A detailed reconstruction of the rupture mechanism of the 1980 Campania-Lucania (southern Italy) earthquake is presented. This event is also improperly known as Irpinia earthquake, which is however only a part of the region influenced by macroseismic effects and where the main faults are located. Relocation of the main hypocenters and the estimation of fault-plane solutions of the aftershocks, through P-wave velocity inversion models provide an overall comprehensive picture of the source mechanism. The analysis of available data suggests a complex rupture mechanism, as already identified by many previous studies, which consists of three separate events. The present work provides however a convincing evidence of almost simultaneous activation of a syntheticantithetic normal fault couple as characterizing rupture source process of this earthquake. The first event activated the northern NW-SE striking segment of a large (~40-km-long), high-angle, NE-dipping, master fault. With the second event the rupture propagated southward along the fault strike and activated the southern WNW-ESE striking segment (~15-km-long) of the same master fault. Conversely, the third rupture occurred along a SW-dipping normal fault antithetic to the master fault northern segment. This mechanism is well evidenced by the revised location of the hypocenter of the main event, and the location of the aftershocks and their fault-plane solutions, as well as by the underlying three-dimensional P-wave velocity structure. The model originally proposed by Amoruso et al., 2005 that was based purely on the inversion of co-seismic vertical displacement data is confirmed by the present analysis, as it satisfies all of the available experimental observations and better constrains the location and fault-plane solutions of the aftershocks, the velocity discontinuities, and the rupture observations at the surface (see Bello et al. this conference). This conclusion is also supported by analyses of the post-seismic data evidenced by Amoruso et al., 2011.
Rupture mechanism of the Campania-Lucania (southern Italy) 1980 earthquake inferred from seismological and geodetic data
Lavecchia G.;Romano P.;Bello S.;Brozzetti F.
2018-01-01
Abstract
A detailed reconstruction of the rupture mechanism of the 1980 Campania-Lucania (southern Italy) earthquake is presented. This event is also improperly known as Irpinia earthquake, which is however only a part of the region influenced by macroseismic effects and where the main faults are located. Relocation of the main hypocenters and the estimation of fault-plane solutions of the aftershocks, through P-wave velocity inversion models provide an overall comprehensive picture of the source mechanism. The analysis of available data suggests a complex rupture mechanism, as already identified by many previous studies, which consists of three separate events. The present work provides however a convincing evidence of almost simultaneous activation of a syntheticantithetic normal fault couple as characterizing rupture source process of this earthquake. The first event activated the northern NW-SE striking segment of a large (~40-km-long), high-angle, NE-dipping, master fault. With the second event the rupture propagated southward along the fault strike and activated the southern WNW-ESE striking segment (~15-km-long) of the same master fault. Conversely, the third rupture occurred along a SW-dipping normal fault antithetic to the master fault northern segment. This mechanism is well evidenced by the revised location of the hypocenter of the main event, and the location of the aftershocks and their fault-plane solutions, as well as by the underlying three-dimensional P-wave velocity structure. The model originally proposed by Amoruso et al., 2005 that was based purely on the inversion of co-seismic vertical displacement data is confirmed by the present analysis, as it satisfies all of the available experimental observations and better constrains the location and fault-plane solutions of the aftershocks, the velocity discontinuities, and the rupture observations at the surface (see Bello et al. this conference). This conclusion is also supported by analyses of the post-seismic data evidenced by Amoruso et al., 2011.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
