Santorini volcano (Greece) strong seismic swarm continues, scientist speak out, finally
Sunday Jan 29, 2012 16:01 PM | BY: TP
The location of the earthquakes SW of SantoriniThe highly unusual swarm of earthquakes SW of Santorini on the main fault zone that also defines the volcanic vents of the region continues with about 10 quakes larger than magnitude 2 during the past 24 hours. 2 of the quakes were magnitude 4 and 4.7, respectively.
Greek media start to pick up the story and become increasingly interested:
Today the wall of silence seems to be falling as a major Sunday newspaper has exclusive interviews with a number of Greek seismologists and geologists on the matter and some information is now public.
From 1993 until 2010 there was deflation in the caldera of about 1cm/year, since the beginning of 2011 that has changed to inflation centered at a radius of 15 km on the north part of the caldera, rapid episodes of inflation have been recorded at intervals that coincide with bursts in seismic activity. Since August the intensity of the phenomenon warranted a rise to alert level 4 (red), where it has remained ever since.
2. Magma column
A displacement of 10 million cubic meters has been located 1 km north of the central island of Nea Kameni at a depth of 4 km, it is hypothesized that it is a magma intrusion, located right at the center of the most seismically active part of the caldera.
Note: 10 million cubic meters sound like a lot, but it is a small volume for volcanic inflation. To visualize the volume, it corresponds roughly to a cube of 200 m length, or a typical cinder cone about 100 m high and a base diameter of 600 m.
Co2 levels have jumped to 39 tonnes/day along with the emission of other gasses, a rising gas column has been observed outside the port of Thirassia in the caldera (the island on the west rim).
4. Water temperature.
The rise in sea water temperature in the caldera has been confirmed.
Most of the Greek scientists have brushed any concerns saying that conditions are normal and that has happened before, Euthimios Lekkas, geologist from Athens University, even said on TV that there is no danger even of a large earthquake in the vicinity of the island, the next day there were 3 earthquakes magnitude 5 and above, 50 km to the SW at the other end of the fault line.
Noticeable exception, foreign geologists have a very different opinion, Michelle Parks, a geologist from Oxford, mentioned that the evidence points to something important, there is volcanic activity and the volcano is now potentially active at depth.
Consensus is that the volcano has woken up in early 2011, but opinions differ mainly on the lines of nationality of the scientists.
More reporting at Santorini - seismic unrest 2011-12
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