Wed Dec 15 2021, 06:42
6:42 am | BY: VN
The La Palma eruption continued from December 8 to 13, characterized by sporadic Strombolian activity, occasional lava jets, advancing and sometimes branching lava flows, and daily ash and gas emissions. Seismicity was weak at depths of 10 to 15 km and very weak at depths of 30 to 40 km. Volcanic quake levels were also generally low, although they fluctuated towards the end of the week alongside explosive activity.
From December 8 to 12, the activity of several vents in the central and SE portions of the main cone was weak, with only sporadic pulses of Strombolian activity and ash emissions. The ash and gas plumes rose to an elevation of 3.7 km and drifted towards the SSE, SSW, SW and W.
Very intense gas emissions were recorded from December 9 to 11. Small landslides originating from fractured zones 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 to the western part of the flow field, although two main rupture flows traveled in W on 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 cliff and widen in the Las Hoyas area. From December 11 to 12, the S-margin lobes of the flow traveled S on new soil in the Las Norias area.
On December 12, several strong pulses of tremor were accompanied by intense Strombolian activity, with the most intense events at 12:00 p.m. and 5:30 p.m. and reduced activity between 1:00 p.m. and 5:00 p.m. A small lava overflow from one of the vents traveled north over older flows. One of the most intense periods produced dark and dense ash plumes which rose to 6 km altitude and ejected bombs (several several meters in diameter) up to 500 m from the vent.
New collapses were visible in the main cone, enlarging the crater, and at the level of the secondary cone. From December 12 to 13, lava continued to move westward through tubes in the central part of the flow field. At the S margins, lava filled the uncovered areas between flows 9 and 11.
On December 13, the tremor levels fluctuated with intense signal pulses. A period of major explosive activity between 1745 and 1900 ejected bombs towards the N flank and produced plumes of ash and gas. At 6:20 p.m., the video showed jets of lava over the vent and glowing material falling on the flanks.
The activity at the vents subsequently subsided; the tremor subsided in 2000 and by 2200 had reached background levels. Vent gas emissions were at high levels until December 14. Lava continued to advance from the main cone’s W base on December 14, but at a much slower rate than the day before.
Small escapes 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 tonnes per day). Suspended ash and high concentrations of volcanic gases, especially sulfur dioxide, have triggered periodic air quality alerts mainly affecting the western part of the island, including Los Llanos de Aridane, El Paso and Tazacorte ; Authorities have warned residents of the affected areas to stay indoors.
Residents and essential staff were often prohibited from entering exclusion zones to irrigate crops, collect personal belongings and remove ashes from streets and buildings, especially in Las Manchas, Las Norias and La Bombilla. From December 12 to 13, diffuse carbon dioxide emissions were 6.9 to 7.2 times average background levels, specifically affecting the La Bombilla region where dead birds were seen.
Sources: Gobierno de Canaries, Instituto Geográfico Nacional (IGN), Instituto Volcanológico de Canarias (INVOLCAN)
From: Smithsonian / USGS Weekly Volcanic Activity Report