Earthquakes: Mag 6 N. Italy and Mag 5.6 W. Bulgaria

[Astronuc]

Something to watch during the next few days and near term

I was looking at information on this quake and subsequent aftershocks:
http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usb0009tk0.php

Sunday, May 20, 2012 at 02:03:52 UTC
Sunday, May 20, 2012 at 04:03:52 AM at epicenter

36 km (22 miles) NNW of Bologna, Italy
69 km (42 miles) E of Parma, Italy
72 km (44 miles) SSE of Verona, Italy
339 km (210 miles) NNW of ROME, Italy

         UTC DATE-TIME       LAT     LON   DEPTH
 MAG      y/m/d h:m:s        deg     deg     km 
 4.5  2012/05/21 16:37:31  44.879  11.378    8.8 
 4.7  2012/05/20 17:37:15  44.885  11.296   21.0 
 5.1  2012/05/20 13:18:02  44.795  11.440    8.9 
 4.5  2012/05/20 10:12:21  44.849  11.162   10.0 
 4.7  2012/05/20 09:13:21  44.800  11.176   10.0 
 5.1  2012/05/20 03:02:50  44.776  11.090   10.0 
 6.0  2012/05/20 02:03:52  44.800  11.192    5.1 
 4.2  2012/05/19 23:13:27  44.956  11.241    6.3

I then went back to the main map to find a report on another earthquake about an hour and 15 minutes ago near Sofiya, Bulgaria. It was initially reported as mag 5.8, but has been since donwgraded to mag 5.6
http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usb0009uyx.php

Tuesday, May 22, 2012 at 00:00:33 UTC
Tuesday, May 22, 2012 at 03:00:33 AM at epicenter

Lat/Long: 42.686°N, 23.009°E
depth: 9.4 km (5.8 miles)

24 km (14 miles) W of SOFIA, Bulgaria
73 km (45 miles) N of Blagoevgrad, Bulgaria
115 km (71 miles) SE of Nis, Serbia
141 km (87 miles) NNE of Strumica, Macedonia

I have a very dear friend in Sofiya who I hope is alright.

I'm wondering if there is any connection between the two events.

 

[davenn]

Hi Astronuc

I just plotted them on google earth
they are a very long way apart, Yoou couldn't even say they were on the same faultline

if they were substantially closer together, say separated by up to ~ 100km or so, you would have a good argument to say either the 6.0 induced the 5.6 or that the 6.0 changed the local stressfield enough to trigger the 5.6.

Induced seismicity as a distance has been observed, notibly in California, as a result of the early 1990's Landers M7+ event, with induced activity much further north long long way outside both the local stressfield or the aftershock zone

my conclusion would be the Italy and Bulgaria events are not likely to be directly related

cheers
Dave

 

[Astronuc]

I wasn't thinking that one caused the other, i.e., that one was a precursor to the other, but tectonically, they are related - African plate pushing up into the Eurasian plate. The two earthquake swarms are in a related (interconnected) system of reverse faults. It's rather complicated in that particular region. There is also some coincidence with the Tethyan Metallogenic Belt, and specifically the Tethyan Eurasian Metallogenic Belt.

See attached.

and - http://www.geo.edu.ro/sgr/mod/downloads/PDF/Jankovic-MinDep-1997.pdf

I wonder if that area (around and including the Adriatic) should be designated a separate plate/zone. The western border would be through Italy and the eastern border through the Carpathians and Balkans in Romania and Bulgaria.

One report from the area around the Italian earthquake swarm mentioned some who indicated that local authorities had informed the locals that they were not in an area of concern. "For years they told us that this was an area of low seismic activity, so nobody was prepared for something like this." If that's true, then the authorities are negligent. Of course that area is in a zone of potentially strong seismic activity.
Ref: http://www.bbc.co.uk/news/world-europe-18143547
Historical seismicity - http://neic.usgs.gov/neis/bulletin/neic_b0009tk0_h.html
Seismic hazard map - http://neic.usgs.gov/neis/bulletin/neic_b0009tk0_w.html

My friend in Sofiya is OK.

 

[davenn]

Ahhh no probs :)

it was just with your last comment about any connections between the two events
Yes the only connection is that they are on the same plate boundary

That first link you gave looks very interesting with the information on mineral deposits. I am going to have to spend some time and have a good read.

I am pleased to hear that your friend is ok

Its a real problem in many of the countries around the Mediterranean that most of the buildings are of the style of construction that doesn't withstand even moderate shaking without crumbling

cheers
Dave

 

[Astronuc]

A few more earthquakes in N. Italy and near Sofiya, Bg.

Northern Italian Earthquakes
MAG    UTC DATE-TIME        LON     LAT   DEPTH
         y/m/d h:m:s        deg     deg    km  
4.7 2012/05/29 08:40:57   44.853  10.990  10.1  
4.7 2012/05/29 08:25:51   44.814  10.948  10.0  
5.8 2012/05/29 07:00:03   44.814  11.079   9.6  
4.2 2012/05/25 13:14:04   44.860  11.142  10.0  
4.5 2012/05/23 21:41:18   44.802  11.296   9.1  


Earthquake near Sofiya,  BULGARIA
4.5 2012/05/29 07:23:31   42.652  23.035   7.9