Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 10 February 2021 – 16 February 2021

Etna – Sicily (Italy) : Strombolian activity from all four of Etna’s summit craters, the Southeast Crater (SEC), Northeast Crater (NEC), Bocca Nuova (BN), and Voragine (VOR), was visible during 8-14 February. The frequency and intensity of explosions at SEC were variable; almost continuous strong explosions originated from two vents in the E part of the top of the cone. Tephra accumulated near the top of the cone and rolled several tens of meters down the flanks. Minor ash emissions rapidly dispersed. Less-intense Strombolian activity occurred at the S vent (also called the saddle vent). Intra-crater Strombolian activity at NEC sometimes produced nighttime crater incandescence. The activity at BN sometimes ejected coarse material beyond the crater rim, and rare emissions that had diffuse ash content. The the VOR Strombolian explosions ejected material that sometimes rose above the crater rim and generated diffuse ash emissions. During the morning of 15 February explosive activity at SEC gradually intensified. Activity originated from the E vents but sometimes intense explosions occurred at the saddle vent. A significant increase in tremor amplitude began at 1700. Tremor amplitude waned at 2100, the same time that explosive activity decreased. At 1700 on 16 February lava began advancing down the E flank of SEC. Part of the cone collapsed at 1705 and generated a pyroclastic flow that traveled 1.5 km along the W wall of the Valle de Bove. An ash plume rapidly dispersed to the S. Explosive activity at SEC increased and lava fountaining began at 1710. Ash clouds drifted S. Lava flows advanced into the Valle de Bove, reaching an elevation of 2,000 m by 1759 at the latest. Lapilli, 1 cm in diameter, was reported in Nicolosi (16 km S) and Mascalucia (19 km S), and ash and lapilli fell in Catania (29 km SSE). Ashfall was also reported in Syracuse, 60-80 km SSE. Another lava flow advanced N into the Valle del Leone. Lava fountains were about 500 m tall, possibly as tall as 600 m. Tremor amplitude began to decrease at 1750 and lava fountains ceased around 1800. Lava effusion from SEC gradually diminished; the flow in the Valle de Bove was a few kilometers long and smaller flows that had traveled N and S reached an elevation of 2,900. Strombolian activity persisted at SEC overnight during 16-17 February and ceased at 0715 on 17 February. Explosions at VOR were sporadic.

Merapi – Central Java (Indonesia) : BPPTKG reported that the 2021 lava dome continued to grow just below Merapi’s SW rim during 5-11 February. The lava-dome volume was an estimated 295,000 cubic meters on 11 February, with a growth rate of about 48,900 cubic meters per day. Incandescent avalanches of material were occasionally visible; they traveled 700 m SW in the upper parts of the Krasak and Boyong drainages during 9-10 February. Weather conditions prevented visual observations of the lava dome in the summit crater. Seismicity was higher than the previous week. Electronic Distance Measurement (EDM) data showed no notable deformation. The Alert Level remained at 3 (on a scale of 1-4), and the public were warned to stay 5 km away from the summit.

Sarychev Peak – Matua Island (Russia) : KVERT reported that a thermal anomaly over Sarychev Peak was identified in satellite images during 5-12 February. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale).

Raung – Eastern Java (Indonesia) : PVMBG reported that daily gray ash plumes rose as high as 2.5 km above Raung’s summit during 10-16 February. Ash plumes were sometimes dense and drifted N, NE, E, and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

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