Volcanic activity worldwide 6 Dec 2021: Etna volcano, Semeru, Grímsvötn, Reventador, La Palma, Nev…

Map of today’s active volcanoes

Etna (Sicily, Italy): Ongoing strombolian activity is now in progress from the South-East crater characterized by weak ash emissions extending to the E-NE of the volcano today.
A volcanic tremor has slowly increased, but remains at medium values detected at 2700 meters altitude.
No significant ground deformation was recorded.

Grímsvötn (Iceland): The Icelandic Meteorological Office (IMO) raised the alert level of the volcano orange, as chances that it might erupt have increased.
This morning, a magnitude 3.6 earthquake occurred at shallow depth at the eastern summit caldera rim of the glacier-covered volcano. The recent glacial flood has more or less ended and resulted in a subsidence of 77 meters of the ice sheet above the summit. Whether or not the resulting significant pressure drop on the volcano’s system will trigger an eruption or not is likely something that will be seen in the next few days.

Today December 6th at 06:16 an M3,0 earthquake was detected at Grimsvatn. A few aftershocks have been detected, the largest M2.3. No volcanic tremor has been detected. GPS measurements in Grímsvötn shows that the ice-cap has subsided by about 77 meters. https://t.co/gbP5ib8dfv

— Icelandic Meteorological Office – IMO (@Vedurstofan) December 6, 2021

La Palma (Canary Islands (Spain)): Activity has been similar as yesterday and overall continued to decline. At the vent, ash emissions and explosions have been rare and intermittent, but produce occasional plumes rising up to approx 2,000 m altitude.
Lava effusion continues at similar levels as yesterday, but seems to be now again mainly coming from the vents at the main cone, while the new fissure that opened last week at the southern margin of the flow field west of Montaña Cogote is less active and has merged with the southernmost older flow. Its front has merged with the flow number #9 in the flat lava delta that had formed in the 1949 eruption, but has so far not entered the ocean.
… [read more] … [show less]
Volcanic tremor remains similar as yesterday at low levels without much fluctuations.
Seismic activity has continued to decrease. Only about 20 quakes were registered during a 24 hour period, likely the lowest number since the beginning of the eruption.

Suwanose-jima (Ryukyu Islands): Volcanic Ash Advisory Center Tokyo (VAAC) issued the following report: ERUPTED AT 20211206/1900Z FL120 EXTD SE OBS VA DTG:06/1900Z
…6 Dec:
A number of stronger eruptions than the average size occurred at the volcano over the past two days.
Surveillance cameras and VAAC Tokyo observed tall and dense ash plumes rising from the crater to estimated 3 km and 4,3 km altitude.
… [read more] … [show less]
Given the volcano’s summit elevation (799 m), generated 3,5 km and 2,2 ash columns may be classified as high ash plumes.
Explosions generated pyroclastic material such as ash, lapilli, bombs and blocks. Blocks were ejected 600 meters distance from the crater.

Semeru (East Java, Indonesia): Volcanic Ash Advisory Center Darwin (VAAC) issued the following report: VA REPORTED TO FL150 MOV N AT 06/1944Z OBS VA DTG:06/1950Z
…6 Dec:
The death toll from the eruption Saturday Dec 4th has risen to 22, the National Emergency Service (BNPB) said. 22 more people are still missing and possibly buried (and most likely dead) underneath thick layers of ash or mud. More than 2,000 people have been evacuated.
What exactly caused the collapse of material is still matter to debate. According to the Indonesian Volcanological Survey (VSI) the hot avalanche on Saturday originated from the 2-km long lava flow on the steep slopes of the mountain and reached a length of 4 km, i.e. extended 2 km beyond the tip of the lava flow. Its deposit consists of very hot material of powder-grain-sized ash and blocks of all sized and has temperatures of 800-900 degrees Celsius. Some of it entered the valley of the Kobokan River and interacted with the water to form the devastating mud flows.
… [read more] … [show less]
The activity at the volcano before the eruption was also characterized by frequent strombolian explosions, up to 70 a day according to vulkane.net. This could have led to a rapid accumulation of additional material in the crater area, making it more and more unstable. During yesterday, only two explosions were reported from the volcano as well as two smaller pyroclastic flows.
However, it seems probable that the events were not really caused by an increase of activity at the volcano (there is strong evidence there was at least no significant explosive activity), but that heavy rainfalls might have also have played a role, and at least been a partial trigger for the massive slide of hot and other rock materia – see the below tweet and the previous update for more details.

Nevado del Ruiz (Colombia): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Washington warned about a volcanic ash plume that rose up to estimated 20000 ft (6100 m) altitude or flight level 200 .
The full report is as follows: NEW VA EMS to 20000 ft (6100 m)

Reventador (Ecuador): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Washington warned about a volcanic ash plume that rose up to estimated 15000 ft (4600 m) altitude or flight level 150 .
The full report is as follows: ONGOING VA EMS to 15000 ft (4600 m)

Sabancaya (Peru): Volcanic Ash Advisory Center Buenos Aires (VAAC) issued the following report: INTERMITTENT EMISSIONS

Nevados de Chillán (Central Chile): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Buenos Aires warned about a volcanic ash plume that rose up to estimated 12000 ft (3700 m) altitude or flight level 120 and is moving at 10 kts in S direction.
The full report is as follows: SPORADIC EMISSIONS to 12000 ft (3700 m)

Volcano Activity Summary for 6 Dec 2021:

Continuous ash emissions from Etna today (image: Boris Behncke/twitter)