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Seismic moment tensors of the April 2009, L'Aquila (Central Italy), earthquake sequence

Pondrelli, S. ; Salimbeni, S. ; Morelli, A. ; Ekström, G. ; Olivieri, M. ; Boschi, E.

In: Geophysical Journal International, 2010, vol. 180, no. 1, p. 238-242

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    Titre
    • Seismic moment tensors of the April 2009, L'Aquila (Central Italy), earthquake sequence
    Auteur
    • Pondrelli, S.. Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Via D. Creti 12, 40128 Bologna, Italy. E-mail: pondrelli@bo.ingv.it
    • Salimbeni, S.. Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Via D. Creti 12, 40128 Bologna, Italy. E-mail: pondrelli@bo.ingv.it
    • Morelli, A.. Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Via D. Creti 12, 40128 Bologna, Italy. E-mail: pondrelli@bo.ingv.it
    • Ekström, G.. Lamont-Doherty Earth Observatory, Columbia University, NY, USA
    • Olivieri, M.. Istituto Nazionale di Geofisica e Vulcanologia, CNT, Via di Vigna Murata 605, 00143 Rome, Italy
    • Boschi, E.. Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:301300
    Summary
    On 2009 April 6, the Central Apennines were hit by an Mw = 6.3 earthquake. The region had been shaken since 2008 October by seismic activity that culminated in two foreshocks with Mw > 4, 1 week and a few hours before the main shock. We computed seismic moment tensors for 26 events with Mw 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