Stress Changes due to Recent Seismic Events in the Central Apennines (Italy) |
| |
| Authors: | Andrea?Tallarico Email author" target="_blank">Stefano?SantiniEmail author Michele?Dragoni |
| |
| Institution: | (1) Dipartimento di Geologia e Geofisica, Universitá di Bari, Orabona 4, 70125 Bari, Italy;(2) Istituto di Fisica, Universitá di Urbino, Via Santa Chiara 27, 61029 Urbino, Italy;(3) Dipartimento di Fisica, Universitá di Bologna, Viale Berti Pichat 8, 40127 Bologna, Italy |
| |
| Abstract: | The Central Apennines, Italy, are characterized by moderate seismic activity on normal faults, oriented in directions parallel
to the Apenninic chain. The subject of this study is the Umbria-Marche Apennines, a segment approximately 200-km long, where
three main seismic events occurred in the last three decades. The 1979 Norcia earthquake was a Mw = 5.8 event, taking place at the south end of the considered segment. The 1984 Gubbio earthquake was a Mw = 5.6 event which took place at the north end. The 1997-1998 Colfiorito sequence constituted 8 main shocks with magnitudes
Mw between 5 and 6 and epicenters located between the Gubbio and the Norcia earthquake areas. A model made of an elastic half-space
is considered, in which the seismic sources are represented by rectangular dislocations which have the appropriate values
of source parameters, and in which the static stress field produced by each event is calculated. The analysis of the Coulomb
stress change (ΔC) as a function of time shows that the coseismic stress transfer and fault interaction played an important role in the region
during the past three decades: 7 earthquakes of the 9 considered took place where ΔC>0. Such an interaction has been confirmed by the analysis of the aftershocks in the Colfiorito zone post September 26, 1997:
about the 61% of the aftershocks considered took place where ΔC>0. The comparison between the ΔCs due to the coseismic stress transfer and the rate ΔĊt due to the tectonic stress allows us to quantify the time advance of the earthquakes. The ΔCs pattern shows positive values in two areas that can be regarded as historical seismic gaps. |
| |
| Keywords: | Seismic sequences fault dislocation stress field Coulomb failure friction Coulomb stress change time advance |
| 本文献已被 SpringerLink 等数据库收录！ |
|
