The focal mechanism solution on the seismic fault plane can reflect the geometric and kinematic characteristics of faults, and it is an important way to further study the fine structure of fault plane. From the focal ...The focal mechanism solution on the seismic fault plane can reflect the geometric and kinematic characteristics of faults, and it is an important way to further study the fine structure of fault plane. From the focal mechanism solution of the earthquakes around the Dujiangyan fault in Longmenshan fault zone, we derived the average dip angle of Dujiangyan fault is 45.1° based on the seismic moment tensor theory. In order to refine the fault geometry structure, this paper decomposed it into multiple sub-fault planes along the length and width of the fault plane and forms a number of models A13, B13, A23 a, A23 b, A23 c, B23 a,B23 b and B23 c, then calculated the sub-fault’s dip of each model. In order to clarify exactly which one of the fault models is closest to the real fault model, the fault slip was carried out for each model in turn, then compared the surface displacement of each model with GPS observations. The results show that B23 c model with high dip in shallow and small dip in deep is the best model, the lengths of each subfault of Dujiangyan fault from south to north are 33 km, 21 km and 46 km, respectively. When the depth of the fault bottom is about 11 km, the dip angles are 70.56°, 67.41° and 45.55°.When the depth of the fault bottom is about 30 km, The fault dip angles are 44.55°, 29.18° and 44.25°.展开更多
基金financially supported by the National Natural Science Foundation of China under Grant No.41304013Science and Technology Project Plan of Weinan of 2016 No.2016KYJ-1-1State Key Laboratory of Geo-information Engineering No.SKLGIE2017-M-3-3
文摘The focal mechanism solution on the seismic fault plane can reflect the geometric and kinematic characteristics of faults, and it is an important way to further study the fine structure of fault plane. From the focal mechanism solution of the earthquakes around the Dujiangyan fault in Longmenshan fault zone, we derived the average dip angle of Dujiangyan fault is 45.1° based on the seismic moment tensor theory. In order to refine the fault geometry structure, this paper decomposed it into multiple sub-fault planes along the length and width of the fault plane and forms a number of models A13, B13, A23 a, A23 b, A23 c, B23 a,B23 b and B23 c, then calculated the sub-fault’s dip of each model. In order to clarify exactly which one of the fault models is closest to the real fault model, the fault slip was carried out for each model in turn, then compared the surface displacement of each model with GPS observations. The results show that B23 c model with high dip in shallow and small dip in deep is the best model, the lengths of each subfault of Dujiangyan fault from south to north are 33 km, 21 km and 46 km, respectively. When the depth of the fault bottom is about 11 km, the dip angles are 70.56°, 67.41° and 45.55°.When the depth of the fault bottom is about 30 km, The fault dip angles are 44.55°, 29.18° and 44.25°.
