Properties of the 2003 Lefkada, Ionian Islands, Greece, earthquake seismic sequence and seismicity triggering

On 14 August 2003, Lefkada Island (Central Ionian) was strongly affected by an M-w = 6.2 earthquake. A dense temporary seismic network was installed one day after and accurately located hundreds of aftershocks that defined in detail the main rupture, as well as the activity distribution in the neighboring fault segments. The main rupture occupied the northwestern part of the coastline and trends north-northeast-south-southwest in agreement with regional tectonics. Regional network locations were appropriately calibrated using the local network data, allowing the relocation of the mainshock and strong (M similar to4.5 or larger) aftershocks during the first day. Intense aftershock activity took place up to 40 km beyond the southern end of the main rupture. Theoretical static stress changes from the mainshock give a preliminary explanation for the aftershock distribution aside from the main rupture, as well as triggering of seismicity in the nearby Kefalonia fault, providing evidence for future seismic hazard ensuing from this fault.