共查询到20条相似文献，搜索用时 125 毫秒
1.
M. Stupazzini J. de la Puente C. Smerzini M. Kaiser H. Igel A. Castellani 袁美巧 《世界地震译丛》2010,(2):54-71
在19和20世纪,地震观测者主要记录地震引起的平移波场,而缺乏对旋转运动的观测和研究。我们的目的是进一步认识地面旋转运动及其与平移波场的关系,着重研究离震源几个波长的近场,在那里可能需要考虑与旋转运动有关的破坏。通过收集大量已公布的强旋转运动数据,得到了一幅包括可获得的旋转振幅及其变化值的基本图件。为了得到更加详细的图件,我们对在格勒诺布尔谷发生的一个走滑型地震进行了大规模的三维数值研究,通过对那里的地形、震源和场地效应相结合,从而产生了逼真的波场。根据旋转和平移的峰值振幅,以及它们与土壤非线性和震源方向性这两个影响因素的关系,分析了合成数据集。在软土层上测得MW6.0级地震的峰值旋转运动量是1mrad,峰值旋转速率是10mrad/s。这些值很大程度上依赖于震源位置、场地条件和地形特征,这些因素会导致20km内的值发生几乎一个数量级的变化。最后,我们利用峰值地面速度(PGV)和峰值地面旋转量(PGω),对数值模拟的结果和类似条件下通过台阵技术得到的野外资料(帕克菲尔德)进行对比,以研究浅源中等大小地震在近场所预期的平移与旋转运动振幅的关系。我们的数值模拟的结果与过去研究中的观测值拟合良好。再有,PGV/PGω比值的空间变化呈现出一个趋势,而这个趋势与研究所选择模型的速度结构有关。 相似文献
2.
《地球物理学进展》2020,(2)
旋转地震学是一门全面研究由地震、爆破以及周围环境震动引发的地面旋转运动的新兴学科.随着观测水平的提高及旋转运动研究的深入,旋转运动研究的重要性也逐渐突显出来.目前国际上对于旋转地震学研究较多,而中国大陆地区鲜有文章提及旋转运动观测.本文从3个方面对旋转运动观测进行描述.首先基于经典弹性力学,介绍了旋转运动的基本理论,表明可以通过直接、间接的两种方法获得旋转量.其次介绍了旋转运动观测进展,表明观测技术的发展对旋转运动的观测具有重要影响.最后考虑到中国台湾是旋转运动观测研究较早并且较为深入的地区,重点介绍了中国台湾地区的观测实例.本文对旋转运动观测进展进行梳理,期望对国内开展旋转地震学观测及研究提供一定的帮助. 相似文献
3.
受仪器限制,地面旋转运动直到过去10年才被观测到。日本对地震近场旋转的观测(Takeo,1998)表明,地面旋转运动是经典弹性理论估计值的很多倍。由于利用类似Takeo所用的旋转传感器没有得到有价值的地面旋转运动,于是我们在台湾东部HGSD台站布设了灵敏得多的旋转速度传感器(R-1型)。在2004年12月7日至2006年11月12日的一期观测实施期间共记录到数百个地震。这主要是解决野外观测问题的一次实习;一期观测最终因其中两台R-1传感器停止工作而结束。2007年春我们重新安装了K2+R1型仪器,从而开展了二期观测。从2007年5月8日到2008年2月17日,我们观测了52个地方震,记录到信噪比～5的好的旋转速度信号和信噪比～10的极好的平移加速度信号。可惜的是,2008年2月中旬HGSD台站被洪水淹没,野外观测由此中断,一直到2008年6月才恢复正常观测。本文叙述了迄今为止HGSD台站对地面旋转和平移运动的观测,集中描述了我们的仪器和二期观测期间所得到的52个地方震的数据,并给出一些很初步的结果。 相似文献
4.
旋转地震学是一门全面研究由地震、爆破以及周围环境振动引发的地面旋转运动的新兴学科。对于它的研究不仅有助于物理学家利用地面观测台开展天体源激发引力波(爱因斯坦在1961年曾预言)的探测研究,同时对广泛的地球物理学(包括:强地面运动地震学、宽频带地震学、地震工程学、地震物理学、地震仪表设备、地震灾害、地震构造、大地测量学)的研究也具有重要的指导意义。本专辑引论包括3个方面的内容:(1)某些背景信息;(2)与本专辑有关的最新事件的概述;(3)对51篇文章的综述(包括27篇论文、11篇短文、4篇综述、6篇教材、3篇补充材料)。本文对51篇文章的综述很简短,只对其内容作了简要说明。本专辑中的文章表明:研究地震运动时,不仅要测量平移运动的三分量,同时也应该对旋转运动的三分量以及应力的多分量进行研究;研究地震运动的最佳场地应选择在大震近场(距地震断裂带25km以内),因为那里的非线性岩石及土壤响应对地动的影响较复杂。 相似文献
5.
在日本伊豆半岛的伊东近海1998年4月震群期间,我们在近场地区观测到了地面旋转和平移运动的6个分量。为了检验我们使用MotionPack传感器观测结果的可靠性,我们安装了8301F传感器,即灵敏度比MotionPack传感器高的惯性角位移传感器。MotionPack的噪声水平远高于8301F的噪声水平,但这些信号分量的波形却相互相当相似,说明MotionPack记录旋转速率正确,但噪声较高。我们的观测使人们知道了垂直轴周围最大旋转位移和最大平移速度之间的线性相关。围绕垂直轴旋转运动的波形与平移水平速度的波形类似,说明最大值之间线性相关。这些旋转运动远大于由圣安德烈斯断层台阵数据计算的旋转运动。这种大差异可由下列一种或一种以上作用来解释:单一回转仪测量和台阵观测所得旋转运动空间尺度的差异;记录伊东近海震群的台站受陡峭地形的影响;圣安德烈斯断层和伊东近海震群区之间成熟度的差异。 相似文献
6.
7.
对日本(Takeo,1998)和台湾地区(Huang et al,2006;Liu et al,2009)的地震近场测量显示,地面旋转运动的测量值比经典弹性理论得到的预期值高出很多倍。为了在地震学和地震工程学层面上研究近场地震的细节,台湾气象机构(CWB)在台湾嘉义中正大学布设了4套仪器,正在监测一个多世纪前的1906年曾发生过大地震的梅山活断层的地面旋转和平移运动。这次观测布设的仪器是:(1)在自由场地32个测点的地震台阵;(2)在大楼内32个测点的地震台阵;(3)带有宽频地震计和加速度计的6通道仪器;(4)带有加速度计和外设旋转速度传感器的6通道仪器。本文是有关该台阵布设的进展报告。虽然从2007年12月12日到2008年7月3日,所布设的4套仪器中的一套或多套已记录到24次近震,但我们仍在对设备进行升级,改善现场观测。 相似文献
8.
2008年11月10日在青海柴达木盆地北缘发生了大柴旦M_W6.3地震,为了研究该地震的区域地震波传播与地面运动特征,本文利用地质资料和地壳速度结构研究成果,构建了柴达木盆地及周边区域三维传播介质模型,采用有限差分方法模拟了大柴旦地震波场传播过程以及地面运动分布特征.结果表明,柴达木盆地对波场传播有明显影响,表现为地震波传入盆地后在边界产生次生面波,盆地沉积物对地震波具有围陷作用,地震地面运动在盆地内振幅增大、持时延长.模拟结果给出的地震地面运动峰值速度分布以及理论地震图均和观测结果符合较好,反映数值模拟较好地给出了观测地面运动的主要特征以及传播介质模型的合理性. 相似文献
9.
本文通过南黄海地震的经验教训,并根据我国海岸线长、海域大、滨海省市多、海洋地震活动频繁的实际情况,概述了海洋地震学研究的重要性;指出海洋地震学研究的主要任务就是以研究海底的构造和运动为主要课题,进而研究地球的构造、运动,乃至地震成因、地球起源等;分析了在我国开展海洋地震学研究的有利因素。最后对如何开展海洋地震学研究提出了几点设想性意见。 相似文献
10.
七十年代以来,许多地震学家用不同的方法更为细致地研究了全球及区域的地下构造,使得地震CT技术迅速发展.其中包括利用地震面波的工作,在地震面波的研究手段上,当前主要有纯路径法,球谐函数法,富氏?数法等.Francis T. Wu(1972)利用纯路径法研究了海洋、大陆、洋脊、岛弧等纯区域的地瑞利面波的频散,得出洋脊速度低于海洋,海洋低于大陆的结果.Ickiro Nakaniski和 D. L. Anderson(1982)采用球谐函数法研究?全球范围的周期为100-300秒的大圆路径瑞利面波的群速度分布.并将周期为100-200秒的结果与纯路 相似文献
11.
12.
地震面波产生的地震动转动分量研究 总被引：7，自引：0，他引：7
本文利用弹性波动理论对地面转动分量，即瑞利（Rayleigh)波和乐夫（Love)波产生的转动分量进行了研究，给出了相应的计算公式和计算方法，特别注意到面波的散射效应对转动分量的影响，并将这一特性引入到转动分量的求取中，使问题的解决更切合于实际，最后选取实际地震记录，利用得到的公式计算出地震面波产生的转动分量。 相似文献
13.
By exploiting the capability of identifying and extracting surface waves existing in a seismic signal, we can proceed to estimate the angular displacement (rotation about the horizontal axis normal to the direction of propagation of the wave; rocking) associated with Rayleigh waves as well as the angular displacement (rotation about the vertical axis; torsion) associated with Love waves.For a harmonic Rayleigh (Love) wave, rocking (torsion) would be proportional to the harmonic vertical (transverse horizontal) velocity component and inversely proportional to the phase velocity corresponding to the particular frequency of the harmonic wave (a fact that was originally exploited by Newmark (1969) [15] to estimate torsional excitation). Evidently, a reliable estimate of the phase velocity (as a function of frequency) is necessary. As pointed out by Stockwell (2007) [17], because of its absolutely referenced phase information, the S-Transform can be employed in a cross-spectrum analysis in a local manner. Following this suggestion a very reliable estimate of the phase velocity may be obtained from the recordings at two nearby stations, after the dispersed waves have been identified and extracted. Synthesis of the abovementioned harmonic components can provide a reliable estimate of the rocking (torsional) motion induced by an (extracted) Rayleigh (Love) wave.We apply the proposed angular displacement estimation procedure for two well recorded data sets: (1) the strong motion data generated by an aftershock of the 1999 Chi-Chi, Taiwan earthquake and recorded over the Western Coastal Plain (WCP) of Taiwan, and (2) the strong motion data generated by the 2010 Darfield, New Zealand earthquake and recorded over the Canterbury basin. The former data set is dominated by basin-induced Rayleigh waves while the latter contains primarily Love waves. 相似文献
14.
By now, it is well known that long‐period surface waves can induce resonant response in high‐rise buildings, in particular those located in sedimentary basins. Rayleigh wave passage has been reported to induce rocking motion at the base of the buildings which can increase displacement demands significantly. However, the building behavior to base rocking has not been extensively studied because commercially available instruments do not record rotational components of ground motion, and thus, rocking time histories have not been available to the analysts. In a recent study, we proposed an effective method for estimating the rocking associated with Rayleigh waves, which takes into account their frequency‐dependent phase velocities. In the present work, we select a number of recorded seismic motions which include surface waves on sedimentary basins from recent well‐recorded earthquake events. Then, we proceed to identify and extract the recorded surface waves by using the technique mentioned above. Using realistic soil‐structure analytical models that have been proposed in the published literature for high‐rise buildings, we study their response to Rayleigh waves as they respond to both translational and rocking motions. Of particular interest is to compare the response of such structures with and without the presence of rotational motions due to surface waves. Using the roof displacement and the building interstory drift as response quantities, our results indicate that demands are controlled by rotational (rocking) motions associated with Rayleigh waves. 相似文献
15.
Crustal structure beneath Liaoning province and the Bohai Sea and its adjacent region in China based on ambient noise tomography 
下载免费PDF全文
下载免费PDF全文 The velocity structure of the crust beneath Liaoning province and the Bohai sea in China was imaged using ambient seismic noise recorded by 73 regional broadband stations. All available three-component time series from the 12-month span between January and December 2013 were cross-correlated to yield empirical Green's functions for Rayleigh and Love waves. Phasevelocity dispersion curves for the Rayleigh waves and the Love waves were measured by applying the frequencytime analysis method. Dispersion measurements of the Rayleigh wave and the Love wave were then utilized to construct 2D phase-velocity maps for the Rayleigh wave at8–35 s periods and the Love wave at 9–32 s periods,respectively. Both Rayleigh and Love phase-velocity maps show significant lateral variations that are correlated well with known geological features and tectonics units in the study region. Next, phase dispersion curves of the Rayleigh wave and the Love wave extracted from each cell of the 2D Rayleigh wave and Love wave phase-velocity maps,respectively, were inverted simultaneously to determine the3 D shear wave velocity structures. The horizontal shear wave velocity images clearly and intuitively exhibit that the earthquake swarms in the Haicheng region and theTangshan region are mainly clustered in the transition zone between the low-and high-velocity zones in the upper crust, coinciding with fault zones, and their distribution is very closely associated with these faults. The vertical shear wave velocity image reveals that the lower crust downward to the uppermost mantle is featured by distinctly high velocities, with even a high-velocity thinner layer existing at the bottom of the lower crust near Moho in central and northern the Bohai sea along the Tanlu fault, and these phenomena could be caused by the intrusion of mantle material, indicating the Tanlu fault could be just as the uprising channel of deep materials. 相似文献
16.
Nguyen Dinh Pham Bor-Shouh Huang Chin-Jen Lin Tuan-Minh Vu Ngoc-Anh Tran 《Journal of Seismology》2012,16(4):709-720
High-frequency rotational motions of P-waves and coda waves were analysed using rotation rate sensors and strong motion array data from the 4 March 2008 TAiwan Integrated GEodynamics Research (TAIGER) explosion experiment in northeastern Taiwan. Theoretical and observational investigations focussed on the effects of this experiment on the free surface. The main goal of this study was to explore possible applications of combined measurements of artificial explosion-derived translational and rotational motions. Also investigated was the consistent ground rotation observed directly by rotation rate sensors and derived using translational seismic arrays. Common near-source high-frequency rotational motion observations and array-recorded translational motions from one shallow borehole explosion are analysed in this study. Using a half-space assumption of plane P-wave propagation across the recording site, we conclude that: (1) rotational motions induced by direct P-waves interacting with a free surface in theory can be used to estimate wave radial direction, velocity and anisotropic properties; (2) rotational motions derived from scattering are predominant among the observed rotations during the TAIGER explosion experiments and allow us to image the heterogeneous structure of the medium at the investigated site; and (3) rotation sensor measurements undertaken during TAIGER explosion experiments may be affected by cross-axis sensitivities, which need to be considered when using the data obtained during these experiments. 相似文献
17.
We estimate Love wave empirical Green's functions from cross-correlations of ambient seismic noise to study the crust and uppermost mantle structure in Italy.Transverse-component ambient noise data from October 2005 through March 2007 recorded at 114 seismic stations from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) national broadband network,the Mediterranean Very Broadband Seismographic Network (MedNet) and the Austrian Central Institute for Meteorology and Geodynamics (ZAMG) yield more than 2 000 Love wave group velocity measurements using the multiple-filter analysis technique.In the short period band (5-20 s),the cross-correlations show clearly one-sided asymmetric feature due to non-uniform noise distribution and high local activities,and in the long period band (20 s) this feature becomes weak owing to more diffusive noise distribution.Based on these measurements,Love wave group velocity dispersion maps in the 8-34 s period band are constructed,then the SH wave velocity structures from the Love wave dispersions are inverted.The final results obtained from Love wave data are overall in good agreement with those from Rayleigh waves.Both Love and Rayleigh wave inversions all reveal that the Po plain basin is resolved with low velocity at shallow depth,and the Tyrrhenian sea is characterized with higher velocity below 8 km due to its thin oceanic crust. 相似文献
18.
采用与作者2014年发表的“大别-苏鲁及其邻近地区基于背景噪声的勒夫波群速度成像”文章相同的资料,用频时分析提取5 000余条瑞雷波和4 000余条勒夫波相速度频散曲线,反演得到了8—32 s的瑞雷波和勒夫波相速度分布图像．结果显示,瑞雷波与勒夫波相速度分布具有很好的一致性．8 s的相速度分布与地表构造特征相吻合,造山带与隆起区均表现为高速,盆地因其规模不同而显示不同程度的低速．随着周期的增大,大别 苏鲁的高速带由强变弱,但始终存在．16—24 s的高速可能主要受到中地壳高速的控制,而32 s的高速则可能与上地幔顶部的高速有关．比较大别造山带与苏鲁造山带的平均频散曲线,发现大别造山带和苏鲁造山带的勒夫波频散曲线均高于AK135模型计算的理论频散曲线,而瑞雷波则没有这一现象. 这可能意味着两个地区有比较强烈的径向各向异性． 相似文献
19.
本文利用中国数字地震台网位于东北地区的122个宽频地震台站的18个月记录的三分量连续地震噪声数据,采用互相关方法提取了Rayleigh和Love波经验格林函数,并利用时频自动分析技术获取了相应的相速度频散曲线.通过反演频散曲线,获得了Rayleigh和Love波周期为8~35s的二维相速度分布.结果表明,东北地区相速度的分布存在横向和垂向的不均匀性.短周期的相速度分布同地表地质构造密切相关,松辽盆地及山间沉积盆地呈现低速异常,而大兴安岭、小兴安岭及东部的一些山岭显示高速异常.随着周期的增加,位于中间的松辽盆地变为高低速相间,两侧的造山带呈现低速异常.这种异常的转变,可能是受构造活动或者莫霍面深度的影响.另外,在周期为20~35s频段内,Rayleigh和Love波同一周期的相速度在松辽盆地和位于吉林地区的郯庐断裂带表现不一致,表明可能存在径向各向异性. 相似文献
20.
Examining ambient noise using colocated measurements of rotational and translational motion 总被引：1，自引：0，他引：1
Celine Hadziioannou Peter Gaebler Ulrich Schreiber Joachim Wassermann Heiner Igel 《Journal of Seismology》2012,16(4):787-796
In the past decade, a number of studies have reported the observation of rotational motion associated with seismic events. We report a first observation of rotational motion in the microseismic ambient noise band. A striking feature of rotational motion measurements is that the information about the seismic phase velocity and source back azimuth is contained in the amplitude ratio of a point measurement of rotation rate and transverse acceleration. We investigate the possibility of applying this method to ambient noise measured with a ring laser and a broadband seismometer at the Wettzell Geodetic Observatory in Germany. Using data in the secondary microseismic band, we recover local phase velocities as well as the back azimuth of the strongest noise source for two different time periods. In order to confirm these findings, we additionally compare the results with classical array processing techniques of the Gr?fenberg array located nearby. 相似文献