Roundup of Global Volcanic Activity – Ongoing Activity for the Week 28 July – 3 August 2021
Aira – Kyushu (Japan) : JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 26 July-2 August. An eruptive event at 2009 on 28 July produced a plume that rose 1.3 km above the crater rim. A very small eruptive event was recorded on 2 August.
Aniakchak – United States : AVO reported that strong winds in a region N of Aniakchak and E of Port Heiden resuspended ash and blew it N on 2 August. A dense cloud of possible resuspended ash near ground levels was identified in Port Heiden webcam views. The cloud was also visible in satellite data drifting about 200 km N.
Bagana – Bougainville (Papua New Guinea) : The Darwin VAAC reported that on 31 July an ash plume from Bagana rose to 4.6 km (15,000 ft) a.s.l. based on a pilot observation. A few hours later steam emissions were identified in satellite images.
Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 27-30 July and 1-3 August ash plumes from Dukono rose to 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NE, E, and SE.
Ebeko – Paramushir Island (Russia) : A thermal anomaly over Ebeko was identified in satellite images on 25 July. According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 26-28 July produced ash plumes that rose as high as 2 km (6,600 ft) a.s.l. and drifted E.
Gareloi – United States : AVO reported that the elevated seismicity first detected at Gareloi in May had continued through June and then declined to background levels.
Kadovar – Papua New Guinea : Based on satellite and wind model data, the Darwin VAAC reported that on 1 August an ash plume from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted W.
Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 23-30 July. Multiple explosions during the week produced ash plumes that rose to 2 km (6,600 ft) a.s.l. and drifted about 350 km E.
Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 28 July-3 August. Lava fountaining and overflows from the fifth vent occurred at intervals of 10-15 hours, with similarly long periods of no activity in between; this pattern emerged around 17 July. According to the Institute of Earth Sciences an overflight was conducted on 27 July; based on new measurements, the lava effusion rate averaged 11 cubic meters per second during 2-27 July, though the average since 17 July was likely lower. The area of the flow field had grown to 4.3 square kilometers, and the total volume erupted was 109 million cubic meters. Lava flowed into the Meradalir Valley and areas to the W and did not advance in the Geldingadalur, Nátthaga, and Sydri Meradalir (SE of the fifth vent) valleys. The flows in Meradalir thickened about 1 m per day.
Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 27 July-2 August. Daily white, gray, and black plumes rose as high as 1 km above the summit and drifted in multiple directions. At 0023 on 28 July an eruptive event accompanied by a loud bang ejected incandescent lava 700-800 m from the crater. At 0722 another event ejected incandescent lava 1 km SE. Vegetated areas on the S and SW flanks caught fire, which quickly spread to the SE and W flanks due to dry conditions, burning forest as far as 2 km from the crater. At 0840 on 30 July lava was again ejected 1 km SE and loud rumbling was reported. By the morning of 30 July, the fire on the flanks was less intense and declining, but remained active at least through 1 August. Banging noises were reported on 31 July and 2 August.
Mayon – Luzon (Philippines) : On 30 July PHIVOLCS lowered the Alert Level for Mayon to 0 (on a 0-5 scale) noting that activity had declined to baseline levels over the previous several months. Ground deformation data indicated tectonic origins rather than magmatic or hydrothermal causes. The frequency of volcanic earthquakes had declined to baseline levels (0-5 events/day) during the previous six months and sulfur dioxide flux had dropped to 156 tonnes/day on 14 July, below the baseline of 500 tonnes/day. Dim crater incandescence from hot gas emissions at the summit continued to be visible in camera images; the last time it was visually observed was in May 2021.
Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both remained active during 23-29 July. The SW rim lava-dome volume was an estimated 1.878 million cubic meters and material continued to collapse down the flank. The volume of the summit lava dome was 2.817 million cubic meters. A total of four pyroclastic flows descended the SW flank as far as 2.5 km. Lava avalanches traveled a maximum of 1.2 km SE (29 times), 2 km SW (145 times), 800 m W (four times), and 500 m NW (one time). Avalanches of material that descended the W flank originated from lava emplaced in 1992 and 1998, and material that descended the NW flank is from 1948 lava.
Rincon de la Vieja – Costa Rica : OVSICORI-UNA reported that an eruptive event at Rincón de la Vieja was recorded at 1133 on 1 August, though weather conditions prevented visual confirmation of emissions.
Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 23-30 July. Activity was notable on 26 July with collapses of lava-dome blocks and small explosions. A gas-and-steam plume with some ash was visible in satellite data drifting 45 km E that same day.
Sinabung – Indonesia : PVMBG reported that at 1320 on 28 July an eruption at Sinabung produced dense ash plumes that rose as high as 4.5 km above the summit that drifted E and S; pyroclastic flows traveled as far as 1 km down the E and SE flanks. The event lasted over 12 minutes, and caused ashfall in areas to the E including the subdistricts of Namanteran, Merdeka, Berastagi, and Simpang Empat. White plumes rose up to 500 m above the summit during 29 July-2 August; weather conditions sometimes prevented visual observations.
Suwanosejima – Ryukyu Islands (Japan) : JMA reported that during 26-30 July bombs ejected from Suwanosejima’s Ontake Crater landed as far as 500 m away from the crater and plumes rose as high as 3.3 km above the rim. Explosive activity had been elevated during June and most of July, with ejected bombs landing as far as 1 km from the crater. Activity peaked on 22 July but then declined afterwards.