Love wave dispersion in central North America determined using absolute displacement seismograms from high‐rate GPS

Abstract

[1] We use seismic array processing of high-rate GPS (HRGPS) displacement time series from the Great, 2004, M w 9+, Sumatra-Andaman earthquake recorded at over 90 nonuniformly distributed HRGPS stations in central North America to determine the fundamental Love wave phase velocity dispersion curve there. These measurements were performed using frequency domain beam forming, which we show reduces the effects of GPS multipath and common mode noise on the measurement of surface wave phase velocity and azimuth. Our HRGPS based results for surface wave phase velocity agree well with those obtained from 28 broadband seismometers between periods of 20 to 300 s. By separating waves based on their apparent velocity, beam forming supports the simple model for relative displacement HRGPS time series as being the difference between the reference and kinematic station's absolute displacements. Beam forming also demonstrates that for differential GPS processing the infinite apparent velocity beam of an array is composed of the sum of common mode noise and the reference station's absolute displacements, multipath and noise. We show the infinite apparent velocity beam, which we call the generalized spatial filter, is similar to the spatial filter commonly used to remove common mode noise from HRGPS seismograms and can be used to produce absolute displacement time series for the kinematic stations with reduced common mode noise. Beam forming also suggests a filtering method, complimentary to sidereal filtering, to produce GPS multipath reduced HRGPS time series.Citation: Davis, J. P., and R. Smalley Jr. (2009), Love wave dispersion in central North America determined using absolute displacement seismograms from high-rate GPS,

Very high rate (10 Hz) GPS seismology for moderate-magnitude earthquakes: The case of theMw6.3 L'Aquila (central Italy) event

“…It has proven that the 30 s–rated epoch by epoch solution is enough to determine instantaneous geodetic positions [ Bock et al , 2000] and rapid estimations of magnitude [ Blewitt et al , 2006]. Other investigations have demonstrated the utility of 1 Hz data to detect seismic waves in good agreement with seismic data [ Larson et al , 2003; Bock et al , 2004; Wang et al , 2007; Emore et al , 2007] and to model fault slip [ Ji et al , 2004; Miyazaki et al , 2004; Davis and Smalley , 2009; Yokota et al , 2009]. However, Smalley [2009] showed that 1 Hz GPS recordings of coseismic displacements at very small epicentral distances from M 6 earthquakes are aliased, and that 5 Hz recordings for M 7 (or larger) events may also be aliased.…”

Centroid-moment tensor inversions using high-rate GPS waveforms

“…GPS networks have been used to make many observations of dynamic displacements caused by earthquakes (e.g. Nikolaidis et al 2001; Kouba 2003; Davis & Smalley 2009; Shi et al 2010; O’Toole & Woodhouse 2011; Bock et al 2011). However, such data have only been used to construct source models for a handful of events: the 2003 Tokachi–Oki earthquake (Miyazaki et al 2004), the 2003 San Simeon earthquake (Ji et al 2004), the 2005 Fukuoka earthquake (Kobayashi et al 2006), the 2008 Iwate–Miyagi earthquake (Yokota et al 2009), the 2008 L’Aquila earthquake (Avallone et al 2011), the 2010 Maule earthquake (Delouis et al 2010; Vigny et al 2011) and the 2011 Tohoku earthquake (Ammon et al 2011; Yue & Lay 2011).…”

Focal Mechanisms of the 2016 Central Italy Earthquake Sequence Inferred from High-Rate GPS and Broadband Seismic Waveforms

“…By comparing the frequency contents of seismic and high-rate GPS data, Avallone et al [25] inferred that GPS sampling rates greater than 2.5 Hz are required in the near-field region of moderate-magnitude events to provide solutions for the coseismic dynamic displacement that are free of aliasing artifacts [28,29]. Therefore, high-rate GPS data recorded at a sampling rate of 10 Hz were selected for this study.…”