scholarly journals Fold style inversion: Placing probabilistic constraints on the predicted shape of blind thrust faults

2000 ◽  
Vol 105 (B6) ◽  
pp. 13281-13301 ◽  
Author(s):  
Benjamin A. Brooks ◽  
Eric Sandvol ◽  
Andrew Ross
Keyword(s):  
Probabilistic Constraints ◽  
Thrust Faults ◽  
Blind Thrust

The role of bed-parallel slip in the formation of blind thrust faults

1998 ◽  
Vol 20 (5) ◽  
pp. 503-516 ◽  
Author(s):  
Fernando Niño ◽  
Hervé Philip ◽  
Jean Chéry
Keyword(s):  
Thrust Faults ◽  
Blind Thrust

Empirical observations regarding reverse earthquakes, blind thrust faults, and quaternary deformation: Are blind thrust faults truly blind?

1997 ◽  
Vol 87 (5) ◽  
pp. 1171-1198
Author(s):  
William R. Lettis ◽  
Donald L. Wells ◽  
John N. Baldwin
Keyword(s):  
Surface Deformation ◽  
Reverse Fault ◽  
Thrust Faults ◽  
Geologic Mapping ◽  
Earthquake Hazards ◽  
Geomorphic Mapping ◽  
Blind Thrust ◽  
Quaternary Deformation ◽  
Mapping Techniques ◽  
Blind Thrust Fault

Abstract Active thrust faults pose a significant seismic hazard worldwide. Many of these faults include “blind” thrusts, where the propagating fault tip does not reach the Earth's surface, and “buried” faults, where the geomorphic expression of the fault is obscured by subsequent sedimentation and/or erosion. This raises the issue of whether conventional geologic, geomorphic, and paleoseismic methods can be used to identify and characterize thrust faults for the assessment of seismic hazards or whether these faults sometimes are truly “blind.” We compiled a data base of 148 worldwide moderate- to large-magnitude thrust/reverse earthquakes to evaluate whether or not the event occurred on a fault that could have been identified prior to the earthquake on the basis of recognizable Quaternary surface deformation (i.e., a pre-existing fault or fold). Analysis of the data shows that interplate reverse earthquakes almost always are associated with pre-existing Quaternary deformation that was or could have been recognized prior to the earthquake. In particular, most interplate reverse earthquakes are associated with an active reverse fault at the surface and/or an active anticline. In contrast, intraplate reverse earthquakes seldom occur on faults associated with pre-existing recognizable surface deformation. We conclude that thrust faults can be detected in interplate regions with careful Quaternary geologic and geomorphic mapping; furthermore, the absence of Quaternary surface deformation can be used to infer the absence of an underlying active blind thrust fault in interplate tectonic settings. However, the data show that Quaternary geologic mapping techniques alone likely are insufficient to characterize blind thrusts in intraplate regions. In these areas, inclusion of a floating or random earthquake may be necessary to assess earthquake hazards.

scholarly journals Surface Displacement and Ground Motion from Dynamic Rupture Models of Thrust Faults with Variable Dip Angles and Burial Depths

2020 ◽  
Vol 110 (6) ◽  
pp. 2599-2618
Author(s):  
Sirena Ulloa ◽  
Julian C. Lozos
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Ground Motions ◽  
Ground Surface ◽  
Surface Displacement ◽  
Initial Stresses ◽  
Thrust Faults ◽  
Dynamic Rupture ◽  
Blind Thrust ◽  
Dip Angle

ABSTRACT Thrust-fault earthquakes are particularly hazardous in that they produce stronger ground motion than normal or strike-slip events of the same magnitude due to a combination of hanging-wall effects, vertical asymmetry, and higher stress drop due to compression. In addition, vertical surface displacement occurs in both blind-thrust and emergent thrust ruptures, and can potentially damage lifelines and infrastructure. Our 3D dynamic rupture modeling parameter study focuses on planar thrust faults of varying dip angles, and burial depth establishes a physics-based understanding of how ground motion and permanent ground surface displacement depend on these geometrical parameters. We vary dip angles from 20° to 70° and burial depths from 0 to 5 km. We conduct rupture models on these geometries embedded in a homogeneous half-space, using different stress drops but fixed frictional parameters, and with homogeneous initial stresses versus stresses tapered toward the ground surface. Ground motions decrease as we bury the fault under homogeneous initial stresses. In contrast, under tapered initial stresses, ground motions increase in blind-thrust faults as we bury the fault, but are still the highest in emergent faults. As we steepen dip angle, peak particle velocities in the homogeneous stress case generally increase in emergent faults but decrease in blind-thrust faults. Meanwhile, ground motion consistently increases with steepening dip angle under the stress gradient. We find that varying stress drop has a considerable scalar effect on both ground motion and permanent surface displacement, whereas changing fault strength has a negligible effect. Because of the simple geometry of a planar fault, our results can be applied to understanding basic behavior of specific real-world thrust faults.

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