Some notes about seismotectonics

June 18, 2012  
Filed under Seismology and Hazard

The May 20th event was generated along a seismogenic structure covered by the sediments of the Po plain; the focal mechanism is clearly reversal as shown in Figure 1. Detailed information about focal mechanism calculation can be found on the INGV website (http://cnt.rm.ingv.it/data_id//7223045800/map_dmt_review.pdf).

Figure 1. Comparison of focal mechanisms reported by other institutions (http://www.emsc-csem.org/Images/EVID/27/270/270116/270116.MT.jpg).

Figure 2 shows the cluster of aftershocks for the two events, the 20th and 29th of May 2012. A migration of seismicity towards west is clearly visible.

The relative location of the two earthquakes and the distribution of Coulomb stress, suggest that the June 20th earthquake Ml 6.1, triggered the Ml 5.8 occurred on the 29th (http://www.emsc-csem.org/Files/event/267440/Coulomb.pdf).

Figure 2.  Aftershocks sequence and focal mechanism for the May 20th and 29th events (CSEM, 2012; http://www.emsc-csem.org/Files/event/267440/M6.1-North-Italy-Seismicity.jpg). 

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