对2004年北Sumatra地震序列两次强余震的灰色预测

应用灰色系统理论对2004年底北苏门答腊9．0级地震序列两次强余震(系指ML≥6)的发震时间进行了尝试性预测．对2004年12月29日6．3级余震时间进行灰色预测，预测出余震将于2004年12月29日9时7分35．6秒发生，事实上在2004年12月29日13时56分51秒发生了6．3级地震，两者相差不到5小时，比较吻合．对2005年1月1日7．0级余震进行灰色预测，预测出余震将于2004年12月31日20时37分24．6秒发生，比实际余震发生时间2005年1月1日14时25分47．2秒提前了将近18h，预测基本正确。

Grey Forecasting Two Strong Aftershocks of the 2004 North Sumatra Earthquake Sequence

The Grey system theory is used for an attempt to forecast occurrence time of two strong aftershocks of the 2004 North Sumatra earthquake sequence with magnitude of 9.0. At first, the paper forecasts the aftershock with magnitude of 6.3 (Ms) that happened at 1:56:51 p.m. on December 29, 2004, will happen at 9:7:35.6 a.m. on December 29, 2004. The forecasting result is the discrepancy of five hours, and basically corresponds to the real occurrence time. Secondly, the paper forecasts the aftershock with magnitude of 7.0(Ms) that happened at 14:25:47.2 on January 1,2005. The foracasting result is the discrepancy of eighteen hours. These results show that the method, at the moment after main shock, has practical significance for a forecasting its trend using the limited sequence data.