Roundup of Global Volcanic Activity – New activity for the week 8 March – 14 March 2023
Karangetang – Sangihe Islands : Webcam images of Karangetang posted in PVMBG daily reports showed very minor incandescence at the summit Main Crater (S crater) during 8-14 March. Short, dimly incandescent trails on images from 8 and 10 March were possibly from avalanches. According to the Darwin VAAC at 1710 on 9 March an ash plume rose to 2.4 km (8,000 ft) a.s.l. and drifted S. A large thermal anomaly was visible in images from 0550 and 0930 on 10 March.
Merapi – Central Java : BPPTKG reported that the eruption at Merapi (on Java) continued during 3-9 March and seismicity remained at high levels. The SW lava dome produced 19 lava avalanches that traveled as far as 1.7 km down the SW flank (upstream in the Bebeng, Boyong, and Sat/Putih drainages). No significant morphological changes to the central and SW lava domes were evident in webcam images. Activity increased on 11 March with collapses of the SW lava dome. During 1212-1500 a series of 21 lava avalanches from the SW lava dome produced pyroclastic flows that traveled less than 4 km down the Bebeng and Krasak drainages. Ash plumes rose from the dome and in dense “curtains” from along the pyroclastic-flow deposits on the SW flank. The ash plumes rose as high as 3 km above the summit during 1212-1306 and drifted W and NW, causing ashfall in several areas downwind, especially in Magelang. Avalanches and pyroclastic flows from additional collapses continued to be recorded on 12 March. A total of 15 avalanches descended the SW flank as far as 2.5 km and 21 pyroclastic flows traveled a maximum distance of 2 km SW. White-and-gray ash plumes of variable densities rose as high as 2.5 km above the summit and drifted N, NW, W, and E based on Darwin VAAC notices and PVGHM VONAs. A drone was deployed to inspect the SW dome and flank, the deposits, and the summit dome; the end of the pyroclastic-flow deposits in the Bebeng drainage was 3.7 km from the center of the summit crater. By early on 13 March a total of 60 pyroclastic flows had been mainly channeled down the Bebeng. On 13 March there was a total of 36 lava avalanches; two pyroclastic flows went as far as 1.5 km down the SW flank. The Darwin VAAC reported that at 0100, 0630, and 0900 ash plumes rose as high as 4.3 km (14,000 ft) a.s.l., or 1.4 km above the summit, and drifted NW. A VONA issued on 14 March described a gray-and-brown ash plume that rose 2.5 km above the summit and drifted E and SE.
Nyamulagira – DR Congo : The Observatoire Volcanologique de Goma (OVG) reported increased activity at Nyamulagira on 13 March. Seismicity indicated magma movement at shallow depths towards the central part of the crater and incandescence above the crater rim was visible beginning at around 1800. The Toulouse VAAC reported at 1130 on 14 March that lava fountains were observed, and an eruption plume rose 1.5 km above the crater rim, based on information from OVG. The VAAC noted that the plume was not identified in satellite images due to weather cloud cover.
Takawangha – Andreanof Islands (USA) : AVO reported that the earthquake swarm at Takawangha that began in November 2022 started to decline on 1 March. Seismicity abruptly increased again on 8 March and was sustained, with M4 or lower earthquakes occurring at depths of less than about 6 km below sea level. Earthquake activity beneath Takawangha volcano and nearby Tanaga Volcano (8 km W), both on Tanaga Island, continued at a high rate during 8-9 March, with more than 100 events per hour at times. Sustained seismicity indicated an increased potential for an eruption. Earthquakes beneath Tanaga and Takawangha occurred at a rate of up to several events per minute during 10-11 March and at a slightly reduced rate during 12-14 March. The earthquakes had magnitudes up to about 4 and were mostly occurring at depths less than about 6 km.
Tanaga- Andreanof Islands (USA) : AVO reported that earthquake activity near Tanaga began to increase on 4 March with events up to the M2 range and located 9-18 km deep. Seismicity again increased around 1330 on 7 March and by 2045 earthquakes were occurring at a rate of 2-3 per minute. AVO raised the Aviation Color Code to Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level to Advisory the second lowest level on a four-level scale). The seismicity was sustained during 8-9 March and had shallowed to depths less than about 6 km, indicating increased potential for an eruption. Seismicity was also elevated at Takawangha, 8 km E; both volcanoes are located on Tanaga Island. Earthquakes beneath Tanaga Island occurred at a rate of up to several per minute, with the largest event during 8-9 March, a M3.9, located under Tanaga Volcano. Earthquakes beneath Tanaga and Takawangha occurred at a rate of up to several events per minute during 10-11 March and at a slightly reduced rate during 12-14 March. The earthquakes had magnitudes up to around 4.