摘要
由云南永善-大关Ms7.1级地震序列中的11个Ms≥4级地震的震源机制解和98个小震震源机制解,分析了震源区应力场的基本图象和变化形态。结果表明,震源区应力场的基本图象和构造应力场的方向相符。Ms7.1级主震未对震源区应力场的方向产生可觉察的改变。大量小震机制解的空间取向的优势方向与主震机制解一致。取向离散的小震机制解多出现在序列的前期,至序列末期则很少发现。小震机制解由较离散向集中过渡,显示了震源区应力场动态调整的过程。因此,小地震在强震序列中也做出不可忽略的贡献。
On the basis of the focal mechanisms of 11 evevts with Ms≥4 and 98 small events in the Yongshan-Daguan,Yunnan,earthquake(Magnitude of the mainshock is Ms 7.1)sequence,the general patterns and variation of the stress field in source region have been discussed.The results show that the stress field in source region corresponds to the tectonic stress field.The orientation of the stress field in source region didn't change obviously when the mainshock(Ms 7.1)took place.The dominant orientation of the focal mechanisms of many small events accord with that of the mainshock.The small events with scattered orientation of the focal mechanisms appeared mostly in the earlier period,and seldom in thelater period,of the sequence.The orientations of the focal mechanisms of the small events vary from scattering to concentration.Judging from this . a contribution made by a host of small earthquakes can not be ignored.
出处
《华北地震科学》
北大核心
1995年第1期28-34,共7页
North China Earthquake Sciences
基金
地震科学联合基金
关键词
地震序列
震源区
应力场
震级
Yongshan-Daguan earthquake,stress field of the source region,focal mechanism