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Erno
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Again wave of earthquakes at dawn south of Chania

by Erno » 07 Mar 2016, 11:31

Again wave of earthquakes at dawn south of Chania - 7 March, 2016

earthquakes070316.jpg


An "unusual" microseismic wave occurred during the night until the early hours in the area south and southwest of Chania.

Apart from the usual and almost daily earthquakes with a magnitude less than 2.0 on the Richter scale, the seismographs recorded five earthquakes greater than 3.0 on the Richter scale as follows:

1: 01:18 am earthquake of 4.2 Richter with epicenter 22 km west of Paleochora with a depth of two kilometers.

2: 01:22 am 3.7 Richter earthquake centered 13 km north of Paleochora with a depth of two kilometers.

3: 02:41 am 3.6 Richter earthquake centered 10 km south of Platanos Kissamos with a depth of two kilometers.

4: 03:27 am 3.5 Richter earthquake centered 14 km south of Platanos with a depth of two kilometers.

5: 05:39 am 3.2 Richter earthquake, centered 9 km southwest of Platanos, with a depth of five kilometers.

(Data from the Euro-Mediterranean Seismological Centre. The indicative map is of the Geodynamic Institute of Athens)

An analog "barrage" of earthquakes in the same area was noted in early February and then the Director of the Laboratory of Geophysics and Seismology and UNESCO Mr. Philippos Vallianatos stated that "usually it is a phenomenon that slowly develops, producing small earthquakes, and then is ending. But we will see ... ".

From: http://flashnews.gr/post/262185/mparaz- ... twn-xaniwn
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Re: Again wave of earthquakes at dawn south of Chania

by mike » 10 Mar 2016, 12:39

It gets even more interesting. The map in the article is the one that is auto-generated by the seismic stations. These readings are checked by a seismologist. Here are the revised results over the past week.

March 5-6. So far, not much activity (as was the previous week):
March5-6.jpg


Then, March 7-8:
march7-8.jpg


And finally March 9-10:
March9-10.jpg


Here is a composite of days 7-10:
composite.jpg


What is so striking is, first, how the earthquakes are oriented in a straight line, roughly NNE-SSW; and second, how many of the earthquakes are below 15km (blue dots are to depth less than 15km, Green15-30km).

Earthquake swarms (translated from Greek as "barrage" in article) are not so unusual. They often follow one big earthquake (called aftershocks). In this case, however, there has not been a big quake to trigger aftershocks. You also see earthquake swarms around volcanoes, such as Santorini, in which case the trigger is the movement of magma in deeper chambers. This is not likely to be the case for west Crete. So, this swarm probably reflects a movement along a deeper fault line. Even so, it is less usual that such swarms happen so rapidly along fault lines. The seismologist quoted in the article says that the development of quakes is usually slower.

Lucky for Crete, that the energy is being released in many small quakes over several days, and over a relatively large area.

It is mentioned in the article you quote that something similar happened in February. Here is a composite map for the entire month:
February.jpg


As you can see, the earthquake swarm is in the same place and so probably the same cause, whatever it is.

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Re: Again wave of earthquakes at dawn south of Chania

by Erno » 10 Mar 2016, 13:05

It is the activity of a large fault system, indeed, called The Fault of Western Crete.

In the area of Sfinari village in West Crete exists a large scale fault, striking NNW-SSE, which passes through the village.

Here is the lithological map of the area:

sfinari-fault.gif


Here is a look at the wider area:

sfinari-fault.jpg


From the images it seems obvious, that if one segment is starting to move, all others will do too. Hence the wave of quakes.

The Fault of Western Crete is a rupture zone of significant length ( > 40km) and a N-S strike, dipping to the West and directly related to D2 tectonics. The fault shapes the western coast of Crete and it is composed of several segments, the most important of which are the Gramvousa (11 km), Falasarna - Sfinari (11 km) and Kampos - Stomion (10 km) segments. These segments cut the basement rocks (the HP/LT phyllite - quartzite unit and limestones of Tripolis and Pindos zones), as well as the Neogene sediments. Moreover, their recent activity affects their own tectonic scree found in older terraces, as well as the erosion materials in more recent terraces.

From (with lots more): http://www.virtualexplorer.com.au/artic ... aults.html
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Re: Again wave of earthquakes at dawn south of Chania

by Erno » 12 Mar 2016, 12:04

Onshore earthquakes in Crete became particularly noticeable - 12 March, 2016

earthquakes120316.jpg


An earthquake that was felt today in Chania occurred at 9.51 in the morning.

According to the latest data from the Euro-Mediterranean Seismological Institute, the earthquake was around 4.1 on the Richter scale, and happened 14 km. northeast of Paleochora.

The earthquake was on land and had a depth of only 2 km, and therefore was particularly felt, not only in Paleochora and neighboring areas, but even in the north of Chania.

From: http://flashnews.gr/post/262885/xersaio ... -aisthhtos
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Re: Again wave of earthquakes at dawn south of Chania

by Erno » 12 Mar 2016, 13:12

earthquakes120316-2.jpg


A LARGE earthquake of 4,7 - 4,9 Richter just happened in Crete! It was felt in all of Greece.

From: http://www.emsc-csem.org/Earthquake/ear ... ?id=493861

The quake was recorded 12 km northwest of Paleochora with a depth of only 10 km.
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Re: Again wave of earthquakes at dawn south of Chania

by Erno » 13 Mar 2016, 13:58

New earthquake shakes Chania - 13 March, 2016

earthquake130316.jpg


24 Hours after the strong earthquake of 4.9 on the Richter scale which occurred west of Chania and the barrage of seismic vibrations recorded for several days in Chania, a new earthquake rattled Chania.

The new earthquake was at 15:22 noon local time today and had a magnitude of 4 degrees on the Richter scale, according to assessment of the Euro-Mediterranean Seismological Centre, and like the previous earthquakes was felt because it occurred on land and on a short focal depth of 2 km.

The epicenter is 11 km to the southwest of Platanos and 45 km west of Chania.

From: http://flashnews.gr/post/262984/nea-sei ... e-ta-xania

At 13:58 it was followed by a 3.6 quake at just 0.7 km depth.

earthquakes130316.jpg
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