Seismotectonic environment of occurring the February 3, 1996 Lijiang M=7.0 earthquake, Yunnan Province |
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| Authors: | Han Zhu-jun Guo Shun-min Xiang Hong-fa Zhang Jia-sheng and Ran Yong-kang |
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| Institution: | (1) Institute of Geology, China Earthquake Administration, 100029 Beijing, China |
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| Abstract: | Lijiang-Daju fault, the seismogenic fault of the 1996 Lijiang M=7.0 earthquake, can be divided into Lijiang-Yuhu segment in the south and Yuhu-Daju segment in the north. The two segments
show clear difference in geological tectonics, but have the similar dynamic features. Both normal dip-slip and sinistral strike-slip
coexist on the fault plane. This kind of movement started at the beginning of the Quaternary (2.4–2.5 Ma B.P.). As to the
tectonic types, the detachment fault with low angle was developed in the Early Pleistocene and the normal fault with high
angle only after the Mid-Pleistocene (0.8 Ma B.P.). Based on the horizontal displacements of gullies and the vertical variance
of planation surfaces cross the Lijiang-Daju fault at east piedmont of Yulong-Haba range, the average horizontal and vertical
slip rates are calculated. They are 0.84 mm/a and 0.70 mm/a since the Quaternary and 1.56 mm/a and 1.69 mm/a since the Mid-Pleistocene.
The movements of the nearly N-S-trending Lijiang-Daju fault are controlled not only by the regional stress field, but also
by the variant movement between the Yulong-Haba range and Lijiang basin. The two kinds of dynamic processes form the characteristics
of seismotectonic environment of occurring the 1996 Lijiang earthquake.
Foundation item: Joint Seismological Science Foundation of China (198023) and National Natural Science Foundation (40272087). |
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| Keywords: | the 1996 Lijiang earthquake variant movement basin boundary fault seismotectonic environment |
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