【摘要】 大同震区先后在 1989、1991和 1999年发生MS >5地震 ,利用大同遥测地震台网的记录资料进行比较精确的地震序列震源定位 ,结合宏观烈度分布和震源机制解资料 ,详细地分析对比了 3次子序列的异同。结果显示 ,1999年MS5 .6地震的震源断层是走向NWW、长 16km、宽12km、埋深 5km以下、倾角近直立的左旋走滑断层。而前 2个子序列是NNE为主的右旋走滑断层活动所致 ,表明地震破裂方向发生了变化。这种 2个以上方向先后出现、并且强弱有别的地震破裂是普遍存在的 ,表明震源环境的复杂程度与地震序列的类型有关。虽然震区存在NE向的大王村断裂和NW向的团堡断裂 ,但目前没有证据说明震源断层和 2条构造断层连通。 3次子序列的震源断层都是走滑断层 ,也和 2条构造正断层有别。 1999年的子序列可能属于新破裂。更多还原

【Abstract】 The earthquakes with M S>5.0 occurred in Datong seismic area in 1989,1991 and 1999.The precise hypocenter measurement of earthquake sequence is taken by the data of the remote sensing seismic station network in Datong. Using those results together with macro intensity distribution and focal mechanism, we analyze the difference among three subsequences. The result shows that the focal fault of M S5.6 earthquake of 1999 is left-lateral strike slip fault, which is strike NWW,16km in length, 12km in width, 5km in depth and nearly straight angle in dip. The two previous earthquake sequences cause from right-lateral strike slip faults of strike NNE. This shows the rupture direction of 1999 earthquakes changes.It is general that rupture has more than two directions, appears successively and has different strengths. This shows that the complex degree of hypocenter circumstance is related to the type of earthquake sequences. There are NE Dawangcun fault and NW Tuanbu fault in seismic area, but no proof indicates the connection between focal faults and two tectonic faults. The feature that focal faults of three subsequences are strike slip is different from the two tectonic faults.1999 subsequence possibly belongs to new rupture.更多还原