Analyzing the Temporal Variation in Macroseismic Intensity Rating Values and Predicting Macroseismic Intensity on the Tibetan Plateau

Abstract

China has relatively rich macroseismic isoseismal maps, which play an important role in seismic hazard analysis and the development of reliable earthquake loss models. The macroseismic intensity is assessed based on the Chinese Seismic Intensity Scale, which is constantly being revised as research progresses and the seismic defense capability is enhanced. To investigate whether intensity rating values show consistency across time in statistical significance, this study collected 543 isoseismal lines for 216 earthquakes on the Tibetan Plateau from 1960 to 2020. Taking intensity prediction equations (IPEs) as a reference, statistical tests of the residuals indicate that there is temporal variation in intensity rating values, which is inconsistent with the default assumption that intensity rating values are consistent for different time periods when developing IPEs. Therefore, we analyze the characteristics of intensity rating values by statistical tests and investigate the mechanism by which the temporal variation in intensity rating values affects IPEs by residual decomposition. The results show that despite the temporal variation in intensity rating values, they can still be used to develop IPEs, and that temporal variability can be reduced by adjustment. Finally, we obtain the regression process of IPEs based on the partially nonergodic assumption considering the temporal variation in intensity rating values, and perform a case study, using the Tibetan Plateau as an example.