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An Experimental Study on Optimization of Large-volume Airgun Source Excitation Conditions in a Reservoir

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earthquake research in China 2016年第3期30卷 355-363页

作者： Chen Huifang Lin Binhua Jin Xing Wu Lihua Cai Huiteng earthquake Administration of Fujian Province Fuzhou 350003 China Institute of Engineering Mechanics China Earthquake Administration Harbin 150080 China

Through manual pickup of seismic phases,the number of recording stations,the farthest observation distance of station and received energy are determined,then optimal operating condition processing software is developed to evaluate the excitation effect of operating conditions. The optimal operating conditions in the Mianhuatan Reservoir are determined using this software. They are: optimal water depth 25 m,airgun array sink depth 9m and airgun array size 7m × 7m. At the same time,accumulative stacking results for every 10 times are analyzed for 300 fixed-point excitations. It is concluded that the excitation effect shows a rapidly rising trend at 10 to 90 times stacking,a slowly rising trend at 100 to 150 times stacking,a rapidly rising trend at 160 to 240 times stacking,and a slowly rising trend at 250 to 300 times stacking. As the number of stacking increases,the propagation distance and the number of recording stations also increase gradually.

关键词： Optimum operating condition Stacking analysis Excitation effect Observation distance

Drift Control Technology Using Wire-Suspension for the Airgun Source Platform in Qilian Mountain

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earthquake research in China 2016年第3期30卷 464-469页

作者： Zhang Yuansheng Zou Rui Yan Wenhua Lanzhou Institute of Seismology CEA

There are several key issues in dynamic monitoring of subsurface structures,such as signal-to-noise ratio( SNR),repeatability of seismic sources and accurate measurement of velocity. Using a large volume airgun source,we constructed a high-performance active system which mainly consists of airgun excitation and signal reception. In order to reduce the platform drift from the shot position,we put forward the platform drift control technique. Experimental results show that the technique can effectively solve the problem of platform drift from the set position under fluid impact after airgun excitation. The results of this study can be a reference for repeated airgun source detection at certain excitation sites.

关键词： Active source large volume airgun Platform drift Repeatability

Seismic airgun exploration of continental crust structures

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Science China Earth Sciences 2017年第10期60卷 1739-1751页

作者： CHEN Yong WANG BaoShan YAO HuaJian School of Earth Sciences and Engineering Nanjing University Nanjing 210046 China Institute of earthquake Science China Earthquake Administration Beijing 100036 China Key Laboratory of Seismic Observation and Geophysical Imaging Institute of Geophysics China Earthquake Administration Beijing 100081 China Laboratory of Seismology and Physics of Earth's Interior School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China National Geophysical Observatory at Mengcheng University of Science and Technology of China Hefei 230026 China

The active sources generate seismic waves transmitting appropriate through the deep is underground key and can be used to image Abstract high-resolution subsurface ***,an seismic source the factor to active source *** order to study the structure of continental crust and its temporal variations,we selected an artificial seismic source generated from releasing air bubbles in water(airgun source hereinafter)out of a variety and of artificial sources like the is explosion,new electronic sparkers,source hammering,eccentric proven vibration,be heavy-duty train vibration,vibroseis *** Three source Fixed a type of artificial that have been to environmentally friendly,safe,and highly *** western Signal China Transmission and Stations(FASTS)have been for built a few years ago in Yunnan,Xinjiang,and Gansu provinces in have been continuously them running several *** waves generated away by the the airgun sources are highly seismic reproducible waves and stacking in of can produce can good seismograms on 1300 stations km far from source,for instance,an produced Xinjiang FASTS be well about recorded 60 nearly away after 5000 stacking,China covering area of 6 million km2 and penetrating down to of a depth of *** about 10 FASTSs in would enable long-term illuminate continuous subsurface underground structures,monitoring can all 9.6 million km2 of land *** from airgun sky active sources as lanterns to we achieve the situation with"Beidou surveys the and lantern illuminates underground".

关键词： Continental crust structure Airgun Green Environmental protection Seismic surveys

Review of the research of the 2011 Mw9.0 Tohoku-Oki earthquake

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earthquake research in China 2017年第3期31卷 309-333页

作者： Shao Zhigang Wang Peng Li Haiyan Institute of earthquake Science China Earthquake AdministrationBeijing 100036China

On March 11,2011, a M_W9.0 earthquake occurred in the Japan Trench, causing tremendous casualties,and attracting extensive concern. Based on the results of related research,this paper analyzes the observations,phenomena and understandings of the earthquake from varied aspects,and obtains four main conclusions.(1) The earthquake,occurring in the subduction zone in the Japan Trench located in the northwest boundary of the pacific plate has two zones of concentrated coseismic slip at different depths,and the slip in the deep zone is relatively small. Though there have been many M7. 0 historical earthquakes,slips in the shallow zone are large,but there have been few historical strong earthquakes.(2) Constrained by GPS data,the study of fault movement shows that fault movement in the Japan Trench has a background of widely distributed stability and locking( the locking zone is equivalent that of coseismic rupture zone). Perturbation occurred after the 2008 M8. 0 Hokkaido earthquake,several M7. 0 events had after slips larger than the coseismic slip,and two obvious slow slip events were recorded in 2008 and2011. Eventually,the March 9,2011 M7. 0 foreshock and the March 11,2011 M_W9.0 mainshock occurred. The pre-earthquake changing of the fault movement in the Japan Trench is quite clear.(3) Traditional precursory observation show no obvious anomaly,possibly due to monitoring reason. Anomaly before earthquake consists of high stress state in focal zone reflected by some seismic activity parameters,short period anomaly in regional ground motion,etc.(4) The analysis of physical property in focal zone aroused more scientific issues,for example,is there obvious difference between physical property in focal zone and its vicinity? Does frictional property of fault determine seismogenic ability and rupture process? Whether pre-earthquake fault movement include pre-slips? Could deep fluid affect fault movement in focal zone? Experience is the best teacher,and authors hope this pap

关键词： The 2011 Mw9.0 Japan earthquake earthquake prediction Seismic monitoring earthquake research

Shear-wave splitting beneath Yunnan area of Southwest China

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earthquake Science 2012年第1期25卷 25-34页

作者： Yutao Shi Yuan Gao Youjin Su Qiong Wang Institute of Geophysics China Earthquake AdministrationBeijing 100081China Institute of earthquake Science China Earthquake AdministrationBeijing 100036China earthquake Administration of Yunnan Province Kunming 650041China

Systematic analyses of seismic data recorded by the Yunnan regional seismograph network reveal significant crustal and upper mantle anisotropy. Splitting of the S phase of local earthquakes and teleseismic SKS, PKS, and SKKS phases indicates time-delays from 1.60 ms/km to 2.30 ms/km in the crust, and from 0.55 s to 1.65 s in the upper mantle which corresponds to an The polarization orientations of fast shear waves in direction, and the mantle anisotropy has a nearly styles and mechanisms exist between the crust and anisotropic layer with a thickness about between 55 165 km. the crust are complicated with a predominantly north-south west-east direction. Our results show different deformation upper mantle.

关键词： seismic anisotropy polarization orientation principal compressive stress shear wave SKS, PKS and SKKS

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

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earthquake Science 2015年第1期28卷 59-69页

作者： Huajian Yao Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of China National Geophysical Observatory at Mengcheng

Seismic anisotropy provides important constraints on deformation patterns of Earth＇s material. Rayleigh wave dispersion data with azimuthal anisotropy can be used to invert for depth-dependent shear wavespeed azimuthal anisotropy, therefore reflecting depth-varying deformation patterns in the crust and upper mantle. In this study, we propose a two-step method that uses the Neighborhood Algorithm （NA） for the point-wise inversion of depth-dependent shear wavespeeds and azimuthal anisotropy from Rayleigh wave azimuthally anisotropic dispersion data. The first step employs the NA to estimate depth- dependent Vsv （or the elastic parameter L） as well as their uncertainties from the isotropic part Rayleigh wave dispersion data. In the second step, we first adopt a difference scheme to compute approximate Rayleigh-wave phase velocity sensitivity kernels to azimuthally anisotropic parameters with respect to the velocity model obtained in the first step. Then we perform the NA to estimate the azimuthally anisotropic parameters Gc/L and Gs/L at depths separately from the corresponding cosine and sine terms of the azimuthally anisotropic dispersion data. Finally, we compute the depth-dependent magnitude and fast polariza- tion azimuth of shear wavespeed azimuthal anisotropy. The use of the global search NA and Bayesian analysis allows for more reliable estimates of depth-dependent shear wavespeeds and azimuthal anisotropy as well as their *** illustrate the inversion method using the azimuthally anisotropic dispersion data in SE Tibet, where we find apparent changes of fast axes of shear wavespeed azimuthal anisotropy between the crust and uppermost mantle.

关键词： Azimuthal anisotropy Shear wavespeed Rayleigh wave Neighborhood Algorithm

Study on the Deconvolution Method and Processing Flow of Airgun Source Data

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earthquake research in China 2016年第3期30卷 394-404页

作者： Zhai Qiushi Yao Huajian Wang Baoshan School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China Mengcheng National Geophysical Observatory Bozhou 233527 Anhui China Key Laboratory of Seismic Observation and Geophysical Imaging Institute of Geophysics CEA Beijlng 100081 China

With its high repeatability,the airgun source has been used to monitor the temporal variations of subsurface structures. However,under different working conditions,there will be subtle differences in the airgun source signals. To some extent,deconvolution can eliminate changes of the recorded signals due to source variations. Generally speaking,in order to remove the airgun source wavelet signal and obtain the Green's functions between the airgun source and stations,we need to select an appropriate method to perform the deconvolution process for seismic waveform data. Frequency domain water level deconvolution and time domain iterative deconvolution are two kinds of deconvolution methods widely used in the field of receiver functions,etc. We use the Binchuan( in Yunnan Province,China) airgun data as an example to compare the performance of these two deconvolution methods in airgun source data processing. The results indicate that frequency domain water level deconvolution is better in terms of computational efficiency;time domain iterative deconvolution is better in terms of the signal-to-noise ratio( SNR),and the initial motion of P-wave is also clearer. We further discuss the sequence issue of deconvolution and stack for multiple-shot airgun data processing. Finally,we propose a general processing flow for the airgun source data to extract the Green 's functions between the airgun source and stations.

关键词： Artificial source Airgun source Deconvolution Data processing flow

earthquake geochemical scientific expedition and research

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earthquake research Advances 2023年第4期3卷 58-64页

作者： Chang Lu Xiaocheng Zhou Zhi Chen Zhaofei Liu Le Hu Fengxia Sun Giovanni Martinelli Ying Li Key Laboratory of earthquake Prediction Institute of Earthquake ForecastingChina Earthquake AdministrationBeijing100036China State Key Laboratory of Geological Processes and Mineral Resources School of Earth Science and ResourcesChina University of Geosciences(Beijing)Beijing100083China INGV-National Institute of Geophysics and Volcanology Dept.of Palermo Palermo90146Italy

Large earthquakes can cause both casualties and economic losses, but they also provide invaluable opportunities for earthquake scientific research. Geofluids, due to their wide distribution, sensitive response to underground conditions, and ease of observation, are widely applied in field investigations after earthquakes. Analyzing the origin of fluids, energy transfer processes, temperature/pressure conditions, and the spatial-temporal evolution of geofluids can provide valuable information concerning the mechanism of earthquake precursor anomalies, shortterm prediction methods, identification of the seismogenic faults, determination of earthquake risk, and the environmental impact of post-earthquake fluids. This article details post-earthquake scientific expeditions and research on fluid geochemistry in China and abroad, aimed at providing ideas and guidance for future scientific expedition work and geochemistry-related earthquake studies.

关键词： Geofluids Geochemistry earthquake investigation

Field source characteristic of gravity variation in Hexi region before Menyuan Ms6.4 earthquake based on the Euler deconvolution

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Geodesy and Geodynamics 2016年第5期7卷 317-322页

作者： Fang Liu Yingwei Wang Weifeng Liang The Second Monitoring and Application Center China Earthquake Administration CCCC First Highway Consultants Co. Ltd

This study adopted the Euler deconvolution method to conduct an inversion and interpretation of the depth and spatial distribution pattern of field source that lead to gravity variation. For this purpose, mobile gravity data from four periods in the Hexi region between 2011 and 2015 were obtained from an observation network. With a newly established theoretical model, we acquired the optimum inversion parameters and conducted calculation and analysis with the actual data. The results indicate that one is the appropriate value of the structure index for the inversion of the mobile gravity data. The inversion results of the actual data showed a comparable spatial distribution of the field source and a consistent structural trend with observations from the Qilian-Haiyuan Fault zone between 2011 and 2015. The distribution was in a blocking state at the epicenter of the Menyuan earthquake in 2016. Our quantitative study of the field source provides new insights into the inversion and interpretation of signals of mobile gravity variation.

关键词： Euler deconvolution Potential field inversion Gravity variation Structural index Menyuan Ms6.4 earthquake