Textual research of 1219 A.D. Guyuan earthquake in Ningxia Hui autonomous region, China and discussion on its causative structure

Yuan, Daoyang; Zhong-sheng, Lei; Zhang, Junling; Bai-chi, Liu; Liang, Mingjian

doi:10.1007/s11589-008-0652-z

Cited by 4 publications

(5 citation statements)

References 1 publication

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“…Significantly low b values are observed along the MXSF fault, and one earthquake with a magnitude of 5.0 has happened since 1970 ( Figure 10 ). GPS data show a gradual increase in the reverse slip from the north to the middle strand of MXSF [ 64 ]; this may have caused the lower b value along the middle part of MXSF. While joining with ZLHF northward, it changed into a higher b value, and a magnitudeof 6.1 earthquake happened at the high- and low- b- value transition zones.…”

Section: Discussionmentioning

confidence: 99%

Spatial Heterogeneity of b Values in Northeastern Tibetan Plateau and Its Interpretation

Hu,

Han,

Wang

et al. 2024

Entropy

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The northeastern margin of the Tibetan Plateau (NE Tibetan Plateau) exhibits active geological structures and has experienced multiple strong earthquakes, with M ≥ 7, throughout history. Particularly noteworthy is the 1920 M81/2 earthquake in the Haiyuan region that occurred a century ago and is documented as one of the deadliest earthquakes. Consequently, analyzing seismic risks in the northeastern margin of the Tibetan Plateau holds significant importance. The b value, a crucial parameter for seismic activity, plays a pivotal role in seismic hazard analyses. This study calculates the spatial b values in this region based on earthquake catalogs since 1970. The study area encompasses several major active faults, and due to variations in b values across different fault types, traditional grid-search methods may introduce significant errors in calculating the spatial b value within complex fault systems. To address this, we employed the hierarchical space–time point–process (HIST-PPM) method proposed by Ogata. This method avoids partitioning earthquake samples, optimizes parameters using Akaike’s Bayesian Information Criterion (ABIC) with entropy maximization, and theoretically allows for a higher spatial resolution and more accurate b value calculations. The results indicate a high spatial heterogeneity in b values within the study area. The northwestern and southeastern regions exhibit higher b values. Along the Haiyuan fault zone, the central rupture zone of the Haiyuan earthquake has relatively higher b values than other regions of this fault zone, which is possibly related to the sufficient release of stress during the main rupture of the Haiyuan earthquake. The b values vary from high in the west to low in the east along the Zhongwei fault. On the West Qinling fault zone, the epicenter of the recent Minxian–Zhangxian earthquake is associated with a low b value. In general, regions with low b values correspond well to areas with moderate–strong seismic events in the past 50 years. The spatial differences in b values may reflect variances in seismic hazards among fault zones and regions within the same fault zone.

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Section: Discussionmentioning

confidence: 99%

Spatial Heterogeneity of b Values in Northeastern Tibetan Plateau and Its Interpretation

Hu,

Han,

Wang

et al. 2024

Entropy

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“…The LPSF is located in the boundary zone between the Lanzhou block and the ORDOS block, which is a thrust fault and has left-lateral strike-slip characteristics [26]. Three earthquakes with a magnitude of above seven have occurred from 1200 to 1700 [28], and the earthquake risk should not be underestimated in the LPSF. The GGBJF is connected with the LPSF to the north and the northern edge of the West Qinling Fault in the south, which trends NNW (Figure 1).…”

Section: Regional Tectonic Backgroundmentioning

confidence: 99%

A Crustal Deformation Pattern on the Northeastern Margin of the Tibetan Plateau Derived from GPS Observations

2023

Remote Sensing

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The northeastern margin is a natural experimental field for studying crustal extrusion and expansion mechanisms. The accurate crustal deformation pattern is a key point in the analysis of regional deformation mechanisms and seismic hazard research and judgment. In this paper, the present-day GPS velocity field on the northeastern margin of the Tibetan Plateau was obtained from encrypted GPS observations around the Haiyuan–Liupanshan fault zone, combined with GPS observations on the northeastern margin of the Tibetan Plateau from 2010 to 2020. Firstly, we divided the study area into three relatively independent blocks: the ORDOS block, Alxa block, and Lanzhou block; secondly, the accurate fault distribution of the Haiyuan–Liupanshan fault zone was taken into account to obtain the optimal inversion model; finally, using the block and fault back-slip dislocation model, the inversion obtained the slip rate distribution, locking depth, and slip deficit rate of each fault. The results indicate that the Laohushan Fault and Haiyuan Fault are dominated by the left-lateral strike-slip, while the Liupanshan Fault is dominated by the thrust dip-slip, and the Guguan–Baoji Fault has both left-lateral strike-slip and thrust dip-slip components. The maximum locking depths of the Laohushan Fault, Haiyuan Fault, Liupanshan Fault, and Guguan–Baoji Fault are 5 km, 13 km, 15 km, and 10 km, respectively, and the locking of the Haiyuan Fault is strong in the middle section and weak in the eastern and western section. The Haiyuan Fault is still in the post-earthquake stress adjustment stage. The slip deficit rate decays from 3.6 mm/yr to 1.8 mm/yr from west to east along the fault zone. Combined with geological and historical seismic data, the results suggest that the mid-long-term seismic risk in the Liupanshan Fault is high.

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“…Recently, with the occurrence of several major earthquakes on the western, eastern, and southern boundaries of the Qinghai-Tibet plateau, particularly after the M8.0 Wenchuan earthquake in 2008, significant deformation and gravitational changes occurred in the same area along the North-South seismic zone. The hazard of major earthquakes in the future has attracted significant attention from researchers [41,42]. This area has the tectonic conditions for the occurrence of strong earthquakes or even large earthquakes.…”

Section: Tectonic Dynamics Environment Of the Lpsfzmentioning

confidence: 99%

“…CO 2 is the second most abundant magmatic gas after H 2 O and is the main gas investigated during diffuse degassing studies as well as at many permanent stations using the accumulation chamber method (ACM) [34,35]. Soil gas anomalies are usually complex because they are subject to multiple influences (atmospheric, biogenic, organic, and from the deep crust and mantle [23,25,36,37]) and occasionally, their relationships with seismic events can be ambiguous [4,7,38,39]. Accordingly, if soil gas observations in fault zones become a useful method of fault activity assessment and seismic forecasting, further analysis of their relationships is required and the source identification of soil gas in the seismically active areas is a prerequisite.…”

Section: Introductionmentioning

confidence: 99%

Geochemical Characteristics of Soil Gas and Strong Seismic Hazard Potential in the Liupanshan Fault Zone (LPSFZ)

Zhou

Hui

et al. 2020

Geofluids

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Eight soil gas measurements were performed in the Liupanshan fault zone (LPSFZ) to observe the concentration and flux of soil gas radon (Rn) and CO2 in October 2017 and October 2018. By combining the historical strong earthquake background and modern seismic activity of the fault zone, the relation between the geochemical distribution characteristics of soil gas and the seismicity of the fault zone was studied herein. Furthermore, the strong seismic hazard potential of the fault zone was discussed. Results show that the concentration of soil gas Rn and CO2 considerably varies in the northern segment of the LPSFZ and is relatively stable in the southern segment. The spatial distribution of the concentration intensity and flux is strong in the north and weak in the south. However, the southern segment of the LPSFZ has a seismic gap that has not been ruptured by strong earthquakes with Ms ≥ 6.5 for the last 1400 years, whereas the seismic activity in the northern segment is relatively frequent, indicating that the fault zone locking degree of the southern segment is higher than that of the northern segment. This observation is completely consistent with the geochemical characteristic distribution of soil gas. Therefore, the southern segment of the LPSFZ should be considered a hazardous segment, where major or strong earthquakes can occur in the future.

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Textual research of 1219 A.D. Guyuan earthquake in Ningxia Hui autonomous region, China and discussion on its causative structure

Cited by 4 publications

References 1 publication

Spatial Heterogeneity of b Values in Northeastern Tibetan Plateau and Its Interpretation

Spatial Heterogeneity of b Values in Northeastern Tibetan Plateau and Its Interpretation

A Crustal Deformation Pattern on the Northeastern Margin of the Tibetan Plateau Derived from GPS Observations

Geochemical Characteristics of Soil Gas and Strong Seismic Hazard Potential in the Liupanshan Fault Zone (LPSFZ)

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