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Journal Article

Monitoring the Earthquake Cycle in the Northern Andes from the Ecuadorian cGPS Network

Patricia A. Mothes, Frederique Rolandone, Jean‐Mathieu Nocquet, Paul A. Jarrin, Alexandra P. Alvarado, Mario C. Ruiz, David Cisneros, Héctor Mora Páez, Mónica Segovia
Published: 14 February 2018
Seismological Research Letters (2018) 89 (2A): 534–541.
DOI: https://doi.org/10.1785/0220170243
...Patricia A. Mothes; Frederique Rolandone; Jean‐Mathieu Nocquet; Paul A. Jarrin; Alexandra P. Alvarado; Mario C. Ruiz; David Cisneros; Héctor Mora Páez; Mónica Segovia ABSTRACT The continuous Global Positioning System (cGPS) network operating in the northern Andes (Ecuador and Colombia) for about...
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Journal Article

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

William E. Holt, Gina Shcherbenko
Published: 01 May 2013
Seismological Research Letters (2013) 84 (3): 455–467.
DOI: https://doi.org/10.1785/0220130004
...William E. Holt; Gina Shcherbenko We use general polynomial functions to interpolate continuous displacement GPS time series and generate time‐dependent model displacements for all cGPS stations in the SCIGN network ( Hernandez et al. , 2005 ; Hernandez, 2007 ). A fourth‐order representation...
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View PDF for article title, Toward a Continuous Monitoring of the Horizontal Displacement Gradient Tensor Field in Southern California Using <span class="search-highlight">cGPS</span> Observations from Plate Boundary Observatory (PBO)
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(a) cGPS as a function of distance to hypocenter. (b) and (c): cGPS as a function of distance to asperities 1 and 2, respectively. The gray curves are the curves time-distance calculated using Campos et al. (2002) velocity model and the black curve are the curves time-distance calculated using a crustal shear velocity. The Time in each figure is the time of start of wave propagation from the hypocenter (a) and asperities (b and c).

(a) cGPS as a function of distance to hypocenter. (b) and (c): cGPS as a fu...

Published: 01 June 2012
Figure 8. (a) cGPS as a function of distance to hypocenter. (b) and (c): cGPS as a function of distance to asperities 1 and 2, respectively. The gray curves are the curves time-distance calculated using Campos et al. (2002) velocity model and the black curve are the curves time-distance
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(A, B) Seasonal horizontal strain calculated from continuous GPS (cGPS) seasonal displacements between 2000 and 2016 (cGPS sites are marked in Fig. 1A). Principal axes of the nontectonic strain are shown by blue (compressional) and red (extensional) lines. Red line segment shown in the inset box represents scale of the horizontal strain. Background color plot is dilatational strain (A) and horizontal strain (B). Reelfoot and Cottonwood Grove faults are marked by green lines. (C, D) Coulomb failure stress changes (ΔCFS) calculated from seasonal horizontal strain, resolved on the Reelfoot fault (C) and Cottonwood Grove fault (D).

(A, B) Seasonal horizontal strain calculated from continuous GPS (cGPS) sea...

Published: 26 August 2024
Figure 4. (A, B) Seasonal horizontal strain calculated from continuous GPS (cGPS) seasonal displacements between 2000 and 2016 (cGPS sites are marked in Fig. 1A ). Principal axes of the nontectonic strain are shown by blue (compressional) and red (extensional) lines. Red line segment shown
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Time series for cGPS station BYSP in Bayamón, Puerto Rico. (a) Results in IGS14 with the blue lines showing linear fits to the position estimates and (b) results in a CA‐fixed frame with the green lines showing the fit relative to the fixed CA plate. Each red dot represents a 24 hr position estimate. The vertical blue line in both the panels denotes the 13 January 2014 Mw 6.4 earthquake and the epoch at which a five‐day offset was calculated (see the Coseismic displacement estimates section). The color version of this figure is available only in the electronic edition.

Time series for cGPS station BYSP in Bayamón, Puerto Rico. (a) Results in I...

Published: 16 December 2022
Figure 3. Time series for cGPS station BYSP in Bayamón, Puerto Rico. (a) Results in IGS14 with the blue lines showing linear fits to the position estimates and (b) results in a CA‐fixed frame with the green lines showing the fit relative to the fixed CA plate. Each red dot represents a 24 hr
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cGPS station PRLT in Cabo Rojo, Puerto Rico, in which method (2), a five‐day offset was applied for the 7 January 2020 and 3 July 2020 earthquakes shown as vertical blue lines. Another regional earthquake occurred on 13 January 2014 is denoted with the dashed vertical red line, although no offset was estimated. (a) The 24 hr position estimates relative to IGS14, (b) relative to the fixed‐CA, and (c) with CA motion removed. Note the well‐resolved afterslip in the north and east components. The color version of this figure is available only in the electronic edition.

cGPS station PRLT in Cabo Rojo, Puerto Rico, in which method (2), a five‐da...

Published: 16 December 2022
Figure 5. cGPS station PRLT in Cabo Rojo, Puerto Rico, in which method (2), a five‐day offset was applied for the 7 January 2020 and 3 July 2020 earthquakes shown as vertical blue lines. Another regional earthquake occurred on 13 January 2014 is denoted with the dashed vertical red line, although
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Postearthquake velocity field derived from all southwestern PR cGPS sites, including the National Science Foundation Rapid Response Research (NSF RAPID) 2021 deployment.

Postearthquake velocity field derived from all southwestern PR cGPS sites, ...

Published: 16 December 2022
Figure 11. Postearthquake velocity field derived from all southwestern PR cGPS sites, including the National Science Foundation Rapid Response Research (NSF RAPID) 2021 deployment.
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Continuous GPS (cGPS) network and recorded deformation at Montserrat. (A) Digital elevation model (Stinton, 2015) of Montserrat showing cGPS stations (red circles) and active vent (blue triangle). Contour intervals are 100 m. Inset map at upper right shows the eastern Caribbean with Montserrat indicated by the arrow. (B) Relative east-west deformation with time for cGPS stations shown in A. Time series are offset in y-axis for added clarity; shaded bars are 95% confidence bounds. (C) Same as in B but for north-south deformation. (D) Same as in B but for vertical deformation.

Continuous GPS (cGPS) network and recorded deformation at Montserrat. (A) D...

Published: 23 August 2022
Figure 1. Continuous GPS (cGPS) network and recorded deformation at Montserrat. (A) Digital elevation model ( Stinton, 2015 ) of Montserrat showing cGPS stations (red circles) and active vent (blue triangle). Contour intervals are 100 m. Inset map at upper right shows the eastern Caribbean
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Normalized and absolute model-data comparison for continuous GPS (cGPS) site GERD (see Fig. 1 for location) and ramp temporal source function (Fig. 3B). (A–C) Normalized surface displacements for east-west (A), north-south (B), and vertical (up-down; U-D) (C) components, where thin black line and shaded gray region display recorded deformation and error bounds, and solid and dashed colored lines show model results for stress-based overpressure (ΔP) and strain-based volume change (ΔV) boundary conditions, respectively. Model and data are normalized to maximum absolute deformation across the three components (in this case, vertical). (D–F) Same as A–C but model and data have not been normalized.

Normalized and absolute model-data comparison for continuous GPS (cGPS) sit...

Published: 23 August 2022
Figure 4. Normalized and absolute model-data comparison for continuous GPS (cGPS) site GERD (see Fig. 1 for location) and ramp temporal source function ( Fig. 3B ). (A–C) Normalized surface displacements for east-west (A), north-south (B), and vertical (up-down; U-D) (C) components, where thin
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Backscattered electron (BSE) photomicrographs of CGPs and ixiolite/wodginite; (A) type-1 (pegmatite-1) as matrix phase with numerous quartz inclusions showing oscillatory zoning with several stages of growth interrupted by resorption and renewed growth (white arrows); (B) type-1 (pegmatite-1) as inclusion in garnet; (C) type-5 (pegmatite-1) as grid-like exsolution lamellae in cassiterite; (D) type-3 (pegmatite-1) intergrown with rutile; (E) type-1 (pegmatite-4) with complex zoning involving ±regular discontinuous as well as irregular and patchy zoning; lower left part of the CGP grain within stippled line is replaced by vigezzite; (F) type-1 (pegmatite-4) with partial vigezzite overgrowth; (G) cluster of ixiolite/wodginite grains with patchy compositional zoning and overgrowth of CGP formed by intense extensional deformation; (H) centimeter-sized ixiolite/wodginite grain with spongy Fe-enriched and Ta-depleted rim and CGP-overgrowth; white stippled line marks ixiolite/wodginite-CGP grain boundary; mineral abbreviations according to Kretz (1983) and Spear (1993) except CGP: columbite-group phase(s).

Backscattered electron (BSE) photomicrographs of CGPs and ixiolite/wodginit...

Published: 23 October 2018
Fig. 3. Backscattered electron (BSE) photomicrographs of CGPs and ixiolite/wodginite; (A) type-1 (pegmatite-1) as matrix phase with numerous quartz inclusions showing oscillatory zoning with several stages of growth interrupted by resorption and renewed growth (white arrows); (B) type-1
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Broad scale coseismic static displacements recorded at cGPS stations in Ecuador and southern Colombia. Red arrows represent horizontal displacements, and black bars are for the vertical. Epicenter of Pedernales 2016 earthquake and rupture area are represented by yellow star and lines, respectively (Nocquet et al., 2017).

Broad scale coseismic static displacements recorded at cGPS stations in Ecu...

Published: 14 February 2018
Figure 3. Broad scale coseismic static displacements recorded at cGPS stations in Ecuador and southern Colombia. Red arrows represent horizontal displacements, and black bars are for the vertical. Epicenter of Pedernales 2016 earthquake and rupture area are represented by yellow star and lines
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Coseismic static displacements recorded at cGPS volcanic stations in the Ecuadorian Sierra region, some 200 km distance from epicenter. The red arrows represent horizontal displacements, whereas black bars are for the vertical.

Coseismic static displacements recorded at cGPS volcanic stations in the Ec...

Published: 14 February 2018
Figure 4. Coseismic static displacements recorded at cGPS volcanic stations in the Ecuadorian Sierra region, some 200 km distance from epicenter. The red arrows represent horizontal displacements, whereas black bars are for the vertical.
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Coseismic static displacements recorded at near‐field cGPS stations at about 100 km from epicenter. The horizontal (red arrows) and vertical (black bars) displacements of each station are shown. Epicenter of Pedernales 2016 earthquake and rupture area are represented by yellow star and lines, respectively (Nocquet et al., 2017).

Coseismic static displacements recorded at near‐field cGPS stations at abou...

Published: 14 February 2018
Figure 2. Coseismic static displacements recorded at near‐field cGPS stations at about 100 km from epicenter. The horizontal (red arrows) and vertical (black bars) displacements of each station are shown. Epicenter of Pedernales 2016 earthquake and rupture area are represented by yellow star
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A: East-west motion at continuous global positioning system station (cGPS) DA25 and along-axis position of earthquakes in the Dabbahu segment against time. Earthquakes are colored and scaled by magnitude, and error bars are measured errors in arrival times. Two horizontal lines correspond to inferred dike source. Data within dashed rectangles are enlarged for detail. Along-axis topographic profile displayed in Figure 2 is in right panel. B: Three days east-west motion at cGPS DA25. Shaded histograms are seismic moment release in 2 h intervals and show that rift opening is coincident with peak in seismicity. C: Along-axis position in seismicity, as in A, but over ~1 day, showing migration of seismic swarms away from Ado'Ale Volcanic Complex. Histograms show seismic moment release binned at hour intervals and plotted on log scale. GMT—Greenwich Mean Time.

A: East-west motion at continuous global positioning system station (cGPS) ...

Published: 01 January 2009
Figure 3. A: East-west motion at continuous global positioning system station (cGPS) DA25 and along-axis position of earthquakes in the Dabbahu segment against time. Earthquakes are colored and scaled by magnitude, and error bars are measured errors in arrival times. Two horizontal lines
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Horizontal displacements of various cgps sites during the first 50 postseismic days following the Sumatra–Andaman earthquake. The estimate at CAR2 in the Andaman Islands is a logarithmic extrapolation based on data collected from days 10 to 100 after the earthquake (Fig. 7). The corresponding predictions of an afterslip model are shown with the red vectors. The slip estimated on the afterslip planes are 2.9 m (planes 1A, 1B, 1C, 1D), 6.0 m (plane 2A), 0.8 m (plane 3A), and 0.4 m (plane 3B).

Horizontal displacements of various cgps sites during the first 50 postse...

Published: 01 January 2007
Figure 6. Horizontal displacements of various cgps sites during the first 50 postseismic days following the Sumatra–Andaman earthquake. The estimate at CAR2 in the Andaman Islands is a logarithmic extrapolation based on data collected from days 10 to 100 after the earthquake ( Fig. 7
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cgps time series and best-fitting analytical function corresponding to frictional afterslip (Perfettini and Avouac, 2004a). The relaxation time was determined from the best fit to Sampali (samp) and Phuket (phkt) time series and applied to fit the Ujung Muloh (umlh) and Lewak (lewk) time series.

cgps time series and best-fitting analytical function corresponding to fr...

Published: 01 January 2007
Figure 17. cgps time series and best-fitting analytical function corresponding to frictional afterslip ( Perfettini and Avouac, 2004a ). The relaxation time was determined from the best fit to Sampali ( samp ) and Phuket ( phkt ) time series and applied to fit the Ujung Muloh ( umlh
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Composite of three-component time series collected at cgps sites PORT and CAR2, both located at Port Blair, on a log-linear plot. Note the linear trend of each time series, conforming to a log(t) function dependence for each composite time series.

Composite of three-component time series collected at cgps sites PORT and...

Published: 01 January 2007
Figure 7. Composite of three-component time series collected at cgps sites PORT and CAR2, both located at Port Blair, on a log-linear plot. Note the linear trend of each time series, conforming to a log( t ) function dependence for each composite time series.
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Figure 1. Continuous global positioning system (CGPS) results showing pre-eruption deformation at Sierra Negra volcano. A: Location map after Yun el al. (2006). B: Summit of Sierra Negra, showing sinuous ridge fault system, location of CGPS stations, and horizontal displacements during inflation from 1 April 2003 to 21 October 2005 (GV01 only to 3 December 2004; GV02 only to 10 June 2005). Fault-related displacements on 16 April 2005 are not included (see Fig. 2). C: Vertical displacements during inflation, as in B. D: Uplift history of center of caldera at Sierra Negra from 1992 to 2006 amounting to nearly 5 m. Times of major trapdoor faulting events and 2005 eruption are indicated. E: Horizontal displacements (north component only) at CGPS stations from 2002 to 2006, relative to stations GALA and GLPS on Isla Santa Cruz. Noise level increases after 10 June 2005, when both dual-frequency receivers had failed (GV01 and GV02). After 1 September 2005, GALA and GLPS were also down; thereafter movement at GV03 is extrapolated (dashed line) and GV04, GV05, and GV06 are shown relative to GV03. F: Vertical displacement time series, as in E. Inset shows kinematic solution for displacements at GV06 during 16 April 2005 trapdoor faulting event, relative to GV03. Vertical dashed lines in E and F show times of 16 April 2005 trapdoor faulting event and eruption on 22 October 2005. InSAR—inferometric synthetic aperture radar; GPS—global positioning system.

Figure 1. Continuous global positioning system (CGPS) results showing pre-e...

Published: 01 December 2006
Figure 1. Continuous global positioning system (CGPS) results showing pre-eruption deformation at Sierra Negra volcano. A: Location map after Yun el al. (2006) . B: Summit of Sierra Negra, showing sinuous ridge fault system, location of CGPS stations, and horizontal displacements during inflation
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Observed displacements versus modeled displacements for cgps sites relative to crbt. See Figure 2 for explanation of symbols. The black line represents the fit of the modified Omori’s law (equation 2) to the data and the green line is the fit of the model proposed by Perfettini and Avouac (2004). The values of τ and index, p, of the modified Omori’s law for baseline are indicated.

Observed displacements versus modeled displacements for cgps sites relati...

Published: 01 September 2006
Figure 3. Observed displacements versus modeled displacements for cgps sites relative to crbt . See Figure 2 for explanation of symbols. The black line represents the fit of the modified Omori’s law ( equation 2 ) to the data and the green line is the fit of the model proposed by Perfettini
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Observed displacements versus modeled displacements for four cgps sites relative to crbt. The time axis is in log(T) centered about the time of the earthquake. The lines represent the fit (equation 1) of the simplified Omori’s law and an offset to these data. The data for each site are plotted with different sampling rates; the red is 1-min samples, blue is 30-min samples, and gray is 1-day samples. The corresponding values of τ for each time series are indicated. The last panel shows the displacement record for carh, which coseismically displaced to the southeast, but for most of the postseismic period, it displaced to the northwest.

Observed displacements versus modeled displacements for four cgps sites r...

Published: 01 September 2006
Figure 2. Observed displacements versus modeled displacements for four cgps sites relative to crbt . The time axis is in log( T ) centered about the time of the earthquake. The lines represent the fit ( equation 1 ) of the simplified Omori’s law and an offset to these data. The data for each