Detecting Large-scale Intracontinental Slow-slip Events (SSEs) Using Geodograms

Wernicke, Brian P.; Davis, J. L.

doi:10.1785/gssrl.81.5.694

Cited by 8 publications

(23 citation statements)

References 17 publications

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“…In order to improve SSE detection in low signal-to-noise ratio environments, we developed a visual spatial-temporal detection technique, resulting in a display we term a positionogram [Jiang and Wdowinski, 2008]. A similar technique was introduced to study CGPS time series in the Basin and Range province of North America [Wernicke and Davis, 2010].…”

Section: Positionogrammentioning

confidence: 99%

Slow slip events in Costa Rica detected by continuous GPS observations, 2002–2011

Jiang

Wdowinski

Dixon

et al. 2012

Geochem Geophys Geosyst

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A network of continuously recording GPS stations has operated in the Nicoya Peninsula of northern Costa Rica since 2002. We processed all available data from this network for the period of 2002–2011 to investigate the occurrence of Slow Slip Events (SSE) on the subduction interface between the Cocos and Caribbean plates. In order to overcome signal masking by high levels of tropospheric noise, we developed a new technique that facilitates detection of transient events in the presence of noise. We identified five significant SSEs during the 2002–2011 period, with event middle times in 2003, 2005, 2007, 2009 and 2011, with an average recurrence interval of 21 ± 6 months. Time series analysis shows that transient deformation imparts a signature similar to random walk. Removal of the SSEs and regional common mode errors from the time series reduced velocity uncertainty by nearly an order of magnitude. Limited available data for the 2003, 2005 and 2011 events preclude detailed characterization of these events. However, good spatiotemporal coverage of the 2007 and 2009 events suggest that both events had irregular duration and distribution. In the 2007 event, slow slip started in the northwest coastal area and migrated southeastward over a period of ∼1 month. The 2009 event had a significantly longer event duration and larger surface displacement. Stations in the northwest area observed two separate SSEs in 2008.6 and 2009.4, correlating well with the tremor episodes offshore, indicating a shallow SSE slip patch with shorter recurrence interval. Significant differences between the 2009 and 2007 events lead us to question the simple recurrence interval model for the SSE in Nicoya.

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Section: Positionogrammentioning

confidence: 99%

Slow slip events in Costa Rica detected by continuous GPS observations, 2002–2011

Jiang

Wdowinski

Dixon

et al. 2012

Geochem Geophys Geosyst

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“…Previous analyses [ Davis et al , ; Wernicke and Davis , ] focused on the east components, which are shown in Figures a and b after removal of velocity and load model terms. We identify three transients that affected a majority of the sites, with T 0 around 1998.3 (period ~1.6 year), 2000.4 (period ~2 years), and 2004.4 (period ~4.3 years) (Figure c).…”

Section: Resultsmentioning

confidence: 99%

“…Transient displacements in the Basin and Range are qualitatively similar to those observed during slow fault slip events, and they have been interpreted as evidence of transient frictional slip [ Davis et al , ; Wernicke et al , ; Wernicke and Davis , ]. Slow slip events were first widely recognized from GPS measurements in subduction zones [ Hirose et al , ; Dragert et al , ; Lowry et al , ], and most subsequent observations of the phenomenon have similarly been associated with subduction megathrusts [e.g., Ohta et al , ; McCaffrey et al , ; Outerbridge et al , ].…”

Section: Introductionmentioning

confidence: 93%

“…Davis et al [] observed an approximate 1 mm/yr eastward perturbation of velocity in the western half of the Basin and Range from roughly 2000 to 2005. Wernicke and Davis [] examined Kalman‐filtered velocity time series to infer two distinct, shorter eastward velocity perturbations across the western half of the province that peaked in 2000 and late 2003, with a westward anomaly in 2006, and an eastward anomaly in the eastern half of the Basin and Range also occurring around 2006.…”

Section: Introductionmentioning

confidence: 99%

“…The maximum rupture depth for Basin and Range earthquakes is roughly 15 km [ Doser and Smith , ], so if Basin and Range transient deformation is indeed similar to slow slip in subduction zones, the source should be in the midcrust. Studies of Basin and Range transients thus far have inferred a megadetachment at the Moho however [ Davis et al , ; Wernicke et al , ; Wernicke and Davis , ], based on observations of strong reflection amplitudes there [ Hauser et al , ], the remarkably broad area activated during events, and temporal association with a lower crustal magmatic intrusion event near the western edge of 2000–2004 transient deformation [ Smith et al , ].…”

Section: Introductionmentioning

confidence: 99%

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Implications of transient deformation in the northern Basin and Range, western United States

2014

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Transient deformation events observed in Global Positioning System (GPS) data from the Basin and Range extensional province may illuminate qualitatively similar transient events observed in subduction zones and other tectonic environments. We model GPS time series at 22 sites using a combination of hyperbolic tangent function analysis and elastic load deformation estimated from climatological data. We identify two transient events,~2000.4 and~2004.4, with roughly similar timing and displacement to those described previously by other researchers. The first few years of GPS observations, adopted as a reference state in earlier studies, are found to be anomalous. Our results differ from previous studies in two respects. First, a significant component of northward transient motion occurs during both events, despite a reversal of sign in east component motion. Second, sites move coherently in the eastern as well as the western Basin and Range. Surface mass loading, the largest source of transient stress forcing in the region, exhibits no evidence of a simple relationship to the deformation transients. Prior studies inferred slip on a single megadetachment at the Moho, but that hypothesis assumes negligible ductile deformation of the lower crust and a dry olivine rheology for the uppermost mantle. Recent measurements of crustal quartz abundance and effective elastic thickness suggest both assumptions are unlikely. Basin and Range transients can be reconciled with the frictional slip mechanism widely accepted for subduction zone transients provided that slip is occurring on discontiguous detachment surfaces at midcrustal depths.

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Hunt for slow slip events along the Sumatran subduction zone in a decade of continuous GPS data

et al. 2015

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Slow slip events (SSEs) have been observed in GPS time series for many subduction zones worldwide but not in decade‐long GPS time series from the Sumatran GPS Array (SuGAr). An outstanding question has been whether SSEs have simply not occurred on the Sunda megathrust or whether they have been obscured by the prodigious number of earthquakes and their ensuing postseismic deformation within the time of geodetic observation. We remove all known tectonic signals from the time series to search for evidence of SSEs. The residuals are essentially flat at the centimeter scale. To search for signals at the millimeter scale we test various filtering and visualization techniques. Despite these efforts, we conclude that it is difficult to confirm that SSEs exist at this scale using the current data, although we do see a few suspicious signals. The lack of evidence for events may reflect SSEs occurring at a magnitude, location, or timescale that renders them undetectable with the current resolution of the SuGAr, that the properties of this megathrust are not conducive to SSEs, or because the megathrust is in an active period of the earthquake cycle.

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Detecting Large-scale Intracontinental Slow-slip Events (SSEs) Using Geodograms

Cited by 8 publications

References 17 publications

Slow slip events in Costa Rica detected by continuous GPS observations, 2002–2011

Slow slip events in Costa Rica detected by continuous GPS observations, 2002–2011

Implications of transient deformation in the northern Basin and Range, western United States

Hunt for slow slip events along the Sumatran subduction zone in a decade of continuous GPS data

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