Site Coefficient of Short Fa and Long period Fv Maps Constructed from the Probabilistic Seismic Hazard Analysis in Yogyakarta Special Province

Abstract

Among the devastated earthquakes that have occurred in theYogyakarta Special Province (YSP) were earthquakes that occur in 1867,1943 and 2006 [1,2]. Macro site coefficient is already available in [3]however, more detailed site coefficient or presented on a micro scale is notyet available. The disaster mitigation program is needed and one of whichis the availability of the microseismic site coefficient maps for short periodFa and long period Fv particularly for building design. The probabilisticseismic hazard analysis (PSHA) has been carried out. The subduction andthe shallow crustal earthquakes within 500km radius from the city ofYogyakarta have been used. In contrast to [4], PSHA was carried out byusing 10% probability of the earthquake being exceeded within 50 years. Result of this study indicates that YSP is dominated by hard SD andmedium soil categories. The medium soil is mainly located at along theOpak and Progo river valleys and along the southern coast of Bantul andKulonprogo districts. The short period site coefficient Fa is stronglyinfluenced by the Opak fault as an earthquake source, while the sitecoefficient for long period Fv is more influenced by the Megathrustearthquake source. For PGA < 1.0g, the seismic coefficient Fa for shortperiod increases with increasing Vs30, meanwhile for long period ofseismic coefficient Fv decreases with increasing Vs30.