Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 15 September – 21 September 2021

Agung – Bali (Indonesia) : PVMBG reported that activity at Agung was last observed on 13 June 2019 and a thermal anomaly over the crater was last identified in satellite images in October 2019. During the previous year deformation data indicated no changes at the volcano and seismicity decreased. During 1 Janaury-13 September white gas-and-steam plumes rose 20-50 m above the summit.

Aira – Kyushu (Japan) : JMA reported that an explosion at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) at 1617 on 19 September produced an eruption plume that rose 1 km above the crater rim. Crater incandescence was visible at night during 20-21 September. The report noted that inflation around the summit continued to be recorded.

Chirinkotan – Kuril Islands (Russia) : SVERT and KVERT reported that volcanic activity at Chirinkotan was last observed during 23-24 August. The Aviation Color Code was lowered to Green in mid to late September.

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 10-11 September produced ash plumes that rose as high as 2 km (6,600 ft) a.s.l. and drifted S and SE.

Etna – Sicily (Italy) : INGV reported that tremor amplitude at Etna began gradually increasing at 0420 on 21 September and then suddenly increased at 0440. Ash emissions rose from the Southeast Crater (SEC) at 0815 and by 0855 Strombolian activity was visible. An eruption plume rose 4.5 km above the summit and drifted ENE. Within an hour lava fountaining began and the plume rose 9 km and drifted ENE. Lava overflowed the crater and traveled SW. Lava fountaining had ceased by 1130, though Strombolian activity within the crater continued. Tremor amplitude decreased at 1250 and explosive activity ceased.

Great Sitkin – Andreanof Islands (USA) : AVO reported that lava effusion continued at Great Sitkin during 15-21 September, though weather clouds often prevented webcam and satellite views. Seismicity remained elevated and was characterized by small earthquakes consistent with lava effusion. A radar image from 16 September indicated that the lava dome had grown to 1,130 m E-W and 910 m N-S, and was about 30 m thick. The edges of the dome touched the S and W rims of the crater. Elevated surface temperatures were identified in satellite data during 20-21 September.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 10-17 September. Ash plumes rose as high as 7 km (23,000 ft) a.s.l. and drifted 180 km E and SE during 10 and 15-16 September.

Katmai – United States : AVO reported that on 21 September strong winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes blew unconsolidated ash SE towards Kodiak Island at an altitude up to 2.4 km (8,000 ft) a.s.l. The ash was originally deposited during the Novarupta eruption in 1912.

Krysuvik-Trolladyngja – Iceland : The eruption from the fifth vent in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 15-18 September. According to a news article lava ponded for a few days in Geldingadalur, and during 14-15 September the crust ruptured and sent a larger lava flow rapidly into the S part of the valley; the flow then turned E into the Nàtthagi valley. Authorities temporarily closed the area due to the activity and the large number of tourists; the Coast Guard rescued two people whose exit route had been cut off by the flow. Lava continued to flow on this path during 16-17 September and overtook the “A” hiking trail. Later that day at around 1800 the flow rate decreased or paused, and only minor incandescence from the vent was visible. The Institute of Earth Sciences reported that based on aerial photography acquired on 17 September the area of the flow field had grown to 4.8 square kilometers, and the total volume erupted was 151 million cubic meters. The lava-flow rate during 11-17 September averaged 16 cubic meters per second. IMO noted that 19 September marked six months since the eruption started.

Merapi – Central Java (Indonesia) : BPPTKG reported that no morphological changes to Merapi’s two lava domes, situated just below the SW rim and in the summit crater, were detected during 10-16 September. As many as 144 lava avalanches traveled a maximum of 2 km SW.

Pavlof – United States : AVO reported that periods of elevated seismic tremor with no clear explosion signals were recorded at Pavlof during 14-18 September. Webcam images were mostly obscured by weather clouds. Minor ash deposits on the upper flanks and at least one minor ash emission was visible in a clear webcam view on 18 September. Small low-level ash emissions that dissipated quickly were noted by observers and visible in webcam images at 1500 on 19 September and at 0900 on 20 September. Ash deposits on the mid-flanks were identified in satellite data. Seismicity remained elevated during 2021 September; an explosion was recorded early on the 21 September. The vent in the crater continued to migrate N based on satellite data.

Popocatepetl – Mexico : CENAPRED reported that each day during 14-21 September there were 89-152 steam-and-gas emissions from Popocatépetl. The plumes drifted mainly NW and some contained ash. As many as five daily explosions were recorded during 14-19 September and some ejected incandescent material onto the flanks. Explosions at 1818, 1839, and 2350 on 14 September produced ash plumes that rose 1.2-1.5 km above the crater rim. Explosions at 1015 and 1441 on 15 September produced ash plumes that rose 1.8-2.2 km. During 15-17 September minor ashfall was reported in the municipalities of Cuernavaca, Valle de Chalco, Chiautla, Ixtapaluca, Nezahualcóyotl, La Paz, Ecatepec, Ayapango, Temamatla, Tenango del Aire, Tlalmanalco, Amecameca, Tepetlixpa, Tlalnepantla, and Acolman in the México State, and in Iztapalapa, Xochimilco, and Tlahuac in México City.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 10-17 September.

Soufriere St. Vincent – St. Vincent : National Emergency Management Organisation (NEMO) reported that activity at Soufrière St. Vincent had been low over the previous few months.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that the number of daily explosions at Suwanosejima’s Ontake Crater increased on 16 September and remained elevated through 20 September. Eruption plumes rose as high as 2.4 km above the crater rim and material was generally ejected 300 m away from the crater. Notably, explosions at 2014 on 16 September and at 0212 on 17 September ejected material almost 1 km S and SE, respectively.

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