Statistical analysis of geodetic deformation (strain rate) derived from the space geodetic measurements of BIFROST Project in Fennoscandia

Cai, Jianqing; Grafarend, Erik W.

doi:10.1016/j.jog.2006.09.010

Cited by 24 publications

(19 citation statements)

References 35 publications

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“…Although the segmentation method is not limited to triangulation only and segments can have any geometrical shape, triangulation of the measuring points, e.g., using the Delaunay method is the most common example for this approach (Frank, 1966;Shen et al, 1996;Cai and Grafarend, 2007;Fernandes et al, 2007;Wdowinski et al, 2007). In this method, the area is segmented into several geometrical units and the local strain and rotation rates are computed for each unit, and finally all the individual results are integrated (Wu et al, 2011).…”

Section: Segmentation Approachesmentioning

confidence: 99%

“…Because ε is symmetric, these eigenvectors make an orthogonal reference system whose axes pointing to the direction of the maximal deformation. For a two dimensional symmetric random strain rate tensor, the eigenvalues 12 ,  or maximum and the minimum principal strains as well as the orientation parameter  known as the principal angle are obtained as (Cai and Grafarend, 2007) …”

Section: Representation Of the Strain Rate Tensormentioning

confidence: 99%

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GeoStrain: An open source software for calculating crustal strain rates

Goudarzi

Cocard

Santerre

2015

Computers & Geosciences

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We developed an open source software for crustal strain analysis using the least-squares collocation method based on the spherical model of the earth. The software is able to simultaneously determine the signal and noise of the velocities at the observation points with the best possible removal of the observational errors, or at any other position with no velocity observation. Furthermore, the software can calculate strain and rotation rate tensors at any points of interest, including observation points, grid points or points along a fault line. The advantage of the software is that the sphericity of the earth is considered in all the calculations. Furthermore, it can optionally consider the effect of the vertical velocities on the strain rates that is principally important for regions where vertical deformation is the major geophysical signal compared to the horizontal deformation.

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Section: Segmentation Approachesmentioning

confidence: 99%

Section: Representation Of the Strain Rate Tensormentioning

confidence: 99%

GeoStrain: An open source software for calculating crustal strain rates

Goudarzi

Cocard

Santerre

2015

Computers & Geosciences

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“…1 shows how the triangle network is formed. In this study, the strain rates at different periods were calculated using the following equations (Cai and Grafarend, 2007). where and are velocities of stations, i = 1, 2, 3. and are velocities at centroid.…”

Section: Strain Rate Calculationmentioning

confidence: 99%

“…From calculated velocity gradient tensors, a two-dimensional symmetric strain tensor can be computed from (Cai and Grafarend, 2007):…”

Section: Strain Rate Calculationmentioning

confidence: 99%

Change of strain rate in Thailand after the 26 December 2004 and 28 March 2005 earthquakes using GPS measurements

et al. 2010

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During the period 1994-2004, before the Mw 9.3 Sumatra-Andaman earthquake of 26 December 2004, Thailand was moving horizontally constantly eastward with an average rate of approximately 33.2±1.1 millimeters per year in ITRF2000. The magnitude of the horizontal strain rate was less than 30 nanostrain per year, which was considered small but significant. After the occurrence of the mega thrust earthquake, a horizontal movement to the southwest direction is evident at different rates all over the Thai region. Large co-seismic horizontal displacements were observed in the southern part of Thailand, while moderate and small displacements were seen in the central and northern parts of Thailand. The Royal Thai Survey Department (RTSD) carried out multiple Global Positioning System (GPS) field campaigns to monitor the post-seismic displacements. However, their efforts were complicated by the second mega thrust (Mw8.7) earthquake, which occurred at Nias, Sumatra on 28 March 2005. This study focuses on the use of GPS data, collected between 1994 and 2006, gathered from six GPS stations located at Phuket, Chumporn, Chonburi, Uthaitani, Srisaket and Lampang in Thailand and an additional station located in the northern part of Malaysia to derive changes in the strain rate. Here we find that today's deformation in Thailand is dominated by SW-NE trending extension. This feature is in agreement with post-seismic relaxation occurring on the Sumatran trench.

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“…In application to contemporary deformation observed with space geodetic techniques, the computation of strain rates has so far mostly been done on the basis of kinematic and/or stochastic concepts, and the potential importance in the vertical motion component has been mentioned only in passing (Cai and Grafarend, 2007). The majority of earlier studies has concentrated on strain accumulation at fault zones (e.g.…”

Section: Introductionmentioning

confidence: 99%

Fennoscandian strain rates from BIFROST GPS: A gravitating, thick-plate approach

Scherneck¹,

Lidberg²,

Haas³

et al. 2010

Journal of Geodynamics

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The aim of this investigation is to develop a method for the analysis of crustal strain determined by station networks that continuously collect measurements of Global Navigation Satellite Systems (GNSS). The major new ingredient is that we require a simultaneous minimum of the observation error and the elastic and potential energy of a thick elastic and gravitating slab. From this outset the method pursues a general approach not limited to the origin of the deforming process nor to assumptions of lateral homogeniety of the elastic and density structure. One present limitation, however, is the assumption of vertical uniformity in elasticity, which is relevant in the flexure mode.The observations that we analyse come from eight years worth of daily solutions from continuous BIFROST GPS measurements in the permanent networks of the Nordic countries and their neighbours. Reducing the observed three-dimensional velocities with best-fitting predictions for the effects of glacial isostatic adjustment (GIA) we find strain rates of typically 4-6 nano/yr in the interior of the rebound area, shear strain being slightly more pronounced compared to areal strain. The largest strain rates, 12 nano/yr, accompanied by a curl feature of 4 nrad/yr, are found in the Finnmarken area where, however, the GNSS network density is much lower than in the central and southern parts. The somewhat poor network geometry is found to create spurious curl at 1 to 2 nrad/yr in the Lapland-Finnmarken area.We also find that the strain generated by flexure due to GIA is important. In th emodel, the extensional regime seen at the surface turns over into a compressive style already at moderate depth, some 50 km.

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Statistical analysis of geodetic deformation (strain rate) derived from the space geodetic measurements of BIFROST Project in Fennoscandia

Cited by 24 publications

References 35 publications

GeoStrain: An open source software for calculating crustal strain rates

GeoStrain: An open source software for calculating crustal strain rates

Change of strain rate in Thailand after the 26 December 2004 and 28 March 2005 earthquakes using GPS measurements

Fennoscandian strain rates from BIFROST GPS: A gravitating, thick-plate approach

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