Assessing Sensitivity of Probabilistic Seismic Hazard Analysis to Fault Parameters : Java and Sumatra Case Study

Abstract

"The aim of this thesis is to study the impact of fault parameter uncertainty on seismic hazard analysis using Java and Sumatra, Indonesia, as case studies. Slip rate and fault geometry are two important inputs in determining seismic hazard, because they are used to estimate earthquake recurrence and maximum magnitude, both of which strongly influence near fault hazard levels. However, the uncertainty of slip-rates and fault geometry are rarely considered in probabilistic seismic hazard analysis (PSHA), which is surprising given that estimates of slip-rate can vary significantly from different data sources (e.g. geologic vs. geodetic). We produce PSHA maps for Java and Sumatra, and study the contribution from the crustal faults and subduction sources. We also analyse the contribution from different components of the subduction source. The importance of the regolith amplification and the method which might be best for application in Indonesia is also discussed. We use the PSHA method to assess the sensitivity of seismic hazard to fault parameters along the Sumatran Fault System (SFS) in Sumatra, Indonesia and we consider the aleatory uncertainty of fault slip by employing the logic tree tools to include epistemic uncertainty alternative slip rates. The weighting of the logic tree branches are determined by the probability density function of the slip rate estimates using the approach of Zechar and Frankel (2009). We consider how the PSHA result accounting for slip rate uncertainty differ from that for a specific slip rate by examining hazard values as a function of return period and distance from the fault. We also consider the locking width of the fault, to study the effect from different maximum magnitudes. Our study demonstrates that uncertainty in fault slip-rates, fault geometry and maximum magnitude have a significant impact on hazard level and area impacted by earthquakes and should be considered in PSHA studies." Show more