How rigid is a rigid plate? Geodetic constraint from the TrigNet CGPS network, South Africa

Malservisi, R.; Hugentobler, Urs; Wonnacott, Richard; Hackl, M.

doi:10.1093/gji/ggs081

Cited by 32 publications

(37 citation statements)

References 70 publications

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“…We define regions of deformation by first using seismicity from the International Seismicity Catalog (Fig. 2B), the locations of existing GNSS observations, and previous studies that indicate rigidity 9–11 . Along the EARS, we outline zones of profuse active seismicity and then reduce the spatial extent of these zones since there are currently no GNSS observations available to constrain the possible deformation, or the region is rigid within observational error 10,11 .…”

Section: Methodsmentioning

confidence: 99%

A Geodetic Strain Rate Model for the East African Rift System

Stamps

Saria

Kreemer

2018

Sci Rep

117

155

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Here we describe the new Sub-Saharan Africa Geodetic Strain Rate Model v.1.0 (SSA-GSRM v.1.0), which provides fundamental constraints on long-term tectonic deformation in the region and an improved seismic hazards assessment in Sub-Saharan Africa. Sub-Saharan Africa encompasses the East African Rift System, the active divergent plate boundary between the Nubian and Somalian plates, where strain is largely accommodated along the boundaries of three subplates. We develop an improved geodetic strain rate field for sub-Saharan Africa that incorporates 1) an expanded geodetic velocity field, 2) redefined regions of deforming zones guided by seismicity distribution, and 3) updated constraints on block rotations. SSA-GSRM v.1.0 spans longitudes 22° to 55.5° and latitudes −52° to 20° with 0.25° (longitude) by 0.2° (latitude) spacing. For plates/sub-plates, we assign rigid block rotations as constraints on the strain rate calculation that is determined by fitting bicubic Bessel splines to a new geodetic velocity solution for an interpolated velocity gradient tensor field. We derive strain rates, velocities, and vorticity rates from the velocity gradient tensor field. A comparison with the Global Geodetic Strain Rate model v2.1 reveals regions of previously unresolved spatial heterogeneities in geodetic strain rate distribution, which indicates zones of elevated seismic risk.

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Section: Methodsmentioning

confidence: 99%

A Geodetic Strain Rate Model for the East African Rift System

Stamps

Saria

Kreemer

2018

Sci Rep

117

155

View full text Add to dashboard Cite

show abstract

“…7). Preliminary analysis of GPS data related to a fairly dense network of continuous stations in the southernmost part of Africa suggests the almost rigid behaviour of that cratonic zone (Malservisi et al, 2009). These authors also underline that the sparse distribution of continuous stations in Africa cannot provide a highly precise solution for an Eulerian pole of this plate and a statistically significant test of its rigidity.…”

Section: Geodetic Measurementsmentioning

confidence: 98%

Plate kinematics and geodynamics in the Central Mediterranean

Viti

Mantovani

Babbucci

et al. 2011

Journal of Geodynamics

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“…[ Niemi et al ., ; Prawirodirdjo and Bock , ; Wdowinski et al ., ; D'Agostino and Selvaggi , ; Hill and Blewitt , ; Walpersdorf et al ., ; Calais et al ., ; Fernandes et al ., ; Kogan and Steblov , ; Teferle et al ., ; Bechtold et al ., ; Argus et al ., ; Kreemer et al ., ; Le Pichon and Kreemer , ; Hammond et al ., ; Asensio et al ., ; Nocquet , ; ten Brink and López‐Venegas , ; Berglund et al ., ; Malservisi et al ., ; de Lis Mancilla et al ., ; Ganas et al ., ]; Those studies all provided valuable data and interpretations, but we analyze the same stations, with typically (much) longer time series than available in those original studies.…”

Section: Synthesis Of Published Velocitiesmentioning

confidence: 99%

“…studies were excluded when the velocity field was entirely based on publicly available data from (semi-) CGPS stations already analyzed for the core solution. Some examples since 2004 are: [Niemi et al, 2004;Prawirodirdjo and Bock, 2004;Wdowinski et al, 2004;D'Agostino and Selvaggi, 2004;Hill and Blewitt, 2006;Walpersdorf et al, 2006a;Calais et al, 2006b;Fernandes et al, 2007;Kogan and Steblov, 2008;Teferle et al, 2009;Bechtold et al, 2009;Argus et al, 2010;Kreemer et al, 2010aKreemer et al, , 2010bLe Pichon and Kreemer, 2010;Hammond et al, 2011;Asensio et al, 2012;Nocquet, 2012;ten Brink and L opez-Venegas, 2012;Berglund et al, 2012;Malservisi et al, 2013;de Lis Mancilla et al, 2013;Ganas et al, 2013]; Those studies all provided valuable data and interpretations, but we analyze the same stations, with typically (much) longer time series than available in those original studies.…”

Section: Synthesis Of Published Velocitiesmentioning

confidence: 99%

A geodetic plate motion and Global Strain Rate Model

Kreemer

Blewitt

Klein

2014

Geochem. Geophys. Geosyst.

764

785

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We present a new global model of plate motions and strain rates in plate boundary zones constrained by horizontal geodetic velocities. This Global Strain Rate Model (GSRM v.2.1) is a vast improvement over its predecessor both in terms of amount of data input as in an increase in spatial model resolution by factor of $2.5 in areas with dense data coverage. We determined 6739 velocities from time series of (mostly) continuous GPS measurements; i.e., by far the largest global velocity solution to date. We transformed 15,772 velocities from 233 (mostly) published studies onto our core solution to obtain 22,511 velocities in the same reference frame. Care is taken to not use velocities from stations (or time periods) that are affected by transient phenomena; i.e., this data set consists of velocities best representing the interseismic plate velocity. About 14% of the Earth is allowed to deform in 145,086 deforming grid cells (0.25 longitude by 0.2 latitude in dimension). The remainder of the Earth's surface is modeled as rigid spherical caps representing 50 tectonic plates. For 36 plates we present new GPS-derived angular velocities. For all the plates that can be compared with the most recent geologic plate motion model, we find that the difference in angular velocity is significant. The rigid-body rotations are used as boundary conditions in the strain rate calculations. The strain rate field is modeled using the Haines and Holt method, which uses splines to obtain an self-consistent interpolated velocity gradient tensor field, from which strain rates, vorticity rates, and expected velocities are derived. We also present expected faulting orientations in areas with significant vorticity, and update the no-net rotation reference frame associated with our global velocity gradient field.Finally, we present a global map of recurrence times for M w 57.5 characteristic earthquakes.

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How rigid is a rigid plate? Geodetic constraint from the TrigNet CGPS network, South Africa

Cited by 32 publications

References 70 publications

A Geodetic Strain Rate Model for the East African Rift System

A Geodetic Strain Rate Model for the East African Rift System

Plate kinematics and geodynamics in the Central Mediterranean

A geodetic plate motion and Global Strain Rate Model

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