波形反演法测量Q值的实验室研究   总被引：2，自引：0，他引：2  

叶林  李伟东  施行觉 《地球物理学进展》2001,16(1):31-38

用波形反演法对杆状样品的实测波形进行了Q值计算，用高Q值金属样品和岩石样品分别进行计算对照的结果表明，该方法具有比较好的可靠性，分析了实验波形的速度频散现象，认为，由衰减引起的速度对数频散在杆波情况下仍然成立，但即使在Q值较小时，对波形的影响也不显著，因此并不会对反演计算结果的可靠性造成太大的影响。  相似文献   

High precision locations of multiplets on south-eastern flank of Mt. Etna (Italy): reconstruction of fault plane geometry     

Salvatore AlparoneSalvatore Gambino 《Physics of the Earth and Planetary Interiors》2003,135(4):281-289

On 9 January 2001, a seismic swarm, located on the south-eastern flank of Mt. Etna and with nearly identical waveforms, caused some damage to Zafferana Etnea village, 3 km from the epicentral area.An analysis of the seismicity occurring in the last 8 years in this area has revealed other earthquakes with the same characteristics; some pre-empted and followed (up to a few months) the 2001 January swarm, others were recorded more than five years beforehand.Using similarity of waveforms, these earthquakes were classified into three families.The use of a multiplet-technique has allowed to obtain the spatial distribution of the events with higher precision (mean error of 10-20 m) with respect to traditional localization techniques.Mt. Etna earthquakes relocation clearly describes the geometry of the seismogenic tectonic structure; the hypocenters lie on a NE-SW oriented plane that is coincident with one of the focal planes obtained by first-arrival polarities. This alignment is also coherent with one of the main regional tectonic trends cutting the Mt. Etna area, and can be interpreted as a right-lateral strike seismic source on the south-eastern flank of Mt. Etna, distant from eruptive centres, which repeats from time to time and is able to produce strong energy releases.  相似文献   

玛曲地区地震活动特征及记录波形特征          下载免费PDF全文

张昱  巴志平  王先  李春森  董宗明 《地震工程学报》2002,24(2):187-189

研究了甘青川交界的玛曲地区1987－2000年之间地震的活动特征以及地震记录波形特征，发现1998年以来的小震群与以前不同，具有发生中强地震的异常背景。  相似文献   

利用乌鲁木齐遥测地震台记录识别人工爆破与地震   总被引：5，自引：0，他引：5  

夏爱国  刘贤伦 《内陆地震》2002,16(4):337-345

选取乌鲁木齐遥测地震台记录的乌鲁木齐市附近人工爆破与天然地震资料 ,运用波谱分析、波形空间线性度等方法作对比研究 ,发现人工爆破与天然地震的波谱特征量和波形空间线性度多数情况下差异较大。在震级与震中距相近的条件下 ,主要差异表现在天然地震的纵、横波拐角频率 fc P和 fc S明显大于人工爆破 ,两者比值约为 2∶ 1 ;天然地震的最大谱值比 Ωm P/ Ωm S也明显大于人工爆破 ,两者比值约为 3∶ 1 ;地震 P波功率谱的频谱特征量 fm W、Δf W也比人工爆破大很多。这些差异可以作为识别人工爆破与天然地震的测震学指标。  相似文献   

非弹性表面波大尺度波形反演（理论和方法）     

李平  朱介寿 《东北地震研究》1997,13(4):41-53

非弹性的表面波大尺度波形反演的理论方法以如下三方面提出的。（１）计算本征值和本征函数可获得第一阶的频散参数，并把体波的复数形式和波能的吸收引入非弹性中，（２）根据弗拉尔和斯奈德的理论方法，计算了非弹性表面波的激发和合成地震图，球阶非弹性用频散的计算按Ｂｉｓｗａｓ－Ｋｎｏｐｐｏｆ公式被变换成平滑的弹性形式，（３）使用自伴微工子导出关于模型参数的波形Ｆｒｅｃｈｅｔ导数，然后应用非线性反演拟合波形。  相似文献   

小波去噪效果评价的另一指标   总被引：4，自引：0，他引：4  

陈强  黄声享  王韦 《测绘信息与工程》2008,33(5)

给出了评价小波去噪效果的平滑度指标,分析了其均方误差、信噪比及平滑度,实现了评定小波去噪的质量.  相似文献   

福建数字地震台网与模拟台网记录的震相差异初析     

薛雪冰 《福建地震》1998,(4)

本文通过对数字台网记录的地震震相和波形的分析,初步比较了模拟台网与数字台网记录波形,认为数字台网地震波震相具有高频成份表现突出,及初动清晰的特点,并对此作了进一步的探讨。  相似文献   

雁列断层变形过程中的声发射特征   总被引：12，自引：4，他引：12  

马文涛  马瑾 《地震地质》1995,17(4):342-348

对拉张型、挤压型雁列断层变形过程中岩桥区和主断层上的声发射特征进行了对比研究，结果表明，雁列断层变形中的声发射对应着多种机制：拉张型雁列岩桥区的声发射为单一事件组成，波振幅小、持续时间短、主频高、震源机制为张裂型；挤压型雁列岩桥区的声发射也是单一事件，波振幅较大、持续时间短、主频较低、震源机制为双剪型；而雁列主干断层上的声发射由多事件组成，波振幅大、持续时间长、主频低、震源机制与挤压型雁列岩桥区的声发射机制不同。这些特点与各区域所处力学状态有关  相似文献   

不需提取激发脉冲的探地雷达波形反演方法   总被引：2，自引：2，他引：0       下载免费PDF全文

周辉  陈汉明  李卿卿  王杰  张庆臣 《地球物理学报》2014,57(6):1968-1976

利用麦克斯韦方程的波形反演方法,能充分利用雷达数据中反映地下介质特性的波形、走时、相位等信息.它要事先已知激发脉冲信号,需从实际资料中提取,但受到诸多因素的影响.本文尝试避免从实际雷达资料提取激发脉冲的方法.首先,借助于一个已知地质模型上的探地雷达系统采集的记录以及给定激发脉冲、给定激发接收天线的正演模拟信号,计算出转换算子.其次,将转换算子作用于实测雷达信号,将其转换成给定激发脉冲激发的、给定激发接收天线采集的信号.最后,用转换后的数据进行波形反演.二维模型数据的转换表明,转换后的数据与正演模拟数据一致,反演结果差异甚小.实验室实测数据的反演结果与实际情况相符.  相似文献   

Misfit functionals in Laplace‐Fourier domain waveform inversion,with application to wide‐angle ocean bottom seismograph data     

Rie Kamei  R. Gerhard Pratt  Takeshi Tsuji 《Geophysical Prospecting》2014,62(5):1054-1074

In seismic waveform inversion, non‐linearity and non‐uniqueness require appropriate strategies. We formulate four types of L2 normed misfit functionals for Laplace‐Fourier domain waveform inversion: i) subtraction of complex‐valued observed data from complex‐valued predicted data (the ‘conventional phase‐amplitude’ residual), ii) a ‘conventional phase‐only’ residual in which amplitude variations are normalized, iii) a ‘logarithmic phase‐amplitude’ residual and finally iv) a ‘logarithmic phase‐only’ residual in which the only imaginary part of the logarithmic residual is used. We evaluate these misfit functionals by using a wide‐angle field Ocean Bottom Seismograph (OBS) data set with a maximum offset of 55 km. The conventional phase‐amplitude approach is restricted in illumination and delineates only shallow velocity structures. In contrast, the other three misfit functionals retrieve detailed velocity structures with clear lithological boundaries down to the deeper part of the model. We also test the performance of additional phase‐amplitude inversions starting from the logarithmic phase‐only inversion result. The resulting velocity updates are prominent only in the high‐wavenumber components, sharpening the lithological boundaries. We argue that the discrepancies in the behaviours of the misfit functionals are primarily caused by the sensitivities of the model gradient to strong amplitude variations in the data. As the observed data amplitudes are dominated by the near‐offset traces, the conventional phase‐amplitude inversion primarily updates the shallow structures as a result. In contrast, the other three misfit functionals eliminate the strong dependence on amplitude variation naturally and enhance the depth of illumination. We further suggest that the phase‐only inversions are sufficient to obtain robust and reliable velocity structures and the amplitude information is of secondary importance in constraining subsurface velocity models.  相似文献