Centroid-moment tensor inversions using high-rate GPS waveforms

Abstract

SUMMARY Displacement time‐series recorded by Global Positioning System (GPS) receivers are a new type of near‐field waveform observation of the seismic source. We have developed an inversion method which enables the recovery of an earthquake’s mechanism and centroid coordinates from such data. Our approach is identical to that of the ‘classical’ Centroid–Moment Tensor (CMT) algorithm, except that we forward model the seismic wavefield using a method that is amenable to the efficient computation of synthetic GPS seismograms and their partial derivatives. We demonstrate the validity of our approach by calculating CMT solutions using 1 Hz GPS data for two recent earthquakes in Japan. These results are in good agreement with independently determined source models of these events. With wider availability of data, we envisage the CMT algorithm providing a tool for the systematic inversion of GPS waveforms, as is already the case for teleseismic data. Furthermore, this general inversion method could equally be applied to other near‐field earthquake observations such as those made using accelerometers.

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

“…Recently, O'Toole et al . [] showed that high‐rate GPS waveforms can be inverted using the centroid–moment tensor (CMT) algorithm of Dziewonski et al . [], allowing an optimal point source description of an earthquake to be determined from these time series.…”

High-precision coseismic displacement estimation with a single-frequency GPS receiver

“…However, there are still some practical issues with the existing high-rate GPS networks, such as the insufficient density of stations. A dense network of stations is needed, which is important not only for rapid response to make source models of earthquakes quickly after the event but also for EEW to minimize the blind zone that suffers from the destructive waves before an alert is received (O'Toole et al 2012;Kuyuk & Allen 2013). Except for Japan's GNSS Earth Observation Network System (GEONET) with an average intersite distance of about 20 km, other high-rate GPS networks need to be made considerably denser to reduce the spacing between sites.…”

Rapid earthquake focal mechanism inversion using high-rate GPS velometers in sparse network

“…Currently, no studies on inverting earthquake source parameters with GPS velocity information have been published, although GPS displacements have been extensively used in earthquake studies (Crowell et al, 2009;Bock et al, 2011;Duputel et al, 2011;Melgar et al, 2012Melgar et al, , 2013O'Toole et al, 2012;Li et al, 2013aLi et al, , 2014Minson et al, 2014). Given the advantages of easy real-time solutions and no requirement for reference stations, GPS velocity records provide another effective approach for rapid determination of earthquake source parameters.…”

“…Currently, however, the system is used for applications far beyond its original intended design (Misra and Enge, 2006;HofmannWellenhof et al, 2008). In earthquake research, dynamic GPS displacement records with a 1 Hz or higher sampling rate, known as high-rate GPS, are now widely used to capture earthquake dynamic waveforms and to invert earthquake source parameters and rupture processes independently or together with seismological data (Larson et al, 2003Ji et al, 2004;Elósegui et al, 2006;Bilich et al, 2008;Wang et al, 2008;Yokota et al, 2009;Delouis et al, 2010;Yin et al, 2010;Avallone et al, 2011;Yue and Lay, 2011;O'Toole et al, 2012;Guo et al, 2013). Although high-rate GPS is not as sensitive as traditional instruments, e.g., velocity-type broadband seismometers and accelerometer-type strong motion instruments, high-rate GPS has become more popular in the last two decades.…”