This paper documents the evidence of surface faulting associated to the April 6, 2009, moderate-sized earthquake (Mw 6.3) in the Central Apennines of Italy, that determined major damage to L'Aquila town and its surroundings. Coseismic surface ruptures were mapped for a minimum distance of 2.6 km along the Paganica Fault, a "minor" active fault, if compared with other faults nearby, that show more spectacular evidence of recent activity. SRL and MD parameters (2.6 km and 10 cm, respectively) are in good agreement with what expected for a magnitude 5.8 event in that tectonic environment. Although small, the coseismic vertical displacement determined significant damage to houses and infrastructures. The comparison with the past seismicity, especially the much stronger 1703 earthquake, and the evidence for activity of the other active faults, clearly show that the 2009 event cannot be taken as the reference event for assessing the seismic hazard of the region. Nevertheless, it point out once more the need to pay more attention to these moderate events, being relatively frequent in the whole Mediterranean region and potentially even more destructive than in the past, due to the expanding urban centers and infrastructures inside their epicentral regions.
Surface faulting of the April 6, 2009, Mw 6.3 L'Aquila earthquake in Central Italy
MICHETTI, ALESSANDRO MARIA;BERLUSCONI, ANDREA;LIVIO, FRANZ;SILEO, GIANCANIO;
2011-01-01
Abstract
This paper documents the evidence of surface faulting associated to the April 6, 2009, moderate-sized earthquake (Mw 6.3) in the Central Apennines of Italy, that determined major damage to L'Aquila town and its surroundings. Coseismic surface ruptures were mapped for a minimum distance of 2.6 km along the Paganica Fault, a "minor" active fault, if compared with other faults nearby, that show more spectacular evidence of recent activity. SRL and MD parameters (2.6 km and 10 cm, respectively) are in good agreement with what expected for a magnitude 5.8 event in that tectonic environment. Although small, the coseismic vertical displacement determined significant damage to houses and infrastructures. The comparison with the past seismicity, especially the much stronger 1703 earthquake, and the evidence for activity of the other active faults, clearly show that the 2009 event cannot be taken as the reference event for assessing the seismic hazard of the region. Nevertheless, it point out once more the need to pay more attention to these moderate events, being relatively frequent in the whole Mediterranean region and potentially even more destructive than in the past, due to the expanding urban centers and infrastructures inside their epicentral regions.
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