【摘要】 2012年6月24日宁蒗—盐源之间发生MS5.7地震。为了探讨其发震构造,本文首先利用近震宽频带波形记录,基于CrustModel2提供的速度模型,采用"裁剪-粘贴"(CAP,Cut And Paste)方法反演了震源机制解和深度。结果表明,该地震是以正断为主,兼具走滑分量,两个断层节面解的走向/倾角/滑动角分别为189°/59°/-40°和302°/55°/-141°,矩震级为5.3,矩心深度为4km,采用该区其他速度结构模型得到的震源深度为6km。通过分析近距离台站LGH的sPL波震相及远震距离澳大利亚台网上记录的sP波深度震相,进一步确认本次地震震源深度为4～8km,是一次浅源地震。震后2天内的余震分布主要沿北西向分布,结合当地地质构造推断,本次地震可能发生在北西向永宁断裂上。更多还原

【Abstract】 The Ninglang—Yanyuan MS 5.7 earthquake that occurred on June 24,2012 caused certain death and property loss.To explore seismogenic tectonic of this earthquake,we used regional broadband seismic records based on velocity model extracted from Crust Model 2.0to invert focal mechanism with cut and paste(CAP)method.The strikes,dips,rakes of best focal mechanism solutions are 189°/59°/-40°and 302°/55°/-141°,respectively.It is a Mw 5.4 normal dominant event with strike slip component.The centorid depth provided by CAP method is 4km.Two other models were employed to better understand errors introduced by velocity model.The mechanisms and magnitudes are similar,while centroid depths range from 4km to 6km which are much shallower than results based on traveltime.sPL phase recorded by LGH and pP phases recorded by Australian seismic stations confirmed that the centorid depth is between 4～8km.North-West distribution of short term aftershocks(two days after mainshock)suggests that this earthquake occurred at Yongning Fault.更多还原