Probabilistic Seismic Hazard Assessment of North-Eastern Thailand

Abstract

© 2020, Korean Society of Civil Engineers. The Northeast of Thailand is defined as a low seismic hazard region. However, earthquakes were reported and felt by local people around 25 years ago. Using probabilistic seismic hazard analysis (PSHA), this research evaluates the seismic hazard in the Northeast region of Thailand to be the database for seismic design. The seismic hazard is expressed in the term of peak ground acceleration (PGA) at base rock level. The crustal faults and earthquake events are considered as the seismic source in this evaluation. Two crustal faults are evaluated in Thakhaek fault and Phetchabun fault, which have not been considered before in PSHA. Earthquake events are classified into two types: background seismicity zones and subduction zones. The results reveal that the highest peak ground acceleration at base rock level is in Bueng Kan province and Nakhon Phanom province. The evaluated seismic hazard in the Northeast region is approximately 30% g and 12% g with a return period of 2,475 years and 475 years, respectively. Results obtained from this study are about two times higher than the Earthquake Resistant Design code 1302 of Thailand. The evaluated seismic hazard is higher than the peak ground accelerations that can cause damage to building structures (>3.9% g).