Publication Date:
2017-04-04
Description:
In October and November 2002, the Molise region (southern Italy) was struck by two moderate magnitude earth-
quakeswithin 24 hours followed by an onemonth long aftershocks sequence. Soon after the ?rstmainshock (October
31st, 10.32 UTC, Mw 5.7), we deployed a temporary network of 35 three-component seismic stations. At the time of
occurrence of the second main event (November 1st, 15.08 UTC, Mw 5.7) the eight local stations already installed
allowed us to well constrain the hypocentral parameters. We present the location of the two mainshocks and 1929
aftershocks with 2 〈 ML 〈 4.2. Earthquake distribution reveals a E-trending 15 km long fault system composed
by two main segments ruptured by the two mainshocks. Aftershocks de?ne two sub-vertical dextral strike-slip fault
segments in agreementwith themainshock fault plane solutions. P- and T -axes retrieved from170 aftershocks focal
mechanisms show a coherent kinematics: with a sub-horizontal NW and NE-trending P and T -axes, respectively.
Fora small percentage of focal mechanisms (~10%) a rotation of T axes is observed, resulting in thrust solutions.
The Apenninic active normal fault belt is located about 80 km westward of the 2002 epicentral area and signi?cant
seismicity occurs only 20-50 km to the east, in the Gargano promontory. Seismic hazard was thought to be small for
this region because neither historical earthquake are reported in the Italian seismic catalogue or active faults were
previously identi?ed. In this context, the 2002 seismic sequence highlights the existence of trans-pressional active
tectonics in between the extensional Apenninic belt and the Apulian foreland.
Description:
Published
Description:
487-494
Description:
1.1. TTC - Monitoraggio sismico del territorio nazionale
Description:
JCR Journal
Description:
reserved
Keywords:
Molise seismic sequence
;
strike slip fault system
;
04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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