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Laacher See caldera, as seen today.
Laacher See caldera, as seen today.
It's easy to forget that plenty of once-prolific volcanoes around the world have long fallen silent; geologically tame countries were often once replete with effusive or explosive eruptions. Just take Germany's Laacher See Volcano (LSV), found in the Eifel mountain range within the Rhineland-Palatinate state. This lake-filled cauldron ("caldera") is a rather serene site today, but it was originally forged out of fury. Around 12,900 years ago, a cataclysmic eruption, one that coated plenty of Europe in ash, was responsible for creating the crater-like edifice that we can see there today.
Make no mistake: coming in at a 6 on the Volcanic Explosivity Index (VEI), which tops out at 8, this was an unmistakably huge eruption. Today, according to Volcano Discovery, it's the only caldera in Central Europe, which means that in the last 12-13,000 years, this part of the world has never seen an eruption as powerful as the one that formed LSV.
Its days of volcanism aren't necessarily done and dusted, though. A new study, published in Geophysical Journal International, reveals that there are some curious rumblings going on beneath LSV. These specific tremors, known as deep low-frequency earthquakes, are a clear sign that magmatic fluids are on the move.
That's certainly noteworthy. The East Eifel Volcanic Field, of which LSV is part of, hasn't experienced an eruption for roughly 12,000 years, so the movement of magma beneath the surface is something that volcanologists are keen to document and comprehend.
Comment: UPDATE December 3rd
Anchorage Daily News reports that small aftershocks have continued with 1,800 measured between last Friday and Monday. A total of 153 measured greater than 3.0, 18 were at 4.0 or greater and five were greater than 5.0, according to the Alaska Earthquake Center.
Earthquakes associated with Friday's 7.0 earthquake north of Anchorage as of 5:45 p.m. Sunday. The red dots represent shakes in the previous 24 hours, and the yellow dots are from the past week (with virtually all of them since Friday. The large dot directly north of the city was Friday's quake).
Residents in Alaska are still reporting aftershocks from the event: