Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 23 December 2020 – 29 December 2020

Kilauea – Hawaiian Islands (USA) : HVO reported that the eruption from N and W fissure vents on the inner walls of Kilauea’s Halema`uma`u Crater continued to feed a growing lava lake during 23-29 December. Lava erupted from the N and W vents during 23-26 December with lava fountains that were sometimes 10 m high. The lake level rose above the N vent by 0300 on 26 December; later that day, volcanologists noted that the lake was slowly draining at that location. The W vent continued to feed the lake during 27-29 December. An island of cooler, solidified lava (250 m by 135 m in dimension on 28 December) slowly floated around on the lava lake’s surface. The island’s surface was about 6 m above the surface of the lava lake and was covered in tephra, possibly remnants of explosive activity generated when lava first reached the water lake. The depth of the lava lake increased from 155 m to 169 m during 23-24 December. It continued to rise and was 176 m deep by 1400 on 25 December, though a new, narrow, black rim along the N edge suggested that the lake had briefly been 1-2 m deeper, and then drained back. The lake remained 176-177 m deep through 28 December, but by 29 December had deepened to 180 m. The lake volume was an estimated 22 million cubic meters, and was 770 by 490 m in dimension by 29 December. Sulfur dioxide emissions decreased over the week, from around 30,000-40,000 tonnes/day on 23 December, to 20,000 tonnes/day on 25 December, 5,000-5,500 tonnes/day during 26-27, and finally dropping to 3,000 tonnes/day during 28-29 December. The emission plume carried Pele’s Hair and Pele’s Tears SW, depositing the tephra in areas downwind, including on HVO monitoring equipment and solar panels.

Kirishimayama – Kyushu (Japan) : JMA reported that the number of volcanic earthquakes at Shinmoedake (Shinmoe peak, a stratovolcano of the Kirishimayama volcano group) began to increase on 18 December and remained elevated. A total of 300 earthquakes were located beneath the summit crater during 16-25 December. No changes were detected in deformation and emission data. The Alert Level was raised to 2 (on a scale of 1-5) on 25 December, and the public was warned to exercise caution within a 2-km radius of the crater.

Ruapehu – North Island (New Zealand) : On 28 December GeoNet reported that during the previous week the temperature of Ruapehu’s crater lake water slightly decreased from 43 to 41 degrees Celsius. Moderate-to-strong levels of volcanic tremor were recorded along with a small number of shallow volcanic earthquakes. The largest volcanic earthquake was an M 2.2 (on 26 December) which was uncommonly large, and combined with elevated tremor indicated ongoing unrest. The Volcanic Alert Level remained at 2 and the Aviation colour Code remained at Yellow.

Soufriere St. Vincent – St. Vincent : A new effusive eruption had built a lava dome in the summit crater of Soufrière St. Vincent when observed on 29 December by personnel from the National Emergency Management Organisation (NEMO), St. Vincent and the Grenadines, and the Alert Level was raised to Orange (the second highest level on a four-colour scale). The observers noted that the small black-coloured dome had grown on the WSW edge of the 1979 lava dome. The University of the West Indies Seismic Research Centre (UWI-SRC) stated in a press briefing that seismicity at the volcano began to increase in early November and changes in the water lake and fumarolic area were noted on 16 December. A persistent thermal anomaly had been identified in satellite data over the previous couple of days, which is what prompted the NEMO field visit.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that eruptive activity at Suwanosejima’s Ontake Crater increased on 21 December with more frequent explosions; a total of 423 explosions were recorded during 21-28 December. At 0248 on 28 December a large eruptive event ejected large bombs 1.3 km SE of the crater and produced a plume that rose 200 m above the crater rim and entered weather clouds. The Alert Level was raised to 3 (on a 5-level scale).

Tengger Caldera – Eastern Java (Indonesia) : PVMBG reported that during 26-27 December white-and-gray plumes rose 50-700 m above the summit of Tengger Caldera’s Bromo cone. At 0550 on 28 December a gas-and-ash emission rose at least 500 m above the summit according to an observer. Ashfall was reported in the Ngadirejo area, about 5 km NE. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.

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