CAJ | 학술논문

基于一维单侧有限移动震源模式，根据地震波传播过程中的多普勒效应，分别利用 P 波和S波拐角频率的方位变化，反演2012年7月20日江苏高邮、宝应交界 MS4.9地震的发震断层面参数。P 波和S波拐角频率的反演结果一致显示：本次地震的断层面破裂方向为232°左右，破裂面呈 NE-SW 向；地震马赫数 v/c 为0.2左右，平均破裂速度小于S波速度，破裂长度较短，为0.2~0.3 km 左右。破裂面方位与震源机制解、宏观烈度调查和余震精定位的研究结果具有一致性，结合震区周边的地质构造背景，分析认为滁河断裂很可能是高邮、宝应交界 MS4.9地震的发震构造。
기우일유단측유한이동진원모식，근거지진파전파과정중적다보륵효응，분별이용 P 파화S파괴각빈솔적방위변화，반연2012년7월20일강소고유、보응교계 MS4.9지진적발진단층면삼수。P 파화S파괴각빈솔적반연결과일치현시：본차지진적단층면파렬방향위232°좌우，파렬면정 NE-SW 향；지진마혁수 v/c 위0.2좌우，평균파렬속도소우S파속도，파렬장도교단，위0.2~0.3 km 좌우。파렬면방위여진원궤제해、굉관열도조사화여진정정위적연구결과구유일치성，결합진구주변적지질구조배경，분석인위저하단렬흔가능시고유、보응교계 MS4.9지진적발진구조。
Based on a 1D finite moving source model propagating unilaterally with uniform velocity,the rupture transmission in one direction is superior to that in other directions.According to the Doppler Effect in the earthquake rupture process,the seismic wave frequency received by earthquake stations changes in different directions and thus, we can use the directional change of the corner frequency of the P or S waves to obtain the source parameters of the fault plane.In this article,the azimuth of rupture propagation direction and source parameters of the fault plane of the July 20,2012,M S 4.9 earthquake at the boundary zone of Gaoyou and Baoying in Jiangsu Province are obtained u-sing the directional change of the corner frequency of the P and S waves,respectively.The azimuth angle of the fault plane for this earthquake was determined to be 232°by the P waves and 233.5°by the S waves,the seismic Mach number (v/c )was about 0.18 by the P waves and 0.23 by the S waves,and the fault length was about 0.26 km by the P waves and 0.18 km by the S waves.The result inverted by the corner frequency of the P and S waves is consist-ent,which shows that the azimuth angle of the fault plane for this earthquake was about 232°.Because of the lack of a near-station record at an azimuth of 49°,the inversion method is based on a 1D finite moving source model propa-gating unilaterally with uniform velocity.Therefore,the result of a rupture azimuth of 232°cannot represent a rup-ture propagating in the direction from NE to SW;it only indicates that the rupture surfaces were aligned in that di-rection.The seismic Mach number was about 0.2,which shows that the rupture velocity was smaller than the S wave velocity,and the fault length was about 0.2 ~0.3 km.Many scholars have studied the seismogenic structure of the earthquake on July 20,2012,using a variety of methods such as focal mechanism solutions,field seismic intensity in-vestigations,and relocation for aftershocks;however,the results have not been the same.The results of focal mecha-nism solutions show that the strike angle of one fault plane is 14°~28°in the NNE direction,whereas the strike an-gle of the other is in the NWW direction.Analysis shows that the fault plane might be in the NNE direction;howev-er,the results of both field seismic intensity investigations and relocation for aftershocks show the fault plane might be in the NE direction.Our result show that the fault plane is aligned NE-SW,which is in accordance with the field seismic intensity investigations and relocation for aftershocks.The result inverted by the corner frequency of the P and S waves is consistent,showing a rupture azimuth with NE-SW alignment,which indicates that this method is meaningful in the fitting of the azimuth angle of an earthquake fault plane.Combined with regional geological struc-tural data,we suggest that the Chuhe fault is likely to be the seismogenic structure of the M S 4.9 earthquake at the boundary zone of Gaoyou and Baoying.