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 catalogue 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 magnitude calculated from Mediterranean Very Broadband Seismographic Network (Med Net) and the corresponding seismic signal durations at the national network (RSNC). We introduce a station correction factor Scj because of most of the stations located in southern Italy show large residuals that appear to be of regional importance. The relation obtained: Mdij= 2.49•log (Tij) – 2.31+ Scj. Log MO - 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 earthquakes, by linear regressions. We obtained best least square fits for: LogMo = 1.18(±0.06)•ML + 10.92 Mw = 0.79(±0.4)•ML + 1.20