The data of short-period (1～18 s) surface waves recorded by 23 stations belonging to the digital seismic network of Yunnan Province of China are used in this paper. From these data, the dispersion curves of phase vel...The data of short-period (1～18 s) surface waves recorded by 23 stations belonging to the digital seismic network of Yunnan Province of China are used in this paper. From these data, the dispersion curves of phase velocities of the fundamental mode Rayleigh wave along 209 paths are determined by using the two-station narrowband filtering cross-correlation method.Adopting tomography method, the distribution maps of phase velocities at various periods in Yunnan region are inverted. The maps of phase velocities on profiles along 24°N, 25°N, 26°N, 27°N and 100.5°E and the distribution maps of phase velocities at 3 periods in the study region are given. The results show that the phase velocity distribution in Yunnan region has strong variations in horizontal direction, and the phase velocity distribution in short-period range is closely related to the thickness of sedimentary layers in the shallow crust. The phase velocity in southern part of the Sichuan-Yunnan rhombic block encircled by the Honghe fault and Xiaojiang fault is obviously lower than that in surrounding areas. The epicentral locations of strong earthquakes in Yunnan region are mainly distributed in transitional zones between low and high phase velocities.展开更多
基金Joint Seismological Science Foundation of China (101086) and the key project "Digital Crustal and Mantle Structure of Chinese Mainland" from China Earthquake Administration.
文摘The data of short-period (1～18 s) surface waves recorded by 23 stations belonging to the digital seismic network of Yunnan Province of China are used in this paper. From these data, the dispersion curves of phase velocities of the fundamental mode Rayleigh wave along 209 paths are determined by using the two-station narrowband filtering cross-correlation method.Adopting tomography method, the distribution maps of phase velocities at various periods in Yunnan region are inverted. The maps of phase velocities on profiles along 24°N, 25°N, 26°N, 27°N and 100.5°E and the distribution maps of phase velocities at 3 periods in the study region are given. The results show that the phase velocity distribution in Yunnan region has strong variations in horizontal direction, and the phase velocity distribution in short-period range is closely related to the thickness of sedimentary layers in the shallow crust. The phase velocity in southern part of the Sichuan-Yunnan rhombic block encircled by the Honghe fault and Xiaojiang fault is obviously lower than that in surrounding areas. The epicentral locations of strong earthquakes in Yunnan region are mainly distributed in transitional zones between low and high phase velocities.
