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Decadal Seismicity before Great Earthquakes—Strike-Slip Faults and Plate Interiors: Major asperities and Low-Coupling Zones

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International Journal of Geosciences 2021年第9期12卷 784-833页

作者： Lynn R. Sykes Lamont-Doherty Earth Observatory of Columbia University Palisades New York USA

Decadal forerunning seismic activity is examined for very large, shallow earthquakes along strike-slip and intraplate faults of the world. It includes forerunning shocks of magnitude Mw ≥ 5.0 for 21 mainshocks of Mw 7.5 to 8.6 from 1989 to 2020. Much forerunning activity occurred at what are interpreted to be smaller asperities along the peripheries of the rupture zones of great mainshocks at transform faults and subduction zones. Several great asperities as ascertained from forerunning activity agree with the areas of high seismic slip as determined by others using geodetic, mapping of surface faulting, and finite-source seismic modeling. The zones of high slip in many great earthquakes were nearly quiescent beforehand and are identified as the sites of great asperities. Asperities are strong, well-coupled portions of plate interfaces. Different patterns of forerunning activity on time scales of up to 45 years are attributed to the sizes and spacing of asperities (or lack of). This permits at least some great asperities along transform faults to be mapped decades before they rupture in great shocks. Rupture zones of many great mainshocks along transform faults are bordered either along strike, at depth or regionally by zones of lower plate coupling including either fault creep forerunning activity, aftershocks and/or slow-slip events. Forerunning activity to transforms in continental areas is more widespread spatially than that adjacent to oceanic transforms. The parts of the San Andreas fault themselves that ruptured in great California earthquakes during 1812, 1857 and 1906 have been very quiet since 1920;moderate to large shocks have been concentrated on their peripheries. The intraplate shocks studied, however, e

关键词： Earthquakes Strike-Slip Faults Transform Faults Intraplate Prediction Plate Coupling asperities

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Decadal Seismicity Prior to Great Earthquakes at Subduction Zones: Roles of Major asperities and Low-Coupling Zones

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International Journal of Geosciences 2021年第9期12卷 845-926页

作者： Lynn R. Sykes Lamont-Doherty Earth Observatory of Columbia University Palisades New York USA

Decadal forerunning seismic activity of magnitude Mw ≥ 5.0 is mapped for all 45 mainshocks of Mw 7.7 to 9.1 at subduction zones of the world from 1993 to mid 2020. The zones of high slip in nearly all great earthquakes were nearly quiescent beforehand and are identified as the sites of great asperities and zones of strong seismic coupling. Much forerunning activity occurred at smaller asperities along the peripheries of the rupture zones of many great and giant mainshocks. Those sizes of great asperities as ascertained from forerunning activity generally agree with the areas of high seismic slip as determined by others from geodetic and tide-gauge data and finite-source seismic modeling. asperities are strong, well-coupled portions of plate interfaces. Different patterns of forerunning activity on time scales of about 5 to 45 years are attributed to either the sizes and spacing of asperities (or lack of). This permits many great asperities to be mapped decades before they rupture in great and giant shocks. Several poorly coupled subduction zones such as Java, Lesser Sunda, Marianas, Tonga and Kermadec are characterized by few great thrust earthquakes and little, in any forerunning activity. Rupture zones of many great and giant earthquakes are bordered either along strike, updip, or downdip by zones of lower plate coupling. Several bordering regions were sites of forerunning activity, aftershocks, and slow-slip events. The detection of forerunning and precursory activities of various kinds should be sought on the peripheries of great asperities as well as within zones of high co-seismic slip.

关键词： Earthquakes Subduction Prediction Plate Coupling asperities

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Dual threshold search method for asperity boundary determination based on geodetic and seismic catalog data

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Geodesy and Geodynamics 2022年第4期13卷 301-310页

作者： Xiaohang Wang Zhongzheng Zhou Caijun Xu Yangmao Wen Hu Liu School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Key Laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan UniversityWuhan 430079China Key Laboratory of Geophysical Geodesy Ministry of Natural ResourcesWuhan UniversityWuhan 430079China

As an important model for explaining the seismic rupture mode,the asperity model plays an important role in studying the stress accumulation of faults and the location of earthquake *** Qilian-Haiyuan fault as an example,this paper combines geodetic method and b-value method to propose a multi-source observation data fusion detection method that accurately determines the asperity boundary named dual threshold search *** method is based on the criterion that the b-value asperity boundary should be most consistent with the slip deficit rate asperity *** the optimal threshold combination of slip deficit rate and b-value is obtained through threshold search,which can be used to determine the boundary of the *** on this method,the study finds that there are four potential asperities on the Qilian-Haiyuan fault:two asperities(A1 and A2)are on the Tuolaishan segment and the other two asperities(B and C)are on Lenglongling segment and Jinqianghe segment,*** them,the lengths of asperities A1 and A2 on Tuolaishan segment are 17.0 km and 64.8 km,*** the lower boundaries are 5.5 km and 15.5 km,respectively;The length of asperity B on Lenglongling segment is 70.7 km,and the lower boundary is 10.2 *** length of asperity C on Jinqianghe segment is 42.3 km,and the lower boundary is 8.3 km.

关键词： GPS Earthquake catalog Dual threshold search method asperities Haiyuan fault

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A roughness parameter considering joint material properties and peak shear strength model for rock joints

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International Journal of Mining Science and Technology 2021年第3期31卷 413-420页

作者： Liren Ban Weisheng Du Tianwei Jin Chengzhi Qi Xiaozhao Li School of Civil and Transportation Engineering Beijing University of Civil Engineering and ArchitectureBeijing 100044China Deep Mining and Rock Burst Research Institute China Coal Research InstituteBeijing 100013China State Key Laboratory of Coal Mining and Clean Utilization China Coal Research InstituteBeijing 100013China

This study aims at proposing a reasonable roughness parameter that can reflect the peak shear strength(PSS)of rock ***,the contribution of the asperities with different apparent dip angles to shear strength is *** the shear strength of the entire joint asperities is *** results showed that the PSS of the entire joint asperities is proportional to a key parameter hs,which is related to the geometric character of the joint surface and the joint material *** parameter hsis taken as the new roughness parameter,and it is reasonable to associate the PSS with the geometric characteristics of the joint *** on the new roughness parameter and shear test results of 20 sets of joint specimens,a new PSS model for rock joints is *** new model is validated with the artificial joints in this paper and real rock joints in published *** showed that it is suitable for different types of rock joints except for gneiss *** new model has the form of the Mohr-Coulomb model,which can directly reflect the relationship between the 3 D roughness parameters and the peak dilation angle.

关键词： Roughness Joint material properties Rock joints Peak shear strength asperities

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Elastoplastic Contact Mechanics Model of Rough Surface Based on Fractal Theory

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Chinese Journal of Mechanical Engineering 2017年第1期30卷 207-215页

作者： YUAN Yuan GAN Li LIU Kai YANG Xiaohui School of Mechanical and Precision Instrument Engineering Xi'an University of Technology School of Mechanical Engineering Xi'an Jiaotong University

Because the result of the MB fractal model contradicts with the classical contact mechanics, a revised elastoplastic contact model of a single asperity is developed based on fractal theory. The critical areas of a single asperity are scale dependent, with an increase in the contact load and contact area, a transition from elastic, elastoplastic to full plastic deformation takes place in this order. In considering the size distribution function, analytic expression between the total contact load and the real contact area on the contact surface is obtained. The elastic, elastoplastic and full plastic contact load are obtained by the critical elastic contact area of the biggest asperity and maximun contact area of a single asperity. The results show that a rough surface is firstly in elastic deformation. As the load increases, elastoplastic or full plastic deformation takes place. For constant characteristic length scale G, the slope of load-area relation is proportional to fractal dimension D. For constant fractal dimension D, the slope of load-area relation is inversely proportional to G. For constant D and G, the slope of load-area relation is inversely proportional to property of the material ~b, namely with the same load, the material of rough surface is softer, and the total contact area is larger. The contact mechanics model provides a foundation for study of the friction, wear and seal performance of rough surfaces.

关键词： rough surfaces asperities fractal theory contact model

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Study on Potential Strong Earthquake Risks Around the Mabian Area,Southern Sichuan

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Earthquake Research in China 2010年第4期24卷 478-490页

作者： Yi Guixi Wen Xueze Zhang Zhiwei Long Feng Ruan Xiang Du Fang Earthquake Administration of Sichuan Province Chengdu 610041 China Chengdu University of Technology Chengdu 610059 China

Based on seismic data from the regional network for the last 34 years, we analyzed the present fault behavior of major fault zones around the Mabian area, southern Sichuan, and identified the risky fault-segments for potential future. The method of analysis is a combination of activity background of historical strong earthquakes mainly show ~ （ 1 ） The spatial distribution of b-values strong and large earthquakes in the spatial distribution of b-values with and current seismicity. Our results indicates significant heterogeneity in the studied area, which reflects the spatial difference of cumulative stress levels along various fault zones and segments. （2） Three anomalously low b-value areas with different dimensions were identified along the Mabian-Yanjin fault zone. These anomalies can be asperities under relatively high cumulated stress levels. Two asperities are located in the north of Mabian county, in Lidian town in western Muchuan county, and near Yanjin at the south end of the fault zone. These two areas represent potential large earthquake seismogenic sites around the Mabian area in the near future. Besides them, the third relatively smaller asperity is identified at southern Suijiang, as another potential strong- earthquake source. （3） An asperity along the southwestern segment of the Longquanshan fault zone indicates the site of potential moderate-to-strong earthquakes. （4） The asperity along the segment between Huangmu town in Hanyuan county and Longchi town in Emeishan city on Jinkouhe-Meigu fault has potential for a moderate-strong earthquake.

关键词： Spatial distribution of b-values asperities Mabian area Strong earthquake risk

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Experimental and theoretical study on nonlinear characteristics of tangential stiffness

Experimental and theoretical study on nonlinear characterist...

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2023智能制造与机械动力学学术大会

作者： Shenghao Lu Jingyu Han Shaoze Yan School of Mechanical Engineering Tsinghua University

The research on tangential stiffness of joint surface in mechanical system is of great *** the traditional contact model of tangential stiffness of joint surface,less attention is paid to the nonlinear relationship between tangential stiffness and *** this paper,the tangential stiffness measurement experiments of PMMA and 304 steel are carried out,and the relationship among the tangential stiffness of joint surface,real contact area and normal load is studied from the experiments,and the results of experiments are compared with the simulation results of the *** simulation results of the model are in good agreement with the experiments.

关键词： MB model Spherical surface to plane contact surface contact asperities Tangential stiffness Nonlinearity

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