MICROSEISMICITY AND SEISMOTECTONIC PROPERTIES OF THE LEFKADA – KEFALONIA SEISMIC ZONE

Résumé 0

Microseismicity, focal–mechanisms, and previously–published focal parameter data are usedto determine the current tectonic activity of the prominent zone of seismicity in Lefkada and KefaloniaIslands. Recordings from a local network installed and operated on the two Islands, aswell as from permanent stations there, were used to obtain accurate microseismicity locations,which in turn is exploited to reveal properties of smaller localized active structures and thelarge–scale crustal faulting. The microseismicity substantially agrees with the historic seismicityand delineates a relatively narrow, major zone of activity that extends along the westerncoasts of both Islands. Cross sections were used in order to provide a detailedcharacterization of the microseismicity and a high–resolution picture of the seismically definedstructures. For the investigation of the past seismic activity relocation of the hypocenters ofolder events was performed, using a reliable velocity model and time delays for the regional stations,calculated on the basis of the accurately determined focal parameters using the localrecordings. The yielding location improvement contributes to the geometry identification of theactive structures, which were previously obscured by location errors, and which constitute acritical input for the study area seismic hazard assessment.