Duration magnitude scale and analysis of seismicity around the Maltese Islands

Abstract

The aim of this project was to establish the duration magnitude scale for earthquakes in the Central Mediterranean recorded at station WDD, Malta, and to study seismic activity in the region surrounding the Maltese Islands. Since 1983, seismic instrumentation in Malta had seen a growth, enabling useful data sets to unravel very important features of this region. Magnitude is an experimentally determined measure of the size of an earthquake. The duration magnitude utilizes the coda length to establish the magnitude formula. It is the main aim of this project to empirically determine the duration magnitude formula for the Sicily Channel. To derive such a scale a representative group of shocks is essential. The seismic events chosen are recorded in Malta and also located by I.N.G. (lnstituto Nazionale di Geofisica). The equation is determined empirically by the method of least square fitting. In addition, the relationship between the earthquake size and the frequency of occurrence proposed by Richter (1958) was also achieved empirically for the Sicily Channel. Furthermore, the implication of swarm activities in the Pantelleria Rift was discussed. The duration magnitude suffers from a shortcoming in that it is applied only to short distance range. However, it is considered sufficient and convenient for the purpose of this study in the Central Mediterranean.