eprintid: 1811 rev_number: 14 eprint_status: archive userid: 6 dir: disk0/00/00/18/11 datestamp: 2017-01-03 12:52:29 lastmod: 2019-02-06 09:20:13 status_changed: 2017-01-03 12:52:29 type: article metadata_visibility: show creators_name: Cesca, Simone creators_name: Braun, T. creators_name: Maccaferri, F. creators_name: Passarelli, L. creators_name: Rivalta, E. creators_name: Dahm, T. creators_id: simone.cesca@gfz-potsdam.de creators_id: creators_id: creators_id: creators_id: creators_id: torsten.dahm@gfz-potsdam.de corp_creators: Institute of Earth and Environmental Science, University of Potsdam, Potsdam, Germany.Section 2.1, GFZ Potsdam corp_creators: INGV, Istituto Nazionale di Geofisica e Vulcanologia, Italy corp_creators: Section 2.1, GFZ Potsdam, Germany. corp_creators: Section 2.1, GFZ Potsdam, Germany. corp_creators: Section 2.1, GFZ Potsdam, Germany. corp_creators: Section 2.1, GFZ Potsdam, Germany. title: Source modelling of the M5-6 Emilia-Romagna, Italy, earthquakes (2012 May 20-29) subjects: MP1 subjects: RIt1 subjects: SHC divisions: IP8 full_text_status: none abstract: On 2012 May 20 and 29, two damaging earthquakes with magnitudes Mw 6.1 and 5.9, respectively, struck the Emilia-Romagna region in the sedimentary Po Plain, Northern Italy, causing 26 fatalities, significant damage to historical buildings and substantial impact to the economy of the region. The earthquake sequence included four more aftershocks with Mw ≥ 5.0, all at shallow depths (about 7–9 km), with similar WNW–ESE striking reverse mechanism. The timeline of the sequence suggests significant static stress interaction between the largest events. We perform here a detailed source inversion, first adopting a point source approximation and considering pure double couple and full moment tensor source models. We compare different extended source inversion approaches for the two largest events, and find that the rupture occurred in both cases along a subhorizontal plane, dipping towards SSW. Directivity is well detected for the May 20 main shock, indicating that the rupture propagated unilaterally towards SE. Based on the focal mechanism solution, we further estimate the co-seismic static stress change induced by the May 20 event. By using the rate-and-state model and a Poissonian earthquake occurrence, we infer that the second largest event of May 29 was induced with a probability in the range 0.2–0.4. This suggests that the segment of fault was already prone to rupture. Finally, we estimate peak ground accelerations for the two main events as occurred separately or simultaneously. For the scenario involving hypothetical rupture areas of both main events, we estimate Mw = 6.3 and an increase of ground acceleration by 50 per cent. The approach we propose may help to quantify rapidly which regions are invested by a significant increase of the hazard, bearing the potential for large aftershocks or even a second main shock. date: 2013 date_type: published publication: Geophysical Journal International volume: 193 number: 3 publisher: Oxford University Press pagerange: 1658-1672 id_number: doi:10.1093/gji/ggt069 issn: 0956-540X official_url: http://doi.org/10.1093/gji/ggt069 access_IS-EPOS: limited owner: Publisher citation: Cesca, Simone and Braun, T. and Maccaferri, F. and Passarelli, L. and Rivalta, E. and Dahm, T. (2013) Source modelling of the M5-6 Emilia-Romagna, Italy, earthquakes (2012 May 20-29). Geophysical Journal International, 193 (3). pp. 1658-1672. DOI: https://doi.org/10.1093/gji/ggt069