Interseismic Strain Accumulation Across the Zemuhe-Daliangshan Fault Zone in Heavily-Vegetated Southwestern China, From Alos-2 Interferometric Observation

2019 ◽  
Author(s):  
Xiaogang Song ◽  
Xinjian Shan ◽  
Chunyan Qu
Keyword(s):  
Fault Zone ◽  
Southwestern China ◽  
Strain Accumulation ◽  
Interferometric Observation

scholarly journals Stress state along the Anninghe-Zemuhe fault zone, southwestern China, estimated from an array of stress orientation measurements with a new method

2012 ◽  
Vol 64 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Yasuto Kuwahara ◽  
Tsutomu Kiguchi ◽  
Xinglin Lei ◽  
Shengli Ma ◽  
Xueze Wen ◽  
...  
Keyword(s):  
Stress State ◽  
Fault Zone ◽  
New Method ◽  
Southwestern China ◽  
Stress Orientation

scholarly journals Focal Mechanism and Seismogenic Structure of the MS 5.1 Qingbaijiang Earthquake on February 3, 2020, Southwestern China

2021 ◽  
Vol 9 ◽  
Author(s):  
Min Zhao ◽  
Feng Long ◽  
Guixi Yi ◽  
MingJian Liang ◽  
Jiangtao Xie ◽  
...  
Keyword(s):  
Fault Zone ◽  
Focal Mechanism ◽  
Earthquake Sequence ◽  
Southwestern China ◽  
Joint Analysis ◽  
Focal Mechanism Solution ◽  
Inversion Method ◽  
Seismogenic Structure ◽  
Initial Rupture ◽  
Hypocentral Distribution

The 3 February 2020 MS 5.1 Qingbaijiang earthquake, southwestern China, is the closest recorded MS ≥ 5.0 event to downtown Chengdu City to date, with an epicentral distance of only 38 km. Here we analyze seismic data from the Sichuan and Chengdu regional seismic networks, and employ a multi-stage location method to relocate the earthquakes that have occurred along the central and northern segments of the Longquanshan fault zone since 2009, including the MS 5.1 Qingbaijiang earthquake sequence, to investigate the seismogenic structure of the region. The relocation results indicate that the seismicity along the central and northern segments of the Longquanshan fault zone has occurred mainly along the eastern branch since 2009, with the hypocentral distribution along a vertical cross-section illustrating a steep, NW-dipping parallel imbricate structure. The terminating depth of the eastern branch is about 12 km. The distribution of the MS 5.1 Qingbaijiang earthquake sequence is along the NE–SW-striking Longquanshan fault zone. The aftershock focal depths are in the 3–6 km range, with the mainshock located at 104.475°E, 30.73°N. Its initial rupture depth of 5.2 km indicates that the earthquake occurred above the shallow decollement layer of the upper crust in this region. The hypocentral distribution along the long axis of the aftershock area highlights that this earthquake sequence occurred along a fault dipping at 56° to the NW. Our surface projection of the inferred fault plane places it near the eastern branch of the Longquanshan fault zone. We infer the MS 5.1 mainshock to be a thrust faulting event based on the focal mechanism solution via the cut-and-paste waveform inversion method, with strike/dip/rake parameters of 22°/36°/91° and 200°/54°/89° obtained for nodal planes I and II, respectively. We identify that the seismogenic fault of the MS 5.1 Qingbaijiang earthquake lies along the eastern branch of the Longquanshan fault zone, and nodal plane II represents the coseismic rupture plane, based on a joint analysis of the event relocation results, mainshock focal mechanism, and regional geological information. Our study provides vital information for assessing the seismic hazard of the Longquanshan fault zone near Chengdu City.

scholarly journals Dynamic Deformation And Fault Locking of The Xianshuihe Fault Zone, Southeastern Tibetan Plateau: Implications For Seismic Hazards

2021 ◽  
Author(s):  
Layue Li ◽  
Yanqiang Wu ◽  
Yujiang Li ◽  
Wei Zhan ◽  
Xinzhong Liu
Keyword(s):  
Fault Zone ◽  
Dynamic Deformation ◽  
Slip Rate ◽  
Deformation Pattern ◽  
Observation Data ◽  
Strain Accumulation ◽  
Dynamic Adjustment ◽  
Strong Earthquakes ◽  
Coupling Characteristics ◽  
Xianshuihe Fault Zone

Abstract The Xianshuihe Fault Zone is one of the most historically seismically active regions in mainland China. However, the seismicity along this fault zone has been quiescent for the past 40 years, since the Daofu M6.9 earthquake in 1981. Understanding its current deformation patterns and fault coupling characteristics is of great significance to estimate the potential risk of strong earthquakes. In this study, we analyzed the dynamic deformation and fault coupling characteristics along the Xianshuihe Fault Zone using Global Positioning System (GPS) data for 1999–2007 and 2016–2020. The results show that the deformation pattern of the Xianshuihe fault zone underwent a dynamic adjustment after the Wenchuan and Lushan earthquakes, i.e., the maximum shear strain accumulation rates of the Luhuo and Daofu sections significantly decreased from 6.0×10-8/a to 3.2×10-8/a, while that of the southeastern segment (i.e., Kangding and Moxi sections) increased from 4.5×10-8/a to 6.2×10-8/a. Additionally, the slip rate and deformation width of the Xianshuihe Fault Zone also changed during these two periods. Combined with the near-field cross-fault observation data, we suggest that the surrounding strong earthquakes 2008 Wenchuan Mw7.9 and 2013 Lushan Mw6.6 had evident differential impacts on the deformation pattern of the Xianshuihe Fault Zone. The fault-coupling inversion results show that the locking degree of the Xianshuihe Fault Zone continued to increase after the Mw7.9 Wenchuan and Mw6.6 Lushan earthquakes, especially the Qianning and Moxi sections increased significantly, with an average coupling coefficient of greater than 0.9 and left-lateral slip-rate deficits of ~5 mm/a and ~8 mm/a, respectively. In contrast, the locking degree of the Kangding section decreased with almost no slip-rate deficit, which may be due to the partial energy release caused by the Mw5.9 and Mw5.6 Kangding earthquakes in 2014. The analysis of the recent rupture history and strain accumulation characteristics of the Xianshuihe Fault Zone indicates that both the Qianning and Moxi sections have a high seismic potential for the next strong earthquake in the Xianshuihe Fault Zone.

scholarly journals Geochemistry of soil gas in the seismic fault zone produced by the Wenchuan Ms 8.0 earthquake, southwestern China

2010 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaocheng Zhou ◽  
Jianguo Du ◽  
Zhi Chen ◽  
Jianwu Cheng ◽  
Yi Tang ◽  
...  
Keyword(s):  
Fault Zone ◽  
Soil Gas ◽  
Southwestern China ◽  
Seismic Fault ◽  
Wenchuan Ms 8.0 Earthquake

Variations of mercury in soils in the northern segment of Zemuhe fault zone, southwestern China

2021 ◽  
Vol 80 (24) ◽  
Author(s):  
Lei Zhang ◽  
Chuang Bao ◽  
Lishuang Guo ◽  
Deyang Shi ◽  
Liling Zhao ◽  
...  
Keyword(s):  
Fault Zone ◽  
Southwestern China ◽  
Northern Segment

scholarly journals Hydrogeochemical Characteristics and Conceptual Model of the Geothermal Waters in the Xianshuihe Fault Zone, Southwestern China

2020 ◽  
Vol 17 (2) ◽  
pp. 500
Author(s):  
Xiao Li ◽  
Xun Huang ◽  
Xin Liao ◽  
Yunhui Zhang
Keyword(s):  
Conceptual Model ◽  
Fault Zone ◽  
Geothermal Water ◽  
Southwestern China ◽  
Geothermal System ◽  
Geothermal Waters ◽  
Rock Interaction ◽  
Western Sichuan ◽  
Δ18o And Δd ◽  
Xianshuihe Fault Zone

Abundant geothermal waters have been reported in the Yalabamei, Zhonggu, Erdaoqiao, and Yulingong geothermal areas of the Xianshuihe Fault Zone of western Sichuan, southwestern China. This study focused on the hydrogeochemical evolution, reservoir temperature, and recharge origin of geothermal waters using hydrochemical and deuterium-oxygen (D-O) isotopic studies. Shallow geothermal waters represented by geothermal springs and shallow drilled water wells are divided into two hydrochemical groups: (1) the Ca–Na–HCO3 type in the Erdaoqiao area, and (2) Na–HCO3 in other areas. Deep geothermal waters represented by deep drilled wells are characterized by the Na–Cl–HCO3 type. The major ionic compositions of geothermal water are primarily determined by the water–rock interaction with silicate and carbonate minerals. The reservoir temperatures estimated by multi-geothermometries have a range of 63–150 °C for shallow geothermal water and of 190–210 °C for deep geothermal water, respectively. The δ18O and δD compositions indicated geothermal waters are recharged by meteoric water from the elevation of 2923–5162 m. Based on the aforementioned analyses above, a conceptual model was constructed for the geothermal system in the Xianshuihe fault zone.

Field study of a highly active fault zone: The Xianshuihe fault of southwestern China

1991 ◽  
Vol 103 (9) ◽  
pp. 1178-1199 ◽  
Author(s):  
CLARENCE R. ALLEN ◽  
LUO ZHUOLI ◽  
QIAN HONG ◽  
WEN XUEZE ◽  
ZHOU HUAWEI ◽  
...  
Keyword(s):  
Field Study ◽  
Fault Zone ◽  
Active Fault ◽  
Southwestern China ◽  
Active Fault Zone ◽  
Highly Active

scholarly journals Source processes of large earthquakes along the Xianshuihe fault in southwestern China

1983 ◽  
Vol 73 (2) ◽  
pp. 537-551
Author(s):  
Huilan Zhou ◽  
Hsui-Lin Liu ◽  
Hiroo Kanamori
Keyword(s):  
Fault Zone ◽  
Body Wave ◽  
Active Faults ◽  
Strike Slip ◽  
The Body ◽  
Southwestern China ◽  
Total Moment ◽  
Lateral Strike Slip ◽  
Largest Aftershock ◽  
Large Earthquakes

abstract The Xianshuihe fault is one of the most active faults in southwestern China. Recently, three large earthquakes occurred along it in 1967 (Ms = 6.1), 1973 (Ms = 7.5), and 1981 (Ms = 6.8). The 1981 event occurred near the central portion of the fault zone. Modeling of the body and surface waves indicates pure left-lateral strike-slip motion on a vertical fault striking N40°W consistent with the surface trend of the Xianshuihe fault. Two major ruptures are suggested for this source, with a total moment of 1.3 ×1026 dyne-cm. The 1973 event occurred about 65 km northwest of the 1981 event and ruptured about 90 km bilaterally along the fault. The body-wave synthetics indicate three main ruptures during faulting within 43 sec, with a total moment of 1.8 ×1027 dyne-cm. The mechanisms are similar to the 1981 event, and the average slip is determined to be 3.8 m. The largest aftershock (Ms = 5.9) occurred 1 day after the main event with a normal-fault mechanism striking almost perpendicular to the surface breakage. The 1967 event occurred at the northwestern end of the fault zone, with a strike of N65°E. It had a nearly normalfault mechanism with a seismic moment of 4.5 ×1025 dyne-cm. The largest aftershock (Ms = 5.1) occurred 7 hr later with a similar focal mechanism. The primary faulting along the Xianshuihe fault is left-lateral strike-slip, but the normal faulting with strike direction about perpendicular to the Xianshuihe fault trace is common, especially in the northwestern segment. The faulting pattern in this region is consistent with the regional stress field caused by the India-Tibet collision. The normal event which is not on the major fault seems to have more frequent foreshocks and aftershocks than those on the main fault.

scholarly journals Interseismic Slip and Coupling along the Haiyuan Fault Zone Constrained by InSAR and GPS Measurements

2021 ◽  
Vol 13 (16) ◽  
pp. 3333
Author(s):  
Xin Qiao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Dezheng Zhao ◽  
Lian Liu
Keyword(s):  
Fault Zone ◽  
Large Strain ◽  
Slip Rate ◽  
Strain Accumulation ◽  
Near Surface ◽  
Envisat Asar ◽  
Current State ◽  
Surface Creep ◽  
Tectonic Boundary

The Haiyuan fault zone is an important tectonic boundary and strong seismic activity belt in northeastern Tibet, but no major earthquake has occurred in the past ∼100 years, since the Haiyuan M8.5 event in 1920. The current state of strain accumulation and seismic potential along the fault zone have attracted significant attention. In this study, we obtained the interseismic deformation field along the Haiyuan fault zone using Envisat/ASAR data in the period 2003–2010, and inverted fault kinematic parameters including the long-term slip rate, locking degree and slip deficit distribution based on InSAR and GPS individually and jointly. The results show that there is near-surface creep in the Laohushan segment of about 19 km. The locking degree changes significantly along the strike with the western part reaching 17 km and the eastern part of 3–7 km. The long-term slip rate gradually decreases from west 4.7 mm/yr to east 2.0 mm/yr. As such, there is large strain accumulation along the western part of the fault and shallow creep along the Laohushan segment; while in the eastern section, the degree of strain accumulation is low, which suggests the rupture segments of the 1920 earthquake may have been not completely relocked.

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