Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week 8 December – 14 December 2021

Aira – Kyushu (Japan) : JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 6-13 December. As many as five eruptive events generated plumes that rose 1.2 km above the crater rim.

Etna – Sicily (Italy) : INGV reported that during 6-12 December activity at Etna was characterized by gas emissions from all summit craters and ash emissions from Southeast Crater (SEC); weather conditions prevented views during most of the week. During 6-7 December Strombolian activity at SEC produced almost continuous ash emissions that dispersed ENE. On 8 December the ash emissions were diffuse and discontinuous, and dissipated near the summit. At 1805 on 13 December a new vent opened at the base of the W wall of the Valle del Bove, at 2,180 m elevation. A lava flow emerged from the vents and descended a few hundred meters.

Great Sitkin – Andreanof Islands (USA) : AVO reported that slow lava effusion at Great Sitkin continued during 8-14 December and very low seismicity persisted. Elevated surface temperatures at the summit, that were sometimes intense, were detected overnight during 10-11 and 13-14 December. A radar image acquired during 12-13 December showed a growing flow field.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that during 2-3 December explosions at Karymsky generated ash plumes that rose as high as 4.5 km (14,800 ft) a.s.l. and drifted 235 km ENE. A thermal anomaly was visible in satellite images during 2-4, 7, and 9 December. Dates are based on UTC times.

Kilauea – Hawaiian Islands (USA) : HVO reported that lava effusion continued at a vent in the lower W wall of Kilauea’s Halema`uma`u Crater on most days during 8-14 December. The vent contained ponded and sometimes spattering lava that fed the lake through the E part of the W wall cone. The size of the active part of the lake varied, and lava periodically oozed from the cooler, outer margins of the lake onto the lowest of the exposed down-dropped caldera floor blocks. The sulfur dioxide emission rate was about 3,500 tonnes per day on 9 December. The eruption paused on 11 December then resumed at 2100 on 13 December.

La Palma – Spain : The eruption at La Palma continued during 8-13 December, characterized by sporadic Strombolian activity, occasional lava jetting, advancing and sometimes branching lava flows, and daily ash-and-gas emissions. Seismicity was low at depths of 10-15 km and very low at depths of 30-40 km. Volcanic tremor levels were also generally low, though they fluctuated near the end of the week concurrent with explosive activity. During 8-12 December activity at several vents in the central and SE part of the main cone was low, with only sporadic pulses of Strombolian activity and ash emissions. Ash-and-gas plumes rose as high as 3.7 km a.s.l. and drifted SSE, SSW, SW, and W. Very intense gas emissions were recorded during 9-11 December. Small landslides from fractured areas in the upper part of the secondary cone (on the E flank) descended the interior part of the crater as well as the flanks. Lava from the vents moved through tubes towards the western part of the flow field, though two main breakout flows traveled W over older flows. The most active area was along the S margin of flow 9, where 9 and 11 had joined, as lava continued to descend the sea cliff and widen in the area of Las Hoyas. During 11-12 December lobes from the S margins of the flow traveled S over new ground in the Las Norias area. On 12 December several strong pulses of tremor were accompanied by intense Strombolian activity, with the most intense events at 1200 and 1730 and decreased activity during 1300-1700. A small overflow of lava from one of the vents traveled N over older flows. One of the more intense periods produced dense dark ash plumes that rose 6 km a.s.l. and ejected bombs (some several meters in diameter) as far as 500 m away from the vent. New collapses were visible in the main cone, enlarging the crater, and at the secondary cone. During 12-13 December lava continued to travel W through tubes in the central part of the flow field. At the S margins lava filled in uncovered areas between flows 9 and 11. On 13 December tremor levels fluctuated with pulses of intense signals. A period of major explosive activity during 1745-1900 ejected bombs towards the N flank and produced ash-and-gas plumes. At 1820 video showed lava jetting above the vent and incandescent material falling onto the flanks. Activity at the vents quieted afterwards; tremor decreased at 2000 and by 2200 had reached background levels. Gas emissions from the vents were at high levels through 14 December. Lava continued to advance from the W base of the main cone on 14 December, though at a much lower rate compared to the day before. Small breakouts were visible near Montaña Cogote and Las Norias. Gas and ash emissions continued to impact island residents. Daily measurements indicated that sulfur dioxide emissions persisted at “high” levels (between 1,000 and 29,999 tons per day). Suspended ash and high concentrations of volcanic gases, specifically sulfur dioxide, triggered periodic air-quality alerts mostly affecting the W part of the island including Los Llanos de Aridane, El Paso, and Tazacorte; authorities warned residents of affected areas to stay indoors. Residents and essential personnel were often barred from entering the exclusion zones to irrigate crops, gather belongings, and remove ash from streets and buildings, especially in Las Manchas, Las Norias, and La Bombilla. During 12-13 December diffuse carbon dioxide emissions were 6.9-7.2 times average background levels, specifically impacting the La Bombilla area where dead birds were observed.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 8-14 December. Daily white-and-gray ash plumes that were sometimes dense rose as high as 700 m above the summit, though weather conditions prevented visual confirmation during 11-12 December. Incandescent material was ejected from the vent up to 300 m during 7-11 December, and was accompanied by faint rumbling.

Merapi – Central Java (Indonesia) : BPPTKG reported that Merapi’s lava domes, located just below the SW rim and in the summit crater, had both grown during 3-9 December. The estimated dome volumes were almost 1.63 million cubic meters for the SW dome and just over 3 million cubic meters for the summit dome. The intensity of the seismic signals remained at high levels. As many as 190 lava avalanches traveled a maximum of 2 km SW down the Bebeng drainage. Four pyroclastic flows traveled a maximum of 2.2 km SW.

Pavlof – United States : AVO reported seismicity at Pavlof was elevated during 8-14 December, and weak explosive activity was detected by geophysical sensors during 8-11 and 13-14 December. No ash emissions were visible, though satellite and webcam views were often cloudy. Elevated surface temperatures were visible in satellite images during 11-14 December; a lava flow on the E flank was visible in images during 12-13 December.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that low-level eruptive activity and elevated seismicity at Semisopochnoi’s North Cerberus crater continued during 8-14 December. Several daily explosions were detected in seismic and infrasound data. Small ash clouds drifting at least 185 km SE were identified in satellite images during 8-9 December. Persistent steam emissions occasionally punctuated by ash emissions were visible in webcam views during 10-11 December, and ash emissions were visible the next day even though conditions were mostly cloudy.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 3-10 December.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that crater incandescence at Suwanosejima’s Ontake Crater was visible nightly during 6-13 December. No explosions were detected by the seismic network, though eruption plumes rose 1-3.4 km and material was ejected 400-700 m away from the crater. Ashfall was reported in Toshima village (4 km SSW).

Whakaari/White Island – North Island (New Zealand) : GeoNet reported results from a 10 December overflight of Whakaari/White Island, noting a significant increase of temperatures at the active vent area. Temperatures in the main vent area were as high as 516 degrees Celsius, an increase from the range of 202-264 degrees Celsius measured in both September and November; temperatures over 500 degrees Celsius were last recorded during July-August. Very minor ash emissions continued to be visible with deposits only extending around the active vents. Gas emissions had possibly decreased, though measurements had not been taken since 18 November. The water in the lake has receded likely due to recent weather conditions.

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