Global Volcanic Activity – New Activity for the week of 15 May – 21 May 2019

Azumayama | Honshu (Japan) : The number of volcanic earthquakes at Azumayama increased on 5 May and data from a tiltmeter about 1 km SE of Ohana Crater showed inflation on 9 May, prompting JMA to raise the Alert Level to 2 (on a 5-level scale). Field observations on 7 and 10 May indicated no changes in the fumarolic and thermal areas around Ohana. Seismicity began to decrease on 10 May, though continued to fluctuate through 20 May. Deformation continued but at a slower rate.

Hakoneyama | Honshu (Japan) : JMA reported that the number of earthquakes at Hakoneyama increased during 18-19 May, with epicenters centered around the W bank of Lake Ashinoko and around Komagatake. Fumaroles in the Owakudani hot springs area continued to be active. Global Navigation Satellite Systems (GNSS) data showed changes in deformation beginning in mid-March. On 19 May JMA raised the Alert Level to 2 (on a 5-level scale). Elevated seismicity continued to be recorded through 21 May.

Pavlof | United States : AVO reported that low-frequency tremor was detected at Pavlof during 14-15 May and a vigorous steam plume rising from the summit was visible in webcam images on 15 May. The Aviation colour Code was raised to Yellow and the Volcano Alert Level was raised to Advisory primarily because of increased seismicity. Steam plumes recorded by the webcam, low levels of seismic tremor, and warm surface temperatures identified in satellite data continued during 16-19 May; AVO noted that steam emissions and warm surface temperatures are common at Pavlof.

Sangay | Ecuador : IG reported that a new eruption at Sangay began on 7 May and was continuing as of 21 May. Activity was concentrated at two eruptive centers; the Central Crater and the Ñuñurcu dome (located 190 m SSE of Central Crater). Explosive activity at Central Crater produced ash plumes that rose an average of 1 km above the crater rim and drifted W and NW. Ejected blocks rolled as far as 2.5 km down the SE flank. The Ñuñurcu dome produced a lava flow that had a maximum width of 175 m and traveled about 470 m down the SE flank. Collapses of the lava-flow front generated small pyroclastic flows and numerous block flows; one of the pyroclastic flows traveled 340 m.

Sarychev Peak | Matua Island (Russia) : SVERT reported that a weak thermal anomaly over Sarychev Peak was visible in satellite images on 10, 12, and 17 May. At 0830 on 16 May satellite images showed an ash plume drifting 50 km SE at an altitude as high as 2.5 km (8,200 ft) a.s.l. The Aviation colour Code was raised to Yellow on 16 May.

Sinabung | Indonesia : PVMBG reported that white plumes rose as high as 700 m above Sinabung’s crater rim during 13-21 May. On 20 May the Alert Level was lowered to 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km on the SE sector and 4 km in the NE sector. PVMBG noted that the seismic activity surrounding the recent ash emissions during 7 and 11-12 May were not indicative of renewed activity.

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