共查询到20条相似文献，搜索用时 93 毫秒
1.
引入t检验方法对中国1975年以后的30例水库地震震例进行了定量评价。评价中首先分别统计水库蓄水前、后水库区水域线20 km范围内的地震年频度作为统计检验的2个样本,然后通过F检验和t检验方法对2个样本的标准差和均值是否存在显著差异进行检验,根据标准差和均值检验结果判定水库蓄水是否诱发了地震活动。结果显示:①如果水库蓄水前后库区地震年频度标准差和平均值均发生了显著变化,则水库蓄水诱发了地震。②如果水库蓄水前后库区地震年频度标准差无明显变化,但地震年频度平均值变化显著,则水库蓄水可能诱发了地震。③如果水库蓄水前后库区地震年频度标准差和平均值均无明显变化,则水库蓄水没有诱发地震。 相似文献
2.
应用2013年甘肃岷县漳县M_s6.6地震前263天及震后9天的平凉台观测数据研究了该台地电场在时间域、频率域内的变化,得到:(1)在岷县漳县M_s6.6地震以及在2013年四川芦山M_s7.0地震前平凉台地电场观测记录了显著的自然电场变化,在近距离的岷县漳县地震前自然电场变化更显著,异常变化的持续时间长;(2)平凉台地电场最大熵功率谱密度在4月20日四川芦山地震前发生连续增大的现象,并持续到甘肃岷县漳县地震后。最后讨论了本次地震地电场极低频成分异常变化的机理。 相似文献
3.
利用数据跟踪分析信息库，提取2017年8月9日精河6.6级地震前3个月，距震中500 km范围内的观测数据跟踪分析记录，对与地震相关的不明原因事件进行分析讨论。结果表明：精河地震发生前，温泉地震台水平摆、精河地震台水平摆、博乐32井水位出现不明原因的疑似前兆异常变化，地震结束后逐渐恢复正常。巴仑台地震台分量应变在此次地震前也出现不明原因变化，但地震结束后异常持续变化，需后续重点跟踪分析。 相似文献
4.
5.
从分析地震活动性参数变化特征的角度出发,结合实际的地震活动观测资料,对张北６．２级地震前河北省及邻区地震活动性参数的变化,地震序列的衰减特征进行了分析,结果表明张北６．２级地震前在震源区附近１００ｋｍ和大范围地震活动性参数有长、中、短期的异常变化。张北６．２级地震强余震前地震活动性参数有短、临变化。 相似文献
6.
地电阻率各向异性度的动态演化与汶川地震孕育过程 总被引：1，自引：1，他引：0
方炜 《地震地磁观测与研究》2009,30(6):21-26
汶川地震后,利用中国地震前兆观测台网的资料,对地震前后地电阻率各向异性度进行了分析。结果表明,汶川地震前,我国西部地区,特别是临近四川地区台站地电阻率各向异性度的变化较为明显。在震前5～6年内,西部地区部分台站地电阻率各向异性度开始出现准同步下降变化,震前2年内,这种下降变化有加速的迹象,并且下降幅度随着震中距离的减小而增大,汶川地震后,部分台站的异常形态开始恢复。经分析,我们认为这种变化可能与孕震区地下应力场调整有关。 相似文献
7.
本文利用龙陵地区自1958年至1983年进行的一、二等水准测量结果,对该区地震前、地震时和地震后的地面垂直运动情况进行了分析,发现在地震发生前十多年震中区周围自澜沧江向西已出现了一缓慢的抬升趋势,累计值达46毫米,特别在团田至龙陵区段内变化尤为突出。重力测量结果也出现明显减小,二种手段所获得的前兆现象是一致的。地震后八年,由于地下物质发生了新的调整,形变逐渐趋于平稳,重力变化与垂直形变正好与震前相反,呈现整体下沉,留下了震后永久形变的痕迹。作者认为该区的地震形变周期已接近结束,附近地区所出现的新的变化是另一周期的开始。总结这次龙陵地震的垂直形变和重力变化结果,其变化模式如下:膨胀(上升)——突变(震时)——收缩(下沉)——新的膨胀(上升)。 相似文献
8.
9.
本文使用了山东省和河南省地震台网部分台站的地震记录资料,计算了菏泽地震巢及附近地区1980—1985年的多台平均波速比和菏泽、梁山、嘉祥、邹县、泰安等台的单台波速比。分析结果表明:菏泽地震巢及附近地区的多台和单台波速比在1983年11月7日5.9级地震前均出现低值异常,且变化同步。主震前8个月波速比恢复。5.9级地震后,多台和单台波速比均在正常范围内变化。 相似文献
10.
《地震地磁观测与研究》2017,(1)
2013年7月22日甘肃岷县、漳县6.6级地震前,昔阳台SSQ-2I数字化石英水平摆倾斜仪于7月9日出现趋势性变化,通过对震前数据异常变化的特征进行异常判定,并利用前兆矢量图、多台资料对比分析、辅助测项对比分析、与后续发生的甘肃岷县、漳县4.0级地震震情数据变化对比分析等相关研究工作后认为本次昔阳台水平摆在甘肃定西6.6级地震前的数据异常变化与地震有一定的对应关系。 相似文献
11.
DInSAR measurements of ground deformation by sinkholes,mining subsidence,and landslides,Ebro River,Spain 总被引：1，自引：0，他引：1
Carmen Castañeda Francisco Gutiérrez Michele Manunta Jorge P. Galve 《地球表面变化过程与地形》2009,34(11):1562-1574
Differential Interferometric Synthetic Aperture Radar (DInSAR) has been applied to detect and measure ground deformation in a stretch of the Ebro River valley (Spain) excavated in salt‐bearing evaporites. The capability of the Small Baseline Subset (SBAS) DInSAR technique to detect ground displacement is analyzed comparing the DInSAR results with the available geomorphological information. The deformation map derived from 27 European Remote Sensing (ERS) satellite images covering more than five years provides sub‐centimeter displacement measurements in zones coinciding with known active sinkholes and landslides. Moreover the map provides the first account of mining subsidence in the area. The measured deformation rates reach 1·68 cm/y for the sinkholes, 0·80 cm/y for the landslides and 1·45 cm/y for the area affected by mining subsidence. The SBAS DInSAR technique provided deformation measurements in a small proportion (5–10%) of the known active sinkholes and landslides. This limitation is mainly due to the lack of coherence in agricultural areas, the spatial resolution of the deformation map (pixel size of 90 m), and the parallelism between the ERS satellite line of sight and the linear escarpment on which most of the landslides occur. Despite this, the interferometric technique provides valuable data that complement traditional geomorphological studies including the quantification of the deformation phenomena, the identification of mining subsidence otherwise only recognizable by geodetic methods, and the detection of creep deformation which might correspond to premonitory indicators of catastrophic sinkholes and landslides capable of causing the loss of lives. Detailed DInSAR studies combined with field data would be required to improve the analysis of each deformation area. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
12.
13.
Xuemei Cheng Shuyun Cao Junyu Li Zunpu Yu Yanlong Dong Meixia Lv Junlai Liu 《中国科学:地球科学(英文版)》2018,61(8):1023-1041
Diancangshan metamorphic massif is one of the four metamorphic massifs developed along the Ailaoshan-Red River strike-slip fault zone, Yunnan, China. It has experienced multi-stage metamorphism and deformation, especially since the late Oligocene it widely suffered high-temperature ductile shear deformation and exhumation of the metamorphic rocks from the deep crust to the shallow surface. Based on the previous research and geological field work, this paper presents a detailed study on deformation and metamorphism, and exhumation of deep metamorphic rocks within the Diancangshan metamorphic massif, especially focusing on the low-temperature overprinted retrogression metamorphism and deformation of mylonitic rocks. With the combinated experimental techniques of optical microscope, electron backscatter diffraction attachmented on field-emission scanning electron microscopy and cathodoluminescence, our contribution reports the microstructure, lattice preferred orientations of the deformed minerals, and the changes of mineral composition phases of the superposition low-temperature retrograde mylonites. All these results indicate that: (1) Diancangshan deep metamorphic rock has experienced early high-temperature left-lateral shear deformation and late extension with rapid exhumation, the low-temperature retrogression metamorphism and deformation overprinted the high-temperature metamorphism, and the high-temperature microstructure and texture are in part or entirely altered by subsequent low-temperature shearing; (2) the superposition of low-temperature deformation-metamorphism occurs at the ductile-brittle transition; and (3) the fluid is quite active during the syn-tectonic shearing overprinted low-temperature deformation and metamorphism. The dynamic recrystallization and/or fractures to micro-fractures result in the strongly fine-grained of the main minerals, and present strain localization in micro-domians, such as micro-shear zones in the mylonites. It is often accompanied by the decrease of rock strength and finally influences the rheology of the whole rock during further deformation and exhumation of the Diancangshan massif. 相似文献
14.
Soft‐sediment deformation occurs in ancient eolian dune deposits, but understanding its extent and the conditions and forces behind the deformation often remains elusive. Here we gain insight into the aerial extent and environmental conditions related to intense soft‐sediment deformation, based on an exceptional three dimensional (3D) exposure of eolian dune deposits and preserved geomorphic landscape expressions in the Jurassic Navajo Sandstone at White Pocket, Vermilion Cliffs National Monument, Arizona. Deformation features include elongate northeast trending decameter‐scale mounds and raised ridges cored by deformed and upturned eolian dune sets, overlain by a massive blanket sandstone with breccia blocks. The geomorphic mounds display ~40–60 m spacing, roughly perpendicular to the southerly paleoflow dune foreset directions. The geometry of the deformation is imaged by oblique aerial photography using cameras mounted on a remote control airplane and high resolution panoramas with a robotic camera mount. We interpret the exquisitely preserved deformation features as liquefaction‐induced ground failure, consistent with theoretical and laboratory studies of deformation in saturated sand. A shallow water table affected by differential dune loading facilitated lateral spreading and failure. The transition to steady‐state flow liquefaction near the top of the shallow water table destroyed original sedimentary structure, creating a massive sand blanket that entrained brecciated blocks ripped up during flow. The water‐pressurized, upwelled sediment created the mounds (a relief inversion). In underlying deformed dune sets, deformation was intense but sedimentary structure was not obliterated as deformation progressed from initial cyclic mobility to strain‐softening, but ceased prior to steady‐state flow liquefaction. The spatial extent, topographic relief, and intensity of dynamic deformation suggest an origin of strong ground motion driven by long‐duration surface waves of a large earthquake (> Mw 7–8), possibly related to back arc thrusting from Jurassic subduction of the Pacific plate under North America. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
15.
16.
Klaus Regenauer-Lieb David A. Yuen Florian Fusseis 《Pure and Applied Geophysics》2009,166(10-11):1885-1908
The total rate of rock deformation results from competing deformation processes, including ductile and brittle mechanisms. Particular deformation styles arise from the dominance of certain mechanisms over others at different ambient conditions. Surprisingly, rates of deformation in naturally deformed rocks are found to cluster around two extremes, representing coseismic slip rates or viscous creep rates. Classical rock mechanics is traditionally used to interpret these instabilities. These approaches consider the principle of conservation of energy. We propose to go one step further and introduce a nonlinear far-from-equilibrium thermodynamic approach in which the central and explicit role of entropy controls instabilities. We also show how this quantity might be calculated for complex crustal systems. This approach provides strain-rate partitioning for natural deformation processes occurring at rates in the order of 10-3 to 10-9 s-1. We discuss these processes using examples of landslides and ice quakes or glacial surges. We will then illustrate how the mechanical mechanisms derived from these near-surface processes can be applied to deformation near the base of the seismogenic crust, especially to the phenomenon of slow earthquakes. 相似文献
17.
《中国科学D辑(英文版)》2008,(Z2)
As is well known that many decollement layers were developed in the Longmenshan thrust belt,Si-chuan Basin,China. Through field investigation,explanation of seismic profiles and analysis of the balanced sections,we can divide the decollement zones into 3 categories: (1) the deep level decolle-ment zones,including the crust-mantle decollement layer,intracrustal decollement layer,and presinian basal decollement layer. The main structural styles of their deformation are the crust-mantle decoup-ling detachment deformation,the basal ductile shear deformation,etc.; (2) the middle level decollement zones,including the Cambrian-Ordovician decollement layer,the Silurian decollement layer,etc.,the main structural styles of their deformation are the isopachous fold,the angular fold,the saddle struc-ture,and the combination styles of them; and (3) the shallow level decollement zones,including the Xujiahe Formation decollement layer of Upper Triassic and the Jurassic decollement layers,the main structural styles of their deformation are the thrust-nappe tectonic,the pop-up,the triangle zone ,the duplex,etc. Multi-level decollement zones not only made the Longmenshan thrust belt develop many different deformation styles from deep place to shallow place,but also made some local areas have the superimposition of the tectonic deformation apparently. This study indicates that the multi-level de-collement zones have a very important effect on the shaping and evolution of the Longmenshan thrust belt. 相似文献
18.
呼图壁地下储气库部分区域地表垂直形变机理研究 总被引：1，自引：0，他引：1
利用在呼图壁地下储气库开展的2013~2015年7期二等水准测量获得的高差数据,对由于地表气井压力变化影响而发生的地下储气库地表垂直变形进行了分析。研究表明,呼图壁地下储气库区的地表变形除了构造成因引起的盆地下沉以外,其他主要形变成因来源有2个方面：一个是呼图壁地区的地下水超采影响着该地区的地表垂直变化;另一个是储气库集采气期间井口压力变化影响下的地表沉降,根据计算,储气库每MPa气井压力变化影响到的地表变化约为0.625~1.125mm。 相似文献
19.
The relationships among magnetic susceptibility anisotropy, finite strain, and progressive deformation have been studied in Permian red shales and slates of the Maritime Alps (southeastern France). These rocks contain deformed reduction spots which serve as finite strain indicators. The magnetic fabric of undeformed regions is modified during deformation to yield characteristic magnetic susceptibility anisotropy patterns and a magnetic equivalent of the deformation path derived from strain measurements. The magnetic fabric changes progressively from oblate to prolate, and back to oblate as deformation increases. The quantitative relationships between natural strain and magnetic anisotropy in these rocks have been determined. They differ between the less and more deformed areas, perhaps due to a change in deformation mechanism accompanying an increase in metamorphism. The relationships provide a rapid means of strain determination using magnetic measurements but their variation emphasizes the need for local structural control. 相似文献