Seismic microzonation of Semarang, Indonesia, based on probabilistic and deterministic combination analysis

Abstract

One of the most important pieces of information obtained from the new Indonesian seismic hazard maps completed in 2017 was the identification of a fault that crosses the city of Semarang. This fault can be categorized as a new dangerous seismic source and should be taken into account in future seismic mitigation planning of this city. This paper describes the seismic microzonation of Semarang carried out via a combination of probabilistic and deterministic hazard analysis. The purpose of this research was to develop a risk map for Semarang based on one percent building collapse in 50 years. The analysis was performed using the same method employed in developing risk targeted Maximum Considered Earthquake (MCER) maps in 2012, with an improved beta (logarithmic standard deviation) value of 0.65 and adjusted direction factors of 1.1 and 1.3 for short- and long-period spectral acceleration, respectively. Whereas the 2012 maximum MCER spectral acceleration was distributed in the north-east of the study area due to the presence of Lasem fault, the 2018 maximum is located in the north-western part of the city as a result of the newly developed Semarang fault.