TOWARD A JOINT CATALOGUE OF RECENT SEISMICITY IN

Routine catalogue phase data of three Greek permanent seismic networks are merged and jointly used to relocate earthquakes in western Greece. Processed data refer to the time period from 2000 to 2005 and to the geographical area between 35-42ºN and 19-22ºE. After the merging procedure, the number of events in the joint catalogue is increased by more than 3000 compared to the individual pre-existing catalogues. Earthquakes are relocated using the Hypoinverse algorithm and several different combinations of 1D velocity models and phase weighting schemes. Among these two tested factors, S-phase weights are found to affect the relocation results more drastically. In fact, minimum mean rms, erh and erz values (0.28 secs, 3.6 km and 5.8 km, respectively) are found when S-phases are neglected. Relocated epicen-ters appear more clustered and illuminate well-known, as well as obscure, seis-motectonic structures of the area. Key words: relocation, hypoinverse, Ionian 1