摘要
We herein describe a new approach to quantitatively estimate source parameters of historical earthquakes with magnitude ~6 using macroseismic data and synthetic seismograms.This approach enumerates all possible models with different source parameters(such as epicenter location,focal depth and rake),and obtains theoretic intensity distribution of each model from synthetic waveform modeling,then evaluate source models fitting degree for intensity data inferred from historical earthquake records to determine its parameters.We use multiple model solutions and model weights to give quantitatively the uncertainty of source parameters caused by relatively scarce historical information.This approach was tested with Bootstrap numerical cases for given sources with random deviations,and the well determined source parameters of the 2004 Parkfield M6.0 earthquake.The test showed that the result is robust statistically.Finally the approach is applied to the 1882 Shenxian M~6 earthquake occurred in Hebei province,China.Source parameters estimation results show that the Shenxian earthquake is caused possibly by Jiuchengbei fault or Hezhuang fault,or Shenxi fault.We herein describe a new approach to quantitatively estimate source parameters of historical earthquakes with magnitude ~6 using macroseismic data and synthetic seismograms.This approach enumerates all possible models with different source parameters(such as epicenter location,focal depth and rake),and obtains theoretic intensity distribution of each model from synthetic waveform modeling,then evaluate source models fitting degree for intensity data inferred from historical earthquake records to determine its parameters.We use multiple model solutions and model weights to give quantitatively the uncertainty of source parameters caused by relatively scarce historical information.This approach was tested with Bootstrap numerical cases for given sources with random deviations,and the well determined source parameters of the 2004 Parkfield M6.0 earthquake.The test showed that the result is robust statistically.Finally the approach is applied to the 1882 Shenxian M~6 earthquake occurred in Hebei province,China.Source parameters estimation results show that the Shenxian earthquake is caused possibly by Jiuchengbei fault or Hezhuang fault,or Shenxi fault.