Volcanos

Roundup of Global Volcanic Activity - New Activity for the week 28 September - 4 October 2022

Alaid - Kuril Islands (Russia) : KVERT reported that a thermal anomaly over Alaid was identified in satellite images during 22-30 September. Ash plumes were visible drifting 140 km NE and SE during 26-27 September.

Home Reef - Tonga Ridge : The Tonga Geological Services reported that the new island at Home Reef that emerged from the ocean on 10 September continued to grow through 4 October. Daily counts of eruptive events producing gas-and-steam plumes were variable, though during the middle of the week they had decreased to less than 10 events per day. By 1040 on 28 September the dimensions of the new island were estimated to be 268 m N-S and 283 m E-W, and the highest point on the island was about 15 m a.s.l. The island was surrounded by plumes of discolored water within about 200 m from the shore. The plumes were elongated to the S, and were denser with suspended material within 1 km and more diffuse at distances greater or equal to 2 km. Mariners were advised to stay 4 km away from the volcano.

Nishinoshima - Izu Islands : According to JMA and the Tokyo VAAC an eruption at Nishinoshima produced ash plumes that rose to 1.8-2.6 km (6,000-8,500 ft) a.s.l. and drifted E and W during 1-4 October.

Piton de la Fournaise - Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise that began on 19 September was ongoing at a cone adjacent to the SW flank of Piton Kala Pélé during 28 September-4 October. The cone ejected lava to low heights above the rim. Lava flowed from the base of the cone in two main branches, to the SE and E, mainly through lava tubes, as far as 3 km. By 28 September the cone had grown to just over 8 m tall and around 27 m wide at its base. Average daily lava flow discharge rate estimates had a mean value of 8 meters per second at the beginning of the eruption but then stabilized at 2-4 meters per second; the flow rate increased during 28-29 September to more than 6 meters per second. Lava discharge rates were likely underestimated due to measurements hindered by weather conditions or flows obscured by tubes. Tremor levels and gas emissions also began increasing on 29 September and remained at high levels during the rest of the week. The vent at the top of the cone widened and a new, smaller cone formed on the S flank and produced lava flows. The volume of erupted lava was 2.6-5.4 million cubic meters by 30 September; peak discharge rates reached 20 meters per second at times. Sulfur dioxide emission estimates derived from satellite data had increased from about 610 tons per day on 28 September to 1,525 tons per day on 1 October. A well-defined gas plume, denser than those seen during previous days, was identified in a 30 September satellite image drifting 300 km NW at an altitude of 3 km (10,000 ft) a.s.l. A more significant sulfur dioxide plume was identified in satellite data the next day, drifting as far as 400 km. Gas plumes drifted SW during 2-3 October. Sulfur dioxide emissions continued to increase and were about 2,500 tons per day on 3 October. The cone had grown to around 12 m tall and 43 m wide at the base. During 3-4 October the ejection of lava above the cone became less intense, and the new smaller cone was only weakly active. The southernmost lava flow had reached 1,800 m elevation in an area 1.5 km NW of Nez coupé du Tremblet. During 4-5 October tremor levels fluctuated. Lava effusion increased, averaging 10 meters per second with peaks at 25 meters per second. Lava was ejected above the main vent, which was 23 m wide; the smaller vent was not active. The eruption stopped or paused at 0748 on 5 October based on visual observations and a sudden halt in tremor signals.

Trident - Alaska : A swarm began on 24 August and within about four days the seismic network began detecting episodes of weak seismic tremor and low frequency earthquakes. The events were initially located at depths around 25 km, but then they progressively shallowed to around 5 km by 28 August. Earthquakes were located 3-6 km deep since then, though some deeper events were recorded. AVO attributed the swarm to moving magma or magmatic fluids and noted that seismic swarms had previously been recorded with no subsequent eruptions.