Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week 27 October – 2 November 2021

Aira – Kyushu (Japan) : JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 25 October-1 November. Two very small eruptions were detected on 28 and 31 October.

Ebeko – Paramushir Island (Russia) : On 31 October an explosion at Ebeko produced an ash plume that rose to 1.8 km (5,900 ft) a.s.l. and drifted 5 km NE.

Fuego – Guatemala : INSIVUMEH reported that 3-14 explosions per hour were recorded at Fuego during 26 October-2 November, generating ash plumes as high as 1.1 km above the crater rim and shock waves felt in communities around the volcano. Ash plumes mostly drifted as far as 50 km SW, W, and NW and 20 km N and S, causing almost daily ashfall in several areas downwind, including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), Yucales (12 km SW), El Porvenir (8 km ENE), Finca Palo Verde, La Rochela, Sangre de Cristo (8 km WSW), and San Pedro Yepocapa (8 km NW). Block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), and Las Lajas (SE) drainages, often reaching vegetated areas. Explosions ejected incandescent material 100-400 m above the summit each day.

Fukutoku-Oka-no-Ba – Volcano Islands (Japan) : The Japan Coast Guard reported that floating pumice from the mid-August Fukutoku-Oka-no-Ba eruption had arrived at coastlines more than 1,000 kilometers away in early October. The pumice first arrived at Kitadaito Island (1,035 km W) on 8 October. In late October pumice circled Okinawa and Maejima islands (1,422 km W) and several ports in the Kagoshima prefecture (1,322 NW). The pumice damaged hundreds of boats and ships, clogged harbors, and impacted the fishing and tourism industries in several areas. Several local governments began the process of removing the pumice from the water.

Great Sitkin – Andreanof Islands (USA) : AVO reported that lava flows on Great Sitkin’s S and W flanks were 600 m long by 27 October based on satellite images, and lava effusion likely continued during 27 October-2 November. Seismicity remained elevated and was characterized by small earthquakes consistent with ongoing lava flows. Elevated surface temperatures were occasionally detected in satellite images.

Ibu – Halmahera (Indonesia) : PVMBG reported that during 26 October-2 November gray-and-white ash plumes from Ibu rose 200-800 m above the summit and drifted N, W, and S. There were at least 151 eruptive events observed during 28-30 October.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that during 22 and 26-28 October explosions at Karymsky generated ash plumes that rose as high as 4 km (13,100 ft) a.s.l. and drifted 65 km E and SE. A thermal anomaly was visible on 22 and 28 October.

La Palma – Spain : The eruption at La Palma continued during 26 October-2 November, characterized by Strombolian explosions, lava fountaining from multiple vents, advancing and branching lava flows, and daily ash emissions. Eruption details are based on official sources including PEVOLCA (Plan de Emergencias Volcánicas de Canarias) steering committee summaries issued daily. Seismicity remained elevated, with most earthquakes located 10-15 km deep (though some were as deep as 38 km); dozens of events were felt by local residents and some were felt across the entire island. A M 5 earthquake was recorded at 0724 on 30 October at a depth of 35 km and was the largest earthquake recorded since the beginning of the eruption. A second M 5 earthquake was recorded at 1852 on 1 November and had a depth of 38 km. Both of these events, as well as some of the other notable earthquakes, were felt across La Palma Island and in some areas of La Gomera and Tenerife islands. The vents in the main cone continued to effuse lava, eject tephra, and produce sometimes dense and billowing ash-and-gas plumes that rose 2.2-5 km (7,200-16,400 ft) a.s.l. Several vents in the main cone were active, though the activity levels varied in intensity throughout the week. A small collapse of the upper part of the main cone on 26 October caused lava to flow W over previous flows that filled in some small gaps where they had not previously covered. Beginning around noon on 29 October a series of intense and audible explosions occurred for several hours, generating a large amount of ash that was distributed across the valley. The tallest ash plumes were observed during 30-31 October. Audible explosions and significant ash emissions continued intermittently through 2 November, with ashfall affecting the entire W and NW parts of the island. Authorities issued multiple air quality alerts warning residents of some affected areas (Los Llanos de Aridane in particular), to stay indoors and, if going outside, to wear a filtering mask. For a period of time on 31 October the larger explosions were accompanied by shock waves and concurrently, the effusion rate at the NW flank vent notably increased. Sulfur dioxide emissions fluctuated at high levels between 4,990 and 22,000 tons per day during 27 October-2 November and showed an overall downward trend during the last week in October; no estimates were made on 29 October due to technical difficulties. Lava effused at a high rate from a vent on the NW flank of the main cone, flowing through pre-existing lava channels and tubes, and occasionally breaking out and forming new flows. The lava-flow field was characterized by three main areas: the initial main flow that traveled W, flowing around the S part of Montaña de Todoque, toward the sea and creating a lava delta, a flow that had branched off of the main flow to the S, and the flows that traveled W along the N margins of the main flow. Lava flows sometimes overflowed their channels, forming ephemeral flows that spread laterally, descended short distances, and were also transported downslope in lava tubes. The initial flow that reached the sea and formed the delta was not notably fed and was 30 m thick in some areas. The lava flows that had advanced W along the S side of Montaña de La Laguna was 86 m from the coast of Tazacorte, near the beach of El Perdido. The southern flow had advanced at a low rate and by 28 October was 400 m from the sea by 27 October. Lava that travelled SW over older flows emplaced along the S margins of the flow field overflowed the channel, bifurcated, and quickly advanced 1.5 km W and SW over new ground during 28-30 October. This lava flow continued to advance and by 2 November it was 150 m from the LP-211 road, though the advancement rate had slowed considerably to 1 meter per hour. Overall, the flow field widened to 3.1 km, with most of the expansion occurring along the S margins, and covered an estimated 9.77 square kilometers by 2 November.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 26 October-2 November. White-and-gray plumes rose as high as 1 km above the summit and drifted in multiple directions. Rumbling and banging noises were heard daily. Crater incandescence was visible on 28 October and incandescent material was ejected 100-200 m from the vent on 29 October and 1 November.

Merapi – Central Java (Indonesia) : BPPTKG reported no morphological changes to Merapi’s SW lava dome, located just below the SW rim, and in the summit crater during 22-28 October. As many as 30 lava avalanches traveled a maximum of 1.8 km SW.

Pavlof – United States : AVO reported that the eruption at Pavlof continued during 27 October-2 November and was focused at a vent on the upper SE flank, near the location of the 2007 vent. Seismicity remained elevated with tremor and daily small explosion signals. The explosions likely produced low-level ash plumes that rose no higher than 3 km (10,000 ft) a.s.l., though weather clouds often prevented confirmation by satellite and webcam images. Elevated surface temperatures were visible in satellite images during 25-26 October. A small plume and discolored snow at the summit were visible in mostly clear satellite images during 27-28 October. Slightly elevated temperatures were identified in satellite images during 31 October-2 November. Minor steaming at the vent was seen in webcam images on 1 November, as well as a small ash plume that rose to a low height and dissipated quickly.

Popocatepetl – Mexico : CENAPRED reported that each day during 26 October-2 November there were 9-118 steam-and-gas emissions from Popocatépetl. Some of the emissions contained ash during 26-28 October and 31 October-1 November.

Reventador – Ecuador : IG reported that a high level of activity continued to be recorded at Reventador during 26 October-2 November; cloudy weather conditions sometimes prevented webcam and satellite views. Gas-and-ash plumes, often observed multiple times a day with the webcam or reported by the Washington VAAC, rose as high as 1.4 km above the summit crater and drifted mainly W, NW, N, and NE. Ashfall was reported in El Reventador village on 27 October. At night during 26 and 30-31 October and 1 November incandescent blocks were observed rolling 500-700 m down the flanks in all directions.

Sangay – Ecuador : IG reported a high level of activity at Sangay during 27 October-2 November. Seismicity was characterized by 120-175 daily explosions, long-period earthquakes, lahar events, and signals indicating emissions. Weather clouds and rain often prevented visual and webcam observations of the volcano, though almost daily ash-and-gas plumes were identified in satellite images by the Washington VAAC or in webcam views; plumes rose 570-2,000 m above the volcano and drifted N, NW, W, and SW. Thermal anomalies over the volcano were often visible in satellite data. Incandescent material was observed descending the SE flank on 31 October.

Santa Maria – Guatemala : INSIVUMEH reported that almost daily ash plumes from Santa Maria’s Santiaguito lava-dome complex rose 500-900 m during 26 October-2 November, depositing ash on the flanks and in Monte Claro during 1-2 November. Extrusion continued at the summit dome complex and generated block-and-ash flows that traveled down the dome’s flanks in several directions, often reaching the base. Incandescence from the crater was visible at night.

Semeru – Eastern Java (Indonesia) : PVMBG reported that on 31 October two ash plumes from Semeru were observed rising 400-500 m above the summit and drifting SW. Eruptive activity was recorded the next day, though plumes were not visually observed.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that eruptive activity at Semisopochnoi’s North Cerberus crater continued during 26 October-2 November. Daily tremor and minor explosions were detected in seismic and infrasound data. Although weather clouds often prevented webcam and satellite views, intermittent, low-level ash emissions were visible during clear views, rising as high as 3.7 km (12,000 ft) a.s.l. and dissipating quickly. Sulfur dioxide emissions were detected during 26-27 and 30-31 October.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 22-29 October.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that an explosion at 1317 on 26 October at Suwanosejima’s Ontake Crater produced an eruption plume that rose as high as 3.3 km above the crater rim and ejected material 1.9 km away from the crater. Ashfall was reported in Toshima village (4 km SSW). No explosions were recorded during 29 October-1 November, though eruption plumes rose as high as 2.4 km and tephra was ejected 400 m from crater.

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