German - Czech Border: Large swarm may signal magma movemen

[GCANE]

10,000 Earthquakes In Swarm Reported On German-Czech Border: Magma On The Move Say Geologists

August 27, 2011 – W. Bohemia, CZ – The Geophysical Institute, Academy of Sciences of the Czech Republic says it has recorded almost 10,000 earthquakes during the last three days in West Bohemia, a region located close to the Czech Republic’s western border with Germany.

The earthquake swarm started late on Tuesday and continued through Friday. While many have gone unnoticed by the local population some of the larger tremors, including eight quakes exceeding 3 magnitude have been felt in the towns of Chemnitz, Karlovy Vary, Birch, and Luby.

The most recent earthquake measured 3.6 magnitude on the Richter Scale and hit at 0645hrs GMT on Friday at a shallow depth of three miles. The quake epicentre was located 81 miles (129 km) NE of Nürnberg 82 miles (131 km) SW of Dresden, 90 miles (144 km) W of Praha, 128 miles (204 km) NW of Budejovice, 131 miles (210 km) NNW of Schärding, and 227 miles (364 km) NW of Wien.

Commenting on the latest earthquake swarm, the Geophysical Institute, Academy of Sciences of the Czech Republic stated: “The activity started in the evening of 23 August and is almost continuous till now (26 August morning). Almost 10 000 events were recorded in total up to now. Already eight events M>3.0 and 200 M>2.0 occurred. The location of hypocenters directly below the NKC station, so it appears a new patch of the fault plane is being activated.”

In recent years, scientists have noted an increase in the movement of magma towards the earth’s surface in the Cheb Basin, western Czech Republic. They say rising magma could be one of the causes of the earthquake swarms, which regularly occur in the Vogtland, North-West Bohemia, the Fichtelgebirge and the Upper Palatinate. The last earthquake swarm to occur before this week’s activity was in 2008.



http://earthquake-report.com/2011/08/26 ... ny-border/


http://www.irishweatheronline.com/news/ ... 34243.html

[GCANE]

Quakes in swarm listed here under Vogtland:


http://geofon.gfz-potsdam.de/eqinfo/list.php

[Extratropical94]

Wow, that surely is interesting.
My grandparents live in the area, 70 mi. ENE of Nürnberg and 105 mi. SSW of Dresden (kind of directly at 49.8 N / 12.4 E).
I'll ask them if they felt anything.

[Extratropical94]

They said they felt nothing, didnt't even know that such things are happening.
Some buildings a bit closer to the quakes seem to have suffered small structural damage (cracks in the walls etc.)

[Nightwatch]

4.0 southwestern poland. Is that related?

So actually it's a 'normal' swarm? Happened earlier?

Rising magma doesnt sound normal tho.. cant that get to the surface?

[Extratropical94]

Judging from the location of all the other quakes that happened in an area of about 10 mi. diameter and this one being a few hundred miles apart I think it is not a part of the swarm itself, but has its origin in the same tectonic activity.
4.0 is strong for the region, last major quake happened in 2008 as part of another swarm. That one measured 4.4 on the Richter scale.
Rising magma is certainly not a threat for the residents in the Vogtland or adjacent areas. The magma rises and sinks steadily in those caverns beneath the solid layers. This has always been the case, especially in those times when the region had active volcanoes a few million years ago.

[Nightwatch]

Judging from the location of all the other quakes that happened in an area of about 10 mi. diameter and this one being a few hundred miles apart I think it is not a part of the swarm itself, but has its origin in the same tectonic activity.
4.0 is strong for the region, last major quake happened in 2008 as part of another swarm. That one measured 4.4 on the Richter scale.
Rising magma is certainly not a threat for the residents in the Vogtland or adjacent areas. The magma rises and sinks steadily in those caverns beneath the solid layers. This has always been the case, especially in those times when the region had active volcanoes a few million years ago.

Thx for explaining. However, isn't the magma too hot for the layers, so they melt over the years, and is it not possible to reach to the surface again?

[Extratropical94]

Well most of the magma is part of the layer. When the solid rock reaches depths of about 30-50 km, it is compressed and thus heated. This heating can bring temperatures high enough to melt the rock. So the hole layer is steadily melting, but also becoming solid again at other places. This cycle continues on and on until the magma finds a way through a gap in the rock to reduce its pressure.
But I would totally rule out that scenario in this area as volcanic activity mainly happens near tectonic faults.

[GCANE]

Activity dropped earlier part of the week, but appears to be resuming now.


http://geofon.gfz-potsdam.de/eqinfo/eve ... fz2011refc

[Extratropical94]

4.0 quake in the Vogtland yesterday at 23:36 UTC / 1:36 CEDT