2022年9月5日四川泸定6.8级地震初步研究结果

Preliminary Study of Emergency Production and Source Parameters of the M6.8 Earthquake on September 05,2022 in Luding,Sichuan Province

摘要:

北京时间2022年9月5日12时52分四川甘孜州泸定县(29.59°N,102.08°E)发生6.8级地震,中国地震预警网于震后6.1s产出首报预警结果;中国地震台网中心于震后3min发布自动速报结果,震后11min发布正式速报结果,同时联合中国地震局地球物理研究所、地质研究所、地震预测研究所和应急管理部国家自然灾害防治研究院启动地震应急产品产出工作,共产出震源基本参数、历史地震、地震构造、地震矩张量、余震精定位、地震烈度和震源破裂过程等9类应急产品。结合上述应急产品,对本次地震进行了研究,初步刻画了地震的构造环境、震源特征、断层形态和受灾区域,并分析了地震成因。结果表明,本次地震是发生在鲜水河断裂带南东段雪门坎—磨西断裂上的一次倾角近直立的走滑型事件,自起始破裂点向南东破裂,破裂长度约20km,最大滑移点深度约6km。余震精定位结果显示余震呈NW—SE向展布,长度约50km,深度主要集中在3～14km,展布方向与震中区域断裂走向基本一致,主震震中处断层倾角近乎垂直,与震源机制揭示的特征一致。烈度速报推测与地震烈度图显示极震区烈度达Ⅸ度,区域面积约280km²,Ⅷ度及以上区域总面积约505km²,涉及17个乡镇。认为本次地震是青藏高原隆升和高原上地壳物质向南东挤出,导致鲜水河断裂南东段雪门坎—磨西断裂上积累的应力的一次快速释放过程。

Abstract:

An earthquake of magnitude 6.8 occurred in Luding county(29.59°N,102.08°E),Sichuan Province at 12:52 on September 5,2022,of Beijing time. The China Earthquake Early Warning Network produced the first early warning results in 6.1 seconds after the earthquake. The China Earthquake Network Center produced the results of the automatic quick report in 3 minutes after the earthquake. The official quick report results were released in 11 minutes after the earthquake. Then,together with Institute of Geophysics,Institute of Geology and Institute of Earthquake Forecasting of China Earthquake Administration,and National Institute of Natural Hazards,the China Earthquake Network Center produced emergency production in 9 types,including source basic parameters,historical earthquakes,seismic tectonics,seismic moment tensor,aftershock location,and earthquake intensity. Combined with these emergency products,we preliminarily depict the tectonic environment,epicenter characteristics,fault shape and affected area of the earthquake,and analyze the cause of the earthquake in this paper. The results show that the earthquake is a near-upright strike-slip event on the Xuemenkan-Moxi fault in the southeastern section of the Xianshuihe fault zone. The rupture proceeds southeast from the initial rupture point,with the rupture length of about 20km,and the depth of the maximum slip point of about 6km. The results of fine location of aftershocks show that aftershocks are distributed in NW-SE direction,with a length of about 50km and a depth of 3～14km. The distribution direction is basically consistent with the fault strike in the epicenter area,and the dip angle of the fault at the epicenter of the main shock is almost vertical,which is consistent with the evidences revealed by the focal mechanism. Intensity quick report speculation and earthquake intensity map show that the intensity of the meloseismic zone reaches Ⅸ degree,the area is about 280km²,and the total area of Ⅷ degree and above is about 505km²,involving 17 townships. We believe that this earthquake is a rapid release process of the stress accumulated on the Xuemenkan-Moxi fault in the southeastern section of the Xianshuihe fault due to the uplift of the Qinghai-Tibet Plateau and the extrusion of crustal materials on the plateau to the southeast.