17:15 〜 19:15
[SSS11-P16] Referenced Empirical Ground-Motion Model for the Himalayan region
キーワード：Ground motion models, Referenced ground motion models, PSHA
We introduce a referenced empirical approach for developing a ground motion model (GMM) tailored to the Indian context, with a specific focus on the Himalayan region. This method integrates the recently compiled Indian ground-motion database with the empirical predictions of Abrahamson and Silva (2008, AS08), originally developed under the NGA-West2 project. In India and the Himalayas, global GMMs such as those from NGA-West2 and Japanese datasets are commonly used for Probabilistic Seismic Hazard Analysis (PSHA). However, this assumes that these models accurately represent the median ground motions, aleatory variability, and epistemic uncertainties of the region. AS08 was selected based on a residual analysis that demonstrated its close alignment with the Indian dataset. The referenced empirical approach offers a GMM for active crustal regions that aligns well with observed regional ground motions while maintaining the overall ground-motion scaling behavior seen in well-instrumented active tectonic regions. As an alternative to the widely used stochastic ground-motion relations in India, this approach provides robust regional predictions. Ground-motion amplitudes are evaluated at four frequencies: 0, 0.5, 1, and 5 Hz. The model follows a simplified functional form and exhibits trends comparable to stochastic models at short distances and low-to-moderate frequencies but generates higher amplitudes for large events. Additionally, our approach predicts ground motions that are consistent with the hybrid empirical method (Campbell, 2003). Our approach explores alternative methodologies to stochastic GMMs that can provide insights into epistemic uncertainties, ultimately improving seismic hazard assessment in the Himalayan region.