Rapid Estimate and Modeling of Permanent Coseismic Displacements for Large Earthquakes Using High-Rate Global Positioning System Data

Abstract

Online Material: Figures showing application of fitting window approach, residual displacements and trade‐off curves, and finite fault‐slip models. More and more of the Earth’s active plate boundaries are instrumented with continuous Global Positioning System (cGPS) networks that provide both the earthquake research and response communities with the opportunity to observe coseismic surface deformation in much greater detail and rapidity than was possible a decade ago. These measurements of 3D displacements with high temporal resolution are critical for understanding the kinematics and dynamics of events and are complementary to seismic acceleration observations and high spatial resolution Interferometric Synthetic Aperture Radar observations. In addition, low‐latency GPS has been tested for use in rapid hazard assessment (e.g., Blewitt et al. , 2006, 2009; Allen and Ziv, 2011; Ohta et al. , 2012). CGPS data from dense networks with hundreds to thousands of stations (e.g., GEONET in Japan, EarthScope/PBO in western United States) are now routinely available on a variety of time scales, from daily download to real time. Advances in GPS processing capability enable the estimates of high‐rate (e.g., 5 min, 30 s, 1 Hz or higher) GPS positions very rapidly, even for large networks. As part of the Advanced Rapid Imaging and Analysis (ARIA) team’s response to the M w 9.0 Tohoku‐Oki earthquake, we generated and posted online the first coseismic offset values based on Japan’s dense GEONET cGPS network (Owen et al. , 2011) within 48 hours of the event. These offsets were used in the 26 peer‐reviewed publications that had modeled the Tohoku‐Oki event at the time of this publication. Given the heavy usage of this rapidly available data set for scientific studies, and because many algorithms to model earthquakes are better constrained when they have static coseismic displacements to model the event (in particular in the region of the seismogenic fault …