Local and Duration Magnitude Determination for the Italian Earthquake Catalog, 1981-2002

Abstract

In the present work, we update magnitude estimates of the instrumental catalogue of 99,780 Italian earthquakes that occurred during 1981-2002. The catalog contains a large data set of P- and S-arrival times and accurate earthquake locations. We derive duration magnitude estimates from linear regression between local mag- nitude calculated from Mediterranean Very Broadband Seismographic Network (MedNet) and the corresponding seismic-signal durations at the national network Rete Sismica Nazionale Centralizzata (RSNC). We introduce a station correction factor Scj because of most of the stations located in southern Italy show large resid- uals that appear to be of regional importance. The relation obtained: M 2.49 log(T ) 2.31 Sc . di j j ij Log M0 ML and MW ML relations are also computed in the range of 3.5-5.8 from regional centroid moment tensor estimation of medium-strong Italian earth- quakes, by linear regressions. We obtained best least-square fits for: Log M 1.18( 0.06) M 10.92. 0L M 0.79( 0.4) M 1.20. wL