Recovering coseismic point ground tilts from collocated high-rate GPS and accelerometers

Abstract

Rotational along with translational and strain measurements are essential for a complete description of the motion of a deformable body in a seismic event. We propose a new seismogeodetic approach where collocated high-rate GPS and accelerometer measurements are combined to estimate permanent and dynamic coseismic ground tilts at a point, whereas at present, only dynamic tilts are measured with either a dense seismic array or an expensive ring laser gyroscope. We estimate point tilts for a five-story structure on a shake table subjected to 13 earthquake strong motion records of increasing intensity. For the most intense record from the 2002 M7.9 Denali earthquake, we observe a peak-to-peak dynamic tilt of 0.12° and a permanent tilt of 0.16° for the structure's roof. Point tilts derived from networks of collocated GPS and accelerometers can be used to estimate the rotational component of the seismic wavefield for improved earthquake source characterization. Key Points Coseismic point ground tilts are derived from collocated GPS and accelerometer Both permanent and dynamic tilts are recovered at 0.01-degree resolution Coseismic tilts along major faults may lead to improved source imaging ©2013. American Geophysical Union. All Rights Reserved.