On the use of AFOSM to estimate major earthquake probabilities in Taiwan

Advanced first-order second-moment (AFOSM) is commonly used to obtain an upper-bound estimate for a probabilistic analysis. This study presents a new AFOSM application to engineering seismology, estimating major earthquake probabilities based on fault length and slip rate, along with an earthquake empirical model subject to a model error of 0.26 M_w. The AFOSM analysis shows that the probability could be as high as 64 % for a major earthquake in northern Taiwan to exceed M_w7.0, considering the length and slip rate of the Sanchiao fault are equal to 36 km and 2 ± 1 mm per year. By contrast, the other case study shows that for the Meishan fault in central Taiwan, the probability is “only” 4 % for earthquake magnitude to exceed M_w7.0, given a shorter fault length of 14 km and a larger slip rate of 6 ± 3 mm per year.