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1.
选取内蒙古测震台网呼和浩特—乌兰察布地区8个固定台站及呼和浩特附近地区野外观测项目建设的31个流动台站,计算各台站地震监测能力,分析加密区监测能力变化,针对监测能力较弱区域,利用ArcGIS的空间分析功能,实现新建台站选址的点位确定,提出未来合理布局方案。 相似文献
2.
国家地震烈度速报与预警工程项目已启动,内蒙古自治区地震局已完成预警基准台站勘选工作。利用近震计算公式,利用已选定台址与现有台站噪声水平,评估内蒙古自治区预警基准站建成后地震监控能力。结果表明,呼和浩特、包头、鄂尔多斯和乌兰察布市地区,地震监测能力在1.0级,而赤峰—通辽地区监测能力将达0.5级。 相似文献
3.
内蒙古地震预警基准台网监控能力评估 总被引：1，自引：1，他引：0
国家地震烈度速报与预警工程项目已启动,内蒙古自治区地震局已完成预警基准台站勘选工作。利用近震计算公式,利用已选定台址与现有台站噪声水平,评估内蒙古自治区预警基准站建成后地震监控能力。结果表明,呼和浩特、包头、鄂尔多斯和乌兰察布市地区,地震监测能力在1.0级,而赤峰—通辽地区监测能力将达0.5级。 相似文献
4.
介绍了皖南地区区域地震台网20个测震台站的基本情况。对20个台站的背景噪声数字化记录进行了计算和分析,得其背景噪声均方根RMS值、有效测量动态范围,分析了噪声水平并按照地噪声水平的规定对各台进行了台基噪声分类。结果表明,20个测震台站中有9个I类台址、9个Ⅱ类台址、2个Ⅲ类台址。同时,分析了皖南地区区域台网的最小监测能力,结果表明,皖南地区区域台网最小监测能力为M_L≥-0.1—0.6,台站监测能力基本满足皖南地区监测需求。 相似文献
5.
国际上新近发展的“基于概率的完整性震级”(PMC)方法,具有可考察地震定位中由于台站人为选择等造成的台网监测能力下降,以及避免传统基于G-R关系的统计算法因地震数目过少而无法评估等优点.本研究利用PMC方法,计算得到内蒙古区域地震台网39个台站对周边地震事件的检测概率及台网检测概率.单台检测概率结果显示:PMC方法能够客观地反映39个台站对地震事件的检测能力;因台网布局等影响,内蒙古区域地震台网中西部和中东部地区的台站检测能力较强,而靠近蒙古、俄罗斯边境的台站, 阿拉善右旗附近地区的台站,以及邻近吉林、黑龙江等地区的台站检测能力较低.合成检测概率结果显示,由于邻省台站的引入,全区80%的地区基于概率的最小完整性震级MP达到2.2左右,其余地区MP达到3.3左右.为提高地震台网监测能力,建议在监测能力较弱的中蒙交界地区、东北部地区,以及阿拉善左旗以西地区适度加密台站,进一步优化台网布局. 相似文献
6.
为获得辽宁测震台网科学准确的监测能力评估结果,分析辽宁及周边地区的地震监测能力时空分布特征,为测震台网的优化提供科学依据。本研究首次将"基于概率的完整性震级"(PMC)方法应用到辽宁测震台网,通过计算获得辽宁地震台网37个台站的单台检测概率、测震台网合成检测概率以及基于概率的最小完整性震级M_P。单台检测概率表明:PMC方法能够客观地反映台站对地震事件的检测能力;营口—海城老震区周围的台站对较小震级的地震有较高的检测能力,受台网布局影响,位于辽宁边界地区台站的检测能力较弱。M_P时空分布特征显示:辽宁中部沈阳—辽阳—本溪—鞍山—盘锦地区1.5≥M_P≥1.2。辽宁南部大连一带监测能力较低M_P≥3.0,辽宁西部与河北交界地区3.0≥M_P≥2.5,辽宁其他区域2.5≥M_P≥1.8。研究结果表明,为进一步提高辽宁地震台网监测能力,需在辽宁东部、东南部建设台站以提高该区域台站密度,在辽宁西部地区建设部分台站和重新规划需要引入的河北共享台站,以提高该区域的台站密度及改善台站空间布局和该区域的监测能力。 相似文献
7.
针对中国地震台网"十五"项目建成后的地震监测能力科学评估的需求,为进一步优化台网布局、提升边疆海域等重点地区监测能力,本研究利用"基于概率的完整性震级"（PMC）方法,对中国地震台网1001个台站以及2008-10-01-2015-09-17期间实际产出的地震观测资料进行了研究,分析了指定震级档下的检测概率PE和最小完整性震级MP的分布.除台网整体监测能力分布外,为直观地用单分值表述逐个台站的地震检测能力,本文发展了基于等振幅曲线的"地震检测能力评分表",给出了国家台和区域台每个台站的地震检测能力评分统计特征和空间分布特征.此外,研究中还采用设定"最佳"地震监测能力目标函数的方式,模拟了通过改进观测条件可获得的地震台网监测能力提升的理论结果.研究结果表明,我国华北和东南沿海等东部地区地震监测能力较高,西部尤其是青藏高原南部地区Mp仅约为4.5,近海海域Mp仅约为3.5;从单个地震台站的运行效益角度,台网运行水平和地震观测资料的分析程度对台站的实际的地震检测能力影响显著,新疆等部分台站稀疏地区地震检测能力较高,而中等台站密度的贵州等部分区域相对较低;国家台的地震检测能力评分Dscore系统优于区域台,新疆等西部边疆地区,以及福建等东南沿海地区的Dscore明显高于台站密集的东部地区;模拟结果显示,在现有台站布局条件下,通过台站优化改造和提升运维管理水平,可显著提升对内蒙古西部、四川西部、甘肃-青海的北部交界地区、鄂尔多斯地块内部、贵州大部分地区,以及我国近海海域、朝鲜半岛北部和中南半岛北部地区的地震监测能力. 相似文献
8.
以内蒙古中部的呼和浩特-包头地区(40°～42°N,108°～114°E)作为研究区域,收集整理2001年1月1日至2010年4月30日ML≥1.0地震作为研究对象,按地震样本数目滑动扫描并计算最小完整性震级Mc,绘制Mc的时序变化曲线.分析认为Mc在时间上的变化主要反映台网监测能力和地震活动规律,但台站布局、地震信噪比和人为因素也会引起Mc的短期或不连续性的变化.同时在Rydelek等提出的2个假设条件下,对呼包地区的地震目录完整性进行了RS检验,其结果与上述扫描计算结果一致,也与根据台网监测能力所得到的震级范围吻合,证明本文的计算结果能够比较真实的反映2001年以来呼包地区地震目录在各时段内的完整性. 相似文献
9.
采用基于概率的完整性震级（PMC）方法,选取上海测震台网13个地震台站及周边省市地震台2008-2019年记录的171个地震,计算各地震台及上海测震台网地震监测能力,并模拟增加新的地震台站后台网监测能力的变化。结果显示：①地表基岩台的监测能力较深井台强,且受噪声和地铁影响,市区深井台监测能力较低;②整体上,台站密布的松江和青浦地区,地震监测能力较强,最小完整性震级为ML 0.7。台站稀疏的浦东、奉贤、崇明地区,地震监测能力较弱,最小完整性震级为ML 1.3;③若在上海南部增设奉贤海湾台,可整体提高上海测震台网的监测能力。 相似文献
10.
11.
山西地区分区近震走时表的编制与检验 总被引：1，自引：0，他引：1
主要以山西太原、大同、临汾３个遥测台网的记录，结合山西省内及邻省部分台站的地震观测资料，用勘探、爆破与测震方法得出山西地区地壳模型结构。用观测走时与理论走时对比，划分出６个区域，计算出＂山西地区近震走时表＂及＂山西南部地区近震走时表＂。检验结果表明，发震时刻、震中位置及深度等各项参数较Ｊ－Ｂ走时表均有极大的提高。经试用确认其适用于山西地区。 相似文献
12.
完备震级是评估区域地震台网检测能力的一个定量指标,本文采用能反映区域地震台网检测能力的时空分布细节特征的概率完备震级分析方法,对首都圈地震台网的检测能力进行了研究,通过对首都圈2002-2009共8年的地震目录和台站资料的分析处理,得到了首都圈地震台网的完备震级时空分布,据此对台网的检测能力进行了评估,并结合模拟结果探讨了提升台网检测能力的可能性.结果表明：首都圈地震台网的整体检测能力较强,北京地区的检测能力尤其突出,但部分区域检测能力仍有一定的提升空间;模拟结果表明,在东北、西北、西南等位置增加台站可能有助于进一步提高台网的检测能力.相关研究结果可能对未来首都圈地震台网的优化具有参考意义. 相似文献
13.
It is a common opinion that only crustal earthquakes can occur in the Crimea–Black Sea region. Since the existence of deep earthquakes in the Crimea–Black Sea region is extremely important for the construction of a geodynamic model for this region, an attempt is made to verify the validity of this widespread view. To do this, the coordinates of all earthquakes recorded by the stations of the Crimean seismological network are reinterpreted with an algorithm developed by one of the authors. The data published in the seismological catalogs and bulletins of the Crimea–Black Sea region for 1970–2012 are used for the analysis. To refine the coordinates of hypocenters of earthquakes in the Crimea–Black Sea region, in addition to the data from stations of the Crimean seismological network, information from seismic stations located around the Black Sea coast are used. In total, the data from 61 seismic stations were used to determine the hypocenter coordinates. The used earthquake catalogs for 1970–2012 contain information on ~2140 events with magnitudes from–1.5 to 5.5. The bulletins provide information on the arrival times of P- and S-waves at seismic stations for 1988 events recorded by three or more stations. The principal innovation of this study is the use of the original author’s hypocenter determination algorithm, which minimizes the functional of distances between the points (X, Y, H) and (x, y, h) corresponding to the theoretical and observed seismic wave travel times from the earthquake source to the recording stations. The determination of the coordinates of earthquake hypocenters is much more stable in this case than the usual minimization of the residual functional for the arrival time of an earthquake wave at a station (the difference between the theoretical and observed values). Since determination of the hypocenter coordinates can be influenced by the chosen velocity column beneath each station, special attention is focused on collecting information on velocity profiles. To evaluate the influence of the upper mantle on the results of calculating the velocity model, two different low-velocity and high-velocity models are used; the results are compared with each other. Both velocity models are set to a depth of 640 km, which is fundamentally important in determining hypocenters for deep earthquakes. Studies of the Crimea–Black Sea region have revealed more than 70 earthquakes with a source depth of more than 60 km. The adequacy of the obtained depth values is confirmed by the results of comparing the initial experimental data from the bulletins with the theoretical travel-time curves for earthquake sources with depths of 50 and 200 km. The sources of deep earthquakes found in the Crimea–Black Sea region significantly change our understanding of the structure and geotectonics of this region. 相似文献
14.
内蒙古地区场地响应区域特征分析 总被引：2，自引：0，他引：2
本文以内蒙古地区台站分布、地质构造和地震活动性为基础,将内蒙古的大部地区划分为三个研究区域分别进行了场地响应研究。对近几年积累的大量ML≥3.0级以上地震,共计39个台站记录到的124次地震事件的785条波形,根据S波的观测振幅谱,采用遗传算法分别反演了三个区域的介质非弹性衰减系数和台站场地响应,并对其进行了讨论。本文得到的介质衰减模型和台站场地响应,将对台网测定ML震级需要考虑的量规函数、台站校正值等提供重要参考。研究结果表明:除个别台站存在场地放大或缩小的响应外,绝大多数台站的场地响应表现出一定的区域性特征;西部区域(除极个别台站外)对高频存在明显衰减;中东部区域对整个频段的反映都比较稳定;东部区域对整个频段存在明显放大,这与该区域覆盖层厚度大相吻合。 相似文献
15.
O. K. Kedrov E. O. Kedrov N. A. Sergeyeva L. P. Zabarinskaya V. R. Gordon 《Izvestiya Physics of the Solid Earth》2008,44(5):364-380
The dynamic calibration method (DCM), using natural seismicity data and initially elaborated in [Kedrov, 2001; Kedrov et al., 2001; Kedrov and Kedrov, 2003], is applied to International Monitoring System (IMS) stations in Central Asia. The algorithm of the method is refined and a program is designed for calibrating diagnostic parameters (discriminants) that characterize a seismic source on the source-station traces. The DCM calibration of stations in relation to the region under study is performed by the choice of attenuation coefficients that adapt the diagnostic parameters to the conditions in a reference region. In this method, the stable Eurasia region is used as the latter. The calibration used numerical data samples taken from the archive of the International Data Centre (IDC) for the IMS stations MKAR, BVAR, EIL, ASF, and CMAR. In this paper, we used discriminants in the spectral and time domains that have the form and are independent of the magnitude m b and the epicentral distance Δ; these discriminants were elaborated in [Kedrov et al., 1990; Kedrov and Lyuke, 1999] on the basis of a method used for identification of events at regional distances in Eurasia. Prerequisites of the DCM are the assumptions that the coefficient a m is regionindependent and the coefficient b Δ depends only on the geotectonic characteristics of the medium and does not depend on the source type. Thus, b Δ can be evaluated only from a sample of earthquakes in the region studied; it is used for adapting the discriminants D(X i ) in the region studied to the reference region. The algorithm is constructed in such a way that corrected values of D(X i) are calculated from the found values of the calibration coefficients b Δ, after which natural events in the region under study are selected by filtering. Empirical estimates of the filtering efficiency as a function of a station vary in a range of 95–100%. The DCM was independently tested using records obtained at the IRIS (Incorporated Research Institutions for Seismology) stations BRVK and MAKZ from explosions detonated in India on May 11, 1998, and Pakistan on May 28, 1998; these stations are similar in location and recording instrumentation characteristics to the IMS stations BVAR and MKAR. This test resulted in correct recognition of the source type and thereby directly confirmed the validity of the proposed calibration method of stations with the use of natural seismicity data. It is shown that the calibration coefficients b Δ for traces similar in the conditions of signal propagation (e.g., the traces from Iran to the stations EIL and ASF) are comparable for nearly all diagnostic parameters. We arrive at the conclusion that the method of dynamic calibration of stations using natural seismicity data in a region where no explosions were detonated can be significant for a rapid and inexpensive calibration of IMS stations. The DCM can also be used for recognition of industrial chemical explosions that are sometimes erroneously classified in regional catalogs as earthquakes.
相似文献
$D_i = X_i - a_m m_b - b_\Delta \log \Delta $
16.
We assessed the ambient noise level in the Aegean region and analyzed its diurnal variation and its relation to the earthquake detection capability of the Aegean Region Seismic Network (ARSN). We prepared probability density functions (PDFs) for 19 broadband stations in the Aegean region operated by the Earth and Marine Sciences Institute (EMSI) of the Marmara Research Center (MRC) of the Turkish Scientific Research Council (TÜB?TAK). The power spectral densities (PSDs) used to construct PDFs for each station were computed for the periods between ~?0.02 and 180 s. In addition, we generated noise map of the Aegean region for different periods using the PDFs to assess the origin of the noise. We analyzed earthquake activity in the region and found that there are more local events recorded at night than during the day for each station. This difference is strongly related to diurnal variation of background noise level for the period range mostly covering the frequency range for the local events. We observed daytime noise level ~?15 to 20 dB higher than that at the nighttime in high frequencies for almost all stations caused by its proximity to settled areas and roads. Additionally, we observed a splitting peak within the Double Frequency (DF) microseism band; it showed a clear noise increase around the short period DF band at all the stations, decreasing inland. This peak may be related to sea waves locally generated in the Aegean Sea. We also identified a prominent increase related to marble saw companies in some stations’ noise PDFs. 相似文献
17.
An important component of ionospheric plasma irregularity studies in the Indian low latitudes involves the study of the plasma bubbles which produce intense scintillations of the transionospheric satellite signals. Many such plasma bubble induced (FBI) scintillation events were identified while recording 244 MHz signal from the geostationary satellite Fleetsat (73°E) at Delhi (28.6°N, 77.2°E) during March-April 1991. This type of scintillations represents changes in plasma processes. These scintillations are spectrally analyzed using an autoregressive (AR) scheme, which is equivalent to maximum entropy method of spectrum analysis, amenable to extracting optimum spectral content from short data lengths (20–40 s). Each spectrum is assigned a level of detectability using the final prediction error (FPE) derived from the optimum filter order required to resolve the spectrum. Lower detectability together with a higher order filter indicate a higher level of coherence for the plasma irregularities (discrete structures). Consistent patterns for these scintillations emerge from the present analysis as follows: (1) the initial and final phases of a scintillation patch display quasiperiodic oscillations. Their corresponding spectra show dominant (Gaussian shaped) spectral features with detectability levels of –6 dB to –12 dB and requiring a higher order (>6) AR filter for their spectral resolution. These are most likely associated with discrete filament-like or sheet-like plasma structures that exist near the bubble walls. (2) Two main features of the scintillation spectra could be positively associated with the well-developed plasma bubble stage: (a) spectra displaying a power-law process with a single component spectral slope between 1.6 to 3.0. Generally such spectra are resolved with a 2nd order filter and have a 1 dB to 6 dB of detectability. (b) Spectra displaying a double slope, indicating an inner and an outer scale regime for the power-law irregularities. These spectra are resolved with higher order filters (>3 but <7) and possess detectability levels of –1 dB to 3 dB. These spectra display finer spectral changes, perhaps indicative of the nature of continuously evolving plasma irregularities. As an example, an analysis of a single scintillation patch is presented to highlight the geophysical significance of the present approach. Some important parameters used in the AR scheme of spectral analysis are given in the Appendix. 相似文献
18.
利用首都圈数字地震台网接收人工地震信号,进行地下结构研究具有重要意义.但人工震源释放的能量小,激发的地震波以短周期为主,因此本文较全面地研究了地震台网对短周期微弱信号（1～20 Hz）的检测能力：(1) 分析了台网的背景噪声,结果表明基岩台址的地震台噪声比沉积盖层台址的地震台噪声低约13 dB,这相当于近1个震级的检测阈值;夜间的噪声比白天低约5 dB;噪声有逐年增高的趋势,2006年比2001年噪声提高约4 dB.(2 )分析了在台网内进行的药量为25 kg的陆地井下爆破实验,一次爆破相当于0.69级（ML）的天然地震,有18个地震台可辨认爆炸产生的Pg、Pm或Pc波;离爆破点218 km的基岩台,仍可以接收到振幅只有1.6 nm 的Pm波,这个结果可为地震勘探实际工作提供参考.(3) 研究了台网外核爆试验的信号特征,2006年发生在朝鲜的地下核试验是一次检验台网检测微弱信号能力的好机会.波形记录经1～5Hz滤波后,台网中噪声小的18个基岩台可以清晰辨认核爆破产生的P波或Lg波,P波平均振幅为16 nm,计算的平均震级为mb4.3,和NEIC给出的震级相同;分析还表明背景噪声是影响台站信号检测能力的主要因素之一. 相似文献
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中国地震科学台阵第一期(2011—2013年)布设在南北地震带南段,本研究利用中国地震科学台阵布设在云南及相邻地区的部分流动台站记录到的2011年6月至2013年3月的数字地震波形资料,开展地壳各向异性分析.本文使用剪切波分裂系统分析方法(SAM方法),获得了研究区内67个台站的剪切波分裂参数.研究结果表明,受到云南及周边地区复杂的构造、应力环境和纵横交错的断裂分布的影响,该地区快剪切波偏振方向(PAZ)整体上显示出NNE向和NE向的优势取向,但在空间分布上比较复杂,虽然大部分台站的PAZ与构造应力场方向一致,但部分断裂附近台站的PAZ受到断裂的影响.结果显示,本研究区内不同区域的PAZ有一定差异性.本研究划分了5个子区,西部3个不同区域的PAZ从北到南分别为NNW向、近N-S向和NE向,有顺时针旋转的趋势,而东部的2个区域PAZ分别为NEE向和NNW向.研究证实,青藏东南缘地区的地壳各向异性空间分布虽然非常复杂,但大体上与区域内的主压应力的方向和断裂分布相关. 相似文献