GMPE based Shakemap Generation of Peak Ground Motion and Intensity Maps for Pidie Jaya Earthquake

Abstract

An algorithm based on GMPE (Ground Motion Prediction Equation) is used for Generating standard and officially Shakemap as early information for disaster mitigation quick respond. We investigate the method developed by USGS (US Geological Survey) namely ShakeMap for generating Peak Ground Motion and Intensity Maps. The 2016 Mw 6.5Pidie Jaya Earthquake which strike-slip mechanism was selected for the scenario earthquake. The appropriate GMPE (i.e.Zhao06_crustal) was selected for this earthquake, which is located at the crust with focal depth of13km and strike-slip mechanism. Strong ground motion on bedrock, without sediment amplification, generate PGA (Peak Ground Acceleration) and PGV (Peak Ground Velocity) spherically uniform. The algorithm able to consider the site effect only for thin sedimentary layer Vs30 without considering deeper structural layer. The amplification effect is calculated based on Vs30 without considering the nonlinear effect and independently each site-class. Because of unavailable spatial distribution Vs30 measurement, the Vs30 was estimated from the topographic gradient and the method is commonly used. Strong ground motion on sediment layer will be amplified following the Vs30 distribution. The intensity map, which is easier to read, shown in MMI (Modified Mercalli Intensity) and SIG-BMKG (Indonesia Earthquake Intensity Scale). The GMPE based shakemap has bias error because of the general equation has not considering complete structural model and radiation pattern of a focal mechanism. An advance method for thefuture development will be much more realistic with the shakemap based on synthetics seismogram calculation.