Stromboli (Eolian Islands, Italy): The volcano has been quite active recently, with an increase of explosions from its several active vents, clustered in the northern (N) and central-southern (CS) sectors of the current crater terrace.
In particular, the vents of the N2 sector (s. image) have been showing near-continuous lava spattering throughout the past days and weeks. Interestingly, there are also phases of strong intensification when the spattering starts to resemble weak lava fountaining producing near-continuous jets that reach up to a few tens of meters. Such phases can last up to a few hours and were seen and described by colleague Marc Szeglat both the day before yesterday and yesterday.
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La Palma (Canary Islands (Spain)): For 3 days, no eruptive activity has taken place, and the likelihood that the eruption is actually over is clearly increasing. The cone only shows mild degassing and no lava flows are active any more.
Official confirmation when the eruption is declared over will likely need to wait a little longer. Some doubt remains as to the significance of the continuing earthquake activity: although of low energy and overall on a decreasing trend, it remains significant, and could indicate that magma at depth is still able to pressurize and fracture rocks at depth and create intrusions that might eventually allow it to rise further. However, this is far from certain – it could also be adjustments of the system triggered by the massive shifts of masses that has occurred during the eruption. In the latter case, the quakes should slowly die out.
During the past 24 hours, there were 3 quakes of magnitudes 3.3-3.5 at 35-36 km depth, in addition to many more smaller quakes (22 quakes of magnitudes 2.0-2.9 and 48 quakes below magnitude 2.0). If looking at the various maps published of recent quakes, it might seem that there is a a strong increase of quakes. This apparent increase, however, is mostly in the number of quakes, especially for those in the deeper region around 30-40 km. This is mostly an artifact caused by the absence of volcanic tremor, which acted as noise during the eruption and was simply hiding smaller quakes in its signal. Now, the very sensitive seismic devices are again able to pick up very small quakes below magnitudes 2, as well as quakes deeper down (whose signals at the surface are much weaker). In other words, most of the apparent increase of quakes is only an increase in detection sensitivity. Still, a weak increase in the total energy of the seismic activity remains visible for the past 48 hours or so. With most likelihood, it is part of a normal fluctuation, but nobody can be sure.
Suwanose-jima (Ryukyu Islands): Volcanic Ash Advisory Center Tokyo (VAAC) issued the following report: ACTIVITY CONT. VA AT 20211217/1200Z FL040 EXTD SE OBS VA DTG:17/1150Z
Manam (Papua New Guinea): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Darwin warned about a volcanic ash plume that rose up to estimated 10000 ft (3000 m) altitude or flight level 100 and is moving at 20 kts in SE direction.
The full report is as follows: VA ERUPTION TO FL100 EXTN TO SE OBS VA DTG:17/1620Z to 10000 ft (3000 m)
Semeru (East Java, Indonesia): (17 Dec) The volcano produced three pyroclastic flows at 09:01, 09:30 and 15:42 local time today reaching length of at least 4500 meters from the summit.
Block-and-ash flows created billowing ash plumes separating from the pyroclastic density currents (so-called phoenix clouds).
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Santiaguito (Guatemala): 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: OCNL VA CLDS OBS IN STLT IMAGERY to 15000 ft (4600 m)
Fuego (Guatemala): 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: VA EMS OBS IN STLT IMAGERY to 15000 ft (4600 m)
Nevado del Ruiz (Colombia): (16 Dec) Volcanic Ash Advisory Center Washington (VAAC) issued the following report: NO VA OBS IN WEBCAM OR STLT
Sangay (Ecuador): Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Washington warned about a volcanic ash plume that rose up to estimated 24000 ft (7300 m) altitude or flight level 240 .
The full report is as follows: VA CLDS OBS IN SUMMIT WEBCAM to 24000 ft (7300 m)
Reventador (Ecuador): Volcanic Ash Advisory Center Washington (VAAC) issued the following report: VA EMS HAS DISP
Sabancaya (Peru): Volcanic Ash Advisory Center Buenos Aires (VAAC) issued the following report: continuous ash emissions
Volcano Activity Summary for 17 Dec 2021:
