A multi-scale 3-D crust velocity model in the Hefei-Chao Lake area around the southern segment of Tanlu Fault Zone |
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| Authors: | Lingli Li Huajian Yao Song Luo Junhui Li Xiaoli Wang Hongyu Ni Ziwen Bao |
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| Institution: | Anhui Earthquake Agency,Hefei 230031,China;Anhui Mengcheng National Geophysical Observatory,Mengcheng 233500,China;Laboratory of Seismology and Physics of Earth's Interior,School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China;Anhui Mengcheng National Geophysical Observatory,Mengcheng 233500,China |
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| Abstract: | Regional high-precision velocity models of the crust are an important foundation for examining seismic activity, seismogenic environments, and disaster distribution characteristics. The Hefei-Chao Lake area contains the main geological units of Hefei Basin, with thick sediments and the Chao Lake depression. Several major concealed faults of the southern NNE-trending Tanlu Fault Zone cross this area. To further explore the underground distribution characteristics of the faults and their tectonic evolutionary relationship with adjacent tectonic units, this study used ambient noise data recorded by a seismic array deployed in Hefei City and Chao Lake, constructing a 3-D velocity model at the depth of 1–8 km. Then a multi-scale high-resolution 3-D velocity model of this area was constructed by this new upper crustal velocity model with the previous middle and lower crustal model. The new model reveals that a high-velocity belt is highly consistent with the strike of the Tanlu Fault Zone, and a low-velocity sedimentary characteristic is consistent with the Hefei Basin and Chao Lake depression. The distribution morphology of high and low velocity bodies shows that the sedimentary pattern of Hefei-Chao Lake area is closely related to the tectonic evolution of the Tanlu Fault Zone since the Mesozoic. This study also identifies multiple low-velocity anomalies in the southeastern Hefei City. We speculate that strong ground motion during the 2009 Feidong earthquake (magnitude of 3.5) was related to amplification by the thick sediments in the Hefei Basin. We also discuss further applications of multi-scale high-resolution models of the shallow layer to strong ground motion simulations in cities and for earthquake disaster assessments. |
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| Keywords: | Tanlu Fault Zone Hefei-Chao Lake area crust multi-scale velocity model |
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