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1.
白龙江流域构造活动频繁,是本区自然灾害频发的重要控制因素之一.众多学者对该区域的构造运动及影响进行了大量研究,但针对本区隐伏活断层勘查的例子较少.针对白龙江流域隐伏活断层,笔者通过高密度电法、地震反射法、地震折射层析法三种手段进行有效组合勘查,形成了一套行之有效的、适用于白龙江流域隐伏活断层勘查的综合物探方法,该方法不仅查明了断层的性质,还证实了断层的活动性.分别以含水断层与非含水断层两种类型进行举例说明,两者的地球物理特征既有相似点也有区别,所提出的综合物探技术对这两类断层均有较好的勘查效果,可以广泛应用于白龙江流域隐伏活断层的勘查工作,对其他地区的勘查也有一定的借鉴意义. 相似文献
2.
《四川地震》2021,(1)
2010年4月14日7时49分在青海省玉树藏族自治州玉树县发生7.1级地震,地震灾区的恢复重建工作受到隐伏断裂段和余震活动等因素的严重制约,尤其是NW走向的甘孜—玉树断裂的空间展布位置对选址重建及断裂合理避让起着决定性作用。本研究以甘孜—玉树断裂南段为探测目标,在探测工作中采取了小道间距、小偏移距、多道短排列接收、共反射点多次覆盖观测的工作方式,进行跨断层的浅层地震反射波法探测,查明了甘孜—玉树断裂南段的空间展布位置和近地表构造形态,地震剖面揭示出的地层反射具有较高的信噪比和分辨率特征,且在横向上反射波同相轴可以连续追踪,地层界面的起伏变化形态和断裂构造特征也非常清楚,解译出了3支断层在覆盖层中呈花状构造展布,符合大型走滑断裂的构造样式。探测定位结果为灾后恢复重建和工程选址工作中避开断裂带、减少未来可能造成的地震灾害损失提供了科学依据。 相似文献
3.
银川市活断层探测进展概述 总被引：1，自引：1，他引：0
本文介绍了对银川市城区两条隐伏断层所做的多层次、多手段综合探测,包括在同一个试验场点进行的三个层次的浅层人工地震勘探、钻孔联合剖面探测和槽探,从深到浅,逐层捕获隐伏目标,直到明确锁定目标断层在试验场点的准确位置、产状和上断点埋深等情况。通过对银川市活断层探测中目标断层的追踪探测,查明了市区银川隐伏断层和芦花台隐伏断层的平面展布,特别是在市区的延伸位置。通过岩芯样品的绝对年龄测定,得到了银川隐伏断层北段晚全新世活动,南段晚更新世活动,芦花台断层晚更新世以来不活动的结论。 相似文献
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5.
福州市活断层探测与地震危险性评价 总被引：5，自引：0，他引：5
大量震例研究表明，活动断层产生的直下型地震对城市的破坏非常严重，应用先进有效的地质与地球物理探测技术，准确地探明城市之下及附近活动断层分布，确定直下型地震的震源和危害性是我国城市减灾工作面临的一个非常急迫的实际问题。《福州市活断层探测与地震危险性评价》项目作为中国地震局全国城市活动断层探测的试点与示范项目于2001年初开始实施，2004年8月通过中国地震局的验收。项目围绕解决城市范围内的断裂定位、定年、定性、深部背景、地震危险性和危害性及防震减灾对策等一系列科学问题，通过“初查与目标区主要活断层鉴定”、“深部地震构造环境探测”、“地震活断层鉴定与危险性评价”、“地震活断层的详细探测”、“地震活断层危害性评价”和“活断层地理信息系统建设”等阶段的探测和评价工作，同时在福州市城、郊区全面开展壤中气汞、土壤汞、气氡、地质雷达、多道直流电法、瞬变电磁法、浅层地震折射法、浅层地震反射法、勘探震源效果对比、用于建立福州盆地埋藏第四系(标准)剖面的钻探等多种手段的试验探测，总结各种试验探测的技术指标和实践经验，在活断层的综合试验探测、定位定年、地震危险性和危害性评价等方面取得了下列成果与结论：(1)福州市活断层综合试验探测成果表明，在充分收集、整理与分析相关地质、地球物理、钻孔等资料的基础上，以地球化学探测为先导“侦察机”，确定了活断层的可能位置；以浅层地震勘探为主要探测方法，辅以电磁勘探作为补充，并利用钻探建立的第四系(标准)剖面或地层层序及测井获得的各种地球物理参数进行必要的校正和验证，结合裸露地表断层或埋深较浅断层的槽探及古地震调查或隐伏断层两侧钻孔岩芯岩性、层序、绝对年龄或孢粉等相对年龄的测定与对比等，是进行城市活断层探测(定位)与地震危险性、危害性评价(定年、定性)的最佳组合方法。(2)福州盆地位于具有发生中等强度地震的区域地震构造环境中，“台湾动力触角”对其影响相对较弱。(3)福州盆地主要断裂的活动性较弱，经鉴定的6条目标断裂都不是全新世断裂。其中，八一水库-尚干断裂和闽侯-南屿断裂至少为晚更新世中期以来的不活动断裂，其它为晚更新世以来不活动断裂。(4)福州盆地深部不存在发生直下型强烈破坏性地震的构造环境，其邻近的长乐-诏安断裂带是未来可能会发生对福州市有影响的地震震源区。(5)福州盆地主要断裂存在发生中等-中强地震的危险性，但发震概率较小。(6)福州盆地地震危害性较弱，地面发生地震地表破裂带的可能性不大。(7)开发建立了全国第一个活断层地理信息系统，具备信息查询显示、数据管理、数据的分析处理和咨询服务等功能。 相似文献
6.
日喀则地质资料匮乏,地球物理勘探资料更加稀缺,该地区在此之前没有开展过地震勘探的工作.本文针对日喀则地区活动断裂,采用夯源为人工震源的浅层地震勘探方法,结合小折射调查低速层,详细讨论工作中的关键性技术问题;提出在该地区地质条件下实施隐伏断裂勘探时的地震仪器选择、方案设计、参数选取、数据处理、断层识别的基本方法;查明拉堆—乃东断裂、抓各落断裂、毕定—甲舍拉断裂、甲岗—谢通门断裂的走向、产状、上断点埋深及其在地表的垂直投影位置等主要参数.为日喀则地区的深浅构造关系等研究提供基础资料,填补该地区地球物理勘探资料的空白. 相似文献
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《华南地震》2018,(Z1)
2013年芦山7.0级地震发生后,宝兴县作为地震灾区,在灾后重建工作中划设了穆坪镇和五龙乡两个规划区。由于两个规划区均位于龙门山断裂带南段中央断裂附近,中央断裂的晚第四纪活动特征研究可以为宝兴县的的灾后重建工作提供科学依据。通过野外地质调查、地球物理探测及钻探等手段,对中央断裂的两个分支断裂即盐井断裂和五龙断裂的地质地貌及活动特征进行了揭示。研究结果显示五龙断裂线性特征较为清晰,为晚第四纪活动断裂,穿过五龙乡规划区,考虑到未来发生地震造成的地表断错问题,应进行地震活断层避让。盐井断裂线性特征较弱,断层规模较小,为早-中更新世活动断裂,可以不考虑其对穆坪镇规划区的影响。 相似文献
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根据已有地质和地球物理研究结果,北京东部平原地区存在多条第四纪隐伏活动断裂。为了查明该区基岩面的起伏情况、断裂的空间展布以及深部断面的延伸情况,2010年初,在北京顺义区庙卷村和朝阳区孙河地区附近完成了2条可控源音频大地电磁测深剖面。文中介绍了可控源音频大地电磁法(CSAMT)隐伏活动断裂勘探的特点、资料采集过程及数据处理方法,结合区域地质资料对研究区域进行了综合地质解释。结果表明:CSAMT法在隐伏活动断裂探测中能给出工区内断裂的构造位置、倾向、断距以及发育规模,为地质分析工作提供可靠的基础资料。CSAMT法已经成为隐伏活动断裂探测中一种重要的地球物理手段,在城市活动断裂探测中发挥着重要的作用。 相似文献
11.
综合利用GF-1、PALSAR雷达数据、Landsat 8 OLI等多种数据源，分析了商丘路河地区地质地貌的遥感影像特征，进行了水文地质解译和地层遥感解译，综合判定新乡—商丘断裂南支为NW走向并建立了该断层解译标志，有效地弥补了传统技术手段无法在较深覆盖区进行活动断层探测的缺陷，对覆盖区隐伏活动断层探测工作具有借鉴意义。 相似文献
12.
应用可控源音频大地电磁法在福建隐伏煤矿区进行了勘探研究.针对"三下找煤",在试验区做了CSAMT探测,分析原始数据,结合各矿区相关的地质资料,比对反演结果,进行了地层划分,圈定了靶区.研究结果表明,在隐伏煤矿区应用CSAMT法探测煤系地层有切实可行的效果. 相似文献
13.
The so-called hour-mark effect, which reflects a response of the lithosphere to anthropogenic forcing, was initially detected when processing the earthquake catalogues by the method of synchronous detection. When attempting to reveal this effect by spectral analysis, we encountered an interesting feature of global seismicity. Namely, the spectrum of seismic activity indeed contains a peak at a frequency of 0.277 mHz, and this peak has a clearly anthropogenic origin (the hour-mark effect). At the same time, the spectrum also contains a stronger peak at a frequency of 0.309 mHz, which corresponds to a period of 54 min. We have independently detected this period in the aftershock sequences in the epicentral zones of large earthquakes and in the variations of seismicity in the antipodal zones. The 54-min periodicity coincides with the fundamental mode 0 S 2 of the free oscillations of the Earth. It is suggested that oscillations of the Earth as a whole result in a weak but detectable modulation of seismic activity. 相似文献
14.
Earthquake occurrence is well-known to be associated with structural changes in underground dynamics, such as stress level and strength of electromagnetic signals. While the causation between earthquake occurrence and underground dynamics remains elusive, the modeling of changes in underground dynamics can provide insights on earthquake occurrence. However, underground dynamics are usually difficult to measure accurately or even unobservable. In order to model and examine the effect of the changes in unobservable underground dynamics on earthquake occurrence, we propose a novel model for earthquake prediction by introducing a latent Markov process to describe the underground dynamics. In particular, the model is capable of predicting the change-in-state of the hidden Markov chain, and thus can predict the time and magnitude of future earthquake occurrences simultaneously. Simulation studies and applications on a real earthquake dataset indicate that the proposed model successfully predicts future earthquake occurrences. Theoretical results, including the stationarity and ergodicity of the proposed model, as well as consistency and asymptotic normality of model parameter estimation, are provided. 相似文献
15.
H. Arsham 《Stochastic Hydrology and Hydraulics》1997,11(4):323-330
A modified version of the widely used Kolmogorov-Smirnov (K-S) test of null hypothesis is constructed, that a given time series
is Gaussian white noise, against the alternative hypothesis that the time series contains an added or multiplicative deterministic-periodic
component of unspecified frequency. The usual KS test is treated as a special case. The proposed test is more powerful than
the ordinary K-S test in detecting extreme (low or high) hidden periodicities. Computational procedure necessary for implementation
are also given. 相似文献
16.
ABSTRACT Clustering of extremes is critical for hydrological design and risk management and challenges the popular assumption of independence of extremes. We investigate the links between clustering of extremes and long-term persistence, else Hurst-Kolmogorov (HK) dynamics, in the parent process exploring the possibility of inferring the latter from the former. We find that (a) identifiability of persistence from maxima depends foremost on the choice of the threshold for extremes, the skewness and kurtosis of the parent process, and less on sample size; and (b) existing indices for inferring dependence from series of extremes are biased downward when applied to non-Gaussian processes. We devise a probabilistic index based on the probability of occurrence of peak-over-threshold events across multiple scales, which can reveal clustering, linking it to the persistence of the parent process. Its application shows that rainfall extremes may exhibit noteworthy departures from independence and consistency with an HK model. 相似文献
17.
H. Arsham 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(4):323-330
A modified version of the widely used Kolmogorov-Smirnov (K-S) test of null hypothesis is constructed, that a given time series
is Gaussian white noise, against the alternative hypothesis that the time series contains an added or multiplicative deterministic-periodic
component of unspecified frequency. The usual KS test is treated as a special case. The proposed test is more powerful than
the ordinary K-S test in detecting extreme (low or high) hidden periodicities. Computational procedure necessary for implementation
are also given. 相似文献
18.
Following the emblematic flank collapse of Mount St Helens in 1981, numerous models of flank sliding have been proposed. These models have allowed to largely improve the understanding of mechanisms involved in such landslides, which represent a tremendous risk for populations living around volcanoes. In this article, a new mode of landslide formation, related to buried calderas, is described. The model emphasizes the paramount importance of the hidden ring fault that, even when the caldera is buried, still remains a plane of weakness in the core of the edifice. Under certain conditions, this plane of weakness becomes activated as the upper part of a pre-existing critical slip surface and is used in the emplacement of huge landslides which travel downslope at a very high velocity. A natural example is taken from Piton de la Fournaise Volcano (La Réunion Island, Indian Ocean). It reveals that the primary cause triggering caldera rim collapse is partial unbuttressing of the flank of the volcano. In the natural example, this occurs through regressive erosion that excavates deep canyon in the direction of the buried caldera but other mechanisms may exist. On account of the large volumes of material involved in caldera rim collapse as well as their long runout distances, such a volcanic hazard should be taken into account on every volcano where buried calderas are suspected. 相似文献
19.
Site characterization activities at potential unexploded ordnance (UXO) sites rely on sparse sampling collected as geophysical
surveys along strip transects. From these samples, the locations of target areas, those regions on the site where the geophysical
anomaly density is significantly above the background density, must be identified. A target area detection approach using
a hidden Markov model (HMM) is developed here. HMM’s use stationary transition probabilities from one state to another for
steps between adjacent locations as well as the probability of any particular observation occurring given each possible underlying
state. The approach developed here identifies the transition probabilities directly from the conceptual site model (CSM) created
as part of the UXO site characterization process. A series of simulations examine the ability of the HMM approach to simultaneously
determine the target area locations within each transect and to estimate the unknown anomaly intensity within the identified
target area. The HMM results are compared to those obtained using a simpler target detection approach that considers the background
anomaly density to be defined by a Poisson distribution and each location to be independent of any adjacent location. Results
show that the HMM approach is capable of accurately identifying the target locations with limited false positive identifications
when both the background and target are intensities are known. The HMM approach is relatively robust to changes in the initial
estimate of the target anomaly intensity and is capable of identifying target locations and the corresponding target anomaly
intensity when this intensity is approximately 60% higher than the background intensity at intensities that are representative
of actual field sites. Application to data collected from a wide area assessment field site show that the HMM approach identifies
the area of the site with elevated anomaly intensity with few false positives. This field site application also shows that
the HMM results are relatively robust to changes in the transect width. 相似文献
20.
隐块体在连拱隧道工程中引起的灾害 总被引：1，自引：1，他引：0
通过对正建和营运连拱隧道的调研,发现许多连拱隧道二衬有裂缝,并且裂缝漏水,有的渗漏很严重,这样既对连拱隧道的营运带来了困难,又损害了隧道的美观,通过对关键块体的力学研究和对某已完工还未营运连拱隧道二衬裂缝处进行拱顶沉降和水平收敛的监测,可知裂缝和渗漏发生的原因是:这种关键块体的变形和位移的周期比较长,隧道开挖是没有办法发现的,由于块体在施工过程中破坏自然平衡状态,经过一段时间的自稳而破坏了防水板和二衬,给连拱隧道带来了相应的病害.本文称这种块体为隐关键块体,也提出了相应的处理措施. 相似文献