HR: 10:35h
AN: S52A-02    [Abstracts]
TI: Does Tectonic Knowledge Help Identifying Accelerating Moment Release Prior to Large Earthquakes? Examples From Italy
AU: * Barba, S
EM: barba@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Roma, 00154 Italy
AU: Grondin, V
EM: GValeriegrondin@aol.com
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Roma, 00154 Italy
AU: Grondin, V
EM: GValeriegrondin@aol.com
AF: Universit\'{e} de Rennes 1, Campus Scientifique de Beaulieu, Rennes, 35042 France
AB: Before large events, moderate magnitude seismicity has often increased in a broad area around the future epicenter. Apparently, the seismic moment release accelerates (AMR) according to a time-to-failure power law. Several models explain such a phenomenon based on regional damage mechanics or the physics of criticality, where the (critical) region and the (critical) time involved are statistically determined. This work exploits the feasibility of the accelerated moment release concept for Italy, testing if the region showing the AMR pattern can be set a-priori. Specifically, we select areas based only on tectonics by including the major and antithetic faults. In such predetermined areas, we search the historical (1600-1980) and instrumental (1987-2003) earthquake catalogues for constant or accelerated MR patterns. In addition, we consider all earthquakes above a magnitude threshold (M 6.0 historical, M 5.3 instrumental) to define successes, failures, and false alarms. Results show that: (a) all earthquakes occurring in the Apennines fold-and-thrust belt were correctly anticipated; (b) the large shock is not required to occur at the centre of the region. On the contrary, (c) AMR patterns did not precede earthquakes in the less-faulted and slowly-deforming Apulia platform, although (d) identification of false alarms needs additional work. We conclude that tectonics strongly influences the detection of AMR patterns and provides useful a-priori information.
DE: 8123 Dynamics, seismotectonics
DE: 7209 Earthquake dynamics and mechanics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting