TECTONIC INDICATIONS OF OCCURRENCE OF MODERATE-TO-STRONG EARTHQUAKES IN CHAOHU-TONGLING AREA,ANHUI PROVINCE |
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| Authors: | GUO Peng HAN Zhu-jun ZHOU Ben-gang ZHOU Qing MAO Ze-bin |
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| Institution: | 1.Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;2.Yunnan Earthquake Agency, Kunming 650041, China |
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| Abstract: | The Chaohu-Tongling area in Anhui Province is a typical moderate-to-strong earthquake active area in the mainland of China. Four earthquakes occurred in this area, displayed as a NNE-trending zonal distribution, including the 1585 M5(3/4) Chaoxian earthquake and the 1654 M5(1/4) Lujiang earthquake, which formed a striking moderate-to-strong seismic activity zone. Field survey, shallow geophysical prospecting, drilling data, collection and dating of chronology samples and comprehensive analysis of fault activity indicate that the Fanshan, Xiajialing and Langcun faults are not active since Quaternary. The NNE-trending Tongling Fault is a buried middle-Pleistocene fault, but it can produce moderate-to-strong earthquakes and control the evolution and development of three en echelon geologic structures. The intensity of the four earthquakes is characterized by southward progressive decrease, which is in accordance with the characteristics that the subsidence range of Wuwei Basin is obviously larger than that of Guichi Basin to its south since late Cenozoic. In terms of deep structure, the characteristics of spatial distribution of Tongling Fault indicate that it corresponds to a NNE-striking Bouguer gravity anomaly gradient belt. So there is a spatial correspondence between the middle-Pleistocene Tongling Fault, the en echelon structures, the differential movement of the neotectonics, the Bouguer gravity anomaly gradient belt and the moderate-to-strong seismic activity belt in the Chaohu-Tongling area, indicating that they should be the tectonic indications of occurrence for moderate-to-strong earthquakes. |
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| Keywords: | Chaohu-Tongling area Tongling Fault moderate-to-strong earthquake neotectonics gravity anomaly |
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