应用振幅谱反演方法，对2009年3月25日黄海ML4.0地震的震源机制进行求解。在震源位置固定情况下，得到此次地震的地震矩为7.17×1014 N·m，矩震级约3.8级，最佳震源机制解为：走向40°，倾角80°，滑动角150°，与震中附近区域的中国断层线走向基本吻合。

This paper attempts to find focal mechanism of the Yellow Sea ML 4.0 earthquake on Mar 25, 2009 by amplitude spectrum inversion. In case of fixed depth, it is obtained that the scalar moment of this event is 7.17×1014 N·m, with MW≈3.8. And the best focal mechanism solution is: strike=40°, dip=80°, rake=150°. The node plane describe by these angles is consistent with faults′ tendency near the epicenter.