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Viscoelastic representation of surface waves in patchy saturated poroelastic media

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Earthquake Science 2014年第4期27卷 421-431页

作者： yu zhang Yixian Xu Jianghai Xia Ping Ping Shuangxi zhang School of geodesy and Geomatics Wuhan University Key Laboratory of Geospace Environment and geodesy Ministry of Education institute of geophysics and Geomatics China University of Geosciences State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Subsurface Imaging and Sensing Laboratory China University of Geosciences

Wave-induced flow is observed as the domi- nated factor for P wave propagation at seismic frequencies. This mechanism has a mesoscopic scale nature. The inhomogeneous unsaturated patches are regarded larger than the pore size, but smaller than the wavelength. Surface wave, e.g., Rayleigh wave, which propagates along the free surface, generated by the interfering of body waves is also affected by the mesoscopic loss mechanisms. Recent studies have reported that the effect of the wave-induced flow in wave propagation shows a relaxation behavior. Viscoelastic equivalent relaxation function associated with the wave mode can describe the kinetic nature of the attenuation. In this paper, the equivalent viscoelastic relaxation functions are extended to take into account the free surface for the Rayleigh surface wave propagation inpatchy saturated poroelastic media. Numerical results for the frequency-dependent velocity and attenuation and the time-dependent dynamical responses for the equivalent Rayleigh surface wave propagation along an interface between vacuum and patchy saturated porous media are reported in the low-frequency range （0.1-1,000 Hz）. The results show that the dispersion and attenuation and kinetic characteristics of the mesoscopic loss effect for the surface wave can be effectively represented in the equivalent vis- coelastic media. The simulation of surface wave propaga- tion within mesoscopic patches requires solving Blot＇s differential equations in very small grid spaces, involving the conversion of the fast P wave energy diffusion into the Blot slow wave. This procedure requires a very large amount of computer consumption. An efficient equivalent approach for this patchy saturated poroelastic media shows a more convenient way to solve the single phase visco- elastic differential equations.

关键词： Surface wave Patchy saturation Viscoelastic equivalence Approximation

Characteristic Analysis of Anomalies of Strong Earthquakes along the Tancheng-Lujiang Fault Zone and Both Its Sides

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Earthquake Research in china 2015年第4期29卷 498-513页

作者： Li Jianyong Li Jie zhang Rui Li yu Han yufei Wang Tan National Earthquake Infrastructure Service State Key Laboratory of geodesy and Earth's Dynamics Institute of Geodesy and GeophysicsChinese Academy of Sciences Earthquake Administration of Shandong Province

This article made a systematic statistical analysis on the duration,spatial distribution,form,range,type and reliability of precursory anomalies based on the observations of precursors of 2. moderate-strong earthquakes occurring along the Tancheng-Lujiang fault zone and its bilateral areas in Shandong,Liaoning,Hebei,Jiangsu and Jiangxi Provinces in the period from 1966 to 2.05. Results show that:( 1) For M7. 0 and M6. 0earthquakes,med-term abnormities are the greatest in number,short-term abnormities come second,and imminent anomalies are the least. For M5. 0 earthquakes,short-term abnormities are often the most in number,imminent anomalies come second,and the med-term ones are the least.( 2. Precursory anomalies are periodical,part of the med and short-term anomalies are shown as short-term and imminent anomalies during their development.( 3) The development of precursor shows quasi-synchronism; the closer to earthquake occurrence time,the more turning changes of anomalies will appear.( 4)Anomalies mainly occur within an epicenter distance of 100 km, showing a relative concentrated distribution in space,and the shorter the distance to epicenter,the higher the anomaly station / item rate.( 5) The spatial distribution of anomalies is relatively correlated to the strike of structures,having a good consistency with the structure.( 6)There is no significant correlation between duration of abnormities and the epicenter distance.( 7) The higher the magnitude of the earthquake,the greater the amplitude of the abnormities measured with the same observation approach.( 8) In terms of the itemsof the observations,fluid abnormities are the greatest in number,followed by deformation and electromagnetism observations.( 9) For all observation items,med and short-term abnormities make up the majority and short-term and imminent anomalies the minority.( 10) In fluid,deformation and electromagnetism observations,fairly reliable anomalies are about double the number of reliable anomal

关键词： Tancheng-Lujiang fault zone Characteristics of precursory anomaly Fluid anomaly Deformation anomaly Electromagnetic anomaly

Spatial patterns and driving forces of land use change in china during the early 2.st century

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Journal of Geographical Sciences 2010年第4期20卷 483-494页

作者： LIU Jiyuan zhang Zengxiang XU Xinliang KUANG Wenhui ZHOU Wancun zhang Shuwen LI Rendong YAN Changzhen yu Dongsheng WU Shixin JIANG Nan institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China institute of Remote Sensing Applications CAS Beijing 100101 China Chengdu institute of Mountain Hazards and Environment CAS Chengdu 610041 China Northeast institute of Geography and Agroecology CAS Changchun 130012 China wuhan institute of {2. and geophysics CAS Wuhan 430077 China Cold and Arid Regions Environmental and Engineering Research institute CAS Lanzhou 730000 China Nanjing institute of Soil Science CAS Nanjing 210008 China Xinjiang institute of Ecology and Geography CAS Urumqi 830011 China Nanjing institute of Geography and Limnology CAS Nanjing 210008 China

Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science （LCS） in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in china in the early 2. st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern china. The development of oasis agriculture in Northwest china and the reclamation in Northeast china led to a slight increase in arable land area in northern china. Due to the ＂Grain for Green＂ policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of ＂Western Development＂, ＂Revitalization of Northeast＂, coupled with rapidly economic development during this period.

关键词： land use change spatial pattern driving forces the early 2.st century china

Spatiotemporal characteristics, patterns, and causes of land-use changes in china since the late 1980s

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Journal of Geographical Sciences 2014年第2期24卷 195-210页

作者： LIU Jiyuan KUANG Wenhui zhang Zengxiang XU Xinliang QIN yuanwei NING Jia ZHOU Wancun zhang Shuwen LI Rendong YAN Changzhe WU Shixin SHI Xuezheng JIANG Nan yu Dongsheng PAN Xianzhang CHI Wenfeng institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China institute of Remote Sensing and Digital Earth CAS Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China Chengdu institute of Mountain Hazards and Environment CAS Chengdu 610041 China Northeast institute of Geography and Agricultural Ecology CAS Changchun 130012 China wuhan institute of {2. and geophysics CAS Wuhan 430077 China Cold and Arid Regions Environmental and Engineering Research institute CAS Lanzhou 730000 China Xinjiang institute of Ecology and Geography CAS Urumqi 830011 China institute of Soil Science CAS Nanjing 210008 China Nanjing institute of Geography and Limnology CAS Nanjing 210008 China

Land-use/land-cover changes （LUCCs） have links to both human and nature inter- actions. china＇s Land-Use/cover Datasets （CLUDs） were updated regularly at 5-year inter- vals from the late 1980s to 2.10, with standard procedures based on Landsat TM／ETM＋ im- ages. A land-use dynamic regionalization method was proposed to analyze major land-use conversions. The spatiotemporal characteristics, differences, and causes of land-use changes at a national scale were then examined. The main findings are summarized as fol- lows. Land-use changes （LUCs） across china indicated a significant variation in spatial and temporal characteristics in the last 2. years （1990-2.10）. The area of cropland change de- creased in the south and increased in the north, but the total area remained almost un- changed. The reclaimed cropland was shifted from the northeast to the northwest. The built-up lands expanded rapidly, were mainly distributed in the east, and gradually spread out to central and western china. Woodland decreased first, and then increased, but desert area was the opposite. Grassland continued decreasing. Different spatial patterns of LUC in china were found between the late 2.th century and the early 2.st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included （1） an accelerated expansion of built-up land in the Huang-Huai-Hai region, the southeastern coastal areas, the midstream area of the Yangtze River, and the Sichuan Basin; （2. shifted land reclamation in the north from northeast china and eastern Inner Mongolia to the oasis agricultural areas in northwest china; （3） continuous transformation from rain-fed farmlands in northeast china to paddy fields; and （4） effective- ness of the ＂Grain for Green＂ project in the southern agricultural-pastoral ecotones of Inner Mongolia, the Loess Plateau, and southwestern mountainous areas. In the last two decades, although climate

关键词： satellite remote sensing land-use change characteristics spatial pattern china

基于GNSS和InSAR约束的2.2.年玛多M_(S)7.4地震同震滑动分布及应用

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地球物理学报 2022年第2期65卷 509-522页

作者：余鹏飞熊维陈威乔学军王迪晋刘刚赵斌聂兆生李瑜赵利江张怀中国地震局地震研究所武汉430071 中国地震局地震大地测量重点实验室武汉430071 湖北省地震局武汉430071 中国地震局地球物理研究所北京100081 中国地震台网中心北京100045 青海省基础测绘院西宁810001

2.2.年5月2.日青海省果洛藏族自治州玛多县发生M_(S)7.4地震,震中位于青藏高原中部的巴颜喀拉块体,这是近2.多年来在巴颜喀拉块体周边发生8次M≥7级强震后,块体内部的一次强震,也是汶川地震以来中国大陆发生的最大一次地震,因此该地震... 详细信息

2.2.年5月2.日青海省果洛藏族自治州玛多县发生M_(S)7.4地震,震中位于青藏高原中部的巴颜喀拉块体,这是近2.多年来在巴颜喀拉块体周边发生8次M≥7级强震后,块体内部的一次强震,也是汶川地震以来中国大陆发生的最大一次地震,因此该地震的成因及周边地区未来的地震危险性值得重点关注.本文利用震后及时获取的39个近场流动GNSS观测,联合61个GNSS连续观测、Sentinel-1和ALOS-2.InSAR观测获取了本次地震精细的同震形变场,以此为约束,基于均匀弹性半无限位错模型,反演了发震断层的滑动分布,并计算了同震库仑应力变化.GNSS水平同震形变十分显著,断层南北两侧的GNSS点位,最大水平形变分别达0.7 m和-1.2.m,距震中2.0 km的测点仍有1 cm左右的同震形变.Sentinel-1和ALOS-2.升降轨InSAR同震形变场显示此次地震造成了约160 km长的地表破裂,最大视线向形变分别达0.9 m和1.2.m.同震滑动分布模型显示,发震断层由主段和次段组成,长度分别为170 km和2. km,主段倾向北,倾角85°,平均滑动角为-4.36°,表明玛多地震是一次典型的走滑型地震.次段倾向南,倾角68°,平均滑动角为-11.84°.地震破裂主要集中在0~15 km深度范围,最大滑动量为4.4 m,对应深度6.97 km.反演给出的矩震量为1.61×10^(2.)N·m,对应矩震级M_(W)7.4.主发震断层上存在4个凹凸体,玛多地震是一次不对称双侧破裂事件.结合余震精定位、野外调查及地质资料,我们认为主发震断裂为昆仑山口—江错断裂,东部的次级破裂与主破裂机制不同.同震库仑应力结果显示,东昆仑断裂玛沁段应力有所增加(>0.01 MPa),处于应力加载状态,未来发生强震的危险性较高.

关键词： 2.2.玛多地震 GNSS InSAR 同震形变滑动分布

维普期刊数据库博看期刊

东昆仑断裂滑动速率变化及其对2.17年九寨沟地震的应力加载

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地球物理学报 2019年第3期62卷 912-922页

作者：李琦谭凯赵斌张彩红鲁小飞王东振余建胜中国地震局地震研究所中国地震局地震大地测量重点实验室武汉430071

为了解东昆仑断裂活动对2.17年8月8日九寨沟M_S7.0地震的影响,本文选取1999—2.07年、2.13—2.17年GPS速度场作为约束,基于块体-位错模型反演计算东昆仑断裂两个时间段的块体运动速率、断裂滑动速率和滑动亏损率,并进一步研究青藏高原... 详细信息

为了解东昆仑断裂活动对2.17年8月8日九寨沟M_S7.0地震的影响,本文选取1999—2.07年、2.13—2.17年GPS速度场作为约束,基于块体-位错模型反演计算东昆仑断裂两个时间段的块体运动速率、断裂滑动速率和滑动亏损率,并进一步研究青藏高原东缘最大剪应变率场和九寨沟震区的震间库仑应力累积速率.结果显示,东昆仑断裂中西段左旋走滑速率较高,东段走滑速率较低,自西向东逐步递减,存在明显的梯度.在两个时间段,阿坝块体刚性运动的方向顺时针偏转0.2.,运动速率由12.2.mm·a^(-1)增大到15.96mm·a^(-1);东昆仑断裂左旋走滑速率升高,其中西段较为明显(升高约1.2.0.3mm·a^(-1));东昆仑断裂东段闭锁深度和闭锁程度增加;2.13—2.17年,东昆仑断裂滑动引起的九寨沟震区库仑应力累积速率是1999—2.07年的3倍,最大剪应变率也明显升高.因此本文认为:2.08年汶川地震和2.13年芦山地震后,龙门山断裂部分解锁,阿坝地块活动性增强,东昆仑断裂滑动速率增大,导致九寨沟震区库仑应力加载速率增加,加速了九寨沟地震的孕育过程.

关键词：九寨沟地震东昆仑断裂滑动速率震间库仑应力累积速率