Toward a Continuous Monitoring of the Horizontal Displacement Gradient Tensor Field in Southern California Using cGPS Observations from Plate Boundary Observatory (PBO)

Holt, W. E.; Shcherbenko, G. N.

doi:10.1785/0220130004

Cited by 9 publications

(11 citation statements)

References 26 publications

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“…We use a similar methodology to previous work (Beavan & Haines, ; Haines & Holt, ; Holt, Shen‐Tu, et al, , Holt, Chamot‐Rooke, et al, ; Holt & Shcherbenko, ), where the horizontal displacement gradient tensor field (i.e., strains and rotations) is modeled as a continuous field on the surface of a sphere. The forward model of the continuous field is parameterized using a continuous time‐varying 3‐D rotation vector function W ( r , t), where r is a directional cosine vector that passes through the Earth's center, t is time, and both W ( r , t) and r are perpendicular to the Earth's surface.…”

Section: Methods and Datamentioning

confidence: 99%

Seasonal Nontectonic Loading Inferred From cGPS as a Potential Trigger for the M6.0 South Napa Earthquake

2018

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We analyze crustal strain corresponding to transient continuous Global Positioning System (cGPS) horizontal displacements in Northern California, detecting a seasonal positive dilatational strain and Coulomb stress transient in the South Napa region peaking just before the 24 August 2014 M6.0 South Napa earthquake. Using data from 2007 to 2014, we show that average dilatational strain within a 500‐km2 region encompassing South Napa and northern San Pablo Bay peaks in late summer at 76 ± 17 × 10−9, accompanied by a Coulomb stress change of 1.9 ± 0.8 kPa. The situation reverses in winter, with an average dilatational strain of −51 ± 17 × 10−9 and Coulomb stress change of −1.4 ± 0.8 kPa. Within a smaller 100‐km2 area centered on the South Napa rupture, peak values are considerably higher, including a summer Coulomb stress peak of 5.1 ± 1.6 kPa. We examine regional seismicity but see no statistically significant correlation with seasonal Coulomb stressing in the declustered earthquake catalog. Using western U.S. vertical cGPS displacements, we estimate that strain from hydrologic loading explains ≤10% of the observed long‐wavelength strain and only 2–3% of peak strains around the South Napa rupture. Thermoelastic crustal strain estimated from temperature gradients between the San Francisco Bay and Sacramento Valley reaches values as high as 15% of the observed strain, but the strain patterns are not spatially consistent. Vertical deformation within the Sonoma and Napa Valley subbasins inferred from interferometric synthetic aperture radar explains large horizontal motions at nearby cGPS stations and suggests that seasonal changes in groundwater may contribute to observed strain and stress transients.

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Section: Methods and Datamentioning

confidence: 99%

Seasonal Nontectonic Loading Inferred From cGPS as a Potential Trigger for the M6.0 South Napa Earthquake

2018

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Section: Spatio-temporal Change In Interplate Couplingmentioning

confidence: 99%

“…Ohtani et al 2010;Holt & Shcherbenko 2013;Crowell et al 2016). Ohtani et al (2010) and Holt & Shcherbenko (2013) focused to the horizontal strain rate field to find transient deformation events and determine their locations, while Crowell et al (2016) analysed 3-D displacement time-series at station by station to detect episodic tremor and slip events automatically. However, Ohtani et al (2010) and Holt & Shcherbenko (2013) did not involve vertical displacement rates in their analysis even though Ohtani et al (2010) mentioned the extensibility of their method to include the vertical component.…”

Section: Spatio-temporal Change In Interplate Couplingmentioning

confidence: 99%

Monitoring of the spatio-temporal change in the interplate coupling at northeastern Japan subduction zone based on the spatial gradients of surface velocity field

Iinuma

2017

Geophysical Journal International

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S U M M A R YA monitoring method to grasp the spatio-temporal change in the interplate coupling in a subduction zone based on the spatial gradients of surface displacement rate fields is proposed. I estimated the spatio-temporal change in the interplate coupling along the plate boundary in northeastern (NE) Japan by applying the proposed method to the surface displacement rates based on global positioning system observations. The gradient of the surface velocities is calculated in each swath configured along the direction normal to the Japan Trench for time windows such as 0.5, 1, 2, 3 and 5 yr being shifted by one week during the period of 1997-2016. The gradient of the horizontal velocities is negative and has a large magnitude when the interplate coupling at the shallow part (less than approximately 50 km in depth) beneath the profile is strong, and the sign of the gradient of the vertical velocity is sensitive to the existence of the coupling at the deep part (greater than approximately 50 km in depth). The trench-parallel variation of the spatial gradients of a displacement rate field clearly corresponds to the trenchparallel variation of the amplitude of the interplate coupling on the plate interface, as well as the rupture areas of previous interplate earthquakes. Temporal changes in the trench-parallel variation of the spatial gradient of the displacement rate correspond to the strengthening or weakening of the interplate coupling. We can monitor the temporal change in the interplate coupling state by calculating the spatial gradients of the surface displacement rate field to some extent without performing inversion analyses with applying certain constraint conditions that sometimes cause over-and/or underestimation at areas of limited spatial resolution far from the observation network. The results of the calculation confirm known interplate events in the NE Japan subduction zone, such as the post-seismic slip of the 2003 M8.0 Tokachi-oki and 2005 M7.2 Miyagi-oki earthquakes and the recovery of the interplate coupling around the rupture area of the 1994 M7.6 Sanriku-Haruka-oki earthquake. The results also indicate the semi-periodic occurrence of slow slip events and the expansion of the area of slow slip events before the 2011 Tohoku-oki earthquake (M9.0) approaching the hypocentre of the Tohoku-oki earthquake.

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“…Granat et al (2013) present results of three separate detection approaches applied to the synthetic data, all based on spatial and temporal coherence of the signals instead of reliance on a physical model for the underlying deformation. Holt and Shcherbenko (2013) describe an approach for detection of transient deformation that seeks to identify time-varying patterns in the strain-rate field derived from GPS data. Future efforts may evolve to focus on fault-related deformation events, but there may be equal or greater interest in the characteristics of deformation features related to the hydrologic cycle and the extraction and injection of subsurface fluids.…”

Section: Discussionmentioning

confidence: 99%

“…• application of Kalman filtering, with spatial basis functions based either on known faults (Segall and Matthews, 1997;Fukuda et al, 2008) or on smooth functions with a range of scales (Tape et al, 2009;Ohtani et al, 2010); and • modeling of the spatial strain field and the significance of its temporal variations (Holt and Shcherbenko, 2013).…”

Section: Blind Test Exercisementioning

confidence: 99%

The SCEC Geodetic Transient-Detection Validation Exercise

Lohman

Murray

2013

Seismological Research Letters

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Toward a Continuous Monitoring of the Horizontal Displacement Gradient Tensor Field in Southern California Using cGPS Observations from Plate Boundary Observatory (PBO)

Cited by 9 publications

References 26 publications

Seasonal Nontectonic Loading Inferred From cGPS as a Potential Trigger for the M6.0 South Napa Earthquake

Seasonal Nontectonic Loading Inferred From cGPS as a Potential Trigger for the M6.0 South Napa Earthquake

Monitoring of the spatio-temporal change in the interplate coupling at northeastern Japan subduction zone based on the spatial gradients of surface velocity field

The SCEC Geodetic Transient-Detection Validation Exercise

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