HR: 1330h
AN: S42E-0210    [PDF]
TI: Moment Tensor Solutions for the 2002 Molise (southern Italy) Earthquake Sequence: New Insights for Tectonic stress field.
AU: * Di Luccio, F
EM: diluccio@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome, 00143 Italy
AU: Pino, A
EM: pino@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome, 00143 Italy
AU: Fukuyama, E
EM: fuku@bosai.go.jp
AF: National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, 305-0006 Japan
AU: Mazza, S
EM: mazza@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome, 00143 Italy
AU: Olivieri, M
EM: olivieri@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome, 00143 Italy
AU: Pondrelli, S
EM: pondrelli@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome, 00143 Italy
AB: On October 31, 2002 a $M_l=5.4$ earthquake occurred in southern Italy, between Molise and Puglia regions, at margin between the Apennine fold and thrust belt (at west) and the Adriatic subducted lithosphere (at east). In this area no historical event nor seismogenic fault are reported in the literature. In spite of its moderate magnitude, the event generated severe damage in the cities close to the epicentral area and 27 people were killed by the collapse of a primary school in S. Giuliano di Puglia. We computed moment tensor solutions for 15 events, as small as $M_l$$=$$3.5$ ($M_w$$=$$3.7$), inverting broadband regional waveforms. The obtained focal mechanisms display pure strike-slip geometry, mainly with focal planes oriented NS (sinistral) and EW (dextral). Several solutions display a counterclockwise rotation of the planes, in particular for later events, west of the mainshock. Waveform analysis indicates that the major events ruptured the EW planes, while the local stress field resulting from the inversion of the focal mechanisms show NW-SE compression. Imaging the aftershock distribution and moment tensor solutions, it appears that several structures have been initiated rather than a single fault due to the mainshock. How is the Molise sequence related to the normal faulting system at west (along the Apennines) and the dextral strike-slip structure at east (the Mattinata fault)? We attempt at the interpretation of role played by this sequence in the framework of regional tectonics.
DE: 7215 Earthquake parameters
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting