Roundup of Global Volcanic Activity – New Activity for the Week 25 November 2020 – 1 December 2020
Lewotolo – Lomblen Island (Indonesia) : According to PVMBG continuous tremor at Lewotolo began to be recorded at 1943 on 26 November, and a series of volcanic earthquakes began at 1947. A new eruption started at 0557 on 27 November, producing dense blackish gray ash plumes that rose 500 m above the summit and drifted W. Incandescence at the summit was visible, and the emissions turned white around 0630. Seismicity slightly decreased after the eruption, though continuous tremor persisted for a period of time. Dense white plumes rose as high as 400 m and nighttime incandescence was noted during 27-28 November. During the morning of 29 November seismicity again increased, characterized by six deep volcanic earthquakes; continuous tremor appeared around 0930. At 0945 a 10-minute eruption sent dense gray-to-black ash plumes 4 km above the summit that drifted W and NW at lower heights and SE and E near the top of the plume. Ashfall was reported in several surrounding villages and video posted on social media showed tephra falling on roofs in residential areas. According to BNPB, Badan Penanggulangan Bencana Daerah (BPBD) evacuated almost 4,500 residents from 26 villages to seven evacuation centers. At 1300, the Alert Level was raised to 3 (on a scale of 1-4) and the public was warned to stay 4 km away from the summer crater. Ash plumes continued to rise on at least six more occasions, and around 1900 Strombolian activity was visible. A pungent sulfur odor was noted at the Lewotolo observation post. Satellite data showed that a sulfur dioxide plume had drifted over the N half of Australia by 30 November. Ash plumes continued to be emitted during 30 November-1 December, with dense white-and-gray ash plumes rising 700-2,000 m above the summit. Lava flows near the summit were visible and incandescent material traveled down the flanks.
Merapi – Central Java (Indonesia) : BPPTKG reported that during 20-26 November white emissions from Merapi rose as high as 750 m above the summit. Avalanches of material traveled down the flanks, as far as 1 km in the Lamat drainage (W flank) at 0648 on 22 November. A comparison of photos taken on 19 and 26 November showed morphology changes in the summit area from a collapse of part of the 1954 dome. Seismicity was higher than the previous week. Electronic Distance Measurement (EDM) data continued to measure a distance shortening between points in the NW at a rate of 11 cm per day. During overflights on 26 and 27 November BNPB and BPPTKG observers noted many new avalanche deposits on the NW, W, and SW flanks. As of 27 November, there were 2,318 people spread across 15 evacuation shelters, according to BNPB. The Alert Level remained at 3 (on a scale of 1-4).
Semeru – Eastern Java (Indonesia) : PVMBG reported that the eruption at Semeru continued during 1 October-30 November. White-and-gray ash plumes rose as high as 500 m above the summit and drifted in multiple directions. Rock avalanches were intermittently recorded starting on 19 October. A significant increase in the number rock avalanches was detected on 28 November. Pyroclastic flows originating from the ends of lava flows traveled 1 km down the SE flank. At 0123 on 1 December pyroclastic flows from the summit lava dome traveled 2-11 km down the Kobokan drainage on the SE flank. The Darwin VAAC initially reported ash plumes to 15 km (50,000 ft) a.s.l. but after further analysis noted that plumes rose to a lower altitude of 6.1 km (20,000 ft) a.s.l. and drifted SE. BNPB reported that the pyroclastic flows destroyed some mining machinery and impacted livestock, agricultural fields, and businesses. Some residents had evacuated and then returned to their homes; one person was missing. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 4 km in the SSE sector.