By means of inversion of fault slip data, the parameters of 20 tectonic stress tensors in Southwest Yunnan region are determined. Compared with the average stress field of the region obtained from focal mechanism solu...By means of inversion of fault slip data, the parameters of 20 tectonic stress tensors in Southwest Yunnan region are determined. Compared with the average stress field of the region obtained from focal mechanism solutions, the following characteristics of modern tectonic stress field in this region are obtained. From the west of Zhenyuan-Yingpanshan fault to the south of Longling fault zone, the maximum compressional stress is in NNE direction and the stress regime is mainly of strike-slip type. In Longling fault zone and the area north to it, the direction of maximum compressional stress is near-NS or NNW, the stress regime is of strike-slip type.展开更多
It is generally accepted that the Burmese Arc represents a transition zone between the Himalayan collision belt and the Indonesian Arc. The detail analysis of focal mechanism in the Burmese Arc and its vicinity now im...It is generally accepted that the Burmese Arc represents a transition zone between the Himalayan collision belt and the Indonesian Arc. The detail analysis of focal mechanism in the Burmese Arc and its vicinity now implicates two dominant factors responsible for the prevailing stress field in the region. The first is the Indian Plate motion, which produces a SSW-NNE compressive stressl the second is the overthrusting of the Eurasian Plate above the indian Plate, which results in a NEE-SWW compressive stress and a tensile stress approximately perpendicular to the main tectonic lines. The flow of material from the deep crust of Tibet to Burmese region facilitates the overthrusting. The two share a common dynamic source, namely, the NNE motion of the Indian Plate.展开更多
By using 126 earthquake focal mechanism solutions (M S≥4.7) during the period of 1963～1998, modern tectonic stress field in North China is inverted by means of the step by step convergence. The inversion results ind...By using 126 earthquake focal mechanism solutions (M S≥4.7) during the period of 1963～1998, modern tectonic stress field in North China is inverted by means of the step by step convergence. The inversion results indicate that the tectonic stress field in the research region is clearly variational in space and time: (1) The middling principal stress axis σ 2 is basically vertical. The maximum and minimum principal stress axes σ 1 and σ 2 are nearly horizontal, but the azimuths of σ 1 and σ 3 are inconsistent in different districts and periods. (2) Before the Tangshan earthquake in 1976, the three principal stress axes are uniform. The azimuth of maximum principal stress axis σ 1 is 68° (striking in a NEE-SWW direction). (3) After the Tangshan earthquake, the maximum principal stress axis σ 1 and minimum principal stress axis σ 3 have variations in different districts. In the northern area of North China and on the eastern side of the Tancheng-Lujiang fault zone, the maximum principal stress axis σ 1 is also striking in a NEE-SWW direction. Its azimuth is 68°. It is the same as that before the Tangshan earthquake. In the southern area of North China, the maximum principal stress axis σ 1 is striking in a E-W direction and its azimuth is 87°.展开更多
基金Chinese Joint Seismological Science Foundation (9507424).Contribution No. 2001A001, Institute of Crustal Dynamics, China Seism
文摘By means of inversion of fault slip data, the parameters of 20 tectonic stress tensors in Southwest Yunnan region are determined. Compared with the average stress field of the region obtained from focal mechanism solutions, the following characteristics of modern tectonic stress field in this region are obtained. From the west of Zhenyuan-Yingpanshan fault to the south of Longling fault zone, the maximum compressional stress is in NNE direction and the stress regime is mainly of strike-slip type. In Longling fault zone and the area north to it, the direction of maximum compressional stress is near-NS or NNW, the stress regime is of strike-slip type.
文摘It is generally accepted that the Burmese Arc represents a transition zone between the Himalayan collision belt and the Indonesian Arc. The detail analysis of focal mechanism in the Burmese Arc and its vicinity now implicates two dominant factors responsible for the prevailing stress field in the region. The first is the Indian Plate motion, which produces a SSW-NNE compressive stressl the second is the overthrusting of the Eurasian Plate above the indian Plate, which results in a NEE-SWW compressive stress and a tensile stress approximately perpendicular to the main tectonic lines. The flow of material from the deep crust of Tibet to Burmese region facilitates the overthrusting. The two share a common dynamic source, namely, the NNE motion of the Indian Plate.
文摘By using 126 earthquake focal mechanism solutions (M S≥4.7) during the period of 1963～1998, modern tectonic stress field in North China is inverted by means of the step by step convergence. The inversion results indicate that the tectonic stress field in the research region is clearly variational in space and time: (1) The middling principal stress axis σ 2 is basically vertical. The maximum and minimum principal stress axes σ 1 and σ 2 are nearly horizontal, but the azimuths of σ 1 and σ 3 are inconsistent in different districts and periods. (2) Before the Tangshan earthquake in 1976, the three principal stress axes are uniform. The azimuth of maximum principal stress axis σ 1 is 68° (striking in a NEE-SWW direction). (3) After the Tangshan earthquake, the maximum principal stress axis σ 1 and minimum principal stress axis σ 3 have variations in different districts. In the northern area of North China and on the eastern side of the Tancheng-Lujiang fault zone, the maximum principal stress axis σ 1 is also striking in a NEE-SWW direction. Its azimuth is 68°. It is the same as that before the Tangshan earthquake. In the southern area of North China, the maximum principal stress axis σ 1 is striking in a E-W direction and its azimuth is 87°.
