Abstract: An M_S7.1 earthquake hit Yushu area in Qinghai province on April 14th, 2010, and there was a foreshock with M_S4.7 two hours before the main event. According to our analysis, some typical precursory seismic patterns appeared before the earthquake, e.g. seismic gap, seismic band, increased activity, seismicity quiescence, and evolution of those seismic patterns before the M_S7.1 earthquake exhibit a course very similar to that found for earthquake cases with M_S≥7. By tracking the pattens and their evolution, it is possible to identify the foreshock from general middle shocks. Finally we have confirmed the reliability of this method.

Key words: Foreshock identification, Short-term Prediction, the 2011 Yushu M_S 7.1 Earthquake