THE 9TH JULY 1998 FAIAL EARTHQUAKE: COMPARISON OF STOCHASTIC FINITE FAULT DAMAGE SIMULATION WITH SURVEYED DATA

Abstract

The Azores earthquake, July 9, 1998 (Mw 6.2) caused a large damage to the stock of old masonry buildings, with maximum felt intensity Is=VIII (MMI). A stochastic strong ground motion (SM) was simulated on the islands struck by the earthquake using published fault solution, to derive maps of average Peak Ground Acceleration (PGA) at bedrock. Detailed analysis was done at the Horta station comparing stochastic-computed and observed PGA, PGV, Response Acceleration Spectra and Response Spectrum Intensity (SI) values. Although recordings on Faial (Horta) and Terceira Islands are not enough to fully constrain the simulation parameters, they can define the range of possible variation. Relationships between PGA and MMI were used to retrieve intensity. Retrieved and observed intensities allowed to derive an average damage index according to the EMS-98 classification