Resolving static offsets from high-rate GPS data: the 2003 Tokachi-oki earthquake

Abstract

The M w 8.0 2003 Tokachi-oki earthquake offshore Hokkaido is the largest earthquake observed to date by a dense GPS network (GEONET). These GPS data are important both for resolving the geodetic signature of the earthquake itself and studies of postseismic deformation. Because GPS positions are generally estimated by averaging 24 hours of observations, it can be difficult to separate the effects of the earthquake and early postseismic deformation. In order to address this difficulty, a Kalman filtering methodology is developed that allows the estimation of the static offsets for the mainshock, its largest aftershock, and postseismic deformation in the first 24 hours. The static offsets computed for this study can be used for earthquake rupture studies while the early postseismic data can be used to evaluate frictional properties of the fault.

Slip distribution of the 2003 Tokachi‐oki Mw 8.1 earthquake from joint inversion of tsunami waveforms and geodetic data

“…For GPS and PGs data, we add a Gaussian random value to synthetic data sets, with a variance equal to the square of the standard deviation for each component (3 mm for east, 4 mm for north, and 9 mm for vertical component [ Larson and Miyazaki , 2008]).…”

The 2011 off the Pacific coast of Tohoku Earthquake and its aftershocks observed by GEONET

“…The GIPSY software provides two models (i.e., white noise and random walk) to estimate site coordinates. We chose the whitenoise model, which is appropriate to detect a coseismic offset (Larson and Miyazaki, 2008). In addition, to follow highly-rapid deformation, we estimated 30-s coordinates using the final orbits and high-rate clocks of the International GNSS Service (IGS).…”

“…However, the site coordinates estimated from the static positioning by the GEONET routine do not have enough temporal resolution to capture any rapid evolution of the deformation (e.g. Larson and Miyazaki, 2008). In the sequence of the 2011 Tohoku earthquakes, several M > 7 aftershocks occurred within 1 h after the mainshock.…”

Assessment of high-rate GPS using a single-axis shake table

“…These considerable improvements have the potential of measuring earthquake ground motions. Large and moderate earthquakes were successfully observed by permanent 1 sps GPS stations: 1999 M7.1 Hector Mine (Nikolaidis et al 2001(Nikolaidis et al ), 2002 Denali Bock et al 2004;Kouba 2003;Bilich et al 2008Bilich et al ), 2003.0 TokachiOki (Clinton 2004;Miyazaki et al 2004;Emore et al 2007;Larson and Miyazaki 2008), 2004 M9.0 Sumatra Andaman (Kouba 2005;Ohta et al 2006Ohta et al ), 2005 Nias (Kreemer et al 2006), 2008 M8.0 Wenchuan (Shi et al 2010;Yin et al 2013), 2010 M8.8 Chile (Wang et al 2012), and 2011 M9.0 Tohoku-Oki (Munakane 2012; Zhou et al 2012;Hung and Ruey-Juin 2013). Beside these significant global events, moderate earthquakes have produced seismic displacements also observable by GPS: 2003 M6.5 San Simeon (Ji et al 2004;Wang et al 2007) and 2004 M6.0 Parkfield (Langbein and Bock 2004;Langbein 2006).…”