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为了研究利用小当量震源进行远距离探测的可能性，通过现场试验进行了研究.野外实验采用1次大当量激发和16次小当量激发，研究结果表明：①有可能利用数十公斤当量的炸药实现200km距离的探测；②在激发条件相同（或相近）时，不同当量的激发波形滤波后存在一定的相似性；③依据人工震源可重复性采用以下的激发组合方式和处理方法能够有效提高信噪比：针对大当量激发与小当量激发波形的相似性，利用大当量激发的波形作模板与小当量激发的波形作相关，可判断台站是否接受到小当量激发的信号并检测其震相到时信息.针对小当量激发波形的相似性，采用小当量多次激发的方式，通过N次根加权叠加方法，能有效提高记录的信噪比和震相识别精度. 相似文献
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本文基于宾川气枪地震信号发射台激发的地震波信号,利用线性叠加和时频域相位加权叠加方法提高信噪比,通过反褶积、插值拟合和波形互相关等方法,获得2021年漾濞M;6.4地震前后气枪震源初至波信号走时变化特征.结果表明两种叠加方法得到的走时变化趋势基本一致,在沿发震断裂带附近的3个台站观测到的初至波走时延迟为7.3~14.4 ms,在射线路径上平均波速降低了0.08%~0.12%,距离震中位置较远的台站走时延迟为2~6 ms.分析认为,观测到的走时变化主要是漾濞M;6.4地震引起强地面运动造成浅层介质疏松、同震破裂导致震源区地下介质裂隙增加和地下流体侵入等共同作用造成,相关研究成果有助于加深和促进对此次地震震源物理过程的认识和了解. 相似文献
3.
采用叠加、互相关、插值拟合等方法对祁连山气枪主动源台网数据进行处理，针对2016年1月21日青海门源6.4级地震前后气枪激发地震P波、S波震相的走时变化特征进行了分析，结果表明，地震前约6个月时，震中附近3个台站的相对走时出现下降变化（走时减少），至震前约3个月时低值异常恢复正常，之后再次出现走时下降变化，地震即发生于走时变化恢复过程中。S波走时变化最大下降幅度达18ms，震后走时变化逐渐恢复正常，且3个台站变化趋势较为一致，其中，距震中最近的台站的S波走时变化最明显（ZDY38台），较远台站的走时变化幅度较小，其变化特征与震源区位置有关。走时缩短意味着速度增加，可能与区域应力积累间存在一定的关系。 相似文献
4.
Comparative Study on Two Methods for Measuring Wave Velocity Change of Crustal Medium Based on Large Volume Airgun Excitation Data 
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下载免费PDF全文 This paper proposes the application of dynamic programming method to calculate the relative change of wave velocities and compares its similarities and differences with the cross-correlation delay estimation method based on interference. The results show that:①the trend of wave velocities obtained by cross-correlation method and dynamic programming method are consistent. Besides,it is considered that the calculated result using cross-correlation delay method is reliable.② Compared with the cross-correlation delay method,the calculated result of the dynamic programming method has a magnifying effect and is more sensitive to small disturbances.③ Under ideal conditions,the wave velocity change trend calculated by P-wave and S-wave phase should be consistent. In addition,the cross-correlation delay method is used to calculate the wave velocity change.Under appropriate conditions,the process of recovering from the suspected wave velocity before the M_L1. 1 earthquake near the airgun source can be observed. 相似文献
5.
利用南海地区28个陆地地震台站和2个布设于太平岛和东沙岛的新增海岛地震台站2011—2016年间的连续地震背景噪声波形数据,使用互相关方法计算得到了台站间的互相关函数,并提取出Rayleigh面波群速度和相速度频散曲线.采用快速行进和子空间方法反演获得了南海及周边地区12～40s周期的Rayleigh面波群速度和相速度图像,并联合反演得到了研究区深至60km的三维S波速度结构.考虑到南海数千米厚海水层对于面波频散反演的严重影响,本文在反演模型中加入了水层,显著提高了反演结果的可靠性.成像结果表明:南海及周边地区地壳上地幔顶部S波速度结构存在显著的横向不均匀性,并与这一区域的主要构造单元具有较好的空间对应关系.在5～10km深度,莺歌海—宋红盆地区的低速异常特征可能与盆地较厚的沉积层有关.在5～15km深度,海域高速异常区与海盆空间位置具有高度一致性,推测与海盆区地壳厚度相对陆缘区明显偏薄有关.当深度从20km增加至30km,海盆区的高速特征扩展至了陆缘地区,反映了地壳厚度从海盆至陆缘逐渐增厚的趋势,与OBS(海底地震仪)深地震剖面给出的地壳精细结构结果一致.至35～60km深度,海盆的高速异常特征依然明显,且速度值随深度增加整体呈现上升的趋势,推测南海海盆区的岩石圈厚度应该大于60km. 相似文献
6.
地震反演是储层定量描述和地震油气识别的关键技术，反演结果在复杂构造区域的横向连续性和保真性是影响地震资料定量解释精度的重要因素.基于此，本文发展了地震数据互相关驱动的多道反演方法.考虑地层反射系数与地震数据在结构上具有相似性的特点，基于地震数据互相关描述地层反射系数的结构特征，并将其作为多道地震反演的横向约束条件；此外，为改善地震数据本身横向连续性差对反演结果的影响，在目标泛函的惩罚项中引入局部优化算子，构建了一个易于求解的多道地震反演目标泛函.与常规多道地震反演方法相比，本文方法能够设计更合理、更符合实际情况的横向约束算子，提高反演结果的横向连续性，并且能有效降低地震资料质量对反演结果的影响.模型测试和实际应用验证了本方法的可靠性和稳定性. 相似文献
7.
The detection and location of low magnitude earthquakes in northern Norway using multi-channel waveform correlation at regional distances 总被引：1，自引：0，他引：1
Steven J. Gibbons Mathilde Bttger Srensen David B. Harris Frode Ringdal 《Physics of the Earth and Planetary Interiors》2007,160(3-4):285-309
A fortuitous sequence of closely spaced earthquakes in the Rana region of northern Norway, during 2005, has provided an ideal natural laboratory for investigating event detectability using waveform correlation over networks and arrays at regional distances. A small number of events between magnitude 2.0 and 3.5 were recorded with a high SNR by the Fennoscandian IMS seismic arrays at distances over 600 km and three of these events, including the largest on 24 June, displayed remarkable waveform similarity even at relatively high frequencies. In an effort to detect occurrences of smaller earthquakes in the immediate geographical vicinity of the 24 June event, a multi-channel correlation detector for the NORSAR array was run for the whole calender year 2005 using the signal from the master event as a template. A total of 32 detections were made and all but 2 of these coincided with independent correlation detections using the other Nordic IMS array stations; very few correspond to signals detectable using traditional energy detectors. Permanent and temporary stations of the Norwegian National Seismic Network (NNSN) at far closer epicentral distances have confirmed that all but one of the correlation detections at NORSAR in fact correspond to real events. The closest stations at distances of approximately 10 km can confirm that the smallest of these events have magnitudes down to 0.5 which represents a detection threshold reduction of over 1.5 for the large-aperture NORSAR array and over 1.0 for the almost equidistant regional ARCES array. The incompleteness of the local network recordings precludes a comprehensive double-difference location for the full set of events. However, stable double-difference relative locations can be obtained for eight of the events using only the Lg phase recorded at the array stations. All events appear to be separated by less than 0.5 km. Clear peaks were observed in the NORSAR correlation coefficient traces during the coda of some of the larger events; the local stations confirm that these are in fact aftershocks exhibiting very similar waveforms to the main events. Many of the more marginal correlation detections are not made when the calculations are repeated using shorter signal segments, fewer sensors or more distant stations. We demonstrate in addition how these almost repeating seismic sources have been exploited to detect and measure timing anomalies at individual sites within the arrays and network. 相似文献
8.
渤海中部长期流的观测与余流分析 总被引：6，自引：0，他引：6
本文用渤中8号平台长期流观测取得的资料,分析了余流的变化特征。同时,用日平均流与日平均风的互相关函数,探讨了流与风的关系。 相似文献
9.
模板匹配滤波技术(Matched Filter Technique,MFT)是一种近几年发展迅速的可用于检测遗漏信号的算法,在图像识别、行星探测等众多领域均有广泛应用。在地震学中,该技术通过扫描连续波形找出模板事件附近发生的、与模板事件相关性较好的遗漏地震事件,可用于完善地震目录,实现对地震活动性以及区域应力状态的更好刻画。本文综述了模板匹配滤波技术在地震数据处理中的应用,首先概述基本原理,其次介绍该方法用于探测各类地震事件的实例,包括前震和余震、远程动态触发地震、诱发地震和非火山震颤等,最后展望了用于提高算法效率及探测精度的一些改进方法。 相似文献
10.
选取山东省临沂地区的JUN与JUX台站数据资料，运用背景噪声互相关技术计算了2009年1月1日—2011年1月1日台站对间的互相关函数，利用移动窗互谱法计算相对速度变化，并分析其与莒县气象观测站记录的降水和莒南鲁14号井记录的地下水水位变化的关联性。研究结果表明，区域降水呈季节性变化，夏季降水量大，冬季降水量小；地下水水位呈季节性变化，初夏季水位较低，随后水位值逐渐增加，初冬季水位较高，随后水位值逐渐减少；地下介质速度变化亦具有季节性特征，变化幅度约为±0.2%，与水位变化呈一定的负相关趋势，即夏季水位增加、相对速度变化降低，冬季水位减少、相对速度变化升高。 相似文献