Probabilistic analysis of the seismic activity and hazard in northern Thailand

Abstract

The seismic activity and hazard level in northern Thailand, including at the Mae Moh Coal Mine (MMCM), were clarified. For the probability of exceedance (POE), Chiang Mai, Lamphun, and Lampang provinces have a 70–90% and 20–40% POE of a MW-5.0 and MW-6.0 earthquake, respectively, in the next 50 y. In the case of a MW-7.0 earthquake, the POE is less than 10% in the whole study area. Regarding the probabilistic seismic hazard analysis, the ground shaking maps indicated that the southeastern part of the MMCM and northwestern part of Phayao provinces were high hazard areas, with an earthquake ground shaking of around 0.28–0.32g and 0.18–0.24g for a POE of 2% and 10%, respectively, in the next 50 y. In addition, the probability maps revealed that these high hazard areas showed a 60–80% and 30–40% POE of a modified Mercalli intensity (MMI) level III and IV, respectively, in the next 50 y. The low hazard areas of Chiang Mai and Uttaradit provinces had a ground shaking level for a 2% and 10% POE in the next 50 y of around 0.16 and 0.08, respectively, with a POE of a MMI level III or IV of less than 20% each.