GPS and seismic constraints on the M = 7.3 2009 Swan Islands earthquake: implications for stress changes along the Motagua fault and other nearby faults

Graham, Shannon; DeMets, Charles; DeShon, Heather R.; Rogers, Robert D.; Maradiaga, Manuel Rodriguez; Strauch, W.; Wiese, Klaus; Hernández, Daniela

doi:10.1111/j.1365-246x.2012.05560.x

Cited by 20 publications

(20 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1). We estimated the displacement at our sites induced by this earthquake from the model published by Graham et al (2012). Differences between corrected and uncorrected velocities are lower than 2 mm yr -1 , practically within the estimated uncertainties of the GPS velocities.…”

Section: Gps Data Processingsupporting

confidence: 54%

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

et al. 2016

View full text Add to dashboard Cite

This paper presents the results and conclusions obtained from new GPS data compiled along the El Salvador Fault Zone (ESFZ). We calculated a GPS-derived horizontal velocity field representing the present-day crustal deformation rates in the ESFZ based on the analysis of 30 GPS campaign stations of the ZFESNet network, measured over a 4.5 year period from 2007 to 2012. The velocity field and subsequent strain rate analysis clearly indicate dextral strike-slip tectonics with extensional component throughout the ESFZ. Our results suggest that the boundary between the Salvadoran forearc and Caribbean blocks is a deformation zone which varies along the fault zone. We estimate that the movement between the two blocks is at least ~12 mm yr-1. From west to east, this movement is variably distributed between faults or segments of the ESFZ. We propose a kinematic model with three main blocks; the Western, Central and Eastern blocks delimited by major faults. For the first time, we were able to provide a quantitative measure of the present-day horizontal geodetic slip rate of the main segments of ESFZ, ranging from ~2 mm yr-1 in the east segment to ~8 mm yr-1 , in the west and central segments. This study contributes new kinematic and slip rate

show abstract

Section: Gps Data Processingsupporting

confidence: 54%

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

et al. 2016

View full text Add to dashboard Cite

show abstract

“…At the SITF, continental crustal thinning occurs over a distance of ~80 km adjacent to a sharp OCT <10 kmwide. However, in contrast to the margins described above, the SITF is currently an active transform margin, across which the plates continue to drift with a prevalent left-lateral strike-slip motion as evidenced by earthquake focal mechanisms (Hayman et al, 2011;Graham et al, 2012). Thinned old continental crust, resulting from the Jurassic/Cretaceous rifting process (Sanchez et al, 2016) is, thus, then juxtaposed against very thin and young oceanic crust formed at the MCSC.…”

Section: Swan Islands Transform Ocean-continental Marginmentioning

confidence: 95%

“…In the late Cretaceous, a sinistral (~20 mm y -1 left lateral - Rosencrantz and Mann, 1991;Hayman et al, 2011;Graham et al, 2012) strike-slip zone developed between the Caribbean plate and the Yucatan Block, offsetting the "Great Arc of the Caribbean" (Mann, 2007). The MCSC formed within this shear zone in the Eocene (~49 Ma) (Rosencrantz and Mann, 1991;Leroy et al, 2000).…”

Section: Swan Islands Transform Fault Boundarymentioning

confidence: 99%

Seismic investigation of an active ocean–continent transform margin: the interaction between the Swan Islands Fault Zone and the ultraslow-spreading Mid-Cayman Spreading Centre

Peirce

Robinson

Campbell

et al. 2019

Geophysical Journal International

View full text Add to dashboard Cite

SUMMARY The Swan Islands Transform Fault (SITF) marks the southern boundary of the Cayman Trough and the ocean–continent transition of the North American–Caribbean Plate boundary offshore Honduras. The CAYSEIS experiment acquired a 180-km-long seismic refraction and gravity profile across this transform margin, ∼70 km to the west of the Mid-Cayman Spreading Centre (MCSC). This profile shows the crustal structure across a transform fault system that juxtaposes Mesozoic-age continental crust to the south against the ∼10-Myr-old ultraslow spread oceanic crust to the north. Ocean-bottom seismographs were deployed along-profile, and inverse and forward traveltime modelling, supported by gravity analysis, reveals ∼23-km-thick continental crust that has been thinned over a distance of ∼70 km to ∼10 km-thick at the SITF, juxtaposed against ∼4-km-thick oceanic crust. This thinning is primarily accommodated within the lower crust. Since Moho reflections are not widely observed, the 7.0 km s−1 velocity contour is used to define the Moho along-profile. The apparent lack of reflections to the north of the SITF suggests that the Moho is more likely a transition zone between crust and mantle. Where the profile traverses bathymetric highs in the off-axis oceanic crust, higher P-wave velocity is observed at shallow crustal depths. S-wave arrival modelling also reveals elevated velocities at shallow depths, except for crust adjacent to the SITF that would have occupied the inside corner high of the ridge-transform intersection when on axis. We use a Vp/Vs ratio of 1.9 to mark where lithologies of the lower crust and uppermost mantle may be exhumed, and also to locate the upper-to-lower crustal transition, identify relict oceanic core complexes and regions of magmatically formed crust. An elevated Vp/Vs ratio suggests not only that serpentinized peridotite may be exposed at the seafloor in places, but also that seawater has been able to flow deep into the crust and upper mantle over 20–30-km-wide regions which may explain the lack of a distinct Moho. The SITF has higher velocities at shallower depths than observed in the oceanic crust to the north and, at the seabed, it is a relatively wide feature. However, the velocity–depth model subseabed suggests a fault zone no wider than ∼5–10 km, that is mirrored by a narrow seabed depression ∼7500 m deep. Gravity modelling shows that the SITF is also underlain, at >2 km subseabed, by a ∼20-km-wide region of density >3000 kg m−3 that may reflect a broad region of metamorphism. The residual mantle Bouguer anomaly across the survey region, when compared with the bathymetry, suggests that the transform may also have a component of left-lateral trans-tensional displacement that accounts for its apparently broad seabed appearance, and that the focus of magma supply may currently be displaced to the north of the MCSC segment centre. Our results suggest that Swan Islands margin development caused thinning of the adjacent continental crust, and that the adjacent oceanic crust formed in a cool ridge setting, either as a result of reduced mantle upwelling and/or due to fracture enhanced fluid flow.

show abstract

“…We remove some sections of time series with nonlinear deviation from the background trend due to postseismic deformation. This is, for instance, the case of 2009, M 7.3, Swan Islands earthquake [ Graham et al , ], which caused significant coseismic and postseismic displacements at several GPS sites used here.…”

Section: Data and Modelsmentioning

confidence: 99%

Current block motions and strain accumulation on active faults in the Caribbean

et al. 2015

View full text Add to dashboard Cite

The Caribbean plate and its boundaries with north and south America, marked by subduction and large intra-arc strike-slip faults, are a natural laboratory for the study of strain partitioning and interseismic plate coupling in relation to large earthquakes. Here we use most of the available campaign and continuous GPS measurements in the Caribbean to derive a regional velocity field expressed in a consistent reference frame. We use this velocity field as input to a kinematic model where surface velocities results from the rotation of rigid blocks bounded by locked faults accumulating interseismic strain, while allowing for partial locking along the Lesser Antilles, Puerto Rico, and Hispaniola subduction. We test various block geometries, guided by previous regional kinematic models and geological information on active faults. Our findings refine a number of previously established results, in particular slip rates on the strike-slip faults systems bounding the Caribbean plate to the north and south, and the kinematics of the Gonave microplate. Our much-improved GPS velocity field in the Lesser Antilles compared to previous studies does not require the existence of a distinct Northern Lesser Antilles block and excludes more than 3 mm/yr of strain accumulation on the Lesser Antilles-Puerto Rico subduction plate interface, which appears essentially uncoupled. The transition from a coupled to an uncoupled subduction coincides with a transition in the long-term geological behavior of the Caribbean plate margin from compressional (Hispaniola) to extensional (Puerto Rico and Lesser Antilles), a characteristics shared with several other subduction systems.

show abstract

GPS and seismic constraints on the M = 7.3 2009 Swan Islands earthquake: implications for stress changes along the Motagua fault and other nearby faults

Cited by 20 publications

References 27 publications

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

Seismic investigation of an active ocean–continent transform margin: the interaction between the Swan Islands Fault Zone and the ultraslow-spreading Mid-Cayman Spreading Centre

Current block motions and strain accumulation on active faults in the Caribbean

Contact Info

Product

Resources

About