Sunday, January 29, 2012

[Geology2] Santorini Kolumbus Volcano - Europe - Greece

Seems like another one is waking up from a long slumber.
Greeks say do not worry about it, let the tourists continue to come.
Outside experts beg to differ, remembering the 1650 tsunami.

At 19h22 GMT (21h22 local time), a 3.2 earthquake occurred at the little-known submarine volcano Kolumbos ca. 8 km NE of Santorini, Island, Greece. This marks one of the largest events in recent months. The submarine volcano whose peak rises to just 18 m below sea level, is located on the tectonically active SW-NE fault system across Santorini which confines most volcanic vents of the Santorini volcanic complex in the past 500,000 years. Kolumbus volcano last erupted in September 1650 following a year of frequent earthquakes. The eruption produced a large explosive pumice eruption, with ash fall recorded as far as Turkey, and built a temporary island. The main phase of the eruption triggered a devastating tsunami. Toxic gasses killed more than 25 people and hundreds of livestock on Santorini by suffocation (probably H2S). There is no reason to state that new activity from Santorini or Kolumbus is likely in a foreseeable future but on the other hand, there are very few data available, unfortunately, to judge the situation. We regret that the Greek monitoring institutes are not publishing more details about the ongoing activity. Access to important earthquake details such as as their depth, are not published (they are available for earthquakes in all the other regions in Greece, raising some suspect why not for Santorini...)

Event updates:
Situation Update No. 3 on 29.01.2012 at 16:17:15.

The 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.

1. Inflation : From 1993 until 2010 there was deflation in the caldera of about 1cm/year, since the beggining 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 107 cubic meters has been located 1km 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 seismicly active part of the caldera.

3. CO2 : 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 conserns 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 visinity of the island, the next day there were 3 earthquakes magnitute 5 and above, 50 km to the SW at the other end of the fault line. Noticable 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 potencially active at depth. Consencus is that the volcano has woken up in early 2011, but opinions differ mainly on the lines of nationality of the scientists.


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