排序方式： 共有31条查询结果，搜索用时 15 毫秒
1.
Some Thoughts on the Earthquake Science Experimental Site——The Underground Cloud Map 总被引：1，自引：0，他引：1
The Western Yunnan Earthquake Predication Test Site set up jointly by the China Earthquake Administration, the National Science Foundation Commission of America, and United States Geological Survey has played an important role in development of early earthquake research work in China. Due to various objective reasons, most of the predicted targets in the earthquake prediction test site have not been achieved, and the development has been hindered. In recent years, the experiment site has been reconsidered, and renamed the “Earthquake Science Experimental Site”. Combined with the current development of seismology and the practical needs of disaster prevention and mitigation, we propose adding the “Underground Cloud Map” as the new direction of the experimental site. Using highly repeatable, environmentally friendly and safe airgun sources, we could send constant seismic signals, which realizes continuous monitoring of subsurface velocity changes. Utilizing the high-resolution 3-D crustal structure from ambient noise tomography, we could obtain 4-D (3-D space + 1-D time) images of subsurface structures, which we termed the “Underground Cloud Map”. The “Underground Cloud Map” can reflect underground velocity and stress changes, providing new means for the earthquake monitoring forecast nationwide, which promotes the conversion of experience-based earthquake prediction to physics-based prediction. 相似文献
2.
GUO Yang XU Jiajun LIN Chen JIN Xing YAO Huajian YANG Hongfeng CAI Huiteng 《中国地震研究》2019,33(2):265-275
112 short-period seismographs were set up in the 400km2 area of Pingtan Island and its surrounding areas in Fujian. The combined observations of the airgun source and ambient noise source were carried out using a dense array to receive the 387 airgun signals excited around the island and one month of continuous ambient noise recording. The 1-D P-wave and S-wave shallow velocity model of Pingtan Island is obtained by the inversion of the airgun body wave''s first arrival time data, and the reliability of the velocity model is verified by using the surface wave phase velocity dispersion curve, which can provide initial model for subsequent 3-D imaging. The experimental results show that this experiment is a successful demonstration of local scale green non-destructive detection, which can provide basic data for shallow surface structure research and strong vibration simulation of the Pingtan Island. 相似文献
3.
以2017年3月27日漾濞5.1级地震为例，根据区域特性和信噪比要求，选取数据较为完整的6个台站记录的2017年1月1日～6月6日期间的宾川地震信号发射台气枪震源波形资料，采用互相关检测技术提取6个台站各自稳定震相的走时数据，并对漾濞5.1级地震前后走时数据的变化情况进行分析。结果表明，漾濞5.1级地震前后6个台站各自稳定震相存在较为明显的走时变化，且短期内走时变化具有较好的同步性，相关台站异常幅度大小和异常出现时间存在细小差异。地震发生前，6个台站走时低值异常过程明显，以YUL台最为显著。地震发生前后走时变化形态特征为双“V”型，漾濞5.1级地震发生在第1个“V”型末端。地震发生后，不同方位相关台站受地震的影响程度不同，走时波动大小存在差异。 相似文献
4.
5.
大容量气枪震源子波时频特性及其影响因素 总被引：3，自引：3，他引：0
通过分析福建街面水库气枪实验的近场水听器记录，研究气枪子波时频特性及其受沉放深度和工作压力的影响，并结合气泡模型解释气泡振荡过程。数据分析表明：①气枪子波由主脉冲和气泡脉冲组成。主脉冲振幅大，持时短，频带宽，通常应用于浅部探测;气泡脉冲能量集中在低频段，垂直穿透深，水平传播远，通常应用于深部探测。②随沉放深度的增加，主脉冲振幅变化很小，气泡脉冲振幅增加，初泡比减小，气泡周期减小，低频段主频增加。沉放深度为10m时，主脉冲振幅和初泡比最大，可应用于浅部探测；沉放深度为25m时，气泡脉冲振幅很大，初泡比最小，可应用于深部探测。③工作压力增加时，主脉冲振幅、气泡脉冲振幅、初泡比、气泡周期等随之增大，低频段主频则减小。 相似文献
6.
为了研究气枪激发信号的波场,本文利用谱元法对双相介质中波的传播做了数值模拟,分析了波的传播特征.本文主要做了以下工作:(1)研究了使用谱无法(SEM)模拟孔隙弹性介质中波的传播,模拟结果表明,采用谱元法能有效解决双相介质的波场传播模拟问题.(2)验证了Biot理论中慢纵波的存在.双相介质中存在明显的慢纵波,流相波场的慢... 相似文献
7.
8.
Based on the data synthesis simulation and the actual processing of the airgun seismic source signal, three quantitative indicators of signal-to-noise ratio, waveform correlation coefficient and phase offset, are superimposed. We systematically evaluate the functions of the following three stack methods including linearity, phase weighting and S-transform in the extraction of weak signals under strong background noise and quantitatively estimate the reliability of the stack results. Through the comprehensive discussion of the above three methods of stack results, the preliminary comparative analysis believes that the linear stack signal-to-noise ratio is low, but the waveform distortion is minimal; the phase-weighted superimposed signal-to-noise ratio is high and the phase offset is small, but the results of the waveform quality and linear stack are larger than the deviation; the S-transform stack has a relatively higher signal-to-noise ratio and a small loss of waveform amplitude, but there is a certain phase shift phenomenon. It is therefore suggested that linear stack technology should be used when the requirements of both waveform quality and time precision are high. However, the selection of the stack method when the airgun source excitation is limited should be emphasized. If high fidelity is required, the S-transform stack method should be selected; if the required time is high, accuracy can be selected by phase-weighted stack method to achieve reasonable extraction of weak signals. 相似文献
9.
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
10.
Regional Scale Seismological Investigation on the Continent Crust Using Airgun Sources——A Perspective Review 总被引：1，自引：1，他引：0
The investigations on the structure and temporal variations of the continent crust have been the long-lasting topics of seismology. The artificial sources play the most important role in these studies for their well-known locations and occur times among all the sources producing elastic waves, so that precise results are obtained. In past decades, we have successfully excited the airgun sources in on-land water bodies such as reservoirs, expanding their applications in marine seismology. Large volume airguns have been used to produce low frequency signals which can travel hundreds of kilometers after stacking, providing a source connecting the exploration seismology and traditional seismology at regional scale. In this review, we introduce the changes through which we turn the airgun into scientific instruments by experiments. We also present the advances on imaging the continental crust structure and monitoring the velocity variations using the highly repeatable signals emitted by airgun sources. The potential applications such as imaging the subsurface of urban areas and high resolution illuminating of mines are proposed and the challenges for further investigations are also discussed. 相似文献