Verification of attenuation models based on strong ground motion data in Northern Thailand

Abstract

Within the last decade, the number of earthquake events in Northern Thailand has significantly increased. At least, two major earthquakes have occurred in this region: the 2011 Mw 6.8 Tarlay Earthquake and the 2014 Mw 6.3 Mae Lao Earthquake. The lack of understanding on appropriate attenuation models to represent a specific region becomes a major issue if strong ground motion data is not available. This paper aims to determine an appropriate attenuation model for Northern Thailand based on seven recorded earthquake events in the region. Nine attenuation models, including ground motion prediction equations (GMPEs) from both NGA-West1 and NGA-West2 (Next Generation Attenuation Relationships for Western US), were employed to predict peak ground acceleration (PGA) and spectral acceleration (SA) during the selected earthquake events. Ground motion data during the events from twenty nearby seismic stations were collected for verifying the predictions from each attenuation model. Goodness of fit test and root mean square error (RMSE) were evaluated for each attenuation model prediction. The results show that the NGA-West2 are the most appropriate attenuation models to predict ground motion in Northern Thailand. As a consequence of verifying these attenuation models, it is hoped that further development of Thailand's seismic design standards for seismic hazard analysis of specific regions such as Northern Thailand can be based on more accurate, appropriately selected models.