Earthquake Hazard Analysis at Bedrock and at Ground Surface for Java Island, Indonesia using Classical PSHA Method

Garup Lambang Goro, Masyhur Irsyam, M. Asrurifak, Irwan Meilano

One of the mitigation efforts in the context of reducing natural disasters, particularly earthquakes, was by developing earthquake hazard maps in the form of acceleration maps in bedrock and acceleration maps at the ground surface. The spectrum of acceleration at the ground surface was very important for estimating earthquake risk, both against damage to building structures, economic loss, and fatalities. The goal of this study was to calculate the earthquake hazard at bedrock and at the ground surface, subsequently, calculate those amplification factors. The calculation uses the Classical PSHA method with the help of OpenQuake software developed by the Global Earthquake Model (GEM). The seismic sources and GMPEs used in this study were derived from the latest data in the calculation of Indonesia Seismic Hazard Maps 2017. The amplification factor obtained from the calculation is compared with the amplification factor according to the National Standard for Earthquake Resistance Planning for Building and Non- Building Structures of Indonesia (SNI 1726:2019) and ASCE 7-16. Calculations were carried out in the area of Java Island, for the type of measurement of intensity for Peak Ground Acceleration (PGA), short periods of 0.2sec SA(0.2) and for periods of 1.0sec SA(1.0) for 2475 year return period. The results of the study show that most of the amplification factors at intensity measurement of PGA, SA(0.2), and SA(1.0) corresponded to site coefficient in building code (SNI 1726:2019 and ASCE 7-16). The factor of amplification in PGA, the comparability was well suited to all ranges of PGA at all site classes, except for the site class SD for 0.1g< PGA<0.2g, produced the amplification factor about 13% lower than the amplification factor in the building code, and a little bit higher in PGA range of 0.4g to 0.6g. The computation results in short period SA(0.2), the amplification factor at almost all ranges of Ss values at all site classes was matching, except for the SD site classes for 1.0g 1.5g where produced values of the amplification factor of analysis results were about 20%-30% higher than the amplification factor in the building code. Whereas in the 1 second period (SA 1.0), comparability matches for almost all ranges of S1 values in almost all site classes, except for the SD site class for S1<1.0g, SE site class at 0.5g 0.6g, which were results the amplification factor value of about 10%-20% higher than the amplification factor in the building code.

Volume 12 | Issue 6

Pages: 3100-3112

DOI: 10.5373/JARDCS/V12I6/S20201275