摘要:
2014年5月云南省盈江县先后发生MS5.6、MS6.1地震,为确定它们的发震构造及其所反映的区域活动构造格局,笔者围绕该区开展了地震烈度调查、活动构造遥感解译、地质构造及构造地貌野外调查、震源机制解及余震分布资料分析等工作。调查与分析表明,两次地震的宏观震中均位于盈江县勐弄乡麻栗坡村附近,但发震断层明显不同。前者为NE走向左旋走滑的昔马—盘龙山断裂,后者为近SN向右旋走滑的苏典断裂。历史地震资料显示,盈江地区的地震活动多以5~6级的中-强震为主,并具有明显的群发性和沿SN向断层迁移的特征。在实皆断裂及滇西内弧带的共同作用下,腾冲地块内以大盈江断裂为界,北部主要发育近SN向右旋走滑断裂,南部则以NE向左旋走滑断裂为主,其中近SN向断层晚第四纪活动性更强。
Abstract:
Two earthquakes ofMS5.6 andMS6.1 occurred successively on May, 2014, in Yingjiang, Yunnan province. In order to determine their seismogenic structures and the regional active tectonic settings, the authors carried out field investigation of seismic intensity, remote sensing image interpretation, analysis of focal mechanism solutions and aftershock distribution. The results show that the macro-epicenters of two earthquakes were both located near the area of Malipo Village, Mengnong Township, Yingjiang County, but their seismogenic faults are different from each other. The former was associated with the NE-trending left-lateral strike-slip Xima-Panlongshan fault, whereas the latter occurred along the SN-trending right-lateral strike-slip Sudian fault. Historical seismicities were dominated by the earthquakes with magnitude 5~6 in the Yingjiang region, which clustered along the SN-trending fault. Under the combination effect of Sagaing fault and inner arc belt in western Yunnan, the north of Tengchong block bounded by Dayingjiang fault is mainly dominated by nearly SN-trending right-lateral strike slip faults, whereas the south is dominated by NE-trending left-lateral strike slip faults. The activity of nearly NS-tranding faults was relatively stronger in Late Quaternary.
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