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Seismic moment tensors of the April 2009, L’Aquila (Central Italy), earthquake sequence
Author(s) -
Pondrelli S.,
Salimbeni S.,
Morelli A.,
Ekström G.,
Olivieri M.,
Boschi E.
Publication year - 2010
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2009.04418.x
Subject(s) - geology , seismology , seismic moment , foreshock , moment tensor , centroid , focal mechanism , geodetic datum , extensional definition , aftershock , geodesy , slip (aerodynamics) , induced seismicity , fault (geology) , deformation (meteorology) , tectonics , geometry , physics , mathematics , oceanography , thermodynamics
SUMMARY On 2009 April 6, the Central Apennines were hit by an M w = 6.3 earthquake. The region had been shaken since 2008 October by seismic activity that culminated in two foreshocks with M w > 4, 1 week and a few hours before the main shock. We computed seismic moment tensors for 26 events with M w between 3.9 and 6.3, using the Regional Centroid Moment Tensor (RCMT) scheme. Most of these source parameters have been computed within 1 hr after the earthquake and rapidly revised successively. The focal mechanisms are all extensional, with a variable and sometimes significant strike‐slip component. This geometry agrees with the NE–SW extensional deformation of the Apennines, known from previous seismic and geodetic observations. Events group into three clusters. Those located in the southern area have larger centroid depths and a wider distribution of T ‐axis directions. These differences suggest that towards south a different fault system was activated with respect to the SW‐dipping normal faults beneath L’Aquila and more to the north.

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