Orthogonal Fault Rupture and Rapid Postseismic Deformation Following 2019 Ridgecrest, California, Earthquake Sequence Revealed From Geodetic Observations

Feng, Wanpeng; Samsonov, Sergey; Qiu, Qiang; Wang, Yuqing; Zhang, Peizhen; Li, Tao; Zheng, Wenjun

doi:10.1029/2019gl086888

Cited by 40 publications

(57 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Camp 263 fault is almost conjugate to the main nearly EW‐striking fault rupture. A similar rupture pattern was proposed for the 2019 Ridgecrest earthquake sequence, in which two orthogonal faults were ruptured sequentially (Barnhart et al, 2019; Feng et al, 2020). Coseismic slip on the Camp 263 fault can be explained either as slip on a secondary fault plane adjacent to the main fault or as the possible shallow rupture of an aftershock.…”

Section: Discussionsupporting

confidence: 54%

The Complexity of the 2018 Kaktovik Earthquake Sequence in the Northeast of the Brooks Range, Alaska

Wen

et al. 2020

Geophysical Research Letters

View full text Add to dashboard Cite

We use mainly geodetic observations to constrain the fault geometry and coseismic distribution of the 2018 Kaktovik earthquake sequence, Alaska. We find that at least three faults were activated. The earthquake sequence ruptured mainly an ESE-striking, SSW-dipping strike-slip fault and a secondary rupture on an SE-striking, SW-dipping normal fault. Slip also occurred on a small SSW-striking fault plane, which is found first in geodetic data and further verified with geological data and focal mechanism solutions. We also map 6 months of postseismic deformation and find obvious displacements in the center of the Sadlerochit Mountains. A geological model is proposed to interpret the relationship between this earthquake sequence and the regional structure. We suggest that the 2018 Kaktovik earthquake sequence may first have occurred on a fault unknown prior to the mainshock and triggered slip on both the pre-existing ramp structure below the Sadlerochit Mountains and a secondary structure. Plain Language Summary The 2018 Kaktovik event is the largest earthquake ever to be reported and recorded within the eastern Brooks Range and presents an unprecedented opportunity to study the regional tectonic structure and crustal deformation. Here, we present a detailed investigation into the seismogenic structure of this earthquake sequence, which ruptured mainly an ESE-striking, SSW-dipping strike-slip fault and a secondary SE-striking, SW-dipping normal fault. Slip also occurred on a small SSW-striking fault plane, which is found first in the geodetic data and further verified with seismic and geological data. Perhaps the most striking discovery from the InSAR observations of the Kaktovik earthquake sequence is that most of the displacement occurred on a fault whose existence was unknown prior to the earthquake sequence: a blind fault with no surface expression; additionally, a conjugate fault structure could have been triggered in this earthquake sequence. To explain the different orientations and kinematics of the two main ruptures (Faults 1 and 2), we use a ramp structure with variable geometry for the main fault zone: The first rupture has a higher dip and more strike-slip, while the second rupture has a lower dip and a dominant normal component.

show abstract

Section: Discussionsupporting

confidence: 54%

The Complexity of the 2018 Kaktovik Earthquake Sequence in the Northeast of the Brooks Range, Alaska

Wen

et al. 2020

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…The different magnitude of stress rotation over different regions could be related to the spatial heterogeneities in stress and stress drop, as the mainshock coseismic slip is not uniform in space. However, the stress rotation is surprisingly small for Region B, where the largest coseismic slip of M w 7.1 event occurred (Barnhart et al, 2019; Chen et al, 2020; Feng et al, 2020; Goldberg et al, 2020; Ross et al, 2019). Note the stress rotations depend not only on the stress drop ratio but also on the angle between the premainshock stress field and the orientation of fault (Hardebeck & Hauksson, 2001).…”

Section: State Of Stress In the Ridgecrest Regionmentioning

confidence: 99%

“…The spatial distribution of aftershocks of the M w 6.4 event illuminates that it ruptured a conjugated fault system that forming an “L” shape (Ross et al, 2019; Lin, 2020; Liu et al, 2020; Shelly, 2020). The kinematic subevent and finite fault inversions provide additional evidence that the M w 6.4 event ruptured both the NW‐SE and NE‐SW trending faults (Chen et al, 2020; Feng et al, 2020; Jia et al, 2019; Liu et al, 2019; Ross et al, 2019), although only the NE‐SW trending rupture is captured by the InSAR optical image (Barnhart et al, 2019). About 34 hr later, a Mw 7.1 event initialized near the NW end of the aftershock zone of the M w 6.4 event and ruptured bilaterally on a ~50 km NW‐SE striking fault (Barnhart et al, 2019; Chen et al, 2020; Goldberg et al, 2020; Lin, 2020; Liu et al, 2019; Liu et al, 2020; Ross et al, 2019; Shelly, 2020), with clear surface breaks observed by geological surveys and satellite observations (Brandenberg et al, 2019; Fielding et al, 2020; Ross et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Seismotectonics and Fault Geometries of the 2019 Ridgecrest Sequence: Insight From Aftershock Moment Tensor Catalog Using 3‐D Green's Functions

Wang

Zhan

2020

JGR Solid Earth

View full text Add to dashboard Cite

The 2019 Mw 7.1 Ridgecrest earthquake occurred on 6 July, preceded by the Mw 6.4 foreshock on 4 July 2019. These two earthquakes occurred close in space and time with partially overlapping surface ruptures and aftershock patterns, raising the question of the relationship between the two events. Geological surveys and satellite observations provide important constraints on the surface traces of faulting. However, the subsurface fault geometries, which are important for understanding the regional stress field, earthquake initiation, propagation, and termination, are not well resolved. In this study, moment tensor solutions for 256 earthquakes in the 2019 Ridgecrest sequence were determined by waveform inversion using 3‐D velocity model. The obtained moment tensor solutions show rotations of the stresses after mainshock, indicating the ratio of mainshock stress drop to the background stress to be 0.5–0.9. The obtained moment tensor catalog also facilitates a better understanding of the subsurface fault geometries, including (1) splay faults and antithetic faults in the northwest aftershock zone; (2) shallow flower structures near the Mw 7.1 epicenter; and (3) subparallel faults in the southeast aftershock zone. The aftershocks' studies suggest the very complex surface ruptures near the 2019 Ridgecrest Mw 7.1 epicenter are near‐surface features that linked to a simple large throughgoing fault at >5 km depth. We also found that the southeastern‐most aftershocks, which are located less than a kilometer from the Garlock fault trace, have significant different strike directions from that of the Garlock fault, indicating the central Garlock fault remains seismically quiet.

show abstract

“…Presently, studies on the correlation between crustal movement and fault activity have rapidly progressed with the development of satellite-based remote sensing technology, such as GPS [7], InSAR, and gravimetry systems [8,9]. Furthermore, satellites have detected thermal infrared radiation (TIR) anomalies in faulted regions before and after strong earthquakes [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Thermal Infrared Spectral Variation of Fractured Rock

Huang

Liu

et al. 2021

Remote Sensing

View full text Add to dashboard Cite

Previous studies have shown that thermal infrared radiation (TIR) anomalies occur in the vicinity of fractures that form when a rock is loaded to failure. Different types of fracturing modes correspond to different TIR anomaly trends. However, the spectral features and the mechanisms responsible for the TIR changes in the fracturing stage remain poorly understood. In this paper, experiments involving observations of the thermal infrared spectrum (8.0–13.0 μm) of loaded sandstone during the fracturing stage were conducted under outdoor conditions. The experiment yielded the following results: (1) Different fracturing modes can lead to different trends in the spectral radiance variation; (2) when an extensional fissure appeared on the rock surface, the radiance increased with a local peak in the 8.0–9.7 μm range; 3) when local bulging formed at the surface, the radiance decreased, with a local valley in the 8.0–9.7 μm range. The radiance variation caused by morphologic changes is the combined result of changes in both the temperature and the emissivity. The characteristic waveband corresponding to the reststrahlen features (RF) of quartz was mainly related to the emissivity change. This study provides a preliminary experimental foundation for the detection of crustal surface fractures via satellite-based remote sensing technology.

show abstract

Orthogonal Fault Rupture and Rapid Postseismic Deformation Following 2019 Ridgecrest, California, Earthquake Sequence Revealed From Geodetic Observations

Cited by 40 publications

References 52 publications

The Complexity of the 2018 Kaktovik Earthquake Sequence in the Northeast of the Brooks Range, Alaska

The Complexity of the 2018 Kaktovik Earthquake Sequence in the Northeast of the Brooks Range, Alaska

Seismotectonics and Fault Geometries of the 2019 Ridgecrest Sequence: Insight From Aftershock Moment Tensor Catalog Using 3‐D Green's Functions

Experimental Study on the Thermal Infrared Spectral Variation of Fractured Rock

Contact Info

Product

Resources

About