The 10 June 2012 Fethiye Mw 6.0 aftershock sequence and its relation to the 24–25 April 1957 Ms 6.9–7.1 earthquakes in SW Anatolia,Turkey

The 10 June 2012 M_w 6.0 aftershock sequence in southwestern Anatolia is examined. Centroid moment tensors for 23 earthquakes with moment magnitudes (M_w) between 3.7 and 6.0 are determined by applying a waveform inversion method. The mainshock is a shallow focus strike-slip with reverse component event at a depth of 30 km. The seismic moment (M_o) of the mainshock is estimated as 1.28 × 10¹⁸ Nm and rupture duration of the Fethiye mainshock is 38 s. The focal mechanisms of the aftershocks are mainly strike-slip faulting with a reverse component. The geometry of the focal mechanisms reveals a strike-slip faulting regime with NE–SW trending direction of T-axis in the entire activated region. A stress tensor inversion of focal mechanism data is performed to obtain a more accurate picture of the Fethiye earthquake stress field. The stress tensor inversion results indicate a predominant strike-slip stress regime with a NW–SE oriented maximum horizontal compressive stress (S_H). According to variance of the stress tensor inversion, to first order, the Fethiye earthquake area is characterized by a homogeneous interplate stress field. The Coulomb stress change associated with the mainshock and the largest aftershock are also investigated to evaluate any significant enhancement of stresses along the Gulf of Fethiye and surrounding region. Positive lobes with stress more than 0.4 bars are obtained, indicating that these values are large enough to increase the Coulomb stress failure towards NNW–SSE and E–W directions.     

基于灰色模型的煤矿涌水量预测研究

孟加拉巴拉普库利亚煤矿位于孟加拉国西北部,为一独立的半断陷冈瓦纳群含煤盆地。该矿主采的Ⅵ煤层为特厚煤层,煤层均厚36m。受矿井水文地质条件等因素影响,目前仅在南翼采区进行开采。根据煤矿Ⅵ煤一分层开采2000-2012年的涌水量实测资料,建立灰色理论模型并进行模型精度检验。在此基础上,利用灰色理论的预测方法,基于Matlab软件编程计算,对2013-2018年的矿井涌水量动态变化进行预测,并将模型预测值与实测资料进行对比。结果表明,所建立的灰色系统模型具有可靠性和适用性,涌水量预测成果可为矿井排水系统的设计提供依据。     

多基线距DInSAR反演河南省永城煤矿区地表形变

永城是河南省重要的煤炭生产基地,煤矿开采后形成的塌陷区中有70%以上是耕地,已严重威胁到当地居民的生产生活秩序以及生命财产安全,迫切需要采用快速高效的技术手段获取塌陷区的信息来为相关部门提供决策依据;研究中选用2004～2006年的6景ASAR数据,采用基于相干目标的多基线距DInSAR技术对河南永城煤矿区的地表形变进行反演;研究中采用的地表形变反演技术克服了传统DInSAR技术失相干的问题,反演得出的地表形变的范围和程度与调查结果相吻合,表明该项技术具有很强的实用性和推广性;最后分析反演误差产生的原因并提出今后可采用L波段以及多平台联合监测来提高煤矿区地表形变的精度。     

青川县桅杆梁斜坡地震动响应监测研究

本文采用941B型超低频测振仪及G01通用数采仪,自2009年5月13～27日,在青川县桅杆梁监测到4次余震。对山体斜坡高程805m和875m的余震地震动峰值加速度响应监测结果分析表明:相对于805m高程, 875m测点地震动峰值加速度在水平东西向以及垂向均呈减小趋势,而在水平南北向体现显著的放大效应,放大系数可达7～8倍,其FFT主频值主要集中为2～4Hz低频值。分析表明,所监测的微有感地震震中位于测点北侧的青川断裂上,沿地震波传播方向斜坡体具有显著放大效应作用。     

Spatial Scaling of Effective Modulus and Correlation of Deformation Near the Critical Point of Fracturing

Many observations point to the lithosphere being metastable and close to a critical mechanical point. Exercises in modelling deformation, past or present, across subsurface reservoirs need to take account of this criticality in an efficient way. Using a renormalization technique, the spatial scaling of effective elastic modulus is derived for 2-D and 3-D bodies close to the critical point of through-going fracturing. The resulting exponent, d_μ, of spatial scaling of effective modulus with size, , takes the values ~ −2.5 and −4.2 in two- and three-dimensional space, respectively. The exponents are compatible with those for scaling of effective modulus with fracture density near the percolation threshold determined by other workers from numerical experiments; the high absolute values are also approximately consistent with empirical data from a) fluctuations in depth of a seismic surface; b) `1/k' scaling of heterogeneities observed in one-dimensional well-log samples; c) spatial correlation of slip displacements induced by water injection. The effective modulus scaling modifies the spatial correlation of components of displacement or strain for a domain close to the critical point of fracturing. This correlation function has been used to geostatistically interpolate components of the strain tensor across subsurface reservoirs with the prime purpose of predicting fracture densities between drilled wells. Simulations of strain distributions appear realistic and can be conditioned to surface depths and observations at wells of fracture-related information such as densities and orientations, welltest permeabilities, changes in well-test permeabilities, etc.     

探地雷达在岩溶地区勘察中的应用

地质雷达是采用高频电磁波、宽频带短脉冲和高速采样技术的一种新型的物探方法。我国贵州岩溶分布十分广泛,地下岩溶洞穴严重威胁着工程建设和人民的生命安全。以贵州六盘水盘东北循环型煤焦化项目厂址岩溶探测为例,论述了雷达探测方法的技术及其工作原理,并结合岩溶探测实例,分析了岩溶区域雷达波场空间展布特征,划定了该测区溶洞、溶蚀裂缝等岩溶地质异常的空间展布范围,验证结果表明:探地雷达技术在浅层岩溶探测中的有效性。     

红旗渠·林虑山地质公园景观特征及旅游体系研究

红旗渠·林虑山国家地质公园的地质遗迹是华北地区地质演化的缩影,是一座天然的沉积构造陈列馆和教科书。公园不仅有壮观的地质工程——红旗渠,还具有＂雄、奇、险、秀、幽＂的美学特征,可以开展生态、体育和文化游。     

Using hydrologic and hydraulically derived geometric parameters of perennial rivers to determine minimum water requirements of ecological habitats (case study: Mazandaran Sea Basin—Iran)

This paper studies one of the most important problems of dry countries that are confronted with water deficit and the competition of rivals to allocate water. Some common methods have been investigated for computing the minimum water requirement to save a river's biological activity. After a discussion of the currently used method in Iran (the Tenant Method), the application of some other methods, which are known as Hydraulic and Hydrological Methods, is illustrated. The case study is a river in the northern part of Iran and this research addresses the critical situation of this river in near future regarding the planned anthropogenic alteration and its consequences. It has been shown that the application of environmental water allocation methods that have no background in a region could be misleading. The first proposed method is the Texas Method, in which flexibility in water allocation helps to develop an integrated river management paradigm in the study area. The second preferred method is a Hydraulic Method, by which the implementation of morphological parameters or flow geometrical properties could sustain physical habitat within an acceptable range in terms of depth, width, velocity, and bed shear stress. In the case study, the Maximum Curvature Method was superior to the Slope Method. The investigation revealed that using a widely recommended slope of 1 for the discharge‐wetted perimeter function can lead to an overestimated and unacceptable discharge. The Tenant Method in respect to minimum environmental flow requirement yielded the weakest result, and it has been illustrated that its application might impose irrecoverable shock to the ecosystem. The Flow Duration Curve Method (the Q₉₅ Method), in spite of its subjectivity, showed more compatibility with the river's condition in comparison with the Tenant Method. Copyright © 2011 John Wiley & Sons, Ltd.     

台风路径预报的定量分析

针对传统预报台风路径方法不够准确的缺陷,采用动力学方法,定量分析了作用在台风上的地转偏向力、内力、气压梯度力对台风转向所起作用的程度,指出了判定台风转向的动力学和天气学条件,证明了台风强度移速和气压场变化是台风转向的原因.     

应用于数字下变频中CORDIC算法的FPGA实现

正余弦信号在GNSS接收终端的数字下变频中有着重要的应用,CORDIC算法是实现正余弦信号的最重要方法。立足于DDS与CORDIC算法的基本原理,针对CORDIC算法实现主要存在的3个问题,结合变象限法、流水线技术及相幅量化数据格式,在FPGA上通过实现CORDIC算法可在一个时钟周期内计算出正余弦信号幅值。仿真结果表明：与传统CORDIC算法实现相比,本文实现的正余弦信号精度高且速度快,并能满足GNSS接收终端数字下变频对正余弦信号的需求。