Earthquake source parameters from GPS‐measured static displacements with potential for real‐time application

Abstract

[1] We describe a method for determining an optimal centroid-moment tensor solution of an earthquake from a set of static displacements measured using a network of Global Positioning System receivers. Using static displacements observed after the 4 April 2010, M W 7.2 El Mayor-Cucapah, Mexico, earthquake, we perform an iterative inversion to obtain the source mechanism and location, which minimize the least-squares difference between data and synthetics. The efficiency of our algorithm for forward modeling static displacements in a layered elastic medium allows the inversion to be performed in real-time on a single processor without the need for precomputed libraries of excitation kernels; we present simulated real-time results for the El MayorCucapah earthquake. The only a priori information that our inversion scheme needs is a crustal model and approximate source location, so the method proposed here may represent an improvement on existing early warning approaches that rely on foreknowledge of fault locations and geometries. Citation: O'Toole, T. B., A. P. Valentine, and J. H. Woodhouse (2013), Earthquake source parameters from GPSmeasured static displacements with potential for real-time application, Geophys. Res. Lett., 40,[60][61][62][63][64][65]

Long-period surface motion of the multipatch Mw9.0 Tohoku-Oki earthquake

“…As seismic waveforms, GPS time-series provide insights into surface transients observed during seismic wave propagation or during a seismic rupture (Larson, 2001;Bock et al, 2004;Ji et al, 2004;Miyazaki et al, 2004;Blewitt et al, 2006;Kobayashi et al, 2006;Ohta et al, 2006;Emore et al, 2007;Wang et al, 2007;Yokota et al, 2009;Delouis et al, 2010;Feng et al, 2010;Houlié et al, 2011, Bock et al, 2011Avallone et al, 2011;Mitsui andHeki, 2012 Wright et al, 2012;Meng et al, 2013;Guo et al, 2013;Houlié et al, 2014, Psimoulis et al, 2015, tsunami generation for early warning (Blewitt et al, 2006;Sobolev et al, 2007;Blewitt et al, 2009;Crowell et al, 2009;Behrens et al, 2010;, changes in ionosphere status (Ducic et al, 2003;Mai and Kiang, 2009;Karia et al, 2012;Galvan et al, 2012), volcanic plumes (Houlié et al, 2005;Houlié et al, 2006;Newman, et al, 2012), water vapour delays (Perler et al, 2011;Hurter et al, 2012), or moment tensor (O'Toole et al, 2012;O'Toole et al, 2013). However, the studies listed above did not make use of real-time or near real-time data processing strategies.…”

Robust and Fast Probabilistic Source Parameter Estimation from Near‐Field Displacement Waveforms Using Pattern Recognition

“…However, traditional approaches typically require strong regularization if near-field data are to be used, because the associated optimization problem becomes unstable and highly nonunique. In particular, in the case of the El Mayor-Cucapah event, other researchers have found a need to apply strong damping to suppress spurious non-double-couple components and to stabilize the iterative optimization process when inverting a similar static displacement dataset as the one used here for point-source parameters (O'Toole et al, 2013). Here and in Käufl et al (2014), there appears to be no need for additional measures to account for finite-source effects in the case of this event.…”

“…Point-source inversions using either a similar GPS displacement waveform dataset or using static offsets extracted from the displacement time series have recently been conducted by Melgar et al (2012), Zheng et al (2012), O'Toole et al (2013), and Käufl et al (2014) and have shown a good agreement to catalog solutions, although with large uncertainties attached to some of the source parameters.…”

Comparing source inversion techniques for GPS‐based local tsunami forecasting: A case study for the April 2014 M8.1 Iquique, Chile, earthquake

“…Instead of adopting coseismic displacements, O'Toole et al [] developed an algorithm to get centroid moment tensor using high‐rate GPS waveforms. They also suggested an alternative to the fastCMT approach by simultaneously searching for the best centroid position [ O'Toole et al , ]. Crowell et al [] inverted real‐time GPS data for a finite fault slip distribution in homogeneous elastic half‐space.…”