Evaluation of seismic site response in the Maltese archipelago

Abstract

The investigation of local ground conditions is an important part of seismic hazard assessment (Fäh et al., 2003). It is now well–established that earthquake ground shaking is not only a function of the earth- quake magnitude and epicentral distance, but also of the site conditions, including soft layers in the sub–soil stratification and topographical features. Local geology can greatly alter the seismic waves from earthquakes by amplifying their amplitude, changing the frequency content and increasing the shaking duration during an earthquake (Kramer, 1996). In fact, several unconsolidated soft sites have suffered significantly greater damage than rock sites. One case was the 1985 Michoacán earthquake which showed low peak ground acceleration near the epicenter, yet caused severe damage in Mexico City, which is found more than 350 km away and is characterized by soft shallow sediments (Campillo et al., 1989).