Abstract. For regions without enough strong ground motion records, a seismology-based method is adopted to predict motion PGA (peak ground acceleration) values on rock sites with parameters from small earthquake data, recorded by regional broadband digital monitoring networks. Sichuan and Yunnan regions in southwestern China are selected for this case study. Five regional parameters of source spectrum and attenuation are acquired from a joint inversion by the micro-genetic algorithm. PGAs are predicted for earthquakes with moment magnitude (M w ) 5.0, 6.0, and 7.0 respectively and a series of distances. The result is compared with limited regional strong motion data in the corresponding interval M w ± 0.5. Most of the results ideally pass through the data clusters, except the case of M w 7.0 in the Sichuan region, which shows an obvious slow attenuation due to a lack of observed data from larger earthquakes (M w ≥ 7.0). For further application, the parameters are adopted in strong motion synthesis at two near-fault stations during the great Wenchuan Earthquake M8.0 in 2008.

Abstract. For regions lack of strong ground motion records, a method is developed to predict strong ground motion by small earthquake records from local broadband digital earthquake networks. Sichuan and Yunnan regions, located in southwestern China, are selected as the targets. Five regional source and crustal medium parameters are inversed by micro-Genetic Algorithm. These parameters are adopted to predict strong ground motion for moment magnitude (Mw) 5.0, 6.0 and 7.0. Strong ground motion data are compared with the results, most of the result pass through ideally the data point plexus, except the case of Mw 7.0 in Sichuan region, which shows an obvious slow attenuation. For further application, this result is adopted in probability seismic hazard assessment (PSHA) and near-field strong ground motion synthesis of the Wenchuan Earthquake.

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