共查询到19条相似文献，搜索用时 116 毫秒
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本文以承德地震台VP型宽频带倾斜仪以及同址BBVS-120型宽频带地震计采集的同震波形为研究对象,利用小波分析和短时傅里叶变换的方法,分析二者记录到的6次地震同震波形的时频特征和频带响应,能量集中在0～0.5 Hz,二者的波形曲线形态、频带响应及功率谱密度均有较高的一致性。利用经验公式拟合出宽频带倾斜仪最大振幅与震级二者之间的关系,拟合度较好,得到承德地区宽频带倾斜仪近震和远震最大振幅转换公式。承德地区宽频带倾斜仪与宽频带地震计地震波的最大振幅有较好的对应关系。利用地震波体波震级计算公式,对宽频带倾斜仪和宽频带地震计记录到的地震选取其中的3次地震波计算体波震级,结果表明在地震波频率小于0.5 Hz时,二者计算出的体波震级对应关系较好。
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选取2014—2018年海南五指山形变台DSQ型水管倾斜仪和VP型垂直摆倾斜仪记录的20个地震的同震响应资料,对比分析2套仪器的同震响应特征。结果表明:在震中距相近时,二者响应幅度、同震响应持续时间与震级呈正相关;除少数地震外,在震级相近或相同时,二者地震响应幅度与震中距呈负相关;地震响应延迟时间与震中距有关,二者均呈正相关;对于同一地震,一般VP型垂直摆倾斜仪的最大响应幅度较大,且同震持续时间较长。 相似文献
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利用安康地区3个形变台2017—2020年地形变资料,对比分析6套形变仪器的映震能力,并从面波延迟时间、最大响应幅度及同震持续时间等方面系统探讨同震形变波的特征参数与震源参数的关系,获知形变仪器映震效能的影响因素和同震形变波的物理分布特征。结果表明:形变仪器的映震能力受仪器自身响应特性、地下介质特性及仪器系统误差等因素的影响;同震形变波物理分布特征表明面波延迟时间与震中距、同震响应最大幅度与震级、同震持续时间与震级及震中距之间存在一定的比例关系。 相似文献
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DSQ型水管倾斜仪与VS型垂直摆倾斜仪观测的物理量均为地倾斜,然而两套仪器的观测原理不同。本文从同震响应最大响应幅值、延迟时间和持续响应时间3个方面,对赣州地震中心站DSQ型水管仪与VS型垂直摆记录到的同一次地震的地倾斜响应进行对比分析,结果表明：(1)两种倾斜仪器同震响应持续响应时间与震级大小有一定的正相关性;(2)两套仪器地震响应延迟时间与震中距呈一定的正相关性;(3)由于仪器设计和观测原理不同,使得记录到的同震响应信号有所差异。 相似文献
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选取2013—2015年乌加河地震台水平摆和水管仪记录的13个地震资料,对比分析同震响应特征。分析认为:对于同一地震,水平摆最大响应幅度大于水管仪,且响应延迟时间略小;水管仪和水平摆同震响应持续时间与震级成正比。结果表明,该地震台水平摆和水管仪记录同一地震的最大响应幅度、延迟和持续时间,对远震和近震均具有不同程度的响应。 相似文献
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Guangquan Li 《Geophysical Prospecting》2020,68(3):910-917
Biot theory was based on two ideas: the coupling factor to quantify the kinetic energy of fluid and Darcy permeability to quantify the dissipation function. As Biot theory did not well predict attenuation of ultrasonic S wave, we modify the theory to better characterize the S wave attenuation. The range of the coupling factor is at first estimated in view of fluid mechanics. Application of the original theory to water-saturated Boise sandstone and brine-saturated Berea sandstone shows that the model prediction significantly underestimates the S wave attenuation ultrasonically measured. For this reason, we replace Darcy permeability with variable permeability to improve the fluid momentum equation. The new model yields predictions of phase velocity and the quality factor both close to the ultrasonic measurements. The reason why the improved model is superior to Biot theory is that variable permeability is based on the Stokes boundary layer at the fluid–solid interface, thus accurately quantifying the viscous stress between the two phases. Finally, the length scale of the viscous stress is calculated in the mesoscopic sense. 相似文献
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Wind turbines produce mechanical energy that can propagate to the ground and disturb sensitive measurements such as seismic recordings. The aim of the large‐scale experiment Seismic Monitoring And Research of wind Turbine Induced Emissions (SMARTIE1) at a single wind turbine in Pfinztal (SW Germany) is to understand how wind turbines emit seismic signals under different operating conditions and how these seismic signals propagate through the local subsurface. The main objectives of SMARTIE1 are the investigation of wind turbine induced seismic signals, the characteristics of their propagation behaviour, as well as the radiation pattern of a single wind turbine as defined using particle motions. Moreover, we quantify the emission of the wind turbine induced seismic signals with respect to the wind speed. The combination of the wind turbine's emission into the subsurface and the attenuation behaviour of the seismic signals (ground motion velocity) can be used to estimate protection radii around seismic stations to ensure the recording of seismic signals without noticeable influences of the wind turbines. In this study, we detect several discrete wind turbine induced frequency peaks ranging from 1 to 10 Hz. We identify a radiation pattern of the wind turbine, which could give further insights into the interaction between the movement of the wind turbine's nacelle and the generation of the wind turbine induced seismic signals. Using profile measurements with a maximum distance of almost 3 km each, we fit a power‐law decay for power spectral density proportional to . The attenuation factor, , ranges from 0.7 to 1.3 for lower frequencies between 1 and 4 Hz, and increases to = 2.3 for the higher frequency peak around 5.25 Hz. Finally, we present an example of estimation of a protection radius around the seismic station of the Collm Observatorium that is part of the German Regional Seismic Network. The example protection radius around Collm Observatorium regarding this single wind turbine is reached at a minimum distance of 3.7 km. 相似文献
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本研究分析了2011年3月11日发生的Mw9.0日本东北地区太平洋近海地震对亚洲地区和韩国国内GPS卫星常年跟踪站的位移影响.为此,利用了日本东北地区太平洋近海地震发生前后两周(2011年3月4日到3月18日)的GPS站点数据,包括震中附近地区(韩国,中国,中国台湾地区,日本和俄罗斯)55个GPS卫星常年跟踪站和284个IGS 全球跟踪站,并采用GAMIT/GLOBK软件进行处理和平差,估算出所有GPS站点的同震形变.结果显示,日本东北地区太平洋近海地震引起的同震形变影响在亚洲地区比较明显,包括日本和附近国家,距离震中2702 km的中国武汉(WUHN)站也观测到同震形变.为精确分析日本东北地区太平洋近海地震对韩国国家大地控制网的影响,通过GAMIT/GLOBK软件计算出韩国GPS卫星常年跟踪站之间的基线长度变形,并分析出弹性变形量.结果表明:大部分GPS站点均向震中方向膨胀,且向震中的垂直方向收缩.由日本东北地区太平洋近海地震导致的最大剪应变达到韩国国家大地控制网年均变形率的约7倍,对韩国的地壳产生14.5~57.7 mm的水平位移,并导致韩国国家大地控制网产生弹性变形.因此,在不及时更新维护韩国国家大地控制网的情况下,GPS测量成果将会发生最大20 mm的位置误差. 相似文献
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G.-Akis Tselentis 《Pure and Applied Geophysics》1990,133(3):429-446
A new technique for calculating interstation Green's functions and attenuation coefficients for seismic surface waves is presented.The interstation Green's function is evaluated from the autocorrelation functions of the seismograms, which are obtained from a maximum entropy process.Since a data-invariant time window is not used, the evaluated Green's functions gives reliable information on both the amplitude and the phase spectra of the system.This new technique is compared with other methods by applying them to both synthetic and real data from a path in the Canadian shield. 相似文献
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The attenuation of P- and S-waves in Southeastern Sicily was estimated by applying two different methods in time and frequency domains. We analyzed waveforms from about 290 local events (0.6≤ML≤4.6) recorded at a three-component digital network.By applying the pulse broadening method to the first P-wave pulse, we found an average Qp value of ca. 140. The application of the frequency decay method provided a Qp value of ca. 120, in the low-frequency band (3-9 Hz). Conversely, in the high frequency range (16-27 Hz) the average Qp is significantly larger (ca. 640). The frequency decay method was also applied to S-waves spectra. In the low frequency range (2-5 Hz) the estimated average Qs is ca. 190. As for Qp, also Qs, in the high frequency range (16-27 Hz), is larger (ca. 700). These results evidenced a frequency dependence of both the quality factors Qp and Qs, as commonly observed in tectonically active zones characterized by high degree of heterogeneity. 相似文献
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利用检波点能量与震源能量比值构造衰减系数,研究波场各频率成分在自相关与反褶积两类成像条件中偏移成像的作用.分析检波点能量与震源能量比值分布特征,有利于克服反褶积型成像条件中分母趋于零时计算不稳定现象,也有助于平滑检波点波场与震源波场;检波点能量与震源能量比值超出正常范围容易导致偏移结果中出现照明不均匀现象.本文方法有助于改善反褶积型成像条件的偏移计算,也有助于应用照明技术指导偏移成像结果的振幅校正. 相似文献
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地震危险性分析中的不确定性处理和表征,一直是核电厂厂址地震安全性评价中倍受关注的重要问题,尤其是日本福岛核事故后,无论是确定核电厂厂址的设计基准地震动,还是进行核电厂地震风险评价,都更加重视地震危险性分析中的不确定性.本文通过理论分析重点说明了衰减关系的不确定性,包括标准差和截断水平对核电厂地震安全性评价的影响,并在此基础上,通过算例和讨论说明了概率性方法截断水平的选取问题,探讨了现行确定性方法和概率性方法在截断水平选取上的差异.分析计算结果表明,在地震活动较弱的区域,概率性方法截断水平为3,确定性方法截断水平为0的现行做法是恰当的.但是,对于发震构造大震复发间隔较小的区域,为了使二者在超越概率方面协调,恰当提高确定性方法的截断水平更为合理. 相似文献
