共查询到20条相似文献,搜索用时 171 毫秒
1.
利用太原遥测地震台网观测到的1986年9月至1990年12月发生在太原盆地的可交切震中的736个地震,选取多种方法,对盆地的监测能力进行判定,给出了监控下限值,并提出对盆地内台风布局的建议。 相似文献
2.
3.
地电阻率多极距观测系统及试验研究 总被引:1,自引:0,他引:1
目前, 我国用于地震前兆监测的地电阻率观测系统大部分都是单一极距的, 这种观测方法在实际观测中普遍存在着地电阻率季节性变化的现象, 这种季节性变化与地震异常变化一起叠加在观测值中, 给地震异常的识别和判定带来了一定困难。 而解决这一问题的有效途径就是进行地电阻率的多极距观测。 本文介绍了采用ZD8MI电阻率多极距观测系统在山丹地震台的试验观测情况, 该系统是最新研制的、 专用于地震前兆监测的地电阻率多极距观测系统。 一年多的台站试验观测和反演结果表明, 浅层电阻率的变化相对较大, 而深层的相对变化较小, 因此利用多极距观测系统进行不同层位的地电阻率观测, 对排除干扰和识别地震前兆信息显得尤为重要, 是地电阻率观测技术发展的一个趋势。 相似文献
4.
5.
为能够在短时间内建成区域高密度地磁场观测台网,实现地磁场数据成网、成片观测,需要解决精准捕捉极震区特大震前磁场异常现象的问题。项目组利用物联网通信技术,基于RM3100三轴磁传感器,开发低成本地磁场监测设备,并部署在天津市宝坻区、武清区,同时利用人工智能数据分析技术和时序数据存储技术,开展地震前兆异常自动判定和可视化预报技术研究。该成果在2022年6月23日天津宝坻M2.0地震中得到了验证,说明低成本地磁场观测系统不仅对大震有察觉,对于近距离的中小地震同样敏感。 相似文献
6.
针对地震烈度速报工作中快速评估大震断层破裂方向的需求,使用我国西部多个地震的观测资料,根据有限移动源理论,利用趋势面分析方法探讨了震中一定范围内台站初始P波参数的方向差异特征,提出一种利用初始P波快速判定地震破裂断层方向的方法。并通过断层距模型和最小二乘法,统计回归最优拟合参数以确定地震断层破裂方式。通过实际震例对比分析了根据所提方法获得的判定结果与实际地震断层破裂分布的吻合度,证实了方法的可用性。本研究为利用地震实时监测资料快速进行地震断层破裂方向判定提供了新思路,可为地震烈度速报中破裂方向的快速判定和动态修正提供参考。 相似文献
7.
8.
9.
用断层活动强度与地震的对应关系和经验公式估算发震震级的方法,分别对山西永济风柏峪流动水准观测进行了地震监测能力的判定。结果表明,该侧线对山西运城盆地及周边100km范围内ML≥4.0地震具有较好的映震能力。指出,这可作为为山西运城盆地及晋、陕、豫交界区地震预报的一种方法,可为该地区的防震减灾工作提供依据。 相似文献
10.
空间观测技术在地震监测中的应用 总被引:2,自引:0,他引:2
当前地面地震监测系统主要观测单点的相对变化,由于观测台站密度低,观测资料覆盖面小,不能满足地震预测所需的信息。空间观测技术的发展提供了新的地震监测技术和方法,卫星空间监测技术具有覆盖面广、信息量大、动态性好以及分辨率高等优势,因而可提供更为丰富的地震前兆信息。岩石实验的结果和一些应用研究的结果显示,空间观测技术在地震监测中具有优越的应用前景。 相似文献
11.
利用在青藏高原北缘第一个长约400km的MT重复监测剖面上所获得的地震前后最新的地表视电阻率资料,用一维MT反演方法得到了剖面古方电性结构随时间的变化。着重分析相当于大陆多震层深度范围内介质电阻率参数在地震前后的变化。结果表明,地下电阻率的变化呈现分区特征,并与剖面附近地震的强度及位置有关。 相似文献
12.
甘肃景泰MS5.9地震前后小地震视应力计算讨论 总被引:3,自引:2,他引:3
分析处理甘肃数字化地震台网记录到的1999年11月至2000年6月的68个地震,给出了甘肃景泰2000年6月6日Ms5.9地震前后小地震的视应力变化情况,得到该区的视应力水平,并讨论了主震前后的视应力演化特征以及视应力与震级的关系。 相似文献
13.
Parts of the consecutive apparent resistivity monitoring stations of China have recorded clear diurnal variations. The relative amplitudes of diurnal variations at these stations range from 1.3‰ to 5.8‰. The daily accuracies of apparent resistivity observation are better than 1‰, because the background electromagnetic noise is rather low at these stations. Therefore, the diurnal variations of apparent resistivity recorded at these stations are real phenomena. The diurnal variation shapes can be divided into two opposite types according to their characteristics. One type is that the apparent resistivity data decreases during the daytime but increases during the nighttime(Type 1). The other type is the apparent resistivity data increases during the daytime but decreases during the nighttime(Type 2). There is a correspondence between the diurnal and annual variation patterns of apparent resistivity. For the monitoring direction with diurnal variation of Type 1, the apparent resistivity decreases in summer and increases in winter. However, for the monitoring direction with diurnal variation of Type 2, the apparent resistivity increases in summer and decreases in winter.
We take an analysis on the mechanism of apparent resistivity diurnal variation, combining the influence factors of water-bearing medium's resistivity, the electric structure of stations, and the apparent resistivity sensitivity coefficient(SC)theory. Intuitively, diurnal variation of apparent resistivity is caused by diurnal variation of medium resistivity in the measured area. The diurnal variation of medium resistivity will inevitably be caused by the factors with diurnal variation. Among the possible factors, there is diural variation in earth tide and temperature.
Our analysis displays that apparent resistivity diurnal variation is not caused by the usually-believed earth tide, but by the ground temperature difference between daytime and nighttime. The earth tide strain is too small to cause remarkable effects on the apparent resistivity data. On the other hand, the daily tide strain has two peak-valley variations, and its phase and amplitude has a period of approximate 28 days. However, the apparent resistivity data do not show these corresponding features to earth tide. Furthermore, the detection range of current apparent resistivity stations is within a depth of several hundred meters. Within this depth range, the medium deformation caused by solid tide can be regarded as uniform change. Therefore, all monitoring directions and all stations will have the same pattern of diurnal variation.
In general, the temperature increases in the daytime but decreases in the nighttime. For most water-bearing rock and soil medium, its resistivity decreases as temperature increases and increases as temperature decreases. Diurnal temperature difference affects about 0.4m of soil depth. Therefore, resistivity of this surface thin soil layer decreases in the daytime while increases in the nighttime. Under layered medium model, SC of each layer represents its contribution to the apparent resistivity. For the stations with positive SC of surface layer, apparent resistivity decreases in the daytime but increases in the nighttime. While for the stations with negative SC of surface layer, apparent resistivity diurnal variations display the opposite shape. 相似文献
14.
DEEP TECTONIC STRESS CHANGE BASED ON LONG-TERM APPARENT RESISTIVITY TIME SERIES: A CASE STUDY FROM NORTH SECTION OF YISHU FAULT ZONE 下载免费PDF全文
Almost all the destructive earthquakes, so called tectonic earthquake, are produced by tectonic movement. The tectonic movement will cause resistivity changes in the earth. It's valuable for strong earthquake forecast to study the relationship between the resistivity change and tectonic movement. According to magnetotelluric sounding method, we establish a robust estimate method to calculate the long-term apparent resistivity from seismic station monitoring data. We first use 1D layered earth models to test the sensitivity of this method. Then we process the continually observed long term electromagnetic data in 4 years (from 2011 to 2014) from Anqiu seismic station which is very close to the north section of Yishu fault zone. The apparent resistivity curves and the apparent resistivity time series for different frequencies are obtained. The time series show the resistivity increase in the selected 4 years, which is in good agreement with the GPS baseline data. This also satisfies the results from rock mechanics experiments on deep rocks (upper mantle) that the resistivity will increase with improved stress in a high temperature and pressure environment. The method is valuable for studying electromagnetic precursor of strong earthquakes and strong earthquake prediction. 相似文献
15.
16.
针对我国地震监测预报中固定地点和固定观测装置及参数的视电阻率观测,给出了半空间倾斜各向异性介质中电阻率对称四极观测的理论探测深度,研究了地震前兆信息的检测深度问题,得到:(1)在强地震、孕震晚期阶段,在震中区及附近可检测到地壳近地表较深部介质的电阻率变化,其深度大于或远大于均匀介质之;(2)震级、震中距、观测方向不同或在不同的孕震阶段,探测深度存在差异,甚至存在大的差异,且是动态变化的.并依据理论探测深度讨论了地震视电阻率前兆变化的复杂性、地电台址电性条件等问题. 相似文献
17.
台址下表层介质电阻率变化对视电阻率观测值影响特征的初步研究 总被引:2,自引:0,他引:2
气候的交替变化将导致大地表层含水量发生变化,从而使该层介质的电阻率发生变化,进而使得观测结果(即视电阻率)发生变化,显然这对地震前兆观测而言是一种干扰。目前我国绝大多数前兆地电阻率台采用单极距观测方式,因此观测到的视电阻率变化应是表层变化(主要是干扰)和观测范围内深部变化(地下介质应力与应变状态发生变化)的综合反映。作先依据台址下的水平层状模型进行了模拟计算研究,发现大地表层含水量的变化对单极距四极装置视电阻率观测值的影响有两个特征:(1)无论台址下电阻率结构是下伏低阻还是下伏高阻,表层介质电阻率升高对观测值的影响都很小;(2)表层电阻率降低对观测值的影响很明显,且对下伏高阻结构的影响大于对下伏低阻结构的影响。然后用视电阻率实际观测资料说明了将其特征用于预报的可能性。 相似文献
18.
M. E. Sholpo 《Izvestiya Physics of the Solid Earth》2013,49(1):113-119
The sensitivity of transversal apparent resistivity to the changes in the electrical resistivity of elements of a two-dimensional (2D) geoelectrical structure is studied by numerical modeling. This sensitivity is found to have a series of specific features, due to which the monitoring of transversal apparent resistivity can serve as a helpful addition to the monitoring of longitudinal apparent resistivity to trace the dynamics of subsurface and shallow crustal elements of the medium. It is shown that the method previously suggested for the inversion of relative changes in apparent resistivity into relative changes in electrical resistivities of the elements of the geoelectrical structure is applicable to the transversal electrical resistivity. 相似文献
19.
本文研究了青藏高原北缘第一个长约400km的MT监测剖面上所获得的5次5-7级地震前后的资料。着重分析了在相当于大陆多震层深度范围内壳内介质的多种MT参数(视电阻率、相位、主轴方位角、扭曲度等).这些MT参数在大范围内的同步-同相变化和局部区域之间的超前、滞后变化、相对变化幅度随震中距增大而衰减的特征,可能分别对应着构造孕育型大震的地区性场兆和构造运动型强震的区域性场兆,形成了地震活动大背景叠加小背景的一种链式关系。运用"MT监测优显参数"进行择优监测,将可能为大陆地震的震源物理发展过程和中短期预报提供丰富可靠的判据。 相似文献
20.
本文研究了青藏高原北缘第一个长约400km的MT监测剖面上所获得的5次5-7级地震前后的资料。着重分析了在相当于大陆多震层深度范围内壳内介质的多种MT参数(视电阻率、相位、主轴方位角、扭曲度等).这些MT参数在大范围内的同步-同相变化和局部区域之间的超前、滞后变化、相对变化幅度随震中距增大而衰减的特征,可能分别对应着构造孕育型大震的地区性场兆和构造运动型强震的区域性场兆,形成了地震活动大背景叠加小背景的一种链式关系。运用"MT监测优显参数"进行择优监测,将可能为大陆地震的震源物理发展过程和中短期预报提供丰富可靠的判据。 相似文献