Roundup of Global Volcanic Activity – New Activity for the Week 4 August – 10 August 2021
Chirinkotan – Kuril Islands (Russia) : According to KVERT an explosion at Chirinkotan at 1745 on 8 August produced an ash plume that rose 2-2.7 km (6,600-9,000 ft) a.s.l. and drifted 86 km WSW and SW. KVERT raised the Aviation Color Code to Orange (the second highest level on a four-color scale). KVERT, SVERT, and the VAAC reported continuing ash-producing events through 10 August. Notably at 1915 on 9 August an ash cloud, 10 x 13 km in size, possibly rose as high as 3.7 km (12,000 ft) a.s.l. and drifted 26-30 km SSE and S. An explosive event at 0855 on 10 August produced an ash plume 11 x 14 km in size that rose 2-2.5 km (6,600-8,200 ft) a.s.l. and drifted 70 km W.
Great Sitkin – Andreanof Islands (USA) : AVO reported that unrest continued at Great Sitkin during 4-10 August with elevated seismicity, elevated surface temperatures, and explosions associated with a growing lava dome. Numerous earthquakes and small explosions were recorded on local infrasound and seismic stations during 4-5 August. During the morning of 5 August observers reported possible low-level lava fountaining from the active vent; the activity was also visible from Adak Island. Throughout the same day a volcanic plume comprised mostly of gas and steam (and possibly ash) was visible in webcam images rising to 3 km (10,000 ft) a.s.l. By 6 August the lava dome had grown to 250 m in diameter and had an approximate volume of about 1 million cubic meters. AVO noted that most of the crater was full of lava erupted in 1974 and that the current lava covered only 4-5 percent of the total summit crater area. Elevated surface temperatures were identified in satellite images during 6-10 August.
Nyiragongo – DR Congo : Goma Volcano Observatory (GVO) reported that a gas-and-ash plume rose from Nyiragongo at 1420 on 4 August.
Pacaya – Guatemala : INSIVUMEH reported that explosions at Pacaya were recorded at 0905, 1340, and 1421 on 4 August, a departure from the low levels of activity observed during the previous four months. The explosions produced ash plumes that rose about 1 km above the summit and drifted 12 km N, causing ashfall in Mesías Altas, Mesías Bajas, and Villa Canales. The report noted that the cinder cone in Mackenney Crater had been destroyed during the previous eruption phase and the crater was about 100 m deep. Cracks were seen around the crater indicating areas of instability at the summit. Steam-and-gas plumes rose as high as 1 km above the summit and drifted as far as 3 km in multiple directions during 5-10 August. No explosions were heard or visually observed, though the seismic network recorded weak explosion signals during 6-7 August.
Pagan – Mariana Islands (USA) : Felt earthquakes and minor emissions from Pagan were observed on 29 July. No additional activity had been reported by 6 August; the Aviation Color Code and the Volcano Alert Level remained at Yellow/Advisory, respectively. Seismic, infrasound, and web camera data from the volcano remained unavailable; no activity was observed in satellite images.
Pavlof – United States : Intermittent bursts of ash from the summit of Pavlof were visible in webcam views on 5 August, prompting AVO to raise the Volcano Alert Level and Aviation Color Code to Watch and Orange, respectively. The bursts formed diffuse plumes that rose just above the summit and drifted almost 10 km SE before dissipating. Minor daily ash emissions continued to be observed in webcam images during 5-9 August. The seismic network recorded elevated seismicity (tremor) and small explosions. Several small explosions were recorded during 8-9 August though weather clouds prevented satellite and webcam views.
Semisopochnoi – Aleutian Islands (USA) : AVO reported that an eruption at Semisopochnoi’s North Cerberus crater was ongoing during 4-10 August, characterized by daily explosions, ash plumes, and sulfur dioxide emissions identified in satellite images. Multiple energetic explosions were detected almost daily in seismic and infrasound data. An ash cloud rose to 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted 33 km NE during 3-4 August. Ash emissions were also visible in webcam images and photographed by an observer S of the island. An ash cloud was generated at 2123 on 4 August and was visible in satellite data until 0250 on 5 August, drifting 180 km SE over Gareloi and southern Tanaga Island. A small ash cloud at 2040 on 6 August drifted 50 km beyond the N crater vent and quickly dissipated. Another small ash cloud at 2103 caused ashfall on the webcam located 5 km NE about 30 minutes later. Ash-and-steam emissions were visible in webcam images until 2333. A large infrasound signal was recorded at 0653 on 8 August, though weather conditions prevented visual confirmation of emissions. A possible small ash cloud was visible in a satellite image at 0700. At least three separate explosions were recorded at 1714 on 8 August and 0339 and 0417 on 9 August. A small ash cloud at 900 m (3,000 ft) a.s.l. was visible in satellite images on the morning of 9 August. There were 10 explosions recorded during 9-10 August; small ash-and-steam emissions were visible in the webcam and small low-level plumes were occasionally identified in satellite data.
Suwanosejima – Ryukyu Islands (Japan) : JMA reported that 13 explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 3.8 km above the crater rim during 30 July-6 August. Large volcanic bombs were ejected 500 m from the crater. Crater incandescence was visible nightly.
Tengger Caldera – Eastern Java (Indonesia) : PVMBG reported that during 3-9 August white steam-and-gas plumes rose as high as 400 m above Tengger Caldera’s Bromo cone and drifted NW, W, and SW. Thermal anomalies were visible in satellite images on 3 and 8 August; a weaker anomaly was also visible on 29 July.
Whakaari/White Island – North Island (New Zealand) : GeoNet maintained the Volcanic Alert Level at 2 and the Aviation Color Code at Yellow for Whakaari/White Island based on continuing unrest and data collected during a recent overflight. In a 9 August report GeoNet noted that temperatures in the vent area remained high at 520 degrees Celsius; crater incandescence continued to be visible in webcams images at night. Moderate levels of carbon dioxide and sulfur dioxide emissions measured downwind of the volcano were similar to levels observed on 20 July. Low levels of ground deformation around the active vent and lake area were identified in satellite radar data. The interpretation of the data suggested a shallow magma intrusion beginning in June. Very steamy conditions obscured views of the vent area.