Source parameter estimation and stochastic ground motion simulation based on recorded accelerograms in northwestern Vietnam

Estimated source parameters, path characteristics, and site parameters are used to simulate earthquake shaking waveforms in Vietnam. We used recorded accelerograms and point-source stochastic methodologies and included in our analysis empirical relationships between the duration of ground motion, seismic moment, and magnitude, and also those between corner-frequency, high-cut-off frequency, and moment-magnitude derived from earthquakes recorded in Vietnam and adjacent regions. Local site effects were estimated using horizontal-to- vertical spectral ratio methods. Simulated times series are compared with observed accelerograms from the 5.3 Dienbien earthquake in 2001, the first strong earthquake event to be recorded in Vietnam. Our synthetic time series of strong ground motion agrees well with both the observed waveforms and the response spectra, but suggests that PGA values obtained using current Vietnam codes may underestimate probable accelerations by 10-30%.