First direct observation of coseismic slip and seafloor rupture along a submarine normal fault and implications for fault slip history

Abstract The quantitative morphology of bedrock fault surfaces combined with aerial surveys and field identification is a useful approach to identify paleoearthquakes, obtain coseismic slips, and evaluate the seismogenic capacity of active faults in bedrock areas where traditional trenching methods are not applicable. Here, we report a case study of the Jiaocheng Fault (JCF) in the Shanxi Rift, China. Although several studies have been conducted on the JCF, its coseismic slip history and seismogenic capacity are still unclear. To address these problems, we investigated two bedrock fault surfaces, Sixicun (SXC) and Shanglanzhen (SLZ), on the JCF’s northern segment using quantitative morphological analysis together with aerial and field surveys. Quantitative fractal analysis based on the isotropic empirical variogram and moving window shows that both bedrock fault surfaces have the characteristics of vertical segmentation, which is likely due to periodic earthquakes, the coseismic slip of which can be determined by the height of the segments. Three seismic events at SXC, with a coseismic vertical slip of 1.74, 1.65, and 1.99 m, and three seismic events at SLZ, with a coseismic vertical slip of 1.32, 2.35, and 1.88 m, are identified. Compared with the previous studies, these three seismic events may occur in the Holocene, but it requires absolute dating ages to support, which is also the focus of our future work. Considering the seismologic capability (M>7.5) and the relationship between the recurrence interval of ~2.6 kyr and elapsed time of more than 3 kyr, the seismic hazard of the northern and middle segments of the JCF requires immediate attention.

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Geoarchaeology and paleoseismology blend to define the Fucino active normal fault slip history, central Italy

Quaternary International ◽

10.1016/j.quaint.2017.01.028 ◽

2017 ◽

Vol 451 ◽

pp. 114-128 ◽

Cited By ~ 3

Author(s):

S. Gori ◽

E. Falcucci ◽

F. Galadini ◽

M. Moro ◽

M. Saroli ◽

...

Keyword(s):

Central Italy ◽

Normal Fault ◽

Fault Slip ◽

Slip History

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Coseismic slip propagation on the Tohoku plate boundary fault facilitated by slip-dependent weakening during slow fault slip

Geophysical Research Letters ◽

10.1002/2017gl074307 ◽

2017 ◽

Vol 44 (17) ◽

pp. 8749-8756 ◽

Cited By ~ 9

Author(s):

Yoshihiro Ito ◽

Matt J. Ikari ◽

Kohtaro Ujiie ◽

Achim Kopf

Keyword(s):

Plate Boundary ◽

Fault Slip ◽

Coseismic Slip ◽

Boundary Fault

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THE 2014 MW 6.9 NORTH AEGEAN TROUGH (NAT) EARTHQUAKE: SEISMOLOGICAL AND GEODETIC EVIDENCE

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.11877 ◽

2017 ◽

Vol 50 (3) ◽

pp. 1583

Author(s):

V. Saltogianni ◽

M. Gianniou ◽

T. Taymaz ◽

S. Yolsal-Çevikbilen ◽

S. Stiros

Keyword(s):

Broad Band ◽

Strike Slip ◽

Fault Geometry ◽

Coseismic Slip ◽

The North ◽

Finite Fault Inversion ◽

Seismological Data ◽

Finite Fault ◽

Slip History ◽

North Aegean

A strong earthquake (Mw 6.9) on 24 May 2014 ruptured the North Aegean Trough (NAT) in Greece, west of the North Anatolian Fault Zone (NAFZ). In order to provide unbiased constrains of the rupture process and fault geometry of the earthquake, seismological and geodetic data were analyzed independently. First, based on teleseismic long-period P- and SH- waveforms a point-source solution yielded dominantly right-lateral strike-slip faulting mechanism. Furthermore, finite fault inversion of broad-band data revealed the slip history of the earthquake. Second, GPS slip vectors derived from 11 permanent GPS stations uniformly distributed around the meizoseismal area of the earthquake indicated significant horizontal coseismic slip. Inversion of GPS-derived displacements on the basis of Okada model and using the new TOPological INVersion (TOPINV) algorithm permitted to model a vertical strike slip fault, consistent with that derived from seismological data. Obtained results are consistent with the NAT structure and constrain well the fault geometry and the dynamics of the 2014 earthquake. The latter seems to fill a gap in seismicity along the NAT in the last 50 years, but seems not to have a direct relationship with the sequence of recent faulting farther east, along the NAFZ.

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COSEISMIC DEFORMATION FIELD AND FAULT SLIP DISTRIBUTION OF THE 2015 CHILE Mw8.3 EARTHQUAKE

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b7-827-2016 ◽

2016 ◽

Vol XLI-B7 ◽

pp. 827-834

Author(s):

Chunyan Qu ◽

Ronghu Zuo ◽

Xin Jian Shan ◽

Guohong Zhang ◽

Yingfeng Zhang ◽

...

Keyword(s):

Elastic Half Space ◽

Fault Slip ◽

Deformation Field ◽

Coseismic Deformation ◽

Postseismic Deformation ◽

Coseismic Slip ◽

Single Plane ◽

Rupture Length ◽

Continental Plate ◽

Before And After

On September 16, 2015, a magnitude 8.3 earthquake struck west of Illapel, Chile. We analyzed Sentinel-1A/IW InSAR data on the descending track acquired before and after the Chile Mw8.3 earthquake of 16 September 2015. We found that the coseismic deformation field of this event consists of many semi circular fringes protruding to east in an approximately 300km long and 190km wide region. The maximum coseismic displacement is about 1.33m in LOS direction corresponding to subsidence or westward shift of the ground. We inverted the coseismic fault slip based on a small-dip single plane fault model in a homogeneous elastic half space. The inverted coseismic slip mainly concentrates at shallow depth above the hypocenter with a symmetry shape. The rupture length along strike is about 340 km with maximum slip of about 8.16m near the trench. The estimated moment is 3.126×1021 N.m (Mw8.27)，the maximum depth of coseismic slip near zero appears to 50km. We also analyzed the postseismic deformation fields using four interferograms with different time intervals. The results show that postseismic deformation occurred in a narrow area of approximately 65km wide with maximum slip 11cm, and its predominant motion changes from uplift to subsidence with time. that is to say, at first, the postseismic deformation direction is opposite to that of coseismic deformation, then it tends to be consistent with coseismic deformation.It maybe indicates the differences and changes in the velocity between the Nazca oceanic plate and the South American continental plate.

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Quantifying Normal Fault Evolution from River Profile Analysis in the Northern Basin and Range Province, Southwest Montana, USA

Lithosphere ◽

10.2113/2021/7866219 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Ian P. Armstrong ◽

Brian J. Yanites ◽

Nate Mitchell ◽

Clarke DeLisle ◽

Bruce J. Douglas

Keyword(s):

Normal Fault ◽

Basin And Range ◽

Fault Slip ◽

Stream Power ◽

Spatial And Temporal Patterns ◽

Basin And Range Province ◽

Slip Rates ◽

Base Level ◽

River Profiles ◽

Fault Evolution

Abstract Over the past few decades, tectonic geomorphology has been widely implemented to constrain spatial and temporal patterns of fault slip, especially where existing geologic or geodetic data are poor. We apply this practice along the eastern margin of Bull Mountain, Southwest Montana, where 15 transient channels are eroding into the flat, upstream relict landscape in response to an ongoing period of increased base level fall along the Western North Boulder fault. We aim to improve constraints on the spatial and temporal slip rates across the Western North Boulder fault zone by applying channel morphometrics, cosmogenic erosion rates, bedrock characteristics, and calibrated reproductions of the modern river profiles using a 1-dimensional stream power incision model that undergoes a change in the rate of base level fall. We perform over 104 base level fall simulations to explore a wide range of fault slip dynamics and stream power parameters. Our best fit simulations suggest that the Western North Boulder fault started as individual fault segments along the middle to southern regions of Bull Mountain that nucleated around 6.2 to 2.5 Ma, respectively. This was followed by the nucleation of fault segments in the northern region around 1.5 to 0.4 Ma. We recreate the evolution of the Western North Boulder fault to show that through time, these individual segments propagate at the fault tips and link together to span over 40 km, with a maximum slip of 462 m in the central portion of the fault. Fault slip rates range from 0.02 to 0.45 mm/yr along strike and are consistent with estimates for other active faults in the region. We find that the timing of fault initiation coincides well with the migration of the Yellowstone hotspot across the nearby Idaho-Montana border and thus attribute the initiation of extension to the crustal bulge from the migrating hotspot. Overall, we provide the first quantitative constraints on fault initiation and evolution of the Western North Boulder fault, perhaps the farthest north basin in the Northern Basin and Range province that such constraints exist. We show that river profiles are powerful tools for documenting the spatial and temporal patterns of normal fault evolution, especially where other geologic/geodetic methods are limited, proving to be a vital tool for accurate tectonic hazard assessments.

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The July 2020 Mw 6.3 Nima Earthquake, Central Tibet: A Shallow Normal-Faulting Event Rupturing in a Stepover Zone

Seismological Research Letters ◽

10.1785/0220210057 ◽

2021 ◽

Author(s):

Jiuyuan Yang ◽

Caijun Xu ◽

Yangmao Wen ◽

Guangyu Xu

Keyword(s):

Normal Fault ◽

Strike Slip ◽

Deformation Analysis ◽

Postseismic Deformation ◽

Integrated Analysis ◽

Tectonic Deformation ◽

Normal Faulting ◽

Coseismic Slip ◽

Synthetic Aperture Radar Data ◽

Central Tibet

Abstract On 22 July 2020, an Mw 6.3 earthquake with a predominantly normal-faulting mechanism struck the Yibug Caka fault zone, central Tibet, where the overall tectonic environment is characterized by left-lateral strike-slip motion. This event offers a chance to gain insight into the tectonic deformation and the cause of shallow normal-faulting earthquakes in this little studied region. Here, we use Sentinel-1A/B Interferometric Synthetic Aperture Radar data to investigate the coseismic and postseismic deformation related to this earthquake. The earthquake ruptured a previously mapped West Yibug Caka fault and is dominated by normal slip with a peak value of 1.9 m at depth of 6.9 km. Postseismic deformation analysis indicates that the observed subsidence signals of up to ∼4.7 cm are a consequence of afterslip. Most of the afterslip is confined at depths between 0.8 and 8.4 km, peaking at 0.27 m at depth of 6.1 km. The significant coseismic slip and afterslip involved in the earthquake highlights a complex interaction between the major normal fault and the secondary synthetic fault. By an integrated analysis of the inversions, regional geology geomorphology, fault kinematics, and seismicity background, we propose a tectonic model that attributes the occurrence of this normal-faulting event to the release of extensional stress in a stepover zone controlled by the northeast-striking sinistral strike-slip Riganpei Co fault and Bu Zang Ai fault. Compared with that the structural stepover often acts as a barrier to affect the propagation of earthquake rupture, our study demonstrates that the failure of a stepover may potentially induce the occurrence of earthquake along the bounding strike-slip faults.

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