工作面前方隐伏断层综合预测方法

为解决煤矿采掘工作面前方隐伏断层超前预测的实际问题，依据模糊数学和矿井地质理论，提出一种综合预测采掘工作面前方隐伏断层的方法。通过对节理发育程度及煤的强度的实际观测，建立了经验公式，进而对采掘工作面前方是否存在隐伏断层做出综合评判。实践证明，该方法可对采掘工作面前方隐伏断层的性质、产状和发育规模提出较准确的预测结论。     

对隐伏逆冲断层和滑脱构造的预测和分析

逆冲断层或滑脱构造和上盘岩层的褶皱、断层构成有规律的组合和配置,提供了运用浅表构造揭示隐伏断层的可能性。本文利用浅表构造对隐伏断层进行三方面的预测:通过特征性构造推测隐伏逆冲断层和滑脱构造的存在;据不同类型的构造及其空间分布规律预测隐伏断层的产出状态;借助皱褶构造推算隐伏断层的埋藏深度。这种构造综合分析法无疑是研究隐伏断层的重要手段。     

小褶曲在综采工作面隐伏断层预测中的应用

在综采工作面的准备和回采过程中，小褶曲是可能存在隐伏断层的征兆。利用空间解析几何方法，对小型褶曲构造进行观测研究，认为对煤层产状的变化进行观测，可以较早地发现隐伏断层影响范围内的产状异常，较准确地预测采掘前方可能存在的隐伏断层，使井下钻探或物探探测断层的工作得以有目的有重点的进行，并缩短了探测距离。经在绿水洞煤矿实际应用，这一预测方法得到了初步验证。     

基于裂纹扩展的含隐伏断层底板突水评价

 为研究承压水上开采时含隐伏断层底板的安全性,根据断裂力学理论建立导水断层活化扩展的理论模型。将煤层底板看做半平面无限体,把底板中含水层顶部以上的隐伏断层建模为有限宽度板条的倾斜边缘裂纹。根据采场底板的支承压力分布规律,将其简化为若干分段线性载荷加载至底板,纳入断层产状、断层在底板中埋深、工作面推进距离、含水层水压、断层面摩擦角等各种参数,推导得到底板内任意一点的应力公式。将其应用到隐伏断层面上各点,综合考虑各点法向应力、剪应力对裂纹活化的影响,计算得到采动条件下断层面上的有效切应力分布。该有效切应力剔除了裂纹面上摩擦效应对压剪裂纹扩展的影响,将其代入断裂力学相关公式,计算得到隐伏断层前缘的应力强度因子,最后通过定义突水安全指数建立了底板突水判据。以某矿带压开采工作面为例,根据相应水文和地质资料,计算得到在工作面推过隐伏断层的整个过程中断层活化突水危险性的变化规律,所得结论与工作面现场微震监测数据相符,即当工作面推进至采空区位于隐伏断层正上方区域时,断层面承受有效剪切最充分,剪切应力强度因子最大,突水安全指数达到峰值,这与现场微震监测结果中显示的在该推进阶段中,原有隐伏断层附近派生裂隙集中出现、突水危险性最高的结果相符合。     

应用综合电阻率法勘察隐伏断层

探讨隐伏断层在复杂地质条件下的具体位置和形态,进而保障隧道开挖施工的顺利进行.采用综合电阻率法探测拉林线某隧道开挖纵断面顶部的断层发育状况,通过对复杂地质条件下视电阻率异常的综合解释,结果表明“串珠状电阻率异常”和“大小极距交点位移”真实地反映出隐伏断层所在的位置和形态,且通过钻探得到了验证.对隧道隐伏断层的地球物理勘探手段应以综合电阻率法为主.     

川东梁平向斜隐伏断层与气藏关系

川东地区海相地层沉积早（Ｚ—Ｔ２），断褶构造发生晚（Ｎ—Ｑ）。断褶构造发育程度低及隐伏构造内致密储层后生孔洞缝发育区控制气藏分布。梁平向斜内及两翼变陡部位发育众多的隐伏构造，向斜是气源区。根据地震资料解释出隐伏断层及构造，优选了３个构造，定出４口井位供钻探。     

高密度电阻率法在近地表隐伏断层检测中的应用

隐伏断层对于道路、地基等具有重大威胁,高密度电阻率法是以地层之间电阻率差异为基础的探测地下构造和电性异常体的一种间接性的地球物理方法,近年来,在近地表探测隐伏断层方面应用广泛。基于此,首先对断层模型进行正演模拟,研究了断层模型的响应规律,然后以山西某段公路隐伏断层检测为例,简要介绍了高密度电阻率法的基本原理以及常用的两种施工装置,即温纳四极装置(α)和单边三极装置,分析了两种施工装置的优缺点,以实测视电阻率剖面图和反演视电阻率剖面图进行对比研究,揭示了反演结果的优势,并在反演结果的基础上进行背景电阻率值的剔除,在断层产状判断及其影响区域划分上进行定量解释,验证了高密度电阻率法探测近地表隐伏断层的可行性,为后续施工提供了可靠的地质资料。     

底板隐伏导水断层安全性评价

构造地质断层存在着向工作面底板隐伏延伸的可能性,并成为沟通含水层的导水通道,对工作面的安全性造成影响。为了对底板隐伏导水断层的安全性进行评价,以鲁西南某矿三采区31336工作面为例,通过底板钻探,利用钻孔水压和水温异常定位了隐伏导水通道位置。运用递进导升突水的评价法,认为在回采过程中,隐伏导水断层不会和底板破坏区接通,不需要对导水通道治理也不会发生突水。工作面的安全回采证实了结论的正确性,研究成果对条件类似的工作面具有借鉴作用。     

综合地球物理勘探在青川县城区活动断层探测中的应用

针对通过青川县城区的隐伏活动断层问题,采用了综合地球物理勘探方法,查明了平武-青川断裂隐伏段在城区内的展布情况,经探槽开挖验证所确定的主干断裂及其分支断裂的通过位置和相关参数均真实可靠.青川县城区有3条隐伏断裂通过,最北的一支为平武-青川断裂的主干断层,总体走向NEE;中支和南支为平武-青川断裂的次级分支断层,走向都是NE向.3条隐伏断裂中的北支和中支断裂错到浅地表2 m以下的卵石层.     

龙门山中北段遥感图像解译的新发现

对龙门山中北段,采用陆地卫星MSS和TM图像,进行数字图像处理和地质构造解译,共解译出断层35条,隐伏环形构造5个。新发现的茂汶断层北东段和擂东断层对龙门山构造带的进一步划分具有较大的意义;而吴家坪一桂溪U形断层则为唐王寨滑覆体的确定提供了有力的证据。推测武都等三个隐伏环形构造为有利的含油气构造。     

Friction falls towards zero in quartz rock as slip velocity approaches seismic rates

An important unsolved problem in earthquake mechanics is to determine the resistance to slip on faults in the Earth's crust during earthquakes. Knowledge of coseismic slip resistance is critical for understanding the magnitude of shear-stress reduction and hence the near-fault acceleration that can occur during earthquakes, which affects the amount of damage that earthquakes are capable of causing. In particular, a long-unresolved problem is the apparently low strength of major faults, which may be caused by low coseismic frictional resistance. The frictional properties of rocks at slip velocities up to 3 mm s(-1) and for slip displacements characteristic of large earthquakes have been recently simulated under laboratory conditions. Here we report data on quartz rocks that indicate an extraordinary progressive decrease in frictional resistance with increasing slip velocity above 1 mm s(-1). This reduction extrapolates to zero friction at seismic slip rates of approximately 1 m s(-1), and appears to be due to the formation of a thin layer of silica gel on the fault surface: it may explain the low strength of major faults during earthquakes.     

活动断层分段研究

地震发生在活动断层上,而断层活动不一定都发震,为进行地震危险性分析,确定未来可能发生地震的地段和强度。因此,把活动断层分成地震破裂段进行研究,分析断层活动在时间上、空间上的不均匀性,了解破裂段特征和分段标志,确定破坏性地震发震的构造条件是极为重要的。     

潮汐应力与云南及邻区的地震

提出了潮汐应力对发震断层的力学模式,描述了附加潮汐应力对发震断层的促滑作用方式,并将该模式应用于云南及邻区的地震,计算了173个地震震源处沿主压应力P轴和主张应力T轴方向的附加潮汐应力分量,分析了这睦量对发震断层的作用方式以及受潮汐应力促滑作用的发震断层类型,结果表明,所研究的云南及邻区发生的173个地震中,64％的地震发震断层受到潮汐应力的促滑作用,其中,受减压型促滑作用的发震断层数比例略大于受增压型促滑作用的发动层数比例;在受到潮汐应力促滑作用的111个发震断层中,走滑型发震断层占67％,倾滑斜滑型发震断层占33％,说明云南及邻区的走滑型地震较易受到潮汐应力的触发作用。     

A great earthquake doublet and seismic stress transfer cycle in the central Kuril islands

Temporal variations of the frictional resistance on subduction-zone plate boundary faults associated with the stick-slip cycle of large interplate earthquakes are thought to modulate the stress regime and earthquake activity within the subducting oceanic plate. Here we report on two great earthquakes that occurred near the Kuril islands, which shed light on this process and demonstrate the enhanced seismic hazard accompanying triggered faulting. On 15 November 2006, an event of moment magnitude 8.3 ruptured the shallow-dipping plate boundary along which the Pacific plate descends beneath the central Kuril arc. The thrust ruptured a seismic gap that previously had uncertain seismogenic potential, although the earlier occurrence of outer-rise compressional events had suggested the presence of frictional resistance. Within minutes of this large underthrusting event, intraplate extensional earthquakes commenced in the outer rise region seaward of the Kuril trench, and on 13 January 2007, an event of moment magnitude 8.1 ruptured a normal fault extending through the upper portion of the Pacific plate, producing one of the largest recorded shallow extensional earthquakes. This energetic earthquake sequence demonstrates the stress transfer process within the subducting lithosphere, and the distinct rupture characteristics of these great earthquakes illuminate differences in seismogenic properties and seismic hazard of such interplate and intraplate faults.     

Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit

Our understanding of the earthquake process requires detailed insights into how the tectonic stresses are accumulated and released on seismogenic faults. We derive the full vector displacement field due to the Bam, Iran, earthquake of moment magnitude 6.5 using radar data from the Envisat satellite of the European Space Agency. Analysis of surface deformation indicates that most of the seismic moment release along the 20-km-long strike-slip rupture occurred at a shallow depth of 4-5 km, yet the rupture did not break the surface. The Bam event may therefore represent an end-member case of the 'shallow slip deficit' model, which postulates that coseismic slip in the uppermost crust is systematically less than that at seismogenic depths (4-10 km). The InSAR-derived surface displacement data from the Bam and other large shallow earthquakes suggest that the uppermost section of the seismogenic crust around young and developing faults may undergo a distributed failure in the interseismic period, thereby accumulating little elastic strain.     

The role of fluids in lower-crustal earthquakes near continental rifts

The occurrence of earthquakes in the lower crust near continental rifts has long been puzzling, as the lower crust is generally thought to be too hot for brittle failure to occur. Such anomalous events have usually been explained in terms of the lower crust being cooler than normal. But if the lower crust is indeed cold enough to produce earthquakes, then the uppermost mantle beneath it should also be cold enough, and yet uppermost mantle earthquakes are not observed. Numerous lower-crustal earthquakes occur near the southwestern termination of the Taupo Volcanic Zone (TVZ), an active continental rift in New Zealand. Here we present three-dimensional tomographic imaging of seismic velocities and seismic attenuation in this region using data from a dense seismograph deployment. We find that crustal earthquakes accurately relocated with our three-dimensional seismic velocity model form a continuous band along the rift, deepening from mostly less than 10 km in the central TVZ to depths of 30-40 km in the lower crust, 30 km southwest of the termination of the volcanic zone. These earthquakes often occur in swarms, suggesting fluid movement in critically loaded fault zones. Seismic velocities within the band are also consistent with the presence of fluids, and the deepening seismicity parallels the boundary between high seismic attenuation (interpreted as partial melt) within the central TVZ and low seismic attenuation in the crust to the southwest. This linking of upper and lower-crustal seismicity and crustal structure allows us to propose a common explanation for all the seismicity, involving the weakening of faults on the periphery of an otherwise dry, mafic crust by hot fluids, including those exsolved from underlying melt. Such fluids may generally be an important driver of lower-crustal seismicity near continental rifts.     

大地震时空窗口研究

 依据《地震应可预测》一书收录的自中国初建电信传输台网以来,涉及近半个世纪的地震活动性图像,震级跨度自M3.0—M4.0级中强震至M8.0级大震,着眼于地震大尺度的观点,将中国地震的活动性图像置于全球地震活动框架中进行分析研究。认识到大地震不是任何地方都能发生的,大地震不是任何时间都能发生的,大地震有其特定的时空结构。条环交会、差异活动和深震与天外来客事件等是制约发震时空窗口的主要因素。条带与圆环的交会基本上有三种类型：条带与条带、圆环与圆环以及条带与圆环。研究了空区的特征形态,认为似用屈曲传递动力的组合环节以解释可能更为合适。因之重点应着眼于对其两者(活跃与平静)的差异性组合。鉴于大地震发震时刻窗口经常处在天外来客的节点上,因之我们尚需关注那些非随机的天外来客事件。本文阐述了制约发震时空窗口的诸多因素,这些因素也已在2011年3月11日M9.0东北日本大地震观测中得到了印证。     

“311”东北日本M9.0大地震可预测性特征探索

 大地震不是任何地方都能发生的,大地震也不是任何时间都能发生的,大地震有其特定的时空结构。前期工作表明,条环交会、差异活动以及深震与“天外来客”事件等是制约发震时空窗口的主要因素。2011年3月11日发生在日本海沟俯冲带的M9.0大地震,其震前地震活动全面、清晰地展现出了其可预测性特征：(1) 1925年开始出现的板间地震长期平静区;(2) 2003年开始出现的位于平静区中部,起始于深震的海沟垂向地震活动条带;(3) 2009年3月(海沟垂向地震活动条带形成后)开始出现的广义前震发震地方时的非随机显著聚集特征;(4) 2011年3月9日(主震前2天)发生在平静区内的前震。主震发生在平静区边缘,海沟垂向地震活动条带与日本海沟板间地震带的交会处的地震活动差异性较大的地方,其断层面与海沟垂向地震活动条带内另外两个板间地震(2005-08-16地震和前震)的断层面共面。主震发生于广义前震发震地方时非随机聚集时段的中位时辰。日本大地震的可预测性特征逐一印证了我们的前期研究。     

Subcontinental-scale crustal velocity changes along the Pacific-North America plate boundary

Transient tectonic deformation has long been noted within approximately 100 km of plate boundary fault zones and within active volcanic regions, but it is unknown whether transient motions also occur at larger scales within plates. Relatively localized transients are known to occur as both seismic and episodic aseismic events, and are generally ascribed to motions of magma bodies, aseismic creep on faults, or elastic or viscoelastic effects associated with earthquakes. However, triggering phenomena and systematic patterns of seismic strain release at subcontinental (approximately 1,000 km) scale along diffuse plate boundaries have long suggested that energy transfer occurs at larger scale. Such transfer appears to occur by the interaction of stresses induced by surface wave propagation and magma or groundwater in the crust, or from large-scale stress diffusion within the oceanic mantle in the decades following clusters of great earthquakes. Here we report geodetic evidence for a coherent, subcontinental-scale change in tectonic velocity along a diffuse approximately 1,000-km-wide deformation zone. Our observations are derived from continuous GPS (Global Positioning System) data collected over the past decade across the Basin and Range province, which absorbs approximately 25 per cent of Pacific-North America relative plate motion. The observed changes in site velocity define a sharp boundary near the centre of the province oriented roughly parallel to the north-northwest relative plate motion vector. We show that sites to the west of this boundary slowed relative to sites east of it by approximately 1 mm yr(-1) starting in late 1999.     

工程地质环境与可持续发展Ⅱ活动断裂与发震的关系

地震发生在活动断裂上，而断裂活动并非都一定发震。为进行地震危险性分析，确定未来可能发生地震的地段和强度而对活动断裂与发震的关系进行了研究