Global positioning system measurements of deformations associated with the 1987 Superstition Hills Earthquake: Evidence for conjugate faulting

Larsen, Shawn; Reilinger, Robert; Neugebauer, Helen; Strange, William E.

doi:10.1029/92jb00128

Cited by 64 publications

(18 citation statements)

References 45 publications

(4 reference statements)

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“…The inversion yields the slip distribution from the surface deformation. The modeling performed in this study used the computer code GINV developed by S. Larsen (LARSEN et al, 1992). We divide the fault plane into a set of nonoverlapping rectangular elements; each with uniform slip.…”

Section: Coseismic Strain Releasementioning

confidence: 99%

GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

Klotz

Angermann

Michel

et al. 1999

Pure and Applied Geophysics

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In order to study both the interplate seismic loading cycle and the distribution of intraplate deformation of the Andes, a 215 site GPS network covering Chile and the western part of Argentina was selected, monumented and observed in 1993 and 1994. A dense part of the network in northern Chile and northwest Argentina, comprising some 70 sites, was re-observed after two years in October/November, 1995. The M w = 8.0 Antofagasta (North Chile) earthquake of 30th July, 1995 took place between the two observations. The city of Antofagasta shifted 80 cm westwards by this event and the displacement still reached 10 cm at locations 300 km from the trench. Three different deformation processes have been considered for modeling the measured displacements: (1) interseismic accumulation of elastic strain due to subduction coupling, (2) coseismic strain release during the Antofagasta earthquake and (3) crustal shortening in the Sub-Andes.Eastward displacement of the sites to the north and to the south of the area affected by the earthquake is due to the interseismic accumulation of elastic deformation. Assuming a uniform slip model of interseismic coupling, the observed displacements at the coast require a fully locked subduction interface and a depth of seismic coupling of 50 km. The geodetically derived fault plane parameters of the Antofagasta earthquake are consistent with results derived from wave-form modeling of seismological data. The coseismic slip predicted by the variable slip model reaches values of 3.2 m in the dip-slip and 1.4 m in the strike-slip directions. The derived rake is 66°. Our geodetic results suggest that the oblique Nazca-South American plate convergence is accommodated by oblique earthquake slip with no slip partitioning. The observed displacements in the back-arc indicate a present-day crustal shortening rate of 3-4 mm/year which is significantly slower than the average of 10 mm/year experienced during the evolution of the Andean plateau.

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Section: Coseismic Strain Releasementioning

confidence: 99%

GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

Klotz

Angermann

Michel

et al. 1999

Pure and Applied Geophysics

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“…We present the analyses of available earthquake data to suggest that geometric pattern in the inferred faults, which leads to interaction amongst the fault zones, is a major cause for frequent and sustained seismicity of the region, in addition to the favourable reservoir effects on the seismogenic faults. Geometric disposition of fault segments leading to fault interaction plays an important role in the kinematics and dynamics of the earthquake occurrence processes [ Barka and Kadinsky‐cade , 1988; Hudnut et al , 1989; Larson et al , 1992; Segall and Pollard , 1980; King and Nábelek , 1985; Sibson , 1985; Talwani , 1988]. In this article, we first analyse the effect of fault interaction amongst the inferred fault zones in the Koyna‐Warna region and then discuss the effect of reservoirs in triggering earthquakes on the causative faults.…”

Section: Introductionmentioning

confidence: 99%

Fault interaction and earthquake triggering in the Koyna‐Warna region, India

Gahalaut

Kalpna

Singh

2004

Geophysical Research Letters

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[1] Earthquakes in the Koyna-Warna region of peninsular India are considered to be reservoir triggered. However, analyses of the available earthquake data indicate that the sustained high seismicity in this region may be influenced also by the geometry of the fault zones and their interactions through stress transfer. These distinct fault zones, inferred from the earthquake distribution and their focal mechanisms, are favourably oriented to each other in such a way that earthquake occurrences in one of the fault zones increase static stress on the other, facilitating frequent and continuing occurrence of earthquakes in the region. Here we show that though the effect of reservoir operations do promote slip on these faults, stress triggering appears to be an important cause for continuing high seismicity as it brings some of the stabilized faults closer to failure in the manner consistent with the inferred sense of motion.

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“…We attribute this behavior to not only lack of data, but also the fact that the fault trace of this region was estimated by connecting the lower Anza segment with the upper Imperial fault trace. In this region, many small subparallel branches exist [Larsen et al, 1992] and we have most likely oversimplified the fault geometry. Seismicity is not particularly evident within 10 km of our estimated fault trace, and is found primarily to the southwest and constricted to the upper 10 km of the crust [Hill et al, 1991].…”

Section: B2 Profile 2 Segments 2 Andmentioning

confidence: 99%

Coulomb stress accumulation along the San Andreas Fault system

Smith

Sandwell

2003

J. Geophys. Res.

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[1] Stress accumulation rates along the primary segments of the San Andreas Fault system are computed using a three-dimensional (3-D) elastic half-space model with realistic fault geometry. The model is developed in the Fourier domain by solving for the response of an elastic half-space due to a point vector body force and analytically integrating the force from a locking depth to infinite depth. This approach is then applied to the San Andreas Fault system using published slip rates along 18 major fault strands of the fault zone. GPS-derived horizontal velocity measurements spanning the entire 1700 Â 200 km region are then used to solve for apparent locking depth along each primary fault segment. This simple model fits remarkably well (2.43 mm/yr RMS misfit), although some discrepancies occur in the Eastern California Shear Zone. The model also predicts vertical uplift and subsidence rates that are in agreement with independent geologic and geodetic estimates. In addition, shear and normal stresses along the major fault strands are used to compute Coulomb stress accumulation rate. As a result, we find earthquake recurrence intervals along the San Andreas Fault system to be inversely proportional to Coulomb stress accumulation rate, in agreement with typical coseismic stress drops of 1-10 MPa. This 3-D deformation model can ultimately be extended to include both time-dependent forcing and viscoelastic response.

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Global positioning system measurements of deformations associated with the 1987 Superstition Hills Earthquake: Evidence for conjugate faulting

Cited by 64 publications

References 45 publications

GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

Fault interaction and earthquake triggering in the Koyna‐Warna region, India

Coulomb stress accumulation along the San Andreas Fault system

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