We illustrate the impact of ground tilt on baseline offset in an accelerogram and propose a method of estimation of co-seismic tilt based on acceleration record in the near-field of an earthquake. The method is applied to the records from 33 carefully selected stations in the 2008 Wenchuan earthquake, and the validity of the method is preliminarily confirmed. Our results show that large tilts in magnitude are obtained in near-fault or rupture-toward stations. No obvious characteristic is found in distribution of the tilt direction. The validity of the method needs further confirmation.
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