Influence of anelastic surface layers on postseismic thrust fault deformation

Lyzenga, G. A.; Panero, W. R.; Donnellan, Andrea

doi:10.1029/1999jb900269

Cited by 21 publications

(24 citation statements)

References 17 publications

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“…We also notice that there is very likely a strong coupling between the crust and mantle and lower crustal relaxation may not be the primary mechanism for accommodating the shortening in the LA basin. These results are consistent with other published studies that investigate how stress is dissipated after earthquakes, including the Hector Mine and Northridge events (POLLITZ et al, 2001;LYZENGA et al, 2000). Our models also indicate that the geometry of faults does not significantly affect the resulting velocity profiles.…”

Section: Discussionsupporting

confidence: 82%

“…By the time 100 years pass in the model, the velocity profile is nearly flat and does not match the geodetic profile at all. This is contrary to results of recent studies of the Northridge earthquake, in which the stress dissipation has been modeled as fault afterslip, and velocities have returned to preseismic rates less than a decade following the event (LYZENGA et al, 2000). Since we assign slip on only one fault and do not consider fault friction, we most likely are not accounting for all of the mechanisms controlling the deformation, which may explain why we need a recent earthquake in our models to best match the observed data.…”

Section: Compliant Basin Modelscontrasting

confidence: 55%

“…The results of recent studies indicate that anelastic deformation in the upper crust may be largely responsible for the dissipation of stress in the crust following a large earthquake (e.g., the Northridge earthquake, LYZENGA et al, 2000). These results may indicate that the entire crust is strong, rather than having a strong upper crust coupled to a weaker lower crust.…”

Section: Compliant Basin Modelsmentioning

confidence: 54%

“…We used SIMPLEX, an iterative geodetic inversion program to model an elastic crust (LYZENGA et al, 2000). The code input consists of a model that includes one or more rectangular dislocation faults in an elastic half space and data that are used to constrain the faults (in this case, GPS data from SCIGN).…”

Section: Numerical Modelsmentioning

confidence: 99%

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Evidence of Strain Partitioning Between the Sierra Madre Fault and the Los Angeles Basin, Southern California from Numerical Models

Glasscoe

Donnellan

Kellogg

et al. 2004

Pure appl. geophys.

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Geodetic data indicate that the northern Metropolitan Los Angeles region is shortening at a rate of 4.5-6.0 mm/yr between downtown Los Angeles and the San Gabriel Mountains. If we assume that all of the uplift of the San Gabriel Mountains is due to the major frontal fault system (the Sierra Madre fault) and use reported values for bedrock uplift, slip per event and recurrence intervals to determine the slip rate on the Sierra Madre fault, we obtain slip rates between 0.6-1.27 mm/yr. Using these slip rates, the horizontal shortening attributable to the Sierra Madre fault accounts for only $33% of the observed shortening across the basin, leaving $67% of the shortening to be accounted for elsewhere. Herein we present a suite of models that test possible shortening mechanisms to account for this strain deficit. The models incorporate a range of fault geometries and have a layered structure with variable vertical and horizontal rheologies. The models demonstrate how lower-crust rheology and the presence of a low rigidity, anelastically deforming sedimentary basin affects the dissipation of stress imposed on the viscous layers by elastic failure of the faults. We found that viscoelastic models with a single fault, vertically strong crust and a compliant sedimentary basin yield a horizontal velocity profile that best matches the geodetically observed velocity profile across the Los Angeles Basin. Our models also indicate that we are still not accounting for all of the observed deformation. Therefore, more complex models that include both laterally varying rheologies and frictional properties on faults must be considered.

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Section: Discussionsupporting

confidence: 82%

Section: Compliant Basin Modelscontrasting

confidence: 55%

Section: Compliant Basin Modelsmentioning

confidence: 54%

Section: Numerical Modelsmentioning

confidence: 99%

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Evidence of Strain Partitioning Between the Sierra Madre Fault and the Los Angeles Basin, Southern California from Numerical Models

Glasscoe

Donnellan

Kellogg

et al. 2004

Pure appl. geophys.

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“…The high-performance modeling applications include GeoFEST [1], a finite element model that simulates stresses associated with earthquake faults, Virtual California [2], which simulates large, interacting fault systems, and PARK [3], which simulates complete earthquake cycles and earthquake interaction. The portal also contains Disloc, which models surface deformation from faults within an elastic half-space, and Simplex, which is an inversion application, which finds the optical dislocation model of fault slip from GPS and InSAR deformation data [4]. Analysis methods include Pattern Informatics [5], which examines seismic archives to forecast geographic regions of future high probability for intense earthquakes, and RDAHMM [6], a time series analysis application that can be used to determine state changes in instrument signals (such as generated by Global Positioning System arrays).…”

Section: Applicationsmentioning

confidence: 99%

QuakeSim: Efficient Modeling of Sensor Web Data in a Web Services Environment

Donnellan

Parker

Granat

et al. 2008

2008 IEEE Aerospace Conference

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Abstract-QuakeSim is a project to develop a modeling environment for studying earthquake processes using a web services environment. In order to model interseismic processes multiple data types must be ingested including spaceborne GPS and InSAR data, geological fault data, and seismicity data. QuakeSim federates data from these multiple sources and integrates the databases with modeling applications. Because the models are complex and compute intensive we are using the Columbia computer located at NASA Ames to integrate and run software programs to improve our understanding of the solid Earth and earthquake processes. The complementary software programs are used to simulate interacting earthquake fault systems, model nucleation and slip on faults, and calculate run-up and inundation from tsunamis generated by offshore earthquakes. QuakeSim also applies pattern recognition techniques to real and simulated data to elucidate subtle features in the processes.

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Imaging topographic growth by long-lived postseismic afterslip at Sefidabeh, east Iran

Copley

Reynolds

2014

Tectonics

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This paper describes observations and models of the postseismic deformation following the 1994 Sefidabeh earthquake sequence in east Iran, which shed light on the nature of the earthquake cycle and the mechanisms of topographic growth in the region. Interferometric synthetic aperture radar observations show creeping fault motion (“postseismic afterslip”) on an array of faults. Some of these faults probably represent the extensions of those that ruptured in the blind thrust‐faulting earthquakes in 1994, and cut through the entire seismogenic layer, while others are shallow and break up the hanging walls of the coseismic faults. The postseismic slip accommodates at least part of the vertical displacement gradient resulting from the buried coseismic slip, which was concentrated at depths of greater than ∼5 km. The postseismic afterslip is visible for over 16 years following the earthquakes. Agreement between the areas of postseismic uplift and indications of long‐term motion preserved in the geomorphology suggest that shallow fault slip during seismic cycles similar to the one we have observed governs the development of the landscape in the region. Slip on an array of shallow faults provides a mechanism for the development of short‐wavelength topography and geological structures above active thrust faults and has important implications for the interpretation of shallow geological features produced in regions experiencing similar seismic cycles to that at Sefidabeh.

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Influence of anelastic surface layers on postseismic thrust fault deformation

Cited by 21 publications

References 17 publications

Evidence of Strain Partitioning Between the Sierra Madre Fault and the Los Angeles Basin, Southern California from Numerical Models

Evidence of Strain Partitioning Between the Sierra Madre Fault and the Los Angeles Basin, Southern California from Numerical Models

QuakeSim: Efficient Modeling of Sensor Web Data in a Web Services Environment

Imaging topographic growth by long-lived postseismic afterslip at Sefidabeh, east Iran

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