Seismology and Tectonic Setting of the 2002 Molise, Italy, Earthquake

Abstract

Two earthquakes (both having Mw 5.7) struck the eastern portion of Molise on October 31 and November 1, 2002. Both caused severe damage over a 2000 km2 region straddling Molise and Puglia. The two larger shocks and the rather unusual aftershock sequence surprised most Italian seismologists and tectonicists. Although Italy has a good record of historical and instrumental seismicity and its main seismogenic trends are quite established, the epicentral location, depth and kinematics of this earthquake sequence were largely unexpected. In fact, the 2002 Molise earthquakes shed light on a previously unsuspected style of seismogenic faulting in this region. From the seismotectonic perspective, much of the significance of the two quakes arises from the possibility that this style of faulting might be shared by several much larger quakes that took place on the Adriatic side of the southern Apennines. In the first part of this paper we briefly describe the main seismological characteristics of the sequence. These were largely derived from the analysis of data supplied by permanent networks and from a preliminary analysis of data recorded by a portable network deployed a few hours after the first shock. In the second part of the paper we discuss the seismotectonic characteristics of the sequence in the framework of Italian tectonics and the implications for future earthquakes in the same region.