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An explanation of the large PGA value of 2013 MS7.0 Lushan earthquake at 51BXD station through topographic analysis |
Zhijun Dai, Xiaojun Li |
Institute of Geophysics, China Earthquake Administration, 100081 Beijing, China |
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Abstract In MS7.0 Lushan earthquake, a large amount of strong ground motion recordings were collected. In this paper, we analyze the recordings carefully. The abnormality of ground motion recordings is identified through a log linear regression. In the station of 51BXD, the PGA value has exceeded 1 g, which is the biggest peak ground acceleration (PGA) value obtained from all recordings in this earthquake. The log linear relation shows the PGA value in this station is abnormally large. As this station is located on the footage of a hill, the topographic amplification factor is explored in order to explain this abnormality. Through 3D numerical modeling using spectral element method with transmitting boundary conditions, the amplification factor is quantized. In this station, the topographic amplification is highly polarized in the direction of East–West which agrees with the empirical recordings. This research result suggests us in future directionality of topographic amplification should be considered in the aseismic design.
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Received: 13 September 2013
Published: 08 January 2014
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Fund:the National Basic Research Program of China (2011CB013601), the National Natural Science Foundation of China (91215301, 61203276), and the Special Fund of the Institute of Geophysics, China Earthquake Administration (DQJB12B12) |
Corresponding Authors:
Xiaojun Li
E-mail: beerli@vip.sina.com
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