Relationship between Peak Ground Acceleration, Peak Ground Velocity, and Macroseismic Intensity in Western China

Empirical relationships between the macroseismic intensity and the ground-motion parameters (peak ground acceleration [PGA], peak ground velocity [PGV]) for western China are derived in this study. A strong ground-motion database including 34 moderate to large earthquakes is used along with the corresponding modified Mercalli intensity (MMI) information inferred from isoseismal maps and earthquake damage reports. A weighted least-squares regression with analytic hierarchy process (AHP) is used to find the following simple relationships between MMI and PGA or PGV with V <= I <= IX : MMI = 3.311 log PGA - 0.354, MMI = 3.356 log PGV + 3.315. These new relationships are significantly different from the Liu et al. (1980) correlations, which have been used in the Chinese macroseismic seismic intensity scale (CMSIS). The proposed simple relationships are then compared with similar equations developed from other regions. Comparison confirms that such relationships should be regional-dependent because the frequency content of ground motions exhibits local properties. To quantify the regional variations to the global relationships from Caprio et al. (2015), regional correction factors (RCFs) for western China are obtained by the proposed simple relationships. We also refined predictive relationships that include M-s and epicentral distance as independent variables.