Two of the biggest US earthquake faults might be linked

abstract In the absence of near-field records of differential ground motion induced by earthquakes, we simulate the time histories of strain, tilt, and rotation in the vicinity of earthquake faults embedded in layered media. We consider the case of both strike-slip and dip-slip fault models and study the effect of different crustal structures. The maximum rotational motion produced by a buried 30-km-long strike-slip fault with slip of 1 m is of the order of 3 × 10−4 rad while the corresponding rotational velocity is about 1.5 × 10−3 rad/sec. A simulation of the San Fernando earthquake yields maximum longitudinal strain and tilt a few kilometers from the fault of the order of 8 × 10−4 and 7 × 10−4 rad. These values being small compared to the amplitude of ground displacement, the results suggest that most of the damage occurring in earthquakes is caused by translation motions. We also show that strain and tilt are closely related to ground velocity and that the phase velocities associated with strong ground motions are controlled by the rupture velocity and the basement rock shearwave velocity.

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Imaging of earthquake faults using small UAVs as a pathfinder for air and space observations

2017 IEEE Aerospace Conference ◽

10.1109/aero.2017.7943605 ◽

2017 ◽

Author(s):

Andrea Donnellan ◽

Joseph Green ◽

Adnan Ansar ◽

Joseph Aletky ◽

Margaret Glasscoe ◽

...

Keyword(s):

Earthquake Faults ◽

Space Observations

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Fault Attitude of the North Section of Huangzhuang-Gaoliying Fault at Beijing, China and Its Effects on the Ground Rupture

Journal of Environmental and Engineering Geophysics ◽

10.2113/jeeg24.4.549 ◽

2019 ◽

Vol 24 (4) ◽

pp. 549-555

Author(s):

Shuai Zhao ◽

Yongqi Meng ◽

Zhenning Ma ◽

Jiajun Sun

Keyword(s):

Human Life ◽

Geophysical Methods ◽

Beijing Area ◽

The North ◽

Refraction Tomography ◽

Surface Ruptures ◽

Earthquake Faults ◽

Subsurface Geometry ◽

Seismic Images ◽

Beijing China

Worldwide, slip on earthquake faults causes numerous disasters, resulting in large losses in human life and built structures. To minimize future losses associated with earthquakes along such faults, it is important to precisely locate the faults relative to the built environment and to determine the subsurface geometry of the faults. In Beijing, China, we used shallow-depth geophysical methods to evaluate the location and subsurface geometry of the Huangzhuang-Gaoliying fault (HGF), one of the principal tectonic faults of Beijing area. We used seismic reflection and refraction tomography, multi-channel analysis of surface waves (MASW), and paleoseismic trenching to characterize the north section of HGF near the Gaoliying section of Beijing. Our seismic images indicated that there are at least two strands of the HGF that are distributed over an approximately 200-m-wide zone. We identified a principal fault strand (F1) that is observed in all the seismic images, as well as in a paleoseismic trench. The F1 strikes approximately N49°E and dips southeastward at 70° to 75°. Over the past few years, surface ruptures have occurred along the HGF in several locations, but it is unclear if the surface ruptures were the result of tectonic slip on the HGF or were related to land subsidence along the fault.

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