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Regional seismic tectonic setting: (a) rift basins, active faults, and earthquake distribution around the Ordos block (modified from Deng, 2007); (b) locations of the three faults, earthquake distribution in the basin, and the thickness of Quaternary sediments (km); the thickness is from the (Research Group of the National Seismological Administration, 1988); SPF, Sertengshan piedmont fault; WPF, Wulashan piedmont fault; DPF, Daqingshan piedmont fault; (c) AA', Quaternary isopach map from the Hetao Basin; BB', Cenozoic isopach map from the Hetao Basin; the profiles are modified from Li and Nie (1987) based on petroleum geology, hydrology, and seismic data.
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Long paleoearthquake series are crucial for understanding the recurrence patterns of active faults and evaluating the seismic hazards of faults. In this study, the first semiquantitative evaluation of paleoearthquake events from trenches was applied to normal faults, and classification criteria for identifying paleoearthquakes in trenches on normal...
Citations
... A comprehensive analysis of paleoearthquake markers on both trench walls provided robust and abundant evidence for identifying paleoearthquakes. Additionally, to objectively assess the confidence in each event, we use the scheme of Scharer et al. (2007), D. Y. Yuan et al. (2018), and D. Xu et al. (2023) to rank indicators per event by confidence with a scale of 1-4. ...
... Summarizing the Evidence for Each Event in the Trench TC1 at the Shangyaodonggou SiteEvent ID Trench poor, 1 = low. Rank definitions refer to D.Xu et al. (2023). ...
The seismic gaps between ruptures of large earthquakes in tectonically active deformation zones are usually considered to be dangerous areas for future earthquakes. The Western Tianzhu Basin fault (WTBF) with an oblique normal motion is located in the middle of the Tianzhu seismic gap between the M 8.5 Haiyuan and M 8.0 Gulang earthquakes, NE Tibetan Plateau. The faulting activity of the WTBF is key to understanding the seismic hazards of the seismic gap, but it remains poorly constrained. Using satellite images, field investigations, paleoseismic trenching, and radiocarbon dating, we found that the WTBF produced seven paleoearthquakes since ∼8,000 cal. yr BP, with the latest event occurring at 1,005 ± 584 cal. yr BP, yielding an average recurrence interval of 1,102 ± 100 yr and a coefficient of variation of 0.38, indicating that it features a millennial quasi‐periodic recurrence. Based on the comparative analysis of geometry, kinematics, and tectonic activity, we suggest that the Tianzhu seismic gap can be divided into three sections and is characterized by a segmented rupture pattern. Among them, the WTBF and Jinqianghe fault exhibit similar geometry and kinematics and together form the ∼55 km‐long Jinqianghe‐Tianzhu transtensional fault zone (JTTFZ) that is capable of producing earthquakes of Mw 7.2. Given the long elapsed time since the latest event and strong seismogenic potential, it is believed that the JTTFZ poses a high seismic hazard. Our results enhance the understanding of the high seismic hazard in seismic gaps and provide new insights into the seismic rupture behavior in the NE Tibetan Plateau.
... Addressing the challenge of rupturing the overburdened soil body during a severe earthquake requires expensive engineering interventions, such as digging deep trenches. However, this method may not guarantee precision in locating the rupture or determining the overall affected area [34][35][36]. Hence, understanding the rupture traces and widths within the overburdened soil body's interior profile is crucial. ...
Performance-based seismic design methods for bridges are advancing, yet limited research has explored the damage mechanisms of bridges subjected to extreme seismic effects, such as those near or across faults. To investigate the damage mechanisms under bedrock dislocation and bridge rupture resistance, providing essential insights for the standardized design and construction of bridges in close proximity to seismic rupture sites, we developed a large-scale device to model bridges in the immediate vicinity of tilted-slip strong seismic rupture sites. This included a synchronous bedrock dislocation loading system. Four sets of typical sandy soil modeling tests were concurrently conducted. The results indicate: (1) The overall shear deformation zone of the foundation and surface uneven deformation primarily concentrate the overburdened soil body along the fault dip. The damaged area under the low-dip reverse fault is lighter on the surface and inside the soil body compared to the high-dip-positive fault. (2) The presence of bridges reduces the width of the main rupture zone and avoidance distance to some extent. However, this reduction is not as significant as anticipated. The damage to the bridge pile foundation along the fault dislocation tendency notably leads to the bending damage of the bridge deck. (3) Input parameters for fracture-resistant bridge design (surface rupture zone location, extent, maximum deformation, etc.) can be deduced from the free site. Within the rupture zone, a “fuse” design can be implemented using simply supported girders. Additionally, combining the “fuse” design with simple supported girders on both sides and utilizing simple support beams for “fuse” design within the rupture zone, along with structural “disconnection”, allows for reinforcing measures on the bridge structure’s foundation platform and pile in the soil body.
... This Special Issue was organized by Guest Editors Zhikun Ren, Peizhen Zhang, Takashi Oguchi, and Zhongtai He, and they have engaged in active tectonic studies for many years [1][2][3][4][5][6][7][8][9][10]. ...
... Below, we aim to study active tectonic geomorphological processes using high-resolution data acquired by different remote sensing platforms and sensors. This Special Issue was organized by Guest Editors Zhikun Ren, Peizhen Zhang, Takashi Oguchi, and Zhongtai He, and they have engaged in active tectonic studies for many years [1][2][3][4][5][6][7][8][9][10]. ...
The quantity and quality of remote sensing measurements of tectonic deformation have increased dramatically over the past two decades, improving our ability to observe active geomorphological tectonic processes. High-precision and high-resolution topography is the basis for the quantitative study of active geomorphological and tectonic processes. Recently, with the rapid development of computer visual science and the growing application of light detection and ranging (LiDAR), small unmanned aerial vehicles (UAVs) and structure from motion (SfM) photogrammetry have shown great potential in providing high-resolution and high-precision topographic information. In this Special Issue, we focus on the tectonic activity of active faults and the geomorphic processes in various global tectonic regimes that are related to remote sensing measurements. This Special Issue covers major earthquake hazards and seismogenic structures, new methods in seismological studies using high-resolution data sets, and the tectonic and geomorphic application of high-resolution data sets worldwide and, in particular, in the Eastern Tibetan Plateau and Tian Shan. These contributions will provide new insights into the remote sensing perspectives of geomorphological and tectonic processes.
The timing and surface rupture length of large earthquakes are key parameters for seismic hazard studies in the Tanlu fault zone (TLFZ). Existing studies suggest that the M 81/2 Tancheng earthquake in A.D. 1668 may have been generated by the cascading rupture of the Juxian–Tancheng fault (JTF) and the Anqiu–Juxian fault (AJF) in the TLFZ. The Anqiu earthquake in 70 B.C. near the AJF also shook eastern China; however, the latest surface rupturing event along the AJF has not been studied, thus the potential earthquake hazard has large uncertainties. In this study, we excavated three trenches along the AJF to determine the most recent surface rupturing events to address these problems. As evidenced by paleoseismic and chronological investigations, the latest seismic events occurred along the northern segment (S1) and middle segment (S2) at approximately A.D. 63–225 and 2148–48 B.C., respectively. Combined with previous studies and historical records, our study inferred that the Anqiu earthquake in 70 B.C. was generated by S1 and S2, with an estimated magnitude of Mw 7.5 ± 0.2. The most recent event on S3 occurred just before 10297 ± 53 yr B.P. Our study also revealed that the Tancheng M 81/2 earthquake was generated by the JTF alone without surface rupture of the AJF. Thus, the elapsed time of the latest large earthquake along the AJF is more than 2000 yr.
