High-resolution, digital mapping of the seismic hazard within the Gulf of Evia Rift, Central Greece using normal fault segments as line sources

Seismic hazard within juvenile rift systems is modelled by a semi-statistical procedure based on fault segmentation theory. Fault segmentation provides the physical basis for strong earthquake recurrence in regions undergoing extension, and therefore, it may control the position and size of rupture areas for future events. The computer code FRISK (McGuire, 1978) is applied to calculate probabilistic estimates of ground motion parameters. Six normal fault segments, on average 25 km long, are modelled as the earthquake sources within the Gulf of Evia Rift, Central Greece. The position and length of segments have been determined from image processing of remotely-sensed data and field work. FRISK output is directed to a Geographical Information System (GIS) and a series of high-resolution (0.1 by 0.1 of a degree) digital maps are produced. The results for 100 year acceleration (63% not to be exceeded) show a 50% increase in the seismic hazard from previously estimated magnitudes. Areas of maximum hazard (over 0.4 g) are located on the south coast of the Gulf of Evia between the towns of Kammena Vourla and Arkitsa. The obtained shape of Peak Ground Acceleration (PGA) contours is slightly elliptical with the long axis of the ellipse trending E-W, and symmetric, with respect to the rift axis.