» Earthquakes in Austria/Slovenia and Japan

2013-02-03 | Christoph Grützner in Earthquake

On 2 Februar, a magnitude 4.5 earthquake occurred in shallow depth (~2-7 km) directly at the border between Austria and Slovenia. USGS reports an oblique-slip focal mechanism and a magnitude of Mw4.0 only. According to the Austrian Zentralanstalt für Meteorologie und Geodynamik the quake was felt widely and even in Vienna. Very light damage has been reported from the epicentral area.

Moment tensor data from USGS (via EMSC) show an oblique-slip mechanism. Source: http://static1.emsc.eu/Images/EVID/30/303/303150/303150.MT.jpg

There are some studies on earthquakes in Western and Northwestern Slovenia, but I haven’t found papers on paleoseismological studies in central Northern Slovenia. I have to admit I did a quick search only. Some more studies on paleoseismology in this area would be highly appreciated, since the Krško nuclear power plant is only around 100 km away…

Gosar, A. 2012: Application of Environmental Seismic Intensity scale (ESI 2007) to Krn Mountains 1998 Mw = 5.6 earthquake (NW Slovenia) with emphasis on rockfalls. Nat. Hazards Earth Syst. Sci., 12, 1659-1670.
Bajc, J., Aoudia, A., Saraò, A., Suhadolc, P. 2001: The 1998 Bovec-Krn Mountain (Slovenia) Earthquake Sequence. Geophysical Research Letters, 28, 9, 1839-1842.
Fitzko, F., Suhadolc, P., Aoudia, A., Panza, G.F. 2005: Constraints on the location and mechanism of the 1511 Western-Slovenia earthquake from active tectonics and modeling of macroseismic data. Tectonophysics 404, 1-2, 77-90.

Mw6.8 in Japan

A strong earthquake of Mw6.8 rocked Hokkaido, Japan, and left few people injured, despite it occurred in a rather large depth of 100 km. There are two NPPs in the area, but no problems have been reported. USGS estimates intensities of VI – VII and peak ground accelerations of ~15%g only (25% at 0.3s period).

USGS shake map. Source: http://earthquake.usgs.gov/product/shakemap/usc000f03a/us/1359826047993/download/intensity.jpg

Retrofitting in Israel

Meanwhile, there are complaints that reinforcement of buildings in earthquake-prone areas of Israel is limited to the big cities like Tel Aviv and Haifa while areas like Dimona and Kyriat Shimona see only little progress. This is a problem in almost every country that made the decision to reinforce buildings in accordance with the latest scientific findings. At least, they started already, which is good news. A look at the seismic hazard map illustrates the basic problem of seismic hazard in Israel – it’s rather high almost everywhere: