Roundup of Global Volcanic Activity – Ongoing Activity for the week of 24 May – 30 May 2017

Aira | Kyushu (Japan) : JMA reported 22 events at Showa Crater (at Aira Caldera’s Sakurajima volcano) during 22-29 May, seven of which were explosive. The explosions ejected material as high as 800 m above the crater rim, and as far away as 500 m. Ash plumes rose as high as 3.3 km on 23 May and 3.4 km on 29 May. Crater incandescence was detected on 25 May. A very small event occurred at Minamidake summit crater on 26 May. The Alert Level remained at 3 (on a 5-level scale).

Bezymianny | Central Kamchatka (Russia) : On 26 May KVERT reported that after an explosive eruption at Bezymianny on 9 March, and the effusion of several lava flows onto the dome flanks, the volcano became quiet. Gas-and-steam emissions continued, along with a thermal anomaly identified in satellite images. The Aviation colour Code was lowered to Yellow (the second lowest level on a four-colour scale).

Bogoslof | Fox Islands (USA) : An eruption at Bogoslof began at 1416 on 28 May prompting AVO to raise the Aviation colour Code (ACC) to Red and the Volcano Alert Level (VAL) to Warning. Pilot and satellite observations indicated than ash plumes rose at least 10.7 km (35,000 ft) a.s.l. and possibly as high as 13.7 km (45,000 ft) a.s.l. An observer on Unalaska Island reported seeing a large white-gray mushroom cloud form over Bogoslof, with ashfall to the W. The event lasted 50 minutes. On 29 May the ash cloud continued to drift NE. No detectable activity was observed in data from seismic or infrasound stations located on nearby Islands, and no new activity has been observed in satellite data. The ACC was lowered to Orange and the VAL was lowered to Watch.

Cleveland | Chuginadak Island (USA) : AVO reported that no significant volcanic activity at Cleveland was detected in seismic, infrasound, or mostly cloudy satellite images during 24-30 May. The webcam periodically recorded steam emissions. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Colima | Mexico : On 26 May the Centro Universitario de Estudios e Investigaciones de Vulcanologia – Universidad de Colima reported that during the previous week seismic data revealed 36 high-frequency events, 20 long-period events, 2.6 hours of tremor, 12 landslides, and three low-intensity explosions. On 23 May sulfur dioxide emissions were below detectable limits (8.6 tons/day). A short-lived, low-amplitude episode of tremor was detected on 24 May.

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery and wind model data the Darwin VAAC reported that during 24-30 May ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted NW, W, and SW. Plumes drifted over 230 km W on 27 May.

Ebeko | Paramushir Island (Russia) : KVERT reported that during 23-24 May explosions at Ebeko were observed by residents of Severo-Kurilsk (Paramushir Island) about 7 km E. Ash plumes rose as high as 2 km (6,600 ft) a.s.l. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kilauea | Hawaiian Islands (USA) : During 24-30 May HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. A portion of the N Overlook crater wall collapsed into the lake, causing lake agitation and depositing tephra at the Hawaiian Volcano Observatory and Jaggar Museum. Webcams recorded incandescence from long-active sources within Pu’u ‘O’o Crater, from a vent high on the NE flank of the cone, and from a small lava pond in a pit on the W side of the crater. The 61G lava flow, originating from a vent on Pu’u ‘O’o Crater’s E flank, continued to enter the ocean at Kamokuna adding to a growing delta. Narrow cracks on the delta parallel to the coast were noted. Surface lava flows were active above and on the upper slopes of the pali.

Langila | New Britain (Papua New Guinea) : Based on analyses of satellite imagery and wind model data, the Darwin VAAC reported that during 24-27 May ash plumes from Langila rose 2.1-3 km (7,000-10,000 ft) a.s.l. and drifted 75-85 km W and NW.

Manam | Papua New Guinea : RVO reported that Strombolian activity at Manam’s Southern Crater during 13-14 and 18 May generated lava flows that descended the SW valley. Lava flows traveled to 180-220 m elevation during 13-14 May but were significantly small on 18 May. Activity was low on other days during 13-26 May; ash plumes rose from the crater during 15-18 May. Conditions were quiet at Main Crater. RVO recommended that the Alert Level be lowered to Stage 1.

Nevado del Ruiz | Colombia : Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 23-29 May seismicity at Nevado del Ruiz continued to indicate unrest. Five episodes of drumbeat seismicity (low-energy long-period events) were recorded between 1343 and 1930 on 29 May, likely signifying growing lava domes. Significant amounts of water vapor and gas continued to be emitted. Gas, steam, and ash plumes rose 880 m above the crater rim on 27 May and drifted NW and SW. A thermal anomaly was identified on 28 May. The Alert Level remained at III (Yellow; the second lowest level on a four-colour scale).

Pacaya | Guatemala : INSIVUMEH reported nighttime crater incandescence and small Strombolian explosions at Pacaya’s Mackenney cone during 27-28 May.

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that during 22-28 May explosive activity at Sabancaya slightly increased from the previous week, with an average of 41 explosions detected per day. Seismcity was dominated by long-period events, and the number and magnitude of hybrid events were low. Gas-and-ash plumes rose as high as 2.8 km above the crater rim and drifted more than 30 km E and SE. The MIROVA system detected two thermal anomalies.

Santa Maria | Guatemala : INSIVUMEH reported that during 24-25 May avalanches of material from Santa María’s Santiaguito lava-dome complex traveled short distances down the flanks. During 27-30 May weak explosions generated ash plumes that rose 600-700 m and drifted W and SW. Ashfall was reported in Monte Claro (S).

Sinabung | Indonesia : Based on PVMBG observations, webcam and satellite images, and wind data, the Darwin VAAC reported that during 24-29 May ash plumes from Sinabung rose 3.7-5.8 km (12,000-19,000 ft) a.s.l. and drifted in multiple directions.

Turrialba | Costa Rica : OVSICORI-UNA reported that tremor amplitude at Turrialba fluctuated from low to high levels during 23-30 May, often corresponding to emission characteristics. Periods of volcano-tectonic and long-period events were also recorded. During 24-26 May several passive and sporadic ash emissions rose no higher than 500 m above the vent and drifted NW and SW. Frequent and small explosions during 26-27 May generated ash plumes that rose higher than 500 m above the vent, and ejected material higher than 200 m and no farther than 100 m towards Central Crater. Small explosions during 27-29 May produced ash plumes that rose 300-500 m.


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