Volcanos

Roundup of Global Volcanic Activity – New Activity for the week 24 August – 30 August 2022

Bagana – Bougainville (Papua New Guinea) : The Darwin VAAC reported that on 22 August an ash plume from Bagana rose to 3 km (10,000 ft) a.s.l. and drifted SW based on satellite and wind model data.

Chikurachki – Paramushir Island (Russia) : Observers reported that on 22 August an ash emission from Chikurachki rose to 2 km (6,600 ft) a.s.l. and drifted E.

Krysuvik-Trolladyngja – Reykjanes Peninsula : The Institute of Earth Sciences reported that lava effusion at the fissure eruption in the Krýsuvík-Trölladyngja volcanic system continued during 16-19 August. Lava erupted mainly from a central cone, containing a lava pond, and flowed SE. Measurements taken during an overflight on 16 August indicated that the flow rate had decreased to 2 cubic meters per second. An estimated 12 million cubic meters of lava had erupted. The lava near the vent was 20-40 m thick, but flows were 5-15 m thick in the Meradalir valley, outside the crater area. Seismic tremor began to decrease on 19 August. Incandescence from the northern vent and from the lava flows was reflected by the gas plume that rose from the crater, but through the night of 20-21 August incandescence from the flow diminished. Incandescence from the vent was visible until about 0400 on 21 August. Beginning at around 0500 several explosions ejected spatter from the vent over a period of about 15 minutes. Just before 0600 a dense, bluish-gray plume rose from the crater, and simultaneously seismic tremor signals stopped.

Mayon – Luzon (Philippines) : On 21 August PHIVOLCS raised the Alert Level for Mayon to 1 (on a 0-5 scale) noting changes at the summit lava dome that was emplaced in 2018. Changes in morphology of the dome and minor extrusion estimated at about 40,000 cubic meters was detected during 6 June-20 August based on daily visual and camera monitoring data. Minor inflation, particularly on the NW and SE flanks, had been recorded since April. Sulfur dioxide emissions averaged 688 tonnes/day on 12 August, near baseline levels. Seismic activity was at baseline levels for most of 2022, though short-lived spikes in the number of low-frequency volcanic earthquakes were recorded on 26 May and 20 June. Based on the data PHIVOLCS stated that the dome growth was likely the result of gas pressurization at shallow depths.

Nevados de Chillan – Central Chile : On 11 August SERNAGEOMIN reported that the lava dome on the floor of Nevados de Chillán’s Nicanor Crater had grown taller in the previous few days based on webcam views. The portion of the dome that was visible with the webcam was reddish and rocky. The report noted that an increase in sulfur dioxide emissions and more intense explosions had been detected since 18 July. Similarly, an increase in the intensity and occurrence of thermal anomalies in the crater had been noted since 18 July, though anomalies had further intensified during the recent period of dome extrusion. An explosion at 1041 on 10 August was followed by the most intense thermal anomaly recorded during the last month.

Ofu-Olosega and Ta’u – American Samoa (SW Pacific) : HVO reported that an earthquake swarm in the Manu’a Islands of American Samoa continued to be recorded and felt by residents of Ta’u Island and Ofu-Olosega. About 20 earthquakes per hour were recorded by four microseismometers distributed on Tutuila, Ta’u, and Ofu-Olosega Islands. The largest events were estimated to be between magnitudes 2 and 3; most events are too small to be felt. Analysis of the seismic data indicated that the earthquakes were occurring beneath or around the Manu’a Islands, likely closer to Ta’u rather than Ofu-Olosega, though the exact locations, depths, and magnitudes were unknown. The number, size, and frequency of earthquakes recorded by instruments and being felt by people and on both islands indicated that seismicity was above background levels. Earthquakes continued to be recorded at around the same rate during 20-22 August. Two additional seismometers were installed on Ta’u during 22-23 August.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that at 1347 on 21 August a short-lived explosion at Semisopochnoi’s North Cerberus cone produced an ash emission that was visible in webcam images. The ash emission was not visible in satellite images due to weather clouds, indicating that they did not rise above 6 km (20,000 ft) a.s.l. This was the first explosion detected since 12 June.

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