scholarly journals Incipient evolution of the Eastern California shear zone through the transpressional zone of the San Bernardino Mountains and San Gorgonio Pass, California

Geosphere ◽  
2020 ◽  
Vol 16 (4) ◽  
pp. 919-935
Author(s):  
William J. Cochran ◽  
James A. Spotila ◽  
Philip S. Prince
Keyword(s):  
Shear Zone ◽  
Slip Rate ◽  
San Bernardino Mountains ◽  
Eastern California Shear Zone ◽  
The North ◽  
San Bernardino ◽  
Geomorphic Features ◽  
Aerial Vehicle ◽  
Mountainous Landscape ◽  
High Topography

Abstract The nature of the connection between the Eastern California shear zone (ECSZ) and the San Andreas fault (SAF) in southern California (western United States) is not well understood. Northwest of San Gorgonio Pass, strands of the ECSZ may be migrating south and west into the convergent zone of the San Bernardino Mountains (SBM) as it is advected to the southeast via the SAF. Using high-resolution topography and field mapping, this study aims to test whether diffuse faults within the SBM represent a nascent connection between the ECSZ and the SAF. Topographic resolution of ≤1 m was achieved using both lidar and unmanned aerial vehicle surveys along two Quaternary strike-slip faults. The Lone Valley fault enters the SBM from the north and may form an along-strike continuation of the Helendale fault. We find that its geomorphic expression is obscured where it crosses Quaternary alluvium, however, suggesting that it may have a low rate of yet-undetermined activity. The Lake Peak fault is located farther south and cuts through the high topography of the San Gorgonio massif and may merge with strands of the SAF system. We find that this fault clearly cuts Quaternary glacial deposits, although the magnitude of offset is difficult to assess. Based on our interpretation of geomorphic features, we propose that the Lake Peak fault has predominantly dextral or oblique-dextral motion, possibly with a slip rate that is comparable to the low rates observed along other strands of the ECSZ (i.e., ≤1 mm/yr). Comparing the geomorphic expressions of these faults is difficult, however, given that the erosive nature of the mountainous landscape in the SBM may obscure evidence of active faulting. Based on these observations, as well as the occurrence of other diffuse faults in the region, we suggest that dextral strain is overprinting the actively convergent zone of the SBM, thereby creating a throughgoing connection between the ECSZ and the SAF west of San Gorgonio Pass.

scholarly journals Supplemental Material: Incipient evolution of the Eastern California shear zone through the transpressional zone of the San Bernardino Mountains and San Gorgonio Pass, California

2020 ◽  
Author(s):  
W.J. Cochran ◽  
et al.
Keyword(s):  
Shear Zone ◽  
San Bernardino Mountains ◽  
Eastern California Shear Zone ◽  
San Bernardino

Table of UAV parameters and four uninterpreted UAV and lidar topographic hillshade models. Figures are in the RAW format used as the basis for neotectonic interpretations in this paper.

Supplemental Material: Incipient evolution of the Eastern California shear zone through the transpressional zone of the San Bernardino Mountains and San Gorgonio Pass, California

2020 ◽  
Author(s):  
W.J. Cochran
Keyword(s):  
Shear Zone ◽  
San Bernardino Mountains ◽  
Eastern California Shear Zone ◽  
San Bernardino

Table of UAV parameters and four uninterpreted UAV and lidar topographic hillshade models. Figures are in the RAW format used as the basis for neotectonic interpretations in this paper.

scholarly journals Supplemental Material: Incipient evolution of the Eastern California shear zone through the transpressional zone of the San Bernardino Mountains and San Gorgonio Pass, California

2020 ◽  
Author(s):  
W.J. Cochran ◽  
et al.
Keyword(s):  
Shear Zone ◽  
San Bernardino Mountains ◽  
Eastern California Shear Zone ◽  
San Bernardino

Table of UAV parameters and four uninterpreted UAV and lidar topographic hillshade models. Figures are in the RAW format used as the basis for neotectonic interpretations in this paper.

How much can off-fault deformation contribute to the slip rate discrepancy within the eastern California shear zone?

Geology ◽  
2014 ◽  
Vol 42 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Justin W. Herbert ◽  
Michele L. Cooke ◽  
Michael Oskin ◽  
Ohilda Difo
Keyword(s):  
Shear Zone ◽  
Slip Rate ◽  
Eastern California Shear Zone ◽  
Fault Deformation

Spatio-temporal behaviour of continental transform faults: implications from the late Quaternary slip history of the North Anatolian Fault, Turkey

2019 ◽  
Vol 56 (11) ◽  
pp. 1218-1238 ◽  
Author(s):  
Cengiz Zabcı
Keyword(s):  
Shear Zone ◽  
Late Quaternary ◽  
Slip Rate ◽  
Secondary Structures ◽  
North Anatolian Fault ◽  
Marmara Region ◽  
Temporal Behaviour ◽  
The North ◽  
Slip History ◽  
History Of

The slip history of the North Anatolian Fault (NAF) is constrained by displacement and age data for the last 550 ka. First, I classified all available geological estimates as members of three groups: Model I for the eastern, Model II for the central, and Model III for the western segments where the North Anatolian Shear Zone gradually widens from east to west. The short-term uniform slip solutions yield similar results, 17.5 +4/–3.5 mm/a, 18.9 +3.7/–3.3 mm/a, and 16.9 +1.2/–1.1 mm/a from east to the west. Although these model rates do not show any significant spatial variations among themselves, the correlation with geodetic estimates, ranging between 15 mm/a and 28 mm/a for different sections of the NAF, displays significant discrepancies especially for the central and western segments of the fault. Discrepancies suggest that most strain is accumulated along the NAF, but some portion of it is distributed along secondary structures of the North Anatolian Shear Zone. The deformation rate is constant at least for the last 195 ka, whereas the limited number of data show strain transfer from northern to the southern strand between 195 and 320 ka BP in the Marmara Region when the incremental slip rate decreases to 13.2 +3.1/–2.9 mm/a for the northern strand of the NAF. Considering the possible uncertainties of incremental displacements and their timings, more studies on slip rate are needed at different sites, including major structural elements of the North Anatolian Shear Zone. Although most of the strain is localized along the main displacement zone, the NAF, secondary structures are still capable of generating earthquakes that can hardly reach Mw 7.

Active Faulting of Landforms along the Tuosuhu-Maoniushan Fault and Its Seismotectonic Implications in Eastern Qaidam Basin, China

2022 ◽  
Author(s):  
Guihua Chen ◽  
Xun Zeng ◽  
Zhongwu Li ◽  
Xiwei Xu
Keyword(s):  
Late Quaternary ◽  
Qaidam Basin ◽  
Slip Rate ◽  
Northern Margin ◽  
The North ◽  
Fold And Thrust Belt ◽  
Field Investigations ◽  
High Resolution Satellite Images ◽  
Geomorphic Features ◽  
Tectonic Belt

Abstract The fold-and-thrust belt along the northern margin of the Qaidam basin is a typical active tectonic belt located in the northeast Tibetan Plateau. This belt is at a high risk of strong earthquakes with magnitudes larger than 6, as shown by multiple recorded events during 1962–2009. The lack of detailed late Quaternary surficial faulting data and systematic seismotectonic studies has posed difficulties in properly assessing the seismic risks and understanding the ongoing geodynamics in this region. In this study, we mapped the geomorphic features and fault traces from high-resolution satellite images and field investigations of the Tuosuhu-Maoniushan fault (TMF). Field photogrammetry was conducted to obtain deformation measurements using a DJI M300 real-time kinematic (RTK) drone. The TMF displaces the Holocene and late Pleistocene alluvial terraces in the eastern Qaidam basin. This fault dips to the south in the west and central segments (as a boundary of the Denan depression) and to the north in the eastern segment along the piedmont of the Maoniushan Mountains. The vertical slip rate is estimated to be 0.37 ± 0.08 mm/yr, which is similar to that of the active southern Zongwulongshan fault. By integrating our investigations with the previously published studies on deep structures and Cenozoic geology of the region, we propose a deep-seated thrust model for the seismotectonics of the northern margin of the Qaidam basin. The Aimunike, Tuosuhu-Maoniushan, southern Zongwulongshan, and Zongwulong faults, along with many folds, form an active compressional zone. The complex across-strike structures and along-strike segmentation could facilitate the release of strain through earthquakes of magnitude 6–7 in this broad seismotectonics belt, rather than through strong surface-rupturing events resulting from a single mature large fault.

scholarly journals Slip rate of the Calico fault: Implications for geologic versus geodetic rate discrepancy in the Eastern California Shear Zone

2007 ◽  
Vol 112 (B3) ◽  
Author(s):  
Michael Oskin ◽  
Lesley Perg ◽  
Dylan Blumentritt ◽  
Sujoy Mukhopadhyay ◽  
Alexander Iriondo
Keyword(s):  
Shear Zone ◽  
Slip Rate ◽  
Eastern California Shear Zone

A new geological slip rate estimate for the Calico Fault, eastern California: implications for geodetic versus geologic rate estimates in the Eastern California Shear Zone

2018 ◽  
Vol 61 (13) ◽  
pp. 1613-1641 ◽  
Author(s):  
Surui Xie ◽  
Elisabeth Gallant ◽  
Paul H. Wetmore ◽  
Paula M. Figueiredo ◽  
Lewis A. Owen ◽  
...  
Keyword(s):  
Shear Zone ◽  
Slip Rate ◽  
Rate Estimate ◽  
Eastern California Shear Zone
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