangetang’s Main Crater (S) and Dua Crater (N), traveling as far as 1.5 km down the Nanitu, Pangi, and Sense drainages on the SW flank. Sometimes dense white plumes rose to 200 m above the summit. According to the Darwin VAAC a diffuse ash plume rose almost 350 m above the summit and drifted SE on 7 September. The Alert Level remained at 2 (on a scale of 1-4).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Karymsky was visible in satellite images on 5 September. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Krakatau | Indonesia : PVMBG reported that Anak Krakatau’s seismic network recorded six eruptive events during 2-8 September. The events were not followed by visible ash emissions, even though there were favorable weather conditions for viewing. A webcam at the summit recorded diffuse white plumes rising 100 m from the crater rim. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km-radius hazard zone from the crater.

Merapi | Central Java (Indonesia) : PVMBG reported that during 26 August-1 September the lava-dome volume at Merapi did not change and was an estimated 461,000 cubic meters, based on analyses of drone images on 8 August. Extruded lava fell into the upper parts of the SE flank, generating block-and-ash flows that traveled down the Gendol drainage; a block-and-ash flow traveled 2 km on 27 August. Diffuse white plumes rose as high as 80 m above the summit. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.

Semeru | Eastern Java (Indonesia) : The Darwin VAAC reported that on 10 September an ash plume from Semeru rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted WNW based on satellite images and weather models. The Alert Level remained at 2 (on a scale of 1-4).

Semisopochnoi | United States : AVO reported that low-level eruptive activity at Semisopochnoi possibly continued during 4-10 September. Seismic activity was relatively minor and characterized by intermittent low-frequency earthquakes. Satellite images were mostly cloudy, though a low-altitude steam plume drifting 50 km S was visible on 8 September. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a daily thermal anomaly over Sheveluch’s lava dome was identified in satellite images during 30 August-6 September. Ash clouds were seen in satellite images drifting 660 km during 29 August, and 2-3 September, and 5 September. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Shishaldin | Fox Islands (USA) : Low-level lava fountaining and minor explosive activity within Shishaldin’s summit crater was last observed on 17 August and likely continued during 4-10 September; continuous tremor was recorded by the seismic network and moderately-elevated surface temperatures were visible in satellite images. Elevated surface temperatures on the upper SE flank suggested that minor amounts of lava spatter may have extended beyond the summit crater; clear webcam images showed no evidence of hot deposits on the upper flank the next day. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Suwanosejima | Ryukyu Islands (Japan) : JMA reported that during 30 August-6 September white plumes rose 1.2 km above the rim of Suwanosejima’s Ontake Crater and crater incandescence was visible at night. According to the Tokyo VAAC an ash plume rose 2.4 km (8,000 ft) a.s.l. and drifted W on 10 September. The Alert Level remained at 2 (on a 5-level scale).

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that during 2-8 September emissions at Tangkubanparahu’s Ratu Crater were characterized by bursts white vapor plumes. At 0724 on 4 September a dense white-to-gray plume rose about 100 m above the vent and drifted S and SW. Two large eruptive events were recorded at 1657 and 1709 on 7 September. White water vapor plumes rose to 200 m above the vent and dense black tephra plumes rose as high as 180 m. Ashfall was localized around Ratu Crater. The seismic network recorded continuous tremor. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 1.5 km away from the active crater.

Ubinas | Peru : IGP reported that during 3-9 September three volcanic explosions were detected at Ubinas, all producing eruption plumes that rose to heights less than 2.5 km above the crater rim. The largest, and first, was recorded at 1358 on 3 September and produced significant amounts of ash and gas, affecting areas to the S and SE. After the explosions gas-and-steam plumes rose as high as 1 km. The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 10-km radius.

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Volcanos

Global Volcanic Activity – New Activity for the week of 4 September – 10 September 2019

Villarrica | Chile : ONEMI and SERNAGEOMIN reported that the seismic network at Villarrica recorded significant variations in seismicity beginning at 0030 on 8 September, characterized by an increase in the number of long-period (LP) events from 20 to 50 per hour. LP events ceased to be detected around 1030 and short periods of high-energy tremor began. Weather clouds prevented views of the summit crater, though the characteristics of the seismicity indicated fluctuating lava-lake activity. The increased seismicity persisted on 9 September, prompting SERNAGEOMIN to raise the Alert Level to Orange, the second highest level on a four-color scale. ONEMI has maintained an Alert Level Yellow (the middle level on a three-color scale) since 6 August for the municipalities of Villarrica, Pucón (16 km N), and Curarrehue, along with the commune of Panguipulli and stated that the public should stay at least 2 km away from the crater. On 10 September seismicity remained high; infrasound signals were recorded at a rate of 50 events per hour.

Volcanos

Global Volcanic Activity – Ongoing Activity for the week of 28 August – 3 September 2019

Aira | Kyushu (Japan) : JMA reported that during 26 August-2 September very small eruptive events were detected at Minamidake crater (at Aira Caldera’s Sakurajima volcano), though none of them were explosive. Crater incandescence was visible in webcams at night during 1-2 September. The Alert Level remained at 3 (on a 5-level scale).

Asosan | Kyushu (Japan) : JMA and the Tokyo VAAC reported that an eruptive event at Asosan was recorded at 1929 on 29 August; a plume rose 200 m above the crater rim and drifted N. During 30 August-3 September ash plumes rose as high as 250 m and drifted E, NE, N, and NW. The Alert Level remained at 2 (on a scale of 1-5).

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, and information from PVMBG, the Darwin VAAC reported that during 28 August-3 September ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko | Paramushir Island (Russia) : KVERT reported that a thermal anomaly over Ebeko was identified in satellite images on 23 August. Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E, observed explosions during 27-28 August that sent ash plumes up to 3 km (10,000 ft) a.s.l. and drifted E. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Fuego | Guatemala : INSIVUMEH reported that there were multiple explosions per hour recorded at Fuego during 28 August-3 September, generating ash plumes that rose as high as 1.1 km above the crater rim and drifted 10-20 km W and SW. Explosions sometimes produced shock waves that rattled houses in nearby communities. Incandescent material was ejected 200-300 m high and caused avalanches of material that occasionally traveled long distances (reaching vegetated areas) down Seca (W), Taniluyá (SW), Ceniza (SSW), Trinidad (S), El Jute (SE), Las Lajas (SE), and Honda ravines. Ashfall was reported in several areas downwind including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8 km SW), Sangre de Cristo (8 km WSW), Finca Palo Verde, San Pedro Yepocapa (8 km NW), and El Porvenir (8 km ENE).

Ibu | Halmahera (Indonesia) : PVMBG reported that at 1847 on 31 August an ash plume from Ibu rose at least 800 m above the summit and drifted N. Seismicity was characterized by an explosion signal and earthquakes indicating rock avalanches. 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.

Karangetang | Siau Island (Indonesia) : PVMBG reported that during 26 August-1 September lava continued to effuse from Karangetang’s Main Crater (S) and Dua Crater (N), traveling as far as 1.5 km SW down the Nanitu and Pangi drainages, 1.4 km down a drainage W of Pangi, and 1.8 km down the Sense drainage. Sometimes dense white plumes rose to 200 m above the summit. The Alert Level remained at 2 (on a scale of 1-4).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was visible in satellite images during 23-24 August along with ash plumes drifting 51 km SE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kerinci | Indonesia : The Darwin VAAC reported that on 2 September a possible minor ash plume from Kerinci rose to an altitude of 4.9 km (16,000 ft) a.s.l. and drifted WSW, based on satellite images and weather models.

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Klyuchevskoy was sometimes visible in satellite images and that gas-and-steam emissions continued, though ash was last emitted on 2 July. The Aviation colour Code was lowered to Yellow (the second highest lowest on a four-colour scale) on 30 August.

Merapi | Central Java (Indonesia) : PVMBG reported that during 26 August-1 September the lava-dome volume at Merapi did not change and was an estimated 461,000 cubic meters, based on analyses of drone images on 8 August. Extruded lava fell into the upper parts of the SE flank, generating block-and-ash flows that traveled down the Gendol drainage; one flow traveled 2 km on 27 August. Diffuse white plumes rose as high as 80 m above the summit. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.

Nevados de Chillan | Chile : ONEMI and SERNAGEOMIN issued special reports noting as many as three explosions per day at Nevados de Chillán’s Nicanor Crater during 28 August-1 September, with each explosion associated with long-period earthquakes. The webcam recorded gas emissions that turned gray with explosions rising 160-550 m above the crater during the daytime, and explosions ejecting incandescent material onto the NNE flank at night. Plumes drifted SE, NE, and NNW. The Alert Level remained at Orange, the second highest level on a four-colour scale. ONEMI maintained an Alert Level Yellow (the middle level on a three-colour scale) for the communities of Pinto, Coihueco, and San Fabián, and stated that the public should stay at least 3 km away from the crater on the SW flank and 5 km away on the ENE flank.

Pacaya | Guatemala : INSIVUMEH reported that during 28 August-3 September Strombolian explosions at Pacaya’s Mackenney Crater ejected material as high as 30 m above the crater rim. Lava flows on the N and NNW flanks continued to advance, producing minor avalanches from the flow fronts.

Sabancaya | Peru : Instituto Geofísico del Perú (IGP) reported that an average of 26 low-to-medium intensity explosions per day occurred at Sabancaya during 26 August-1 September. Gas-and-ash plumes rose as high as 2 km above the summit and drifted SE, NW, and SW. There were 11 thermal anomalies identified in satellite data. The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 12-km radius.

Sangeang Api | Indonesia : The Darwin VAAC reported that during 28 August-3 September intermittent ash plumes from Sangeang Api were identified in satellite images rising to 3 km (10,000 ft) a.s.l. and drifting N, NW, W, and SW. The Alert Level remained at 2 (on a scale of 1-4).

Santa Maria | Guatemala : INSIVUMEH reported that on most days during 28 August-3 September there were 2-4 explosions per hour detected at Santa María’s Santiaguito lava-dome complex. Ash plumes rose 700-900 m above the complex and drifted SW and W. Avalanches of material descended the E, SE, and S flanks, sometimes producing ash plumes that rose along the path of the avalanche. Ash fell in Monte Claro (S) on 31 August.

Semisopochnoi | United States : AVO reported that low-level eruptive activity at Semisopochnoi possibly continued during 28 August-3 September. Seismic activity was relatively minor and characterized by intermittent low-frequency earthquakes. Minor tremor was detected until 30 August. Satellite images were obscured by clouds. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch’s lava dome was identified daily in satellite images during 22-25 August. Ash plumes on 25 August rose to 4.5-5 km (14,800-16,400 ft) a.s.l. and drifted more than 500 km NW. At 1510 on 29 August explosions produced ash plumes that rose to 10 km (32,800 ft) a.s.l. The leading part of the plume drifted W and then curved counterclockwise to the S, then E, and finally drifted 550 km N. Explosions at 1957 on 30 August produced ash plumes that rose to 7-7.5 km (23,000-24,600 ft) a.s.l. and drifted 50 km SSE. Ash plumes drifted SE at an altitude of 5.5 km (18,000 ft) a.s.l. on 3 September. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Shishaldin | Fox Islands (USA) : Low-level lava fountaining and minor explosive activity within Shishaldin’s summit crater was last observed on 17 August and likely continued during 28 August-2 September; continuous tremor was recorded by the seismic network and moderately-elevated surface temperatures were visible in satellite images. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that during 26 August-1 September emissions at Tangkubanparahu’s Ratu Crater were characterized by puffs of dense black ash plumes rising as high as 20 m above the vent and white vapor plumes containing minor amounts of ash rising as high as 200 m. A larger event recorded at 0930 on 31 August generated a dense black tephra plume that rose 300 m and a white steam plume that rose 600 m. Ashfall was localized around Ratu Crater. The seismic network recorded continuous tremor. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 1.5 km away from the active crater.

Ubinas | Peru : IGP reported that during 27 August-2 September gas-and-water-vapor plumes from Ubinas rose to heights less than 1 km above the summit, and three thermal anomalies were recorded by the MIROVA system. The number of seismic events was 2,828 (all under M 2.3), with volcano-tectonic (VT) signals being the most numerous. There was a slight increase in the number of long-period, hybrid, and VT events compared to the previous week. Beginning at 2145 on 1 September a period of continuous ash emissions was recorded by the webcam. An explosion at 1358 on 3 September generated an ash plume that rose 1.3 km above the summit and drifted more than 10 km S and SE. Prior to this event, the last explosion as recorded on 22 July. The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 15-km radius.

Volcanos

Global Volcanic Activity – New Activity for the week of 28 August – 3 September 2019

Stromboli | Aeolian Islands (Italy) : INGV reported that the paroxysmal eruption at Stromboli recorded at 1217 on 28 August produced an ash plume that rose 4 km above the summit. The eruption consisted of three explosions; the first two occurred at the Area C-S (South Central crater area), and the less intense third event occurred at Area N (north crater area) and ejected material onto the Sciara del Fuoco. Material from the collapse of the eruption plume contributed to the generation of a pyroclastic flow that traveled down the Sciara del Fuoco and several hundred meters out to sea. Morphological changes to Area N were evident after the paroxysm. The complex of small scoria cones, which had grown around the vents during the last few weeks, were destroyed. The NW crater rim of Area N had subsided, allowing lava flows to travel down the Sciara del Fuoco. During an overflight on 30 August volcanologists noted that Area N had collapsed and contained three vents generating Strombolian activity, and Area C-S had one large crater exhibiting Strombolian activity. Strombolian activity resumed after the paroxysm on 28 August; lava flows from Area N reached the coastline by 1945. The next day lava from Area N flowed halfway down the Sciara del Fuoco at 2123 on 29 August and shed material from the front that rolled down to the coast. A new explosive sequence at Area C-S began at 2243 and produced tephra fall in Ginostra (1.5 km from the summit). A low-intensity explosion was recorded at 2329. A lava flow from Area C-S reached the sea during the early part of 30 August. Strombolian activity persisted at moderate levels during 31 August-3 September.

Volcanos

Global Volcanic Activity – Ongoing Activity for the week of 21 August – 27 August 2019

Aira | Kyushu (Japan) : JMA reported that very small eruptive events at Minamidake crater (at Aira Caldera’s Sakurajima volcano) occasionally occurred during 19-26 August. The Alert Level remained at 3 (on a 5-level scale).

Asosan | Kyushu (Japan) : JMA reported that during 18-23 August ash plumes rose from Asosan and drifted N and NW. Crater incandescence was visible at night. An eruption recorded during 1130-1945 on 25 August generated ash plumes that drifted E. The sulfur dioxide emission rate was 1,800 tons per day on 21 August and remained high on 25 August. The Alert Level remained at 2 (on a scale of 1-5).

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, and information from PVMBG, the Darwin VAAC reported that during 21-27 August ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted mainly E, NE, N, and NW. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 17-23 August that sent ash plumes up to 3 km (10,000 ft) a.s.l. and drifted SE. A thermal anomaly was identified in satellite images on 16 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Ibu | Halmahera (Indonesia) : PVMBG reported that at 0704 on 22 August an ash plume from Ibu rose at least 800 m above the summit and drifted W. Seismicity was characterized by an explosion signal and earthquakes indicating rock avalanches. 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.

Karangetang | Siau Island (Indonesia) : PVMBG reported that during 19-25 August lava continued to effuse from Karangetang’s Main Crater (S) and Dua Crater (N). Avalanches of incandescent material traveled 1-1.5 km SW down the Nanitu and Pangi drainages, as far as 2 km down a drainage W of Pangi, and as far as 1.8 km down the Sense drainage. Sometimes dense white plumes rose to 200 m above the summit. The Alert Level remained at 2 (on a scale of 1-4).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that ash plumes from Karymsky were visible in satellite images drifting 500 km SW during 20-22 August. Explosions on 21 August produced ash plumes that rose to 6 km (19,700 ft) a.s.l. A thermal anomaly over the volcano was visible during 21-22 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Klyuchevskoy was visible in satellite images during 17-23 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Krakatau | Indonesia : PVMBG reported that Anak Krakatau’s seismic network recorded 27 eruptive events during 19-25 August. The events were not followed by visible ash emissions, even though there were favorable weather conditions for viewing. An eruption recorded by a summit webcam at 0755 on 22 August produced a white, gray, and black ash plume that rose 100-400 m from the crater rim and drifted N and NW. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km-radius hazard zone from the crater.

Merapi | Central Java (Indonesia) : PVMBG reported that during 19-25 August the lava-dome volume at Merapi did not change and was an estimated 461,000 cubic meters, based on analyses of drone images on 8 August. Extruded lava fell into the upper parts of the SE flank, generating block-and-ash flows that traveled as far as 1.9 km down the Gendol drainage: twice on 20 August, once each on 22 and 24 August, and 10 times during 25-27 August. At 1809 on 27 August a block-and-ash flow traveled 2 km. Diffuse white plumes rose as high as 350 m above the summit. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.

Reventador | Ecuador : IG reported that during 21-27 August seismic data from Reventador’s network indicated a high level of seismic activity, including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions. Weather often prevented views of the summit area, although during clear conditions ash-and-steam plumes were visible rising as high as 1 km above the crater rim and drifting W, NW, and N. Crater incandescence was periodically observed at night. Blocks were observed rolling 800 m down the flanks during 26-27 August.

Sangeang Api | Indonesia : The Darwin VAAC reported that during 21-26 August intermittent ash plumes from Sangeang Api were identified in satellite images rising to 3 km (10,000 ft) a.s.l. and drifting W and WNW. The Alert Level remained at 2 (on a scale of 1-4).

Semisopochnoi | United States : AVO reported that during 17-23 August seismicity at Semisopochnoi remained elevated and was characterized by periods of continuous tremor and discrete low-frequency earthquakes; seismic data went offline starting sometime on 17 August, though was available by around 22 August. Ground-coupled airwaves, indicative of explosive activity, were sometimes recorded in seismic data; an infrasound signal was recorded during 23-24 August. Cloudy weather often prevented satellite views of the volcano, though a steam plume was visible on 18 August and sulfur dioxide emissions were detected during 21-22 August. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch’s lava dome was identified daily in satellite images during 17-23 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Suwanosejima | Ryukyu Islands (Japan) : The Tokyo VAAC reported that on 26 August a plume from Suwanosejima was visible in satellite images rising to 2.1 km (7,000 ft) a.s.l. The Alert Level remained at 2 (on a 5-level scale).

Ubinas | Peru : IGP reported that during 20-26 August blue-coloured gas plumes from Ubinas rose above the crater and eight thermal anomalies were recorded by the MIROVA system. The number of seismic events was 1,736 (all under M 2.4), and there was an increase in the magnitude and number of hybrid and long-period events. Around 1030 on 26 August an ash emission rose to heights below 2 km above the crater rim. Continuous ash emissions on 27 August were recorded by satellite and webcam images drifting S and SW. The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 15-km radius.

Volcanos

Global Volcanic Activity – New Activity for the week of 21 August – 27 August 2019

Asamayama | Honshu (Japan) : JMA reported that at 1928 on 25 August a small eruption at Asamayama generated a grayish-white ash plume that rose 600 m above the crater rim and drifted E. Large blocks were also ejected from the crater. Minor ashfall was reported in Karuizawa Town, Nagano Prefecture, about 4 km E. The plume then turned white and continuous emissions rose 200 m during 25-26 August. The Alert Level remained at 2 (on a scale of 1-5).

Shishaldin | Fox Islands (USA) : AVO reported that during 21-28 August continuous, low-level tremor at Shishaldin was recorded by the seismic network and elevated surface temperatures were often visible in satellite images. The spatter cone in the crater had grown and partially filled the summit crater. NOAA scientists took video of the eruption during an overflight on 17 August and noted repetitive minor explosive activity within the summit crater. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Stromboli | Aeolian Islands (Italy) : INGV reported that a paroxysmal explosive event at Stromboli began at 1216 on 28 August with a series of explosions likely from the Area C-S (South Central crater area). The event of strongest intensity occurred at 1217, generating an ash plume that rose more than 2 km above the crater area and a pyroclastic flow that traveled down the Sciara del Fuoco and several hundred meters out to sea. The report noted a similarity in intensity of the eruption to the 3 July paroxysmal event based on the seismic data.

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that during 19-25 August phreatic events at Tangkubanparahu’s Ratu Crater continued to produce sometimes dense gray-to-white plumes that rose as high as 200 m above the vent, and dense black ash plumes that rose as high as 180 m. Ashfall was localized around Ratu Crater. The seismic network recorded continuous tremor. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 1.5 km away from the active crater.

Veniaminof | United States : AVO lowered the Volcano Alert Level to Normal for Veniaminof and the Aviation colour Code to Green on 25 August, noting that the volcano returned to background activity after low-level tremor was detected and a pilot saw steaming on 1 August.

Environment

Vast ‘pumice raft’ found drifting in the Pacific Ocean

A vast “raft” of volcanic rocks stretching over 150 sq km (93 sq miles) is drifting through the Pacific Ocean.

The sea of pumice – the size of 20,000 football fields – was first reported by Australian sailors earlier this month. Experts say the mass likely came from an underwater volcano near Tonga which erupted around 7 August according to satellite images. Sailors have been warned to stay clear of the potential hazard.

Pumice is a lightweight, bubble-rich rock that can float in water. It is produced when magma is cooled rapidly.

108497831 news image

Volcanos

Global Volcanic Activity – Ongoing Activity for the week of 14 August – 20 August 2019

Aira | Kyushu (Japan) : JMA reported that during 13-16 August crater incandescence at Minamidake crater (at Aira Caldera’s Sakurajima volcano) was occasionally visible in webcams at night. A small eruptive event was recorded on 18 August. The Alert Level remained at 3 (on a 5-level scale).

Asosan | Kyushu (Japan) : JMA reported that increased eruptive activity at Asosan that began on 28 July paused at 1110 on 16 August. An eruptive event was recorded at 1627 on 18 August; elevated eruptive activity continued at least through 19 August. The Tokyo VAAC reported that the eruptive event on 18 August produced an ash plume that rose to 2.1 km (7,000 ft) a.s.l. Ash plumes rose to 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted N and NW during 19-20 August. The Alert Level remained at 2 (on a scale of 1-5).

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, and information from PVMBG, the Darwin VAAC reported that during 14-20 August ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NW, N, NE, and E. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 10-16 August that sent ash plumes up to 3 km (10,000 ft) a.s.l. and drifted SE. A thermal anomaly was identified in satellite images on 10 and 12 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Ibu | Halmahera (Indonesia) : PVMBG reported that at 1107 on 14 August an ash plume from Ibu rose at least 800 m above the summit and drifted N. Seismicity was characterized by an explosion signal and earthquakes indicating rock avalanches. 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.

Kadovar | Papua New Guinea : Based on satellite data and wind model data, the Darwin VAAC reported that on 19 August an ash plume from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW.

Karangetang | Siau Island (Indonesia) : PVMBG reported that during 12-18 August lava continued to effuse from Karangetang’s Main and Dua craters. Avalanches of material traveled 1-1.5 km SW down the Nanitu and Pangi drainages, as far as 1.4 km down a drainage W of Pangi, and as far as 1.8 km down the Sense drainage. Sometimes dense white plumes rose to 500 m above the summit. The Alert Level remained at 2 (on a scale of 1-4).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was visible in satellite images during 11-12 and 15 August. Volcanologists doing fieldwork on 14 August observed explosions and ash plumes that rose to 5 km (16,400 ft) a.s.l. Satellite images showed ash plumes drifting S and SE that same day. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Klyuchevskoy was visible in satellite images during 13-14 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Merapi | Central Java (Indonesia) : PVMBG reported that during 12-18 August the lava-dome volume at Merapi did not change and was an estimated 461,000 cubic meters, based on analyses of drone images. Extruded lava fell into the upper parts of the SE flank, generating a total of two block-and-ash flows that traveled as far as 950 m down the Gendol drainage on 13 and 14 August. Diffuse white plumes rose as high as 100 m above the summit on some days. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.

Nevados de Chillan | Chile : ONEMI and SERNAGEOMIN reported multiple explosions at Nevados de Chillán’s Nicanor Crater during 14-20 August, each associated with long-period earthquakes. Two explosions on 14 August, at 0000 and 0029, produced gas emissions and ejected incandescent material onto the flanks. An explosion at 1200 on 16 August produced a grayish ash plume that rose 110 m. Another explosion was detected at 1625 on 17 August. A grayish gas plume from an explosion at 1343 on 18 August rose 400 m, and an explosion at 1938 on 20 August ejected incandescent material onto the flanks. The Alert Level remained at Orange, the second highest level on a four-colour scale. ONEMI maintained an Alert Level Yellow (the middle level on a three-colour scale) for the communities of Pinto, Coihueco, and San Fabián, and stated that the public should stay at least 3 km away from the crater on the SW flank and 5 km away on the ENE flank.

Piton de la Fournaise : OVPF reported that the eruption at Piton de la Fournaise that began on the E part of l’Enclos Fouqué at 1620 on 11 August paused for about four hours beginning around 0420 on 15 August; tremor and deep earthquakes indicating magma movement continued to be detected. Lava fountaining resumed at 0830 at two vents residing along the second fissure at 1,500 m elevation, producing flows that did not extend beyond 500 m in length. The lava-flow front from the main flow did not advance past 600-650 elevation. Activity ceased around 2200 on 15 August.

Poas | Costa Rica : OVSICORI-UNA reported that an eruptive event from vent A (Boca Roja) at Poás generated a 1-km-high plume of steam, gas, and fine particulates at 0650 on 17 August. The event was preceded by an increase in tremor amplitude starting at 0500 that same day.

Sabancaya | Peru : Instituto Geofísico del Perú (IGP) reported that an average of 25 low-to-medium intensity explosions per day occurred at Sabancaya during 12-18 August. Gas-and-ash plumes rose as high as 3 km above the summit and drifted SE, S, and SW. There were eight thermal anomalies identified in satellite data. The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 12-km radius.

Sangeang Api | Indonesia : The Darwin VAAC reported that during 14-20 August intermittent ash plumes from Sangeang Api were identified in satellite images rising to 2.4-3 km (8,000-10,000 ft) a.s.l. and quickly dissipating to the N, NW, W, and SW. The Alert Level remained at 2 (on a scale of 1-4).

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch’s lava dome was identified daily in satellite images during 9-16 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Volcanos

Global Volcanic Activity – New Activity for the week of 14 August – 20 August 2019

Asamayama | Honshu (Japan) : JMA reported that, after a small phreatic eruption occurred at Asamayama on 7 August, both seismic activity and sulfur dioxide emissions temporarily increased and then decreased later that day. During 8-19 August white plumes generally rose 400 m above the crater rim; occasionally they rose as high as 800 m. Sulfur dioxide emissions were 70-300 tons per day. On 19 August the Alert Level was lowered to 2 (on a scale of 1-5).

Semisopochnoi | United States : AVO reported that during 14-17 August seismicity at Semisopochnoi remained elevated and was characterized by periods of continuous tremor and discrete low-frequency earthquakes; seismic data became unavailable starting sometime on 17 August. Cloudy weather often prevented satellite views of the volcano, however some recent clear views indicated that the N cone crater had a smooth featureless area, indicating water or tephra at an elevation several meters below the previous floor. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

Shishaldin | Fox Islands (USA) : AVO reported that during 14-20 August continuous, low-level tremor at Shishaldin was recorded by the seismic network and elevated surface temperatures were visible in infrared satellite images. The spatter cone in the crater had grown and partially filled the summit crater. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that during 12-18 August phreatic events at Tangkubanparahu’s Ratu Crater continued to produce sometimes dense gray-to-white plumes that rose as high as 200 m above the vent, and dense black ash plumes that rose as high as 100 m. The emissions were accompanied by roaring. Ashfall was localized around Ratu Crater. The seismic network recorded continuous tremor. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 1.5 km away from the active crater.

Ubinas | Peru : IGP reported that during 13-19 August blue-coloured gas plumes from Ubinas rose to heights of less than 1.5 km above the base of the crater. Seven thermal anomalies were recorded by the MIROVA system. The number of seismic events was 1,716 (all under M 2.4), a decrease in the total number recorded during the previous week. The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 15-km radius.

Tonga Islands : A submarine eruption in early August from an unnamed seamount about 50 km NW of Vava’u in Tonga created extensive areas of pumice rafts. Sailing crews encountered the pumice starting on 9 August about 40 km NNW of Late Island. Rachel Mackie described a pronounced odor of sulfur, and eventually being surrounded as far as she could see, with the surface pumice layer being 30 cm deep and containing pieces up to 80 cm in diameter. Sentinel-2 satellite imagery from 11 August showed the raft, averaging about 2.5 km across but strung out for 35 km NE-SW, located 70 km WNW of Late Island; another band of scattered rafts extended directly back from the main mass towards Late for 50 km. The raft continued drifting, and was at least another 60 km SW from its previous location as of 16 August. Eruptive activity at this location was previously reported in September-October 2001.

Volcanos

Global Volcanic Activity – Ongoing Activity for the week of 7 August – 13 August 2019

Aira | Kyushu (Japan) : JMA reported that during 5-13 August very small eruptive events were detected at Minamidake crater (at Aira Caldera’s Sakurajima volcano), though none of them were explosive. Crater incandescence was occasionally visible in webcams at night. The Alert Level remained at 3 (on a 5-level scale).

Asosan | Kyushu (Japan) : JMA reported that increased eruptive activity at Asosan that began on 28 July continued at least through 13 August. Ash plumes drifted N and NW, and crater incandescence was visible at night. Sulfur dioxide gas emissions were very high at 2,000-5,000 tons per day. The Alert Level remained at 2 (on a scale of 1-5).

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, and statements from ground-based observers, the Darwin VAAC reported that during 7-13 August ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted in multiple directions. Ashfall was reported on 8 August at the Galela Airport, Maluku Utara, 17 km NW. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions on 2 and 4 August that sent ash plumes up to 3 km (10,000 ft) a.s.l. and drifted SE. A thermal anomaly was identified in satellite images on those same two days. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Ibu | Halmahera (Indonesia) : PVMBG reported that during 7-12 August white-to-gray plumes rose 200-800 m above Ibu’s crater rim. 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.

Karangetang | Siau Island (Indonesia) : PVMBG reported that during 5-11 August lava continued to effuse from Karangetang’s Main Crater and travel down drainages on the W and SW flanks, producing incandescent avalanches that descended those same drainages. White plumes rose from the summit craters rose 50-100 m above the peak. The Alert Level remained at 2 (on a scale of 1-4).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was visible in satellite images during 2 and 4-6 August. Ash plumes drifted 180 km SE and NW during 3-5 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

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

Merapi | Central Java (Indonesia) : PVMBG reported that during 5-11 August the lava-dome volume at Merapi had decreased compared to the week before and was an estimated 461,000 cubic meters, based on analyses of drone images. Extruded lava fell into the upper parts of the SE-flank, generating a total of two block-and-ash flows that traveled as far as 1.2 km down the Gendol drainage on 4 and 6 August. Diffuse white plumes rose as high as 50 m above the summit on some days. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.

Nevados de Chillan | Chile : ONEMI and SERNAGEOMIN reported that during 8-13 August multiple explosions at Nevados de Chillán’s Nicanor Crater generated gas-and-ash plumes and ejected incandescent material around the crater. These explosions were recorded at 0438 on 8 August, at 2223 on 10 August, at 1831 and 1952 on 12 August, and at 0427, 1058, and 1116 on 13 August. Eruption plumes rose as high as 765 m above the summit. The Alert Level remained at Orange, the second highest level on a four-colour scale, and residents were reminded not to approach the crater within 3 km. ONEMI maintained an Alert Level Yellow (the middle level on a three-colour scale) for the communities of Pinto, Coihueco, and San Fabián; on 13 August they stated that the public should stay at least 3 km away from the crater on the SW flank and 5 km away on the ENE flank.

Piton de la Fournaise | Reunion Island (France) : OVPF reported that a seismic crisis at Piton de la Fournaise began at 0700 on 11 August and was accompanied by rapid deformation. The locations of the earthquakes and area of deformation indicated that magma rose from deep under the SE edge of Dolomieu Crater to beneath the E and SE flanks. Tremor began around 1620, indicating the likely start of this year’s fourth eruption, though inclement weather conditions prevented visual confirmation. The Alert Level was raised to 2-2. On 12 August OVPF confirmed that fissures had opened in the E part of l’Enclos Fouqué, SE of the upper Grandes Pentes. Scientists saw two fissures, about 1.4 km apart, at 1,700 and 1,500 m elevation during an overflight on 13 August. Only the lowest elevation fissure was active. Three distinct cones along the fissure fed lava flows that merged into one which traveled to 665 m elevation and caused small fires as it burned local vegetation.

Popocatepetl | Mexico : CENAPRED reported that each day during 7-13 August there were 125-209 steam-and-gas emissions from Popocatépetl, some of which contained ash. As many as seven explosions were recorded daily, with the exceptions of 7 August (no explosion were detected) and 11 August (16 were documented). Two explosions on 13 August were characterized as major (at 0427 and 0453) and ejected incandescent material onto the flanks. The Alert Level remained at Yellow, Phase Two (middle level on a three-colour scale).

Sangeang Api | Indonesia : The Darwin VAAC reported that during 7-13 August ash plumes from Sangeang Api were identified in satellite images rising to 2.4-3 km (8,000-10,000 ft) a.s.l. and drifting in multiple directions. The Alert Level remained at 2 (on a scale of 1-4).

Semisopochnoi | United States : AVO reported that during 7-13 August seismicity at Semisopochnoi remained elevated and was characterized by periods of continuous tremor and discrete low-frequency earthquakes. No unusual activity was observed in satellite images, though views were often cloudy. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch’s lava dome was identified daily in satellite images during 2-9 August. A diffuse ash plume rose to 2.5 km (8,200 ft) a.s.l. and drifted 40 km NW on 5 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Stromboli | Aeolian Islands (Italy) : INGV reported that Stromboli’s crater terrace activity was analyzed during 5-11 August through webcam views, and field inspections during 7-8 August. At least nine vents in Area N (north crater area, NCA) were active on 7 August, three of which had well-formed spatter cones, with Strombolian activity ejecting material 150 m high. A large scoria cone in Area C-S (South Central crater area) jetted material 200 m high. Lava from Area C-S vents continued to travel down the upper part of the Sciara del Fuoco, reaching 500-600 m elevation.

Suwanosejima | Ryukyu Islands (Japan) : JMA reported that volcanic earthquakes began to be detected at Suwanosejima on 4 August and volcanic tremors were occasionally recorded during 4-9 August. Four eruptive events occurred at Ontake Crater on 5 August and one on 6 August. Large blocks were ejected as far as 400 m and ash plumes rose as high as 1.5 km above the crater rim. The Alert Level remained at 2 (on a 5-level scale).

Villarrica | Chile : POVI reported that a portion of the E edge of Villarrica’s summit crater rim collapsed between 9 and 12 August.

Volcanos

Global Volcanic Activity – New Activity for the week of 7 August – 13 August 2019

Asamayama | Honshu (Japan) : JMA reported that at 2208 on 7 August a small phreatic eruption at Asamayama produced an ash plume that rose higher than 1.8 km above the crater rim and drifted N. Blocks were ejected 200 m from the crater. The eruption lasted about 20 minutes and was the first since 19 June 2015. The Alert Level was raised to 3 (on a scale of 1-5). Ash fell in Tsumagoi Village and Naganohara Town, in the Gunma Prefecture. White plumes rose as high as 700 m above the crater rim during 8-13 August, and the amount of sulfur dioxide released was 90-200 tons per day.

Sarychev Peak | Matua Island (Russia) : SVERT reported that an ash plume from Sarychev Peak rose to 2.7 km (9,000 ft) a.s.l. and drifted 50 km SE on 11 August, based on Tokyo VAAC notices. The Aviation Color Code was raised to Yellow.

Shishaldin | Fox Islands (USA) : AVO reported that during 7-13 August continuous, low-level tremor at Shishaldin was recorded by the seismic network and elevated surface temperatures were visible in satellite images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Slamet | Central Java (Indonesia) : PVMBG reported that seismicity at Slamet significantly increased beginning in June, with 51,511 signals indicating emissions and 22 tectonic earthquakes recorded through 8 August. White plumes with variable density rose as high as 300 m above the crater rim.Tremor began to be recorded at the end of July with gradually increasing amplitude. In addition, notable inflation was detected at the end of July and long-term temperatures of hot springs showed an upward trend. The Alert Level was raised to 2 (on a scale of 1-4) and the public was warned to stay outside a radius of 2 km.

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that during 5-11 August phreatic events at Tangkubanparahu’s Ratu Crater continued to produced sometimes dense, gray-to-white plumes that rose as high as 200 m above the vent and ash plumes rose as high as 100 m. The emissions were accompanied by roaring. Ashfall was localized around Ratu Crater. The seismic network recorded continuous tremor. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 1.5 km away from the active crater.

Ulawun | New Britain (Papua New Guinea) :RVO reported that during 7-8 August minor emissions of white vapor rose from Ulawun’s summit crater. Seismicity was dominated by low-level volcanic tremor and remained at low-to-moderate levels. RSAM values fluctuated between 400 and 550 units; peaks did not go above 700.

Veniaminof | United States : AVO reported that seismic unrest at Veniaminof continued during 7-13 August with low-frequency earthquakes being common. Satellite and webcam views showed nothing unusual. The Volcano Alert Level remained at Advisory and the Aviation Color Code remained at Yellow.

Volcanos

Global Volcanic Activity – Ongoing Activity for the week of 31 July – 6 August 2019

Aira | Kyushu (Japan) : JMA reported that during 30 July-5 August very small eruptive events were detected at Minamidake crater (at Aira Caldera’s Sakurajima volcano), though none of them were explosive. Crater incandescence was occasionally visible in webcams at night. The Alert Level remained at 3 (on a 5-level scale).

Asosan | Kyushu (Japan) : JMA reported that increased eruptive activity at Asosan that began on 28 July continued at least through 5 August. Volcanologists confirmed that high-temperature, gray-white plumes rose from the center of Nakadake Crater during fieldwork conducted on 31 July. Grayish white plumes rose 1.3 km and 1.5 km above the crater rim on 1 and 5 August, respectively. Incandescence from the crater was visible at night. The Alert Level remained at 2 (on a scale of 1-5).

Chiles-Cerro Negro | Colombia-Ecuador : Instituto Geofísico de la Escuela Politécnica Nacional (IGEPN) and the Observatorio Vulcanológico y Sismológico de Pasto del Servicio Geológico Colombiano (SGC OVSP) jointly reported that the most recent seismic swarm below Cerro Negro de Mayasquer and Chiles volcanoes began in September 2018 and continued at least through 1 August. The swarm has consisted of 147,000 earthquakes, recorded up to the time of the report publication, mostly with magnitudes less than 3.6. Notably, at least 91 very-long-period earthquakes and 89 long-period earthquakes have been detected, indicative of a magmatic body at depth. In addition, at 0738 on 25 July a M4 earthquake was located 4 km below the summit of Chiles and felt by residents. About 850 volcano-tectonic events were recorded during 25-28 July.

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 31 July-6 August ash plumes from Dukono rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted mainly N and NE. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 25-26 and 29 July, and 1 August, that sent ash plumes up to 2.5 km (8,200 ft) a.s.l. The plumes drifted in multiple directions. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Etna | Sicily (Italy) : INGV reported that on 25 July Etna’s New Southeast Crater (NSEC) periodically emitted gas and ash. At 0630 on 27 July the seismic network detected a sudden increase in tremor amplitude, and at 0915 a new fissure opened on the S flank of NSEC. Explosive activity at the crater intensified at 1020 and a dense, ash-rich plume rose to 4.5-5 km a.s.l. and drifted E. A thin layer of ash was deposited in Giarre, Riposto and Torre Archirafi. Lava emerged from the S part of the new fissure and traveled SW and S; by 1235 the longest part of the flow had reached 2,850 m elevation and by 1330 it had reached 2,600 m elevation. Beginning at 1321 a sequence of particularly strong explosions generated ash plumes that rose as high as 7.5 km a.s.l. Explosive activity decreased around 0440 on 28 July, and lava effused from the vent at a lower rate. Starting at 0846 the Northeast Crater (NEC) occasionally emitted small plumes of red-brown ash. Explosive and effusive activity at NSEC ceased that evening. Activity during 29 July-4 August consisted of a few episodes of ash emissions at Bocca Nuova Crater and NEC.

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that on 26 July a thermal anomaly over Karymsky was visible in satellite images along with an ash plume drifting 60 km SE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kerinci | Indonesia : PVMBG reported that at 1248 on 31 July a gray ash emission from Kerinci rose around 800 m above the summit and drifted E and NE according to a ground observer. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone.

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Klyuchevskoy was visible in satellite images during 26, 29, and 31 July, and 1 August. An ash emission was visible in webcam images on 1 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Krakatau | Indonesia : PVMBG reported that Anak Krakatau’s seismic network recorded 10 eruptive events during 29 July-4 August. The events were not followed by visible emissions, though observations were hindered by weather conditions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km radius hazard zone from the crater.

Merapi | Central Java (Indonesia) : PVMBG reported that during 29 July-4 August the lava-dome volume at Merapi did not change and was an estimated 475,000 cubic meters, based on analyses of drone images. Extruded lava fell into the upper parts of the SE-flank, generating a total of four block-and-ash flows that traveled as far as 1 km down the Gendol drainage on 31 July and 4 August. Diffuse white plumes rose as high as 50 m above the summit on some days. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.

Nevados de Chillan | Chile : On 6 August ONEMI and SERNAGEOMIN reported that activity at Nevados de Chillán’s Nicanor Crater increased in the previous few days, characterized by an increase in the size and occurrence of explosions. Specifically, there were 129 explosive events recorded since 3 August. Dense gas-and-ash plumes rose as high as 1.6 km above the crater rim and ejected material onto the flanks. Crater incandescence was visible at night. A lahar traveled 1.5 km NNE. The Alert Level remained at Orange, the second highest level on a four-colour scale, and residents were reminded not to approach the crater within 3 km. ONEMI maintained an Alert Level Yellow (the middle level on a three-colour scale) for the communities of Pinto, Coihueco, and San Fabián.

Nyamuragira | DR Congo : The Observatoire Volcanologique de Goma (OVG) reported that collapses of Nyamuragira’s inner crater walls observed in May 2019 continued during 1-31 July. Lava fountaining from a small cone was visible.

Nyiragongo | DR Congo : The Observatoire Volcanologique de Goma (OVG) reported that during 1-31 July the level Nyiragongo’s lava lake had dropped, making it not visible in the daytime. Incandescence from the lake continued to be visible at night. Activity also declined at a small eruptive cone that formed in the crater in 2014.

Sabancaya | Peru : Instituto Geofísico del Perú (IGP) reported that an average of 13 low-to-medium intensity explosions per day occurred at Sabancaya during 22-28 July. Gas-and-ash plumes rose as high as 2.3 km above the crater rim and drifted NE, E, and SE. There were eight thermal anomalies identified in satellite data. The report noted that the public should not approach the crater within a 12-km radius. Single explosions on 1 and 5 August produced an ash plume that drifted more than 30 km E and W, respectively.

Sangeang Api | Indonesia : The Darwin VAAC reported that during 31 July-3 August ash plumes from Sangeang Api were identified in satellite images rising to 2.4-3 km (8,000-10,000 ft) a.s.l. and drifting in multiple directions. The Alert Level remained at 2 (on a scale of 1-4).

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch’s lava dome was identified daily in satellite images during 26 July-2 August. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Suwanosejima | Ryukyu Islands (Japan) : JMA reported that at 2331 on 1 August an explosion at Suwanosejima’s Ontake Crater ejected blocks 400 m from the crater. Weather clouds prevented visual confirmation of an ash plume. Crater incandescence was sometimes visible at night. The number of volcanic earthquakes increased on 4 August and four explosions were recorded on 5 August. The Alert Level remained at 2 (on a 5-level scale).

Villarrica | Chile : ONEMI and SERNAGEOMIN reported that on 6 August the Alert Level for Villarrica was raised to Yellow, the second lowest level on a four-colour scale, reflecting the recent increase in minor Strombolian activity ejecting spatter onto the flanks near the rim during the past weeks.

Volcanos

Global Volcanic Activity – New Activity for the week of 31 July – 6 August 2019

Awu | Sangihe Islands (Indonesia) : The Darwin VAAC reported that on 4 August an ash plume from Awu was visible in satellite images rising to an altitude of 1.8 km (6,000 ft) a.s.l. and drifting N.

Karangetang | Siau Island (Indonesia) : PVMBG reported that beginning at 1858 on 20 July incandescent avalanches of material from Karangetang’s Main Crater traveled as far as 1 km W down the Pangi and Kinali drainages. By 22 July incandescent material had traveled another 500 m down the same drainages, and 1 km down the Nanitu and Beha drainages. Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 30-31 July intermittent discrete ash plumes rose to an altitude of 7.6 km (25,000 ft) a.s.l. and drifted W, and continuous ash emissions rose to 3 km (10,000 ft) a.s.l. A thermal anomaly was visible. On 5 August ash plumes rose to 3 km (10,000 ft) a.s.l. and drifted E; a thermal anomaly was again visible. The Alert Level remained at 2 (on a scale of 1-4).

Semisopochnoi | United States : AVO reported that during 31 July-6 August seismicity at Semisopochnoi remained elevated and was characterized by periods of weak, continuous tremor and discrete low-frequency earthquakes. Satellite images were mostly cloudy, though a possible steam plume was visible during 5-6 August. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

Shishaldin | Fox Islands (USA) : AVO reported that satellite images of Shishaldin acquired on 28 July showed a small spatter cone with lava flows in the summit crater. During 31 July-6 August continuous weak tremor was recorded by the seismic network and elevated surface temperatures were sometimes visible in satellite images. A small steam plume was observed in a few satellite and web camera images. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that an eruption at Tangkubanparahu’s Ratu Crater, recorded at 2046 on 1 August, generated a dense black ash-and-sediment-laden plume that rose about 180 m from the bottom of the crater, and light-coloured ash plumes mixed with water vapor that rose 200 m and drifted N and NE. The event lasted 11 minutes and 23 seconds based on seismic data. Ash and sediment fell in areas around the crater. Four eruptive events were recorded during the morning of 2 August, though ash emissions were not visually observed. The Alert Level was raised to 2 (on a scale of 1-4). A period of continuous ash emissions was recorded during 2-4 August.

Ulawun | New Britain (Papua New Guinea) : RVO reported that during 1-2 August white-to-grayish vapor plumes rose from Ulawun’s summit crater and drifted NW. Incandescence from the summit crater was visible at night and jetting noises were audible for a short interval. RSAM values fluctuated but peaked at high levels. During the night of 2-3 August crater incandescence strengthened and roaring noises became louder around 0400. An eruption began between 0430 and 0500 on 3 August; booming noises commenced around 0445. By 0600 dense light-gray ash emissions were drifting NW, causing ashfall in areas downwind including Ulamona Mission. Ash emissions continued through the day and grew from light to dark gray with time. The eruption intensified at 1900 and a lava fountain rose more than 100 m above the crater rim. A Plinian ash plume rose 19 km and drifted W and SW, causing ashfall in areas downwind such as Navo and Kabaya, and as far as Kimbe Town. The Darwin VAAC reported that the ash plume expanded radially and reached the stratosphere, rising to 19.2 km (63,000 ft) a.s.l. The plume then detached and drifted S and then SE. The Alert Level was raised to Stage 3 (the second highest level on a four-stage scale). The areas most affected by ash and scoria fall were between Navo (W) and Saltamana Estate (NW). Two classrooms at the Navo Primary School and a church in Navo collapsed from the weight of the ash and scoria; one of the classroom roofs had already partially collapsed during the 26 June eruption. Evacuees in tents as a result of the 26 June eruption reported damage. Rabaul town (E) also reported ashfall. Seismicity declined rapidly within two hours of the event, though continued to fluctuate at moderate levels. According to a news source flights in and out of Hoskins airport in Port Moresby were cancelled on 4 August due to tephra fall. The Alert Level was lowered to Stage 1. Small amounts of white and gray vapor were emitted from the summit crater during 4-6 August.

Veniaminof | United States : Low-level tremor at Veniaminof coincided with a pilot observation of a steam plume at 1230 on 1 August, prompting AVO to raise the Aviation colour Code to Yellow and the Volcano Alert Level to Advisory. On 2 August AVO noted that tremor had subsided, though low-level seismicity persisted at least through 6 August. Elevated surface temperatures were visible in satellite images. A small steam plume was also visible on 3 August.

Volcanos

Global Volcanic Activity – Ongoing Activity for the week of 24 July – 30 July 2019

Aira | Kyushu (Japan) : JMA reported that on 22 July an explosion at Minamidake crater (at Aira Caldera’s Sakurajima volcano) generated an ash plume that rose to 1.5 km above the crater rim. At 1725 and 1754 on 28 July ash plumes rose 3.5-3.8 km above the crater rim and causing ashfall in areas N of the crater including Kirishima (20 km NE), Shimizu Town, and parts of the Kumamoto Prefecture. The Alert Level remained at 3 (on a 5-level scale).

Asosan | Kyushu (Japan) : JMA reported that at 0757 on 26 July a small eruption at Asosan’s Nakadake Crater generated grayish-white ash plumes that rose 1.6 km above the crater rim and drifted NW. Webcam images showed incandescent material in the vent. Minor ashfall was reported in areas downwind including Minamioguni-cho (Kumamoto Prefecture, N) and Kuze-cho (Oita Prefecture, NE). Plumes continued to be emitted during 0900-1300, rising to 400 m. Activity increased at 0442 on 28 July and remained elevated at least through 1500 on 29 July. Grayish-white plumes rose as high as 1.2 km above the crater rim and drifted NE and N. Sulfur dioxide emissions were very high on 29 July, at 4,300 tons per day. The Alert Level remained at 2 (on a scale of 1-5).

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, and notices from PVMBG, the Darwin VAAC reported that during 24-30 July ash plumes from Dukono rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted mainly W, N, NE, and E. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 20-26 July that sent ash plumes up to 4 km (13,100 ft) a.s.l. The plumes drifted in multiple directions. A thermal anomaly was visible in satellite images on 18, 20, and 25 July. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was visible in satellite images during 18-19 and 25 July. An ash plume drifted 134 km SE on 25 July. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Klyuchevskoy was visible in satellite images during 18-19 July. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Merapi | Central Java (Indonesia) : PVMBG reported that during 22-28 July the lava-dome volume at Merapi did not change and was an estimated 475,000 cubic meters, based on analyses of drone images. Extruded lava fell into the upper parts of the SE-flank, generating two block-and-ash flows that traveled 1,000 m and 950 m down the Gendol drainage on 24 and 27 July, respectively. Diffuse white plumes rose as high as 50 m above the summit on some days. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to remain outside of the 3-km exclusion zone.

Nevado del Ruiz | Colombia : Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 23-30 July small plumes of gas and ash rose from Nevado del Ruiz based on webcam images. A weak thermal anomaly was identified in satellite data. The Alert Level remained at 3 (Yellow; the second lowest level on a four-colour scale).

Sangeang Api | Indonesia : The Darwin VAAC reported that during 24-30 July multiple ash plumes from Sangeang Api were identified by pilots and in satellite images rising to 2.4-3 km (8,000-10,000 ft) a.s.l. and quickly dissipating N, NW, W, and SW. The Alert Level remained at 2 (on a scale of 1-4).

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch’s lava dome was identified daily in satellite images during 19-26 July. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Tengger Caldera | Eastern Java (Indonesia) : The Darwin VAAC reported that on 28 July ash plumes from Tengger Caldera’s Bromo cone rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted NW based on webcam images, satellite data, and weather models. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.

Tengger Caldera | Eastern Java (Indonesia) : The Darwin VAAC reported that on 28 July ash plumes from Tengger Caldera’s Bromo cone rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted NW based on webcam images, satellite data, and weather models. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.

Turrialba | Costa Rica : OVSICORI-UNA reported that an eruptive event at Turrialba was detected at 1441 on 28 July, though inclement weather conditions prevented visual confirmation. Ashfall was reported in La Picada (N) and El Retiro farms.

Villarrica | Chile : POVI reported that during 24-25 July multiple Strombolian explosions in Villarrica’s summit crater were detected in seismic data and ejected incandescent material onto the flanks.

Volcanos

Global Volcanic Activity – New Activity for the week of 24 July – 30 July 2019

Masaya | Nicaragua : INETER reported that at 1655 on 21 July a small explosion at Masaya’s Santiago Crater produced a gas-and-ash plume that drifted NW and W. A thin layer of ash was deposited near the volcano and in surrounding communities downwind, including San Ignacio, Panamá, and Arenal. During field visits during 21-22 July, INETER volcanologists confirmed that the emissions had originated from a vent on the crater floor.

Piton de la Fournaise | Reunion Island (France) : OVPF reported that a seismic crisis at Piton de la Fournaise began at 0513 on 29 July and was accompanied by rapid deformation. Tremor beneath the N flank began to be recorded around 1200, indicating the likely start of the eruption, though inclement weather conditions prevented visual confirmation. OVPF visited the site and conducted helicopter overflights around 1630 and observed three active fissures, with a total length of 450 m, that crossed the July 2018 flows on the NW flank (600 m from the Formica Léo). The fissures produced 20-30-m-high lava fountains and ‘a’a lava flows that traveled no more than 500 m. After a gradual decline, volcanic tremor ceased at 0430 on 30 July signaling the end of the eruption.

Semisopochnoi | United States : On 24 July AVO reported that satellite data from the previous week indicated that the 100-m-wide crater lake in the N cone of Semisopochnoi’s Cerberus three-cone cluster was gone, and a new shallow inner crater about 80 m in diameter had formed on the crater floor. The lake had persisted since January 2019. Seismicity during 25-30 July was characterized by periods of continuous tremor, low-frequency earthquakes, and small explosion signals. Small steam plumes were visible in periodic, cloud-free satellite images, along with minor sulfur dioxide emissions.

Shishaldin | Fox Islands (USA) : On 23 July field crews observed minor spattering and surface lava flows in Shishaldin’s summit crater during an overflight, prompting AVO to raise the Aviation colour Code to Orange and the Volcano Alert Level to Watch. Elevated surface temperatures were observed in multiple satellite images during 24-30 July, though views were sometimes obscured by weather clouds. Nearly continuous weak seismic tremor was detected, and occasional infrasound signals consistent with small Strombolian explosions were recorded during 26-27 July.

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that a phreatic eruption at Tangkubanparahu’s Ratu Crater began at 1548 on 26 July and was recorded in seismic data for about five minutes and 30 seconds. Dense blackish-gray, sediment-laden plumes rose around 200 m above the lake surface, and a lighter-coloured component containing fine ash rose 600 m and spread NE and S. Tephra fell in a concentrated area within 500 m of the vent, creating deposits 5-7 cm thick. Visitors to the Kawasan Wisata Gunung Tangkuban Parahu tourist area that borders a section of the E and SE crater rim immediately evacuated. BNPB reported that the local government closed the tourist area noting that ash fell within a 1-2 km radius, in Jayagiri Village, Lembang District, and areas of the West Bandung Regency. Activity decreased after the eruption; tremor amplitude decreased during 27-28 July, and diffuse white plumes rose from the vent.

PVMBG noted that during the previous month white plumes of variable density rose as high as 150 m above the crater floor. Small local inflation was recorded, and deformation data continued to indicate instability at least through 27 July. Hydrogen sulfide and sulfur dioxide concentrations began to increase on 10 July and then significantly declined at 1200 on 13 July. Measurements on 21 July indicated that gas emissions continued to fluctuate but decreased overall. The Alert Level remained at 1 (on a scale of 1-4).

Ubinas | Peru : IGP reported that activity at Ubinas continued to be elevated after the 19 July explosions. A total of 1,522 earthquakes, all with magnitudes under 2.2, were recorded during 20-24 July. Explosions were detected at 0718 and 2325 on 22 July. The Buenos Aires VAAC reported that an ash plume rising to 9.4 km (31,000 ft) a.s.l. and drifting SE was identified in satellite data at 0040 on 22 July. Continuous steam-and-gas emissions with sporadic pulses of ash were visible in webcam views during the rest of the day. Ash emissions near the summit crater were periodically visible on 24 July though often partially hidden by weather clouds. Ash plumes were visible in satellite images rising to 7 km (23,000 ft) a.s.l. Diffuse ash emissions near the crater were visible on 25 July, though a thermal anomaly was identified in satellite images. During 26-28 July there were 503 people evacuated from areas affected by ashfall.