背景噪声成像技术是21世纪以来地震学研究最为重要的突破性进展之一.该方法不依赖于天然地震事件的发生,利用连续地震记录中普遍存在的"背景噪声",通过不同台站对间连续时间信号的互相关来提取经验格林函数并用以进行地下介质结构成像研究.与传统的天然源地震探测手段相比,背景噪声成像技术从随机场源信号中提取介质结构的信息,具有成像分辨率高、观测时效高、重复性好等优势.近年来,随着该方法的不断深入发展,背景噪声成像技术在城市地下空间和矿集区等浅地表探测、地壳与岩石圈结构探测、地幔和地核等地球深部结构探测以及地下介质时移变化监测等方面取得了日渐广泛的应用.在信噪比增强和弱信号提取、体波信号提取与应用、成像新方法研究等方面也取得了快速进展.本文系统总结了背景噪声成像技术的基本原理与发展历程及其在对不同尺度探测领域的应用和新方法技术方面的进展,并提出了未来的研究展望.可以预期,背景噪声成像方法在利用面波和体波信号研究地球空间结构、通过时移成像开展地下介质活动性监测研究等方面将发挥越来越重要的作用.

The Jiangnan Orogen is located between the Yangtze Block and the Cathaysia Block, the central part of the South China continent. Rich polymetallic deposits are developed in its interior and adjacent areas, forming a giant Cu-Au-Pb-Zn-Ag polymetallic metallogenic belt. The crustal structure of the Jiangnan Orogen records the integration and interaction between the Yangtze Block and the Cathaysian Block, and is a key area for further studying the crustal evolution, magmatism and metallogenic system of the South China continent. To reveal the crustal structure and physical properties of the crust in South China, we conducted a dense broad-band seismic survey profile, funded by the National Key Research and Development Program of the "Deep Processes and Material Response of South China Intra-Continental Metallogenic System". In this paper, we use the teleseismic data of the portable seismic stations along the 320-km-section between Guangchang, in Jiangxi Province and Liuyang, in Hunan Province to study the crustal structure of the Jiangnan Orogen. We apply teleseismic P-wave receiver function method to study the architecture and the bulk V-p/V-s ratio of the crust beneath the middle section of the Jiangnan Orogen. The results show that : (1) The Moho depth varies in a range of 29 similar to 35km, with a dome-shaped distribution. The average depth of Moho is similar to 31km, lower than the average value of the global continental crust, and mirror the topographic elevation well. ( 2) The crustal bulk V-p /V-s ratio varies in a range of 1. 64 similar to 1. 83 along the profile, with an average value of similar to 1. 72, and is slightly higher in the Cathaysia Block than in the Jiangnan Orogen. (3) The crustal thickness and V-p / V-s ratio on both sides of the Ganjiang fault are significantly different, indicating that the Ganjiang fault is a crustal scale fault. (4) The subduction of the paleo-Pacific plate may not directly influence the crustal deformation of the middle section of the Jiangnan Orogen. Instead, it may have an indirect influence on the crustal evolution and mineralization in this area.

The northeastern Tibetan Plateau is the leading-edge of the Tibetan Plateau extension to the NE direction.Also,it is one of the key regions to explore the deep dynamical process of the Tibetan Plateau.Based on the pre-existing geophysical exploration in the research area,numerical model has been constructed.In this paper,2-D Finite Element Method is used with viscoelastic model to simulate the tectonic evolution process and the dynamic response of the vertical gravity field distribution through the profile across the northeastern Tibetan Plateau,Liupanshan tectonic belt and Ordos basin.The results shows that:(1)The deep vertical abnormal characteristics of gravitational field resulted in the complicated vertical dynamic response,which caused the complex migration of the deep material.The thrust force of the northward movement of the India plate is still the dominant factor of the deep dynamic response in the northeastern Tibetan-Ordos basin.(2) The distribution of the strain energy,the rheological structure and other results are calculated numerically,which show that the sections with energy concentration roughly the same as the depth of the Haiyuan earthquake.There are differences in the physical structure,deformation rate,heave amplitude of the northeastern Tibetan Plateau and Liupanshan tectonic belt.Which is resulted in the rock rupture in the low velocity layer boundary,and the major cause of the Haiyuan earthquake.(3) The specific rheological structure of the northeastern Tibetan Plateau and Ordos basin is not favorable for the movement of the low crustal material.

Whether concealed small faults in coal seams can be found out during geological exploration is a main geological factor that affects the safety production of a coal mine. Seam Channel waves in coal seams are very suitable for detecting abnormal structures in a coal field, because they are characterized by strong energy, obvious dispersion and easy to identify. In this paper, we use the spectral element method to simulate 2D Rayleigh channel wave propagation in coal seams containing small faults, and analyze the characteristics of wave fields, dispersion and spectra of direct, reflected and transmitted channel waves. Based on different fault models with small throws (vertical offsets 1/4, 1/2, 3/4, one thickness of a coal seam; dips 90 degrees, 60 degrees, and 45 degrees), we address the influential effects of small faults on these waves. By virtue of the analysis above, we obtain some new insights into Rayleigh channel wave in coal seams with small faults, and discuss the application of such waves in exploration.

In view of the propagation characteristics of seismic channel waves in the low-velocity layer, we make a preliminary study on the numerical simulation and physical simulation of these waves. In the aspect of numerical simulation, this paper adopts the staggered-grid finite difference method to conduct a 3-D seismic wavefield forward modeling of the channel waves in the coal seam. Based on the wave field snapshots and synthetic seismic records, the wave field characteristics of different models and the propagation laws of various waves are studied. In the physical simulation, this paper adopts the different proportions of the epoxy resin and the silicone rubber material to build a physical model. The clear channel waves are recorded by the transmission and reflection observation system. The results show that in the seismic wave field excited by the explosive source in the coal seam, the energy of Love channel waves are less than those of SV component of Rayleigh channel waves and greater than those of SH component of Rayleigh channel waves in the coal seam. With respect to the SH component of Rayleigh channel waves and Love channel waves, Rayleigh channel waves leakage energy in the surrounding rock is relatively strong. The seismic waves in surrounding rock near the coal seam still propagate as channel waves. With the decreasing thickness of the coal seam, the channel waves are shifting toward dominant frequency, with stronger dispersion, and larger wave speed.

2015年4月25日发生在尼泊尔博克拉M S 8.1大地震的深层动力过程与"地中海—喜马拉雅—南亚地震带"的中段喜马拉雅地震活动带密切相关.这次大地震是该地震强烈活动带上长期以来深部物质与能量强烈交换、运动,并导致构造活动和应力积累的产物.综合分析与研究提出:（1）博克拉M S 8.1大地震的孕育、发生和发展具有长期活动和近年来相邻地带地震活动频繁的背景;这一地带自1505年—2015年,即500多年来相继发生多次M S ≥8.0的大地震.（2）这一地带具有特异的地球物理边界场响应和深层动力过程,显示深部物质的重新分异、调整与能量交换.（3）大地震发生与周边地带应力场分布特异,壳、幔结构与介质属性变异及破裂响应与断层面解的属性相关.（4）喜马拉雅地带的三条北倾断裂带以不同角度向深部延伸、震源位置及浅表层的变形特征尚应深化理解.（5）M S 8.1大地震的发生对相邻地带的波场影响强烈,故应强化高精度地球物理场的观测和探测,以"捕捉"未来可能大地震的孕育与发生.

Deep processes of the M(s)8.1 earthquake on April 25, 2015 located in Pokhara, Nepal is closely related to Himalayan seismically active area which is the middle part of "Mediterranean Himalaya-South Asia seismic zone". This huge event is the result of long-term tectonic activity and accumulation of stresses in this intense activity area which is due to the strong deep material movement and severe energy exchange. Our comprehensive analysis and study suggest that (1) The generation, occurrence and development of this great earthquake has a frequently seismic activity background both in its locality and adjacent regions; There have been several megaseisms (M-s >= 8.0) in 500 years from 1505 to 2015. (2) The specific geophysical boundary conditions and deep dynamic processes in this area show deep material redifferentiation and energy exchange. (3) The occurrence of the megaseism is related to peculiar stress distribution of the surrounding areas, special crust-mantle structure, differentiation of media attributes and rupture responses, as well as properties of fault plane solutions. (4) There are still some aspects which need to deepen understandings including three north-trending faults with different angles towards to depth in the Himalaya, the hypocentral locations and shallow surface deformation features. (5) The M(s)8.1 earthquake has strong influences on the wave field of its adjacent regions, so we should strengthen the observation and detection of geophysical fields to capture the generation and occurrence of possible great earthquakes in the future.

In order to investigate the structure of the crust beneath the Inner Mongolia tectonic belt, the Yinshan orogen, the North China Craton, the Qinling orogen, the Yangtze Craton and the intra-continental orogens in South China, a 2280 km long gravity survey profiling was conducted from Mandula town in Inner Mongolia to Pingxiang city in Guangxi province in nearly NS direction. By using the gravity data collected, we constructed the 2D density model, analyzed the deep structure and tectonic characteristics, reliefs of the intra-crust interfaces and Moho discontinuity and major deep faults along this profile. In addition, we revealed the differences among the different tectonic units in the gravity field, density distribution, undulation of layers and so on. Finally, based on the research in these tectonic units as a whole, we discussed the correlation between the tectonic units along this profile. Our research could provide evidence of the gravity field for the further study of the crustal structure and geodynamics of the continent in central China.

An 1800 km long gravity profile was conducted from Yulin city in Shaanxi province to Pingxiang city in Guangxi province and crossed North China Craton, Qinling Orogen, and Yangtze Craton. By processing and analyzing the data, we constructed the 2D crustal density model and discussed the deep structure, tectonics and faults along the profile. In addition, we discussed the differences between craton, orogen and their coupling belt and interpreted the geological implications of the deep structure along this profile. Our research results can provide evidences in the viewpoint of gravity field to the further study of the crustal structure, tectonic units and geodynamics in this region.

大数据时代——未来人类社会发展的大变革,它作为人类社会信息发展的产物,以“信息风暴”为预测变革手段的发展模式,正在改变并决定着人类的生活、生产和思维方式.大数据所具有的各项功能,深刻地影响着人类社会未来的格局.然而,人们尚需要深刻地认识到它在科技创新中的潜在响应.基于当今报刊业广泛发表的科研、信息、管理等领域的相关论述,通过分析认为必须统一在一个有机的平台上进行深刻理解:1)大数据的定义与属性和对大数据的发展的理解;2)当代大数据隐含在科学与技术中的新内涵;3)信息与网络技术的快速发展与大数据响应;4)大数据催促地球科学的创新再生;5)大数据转化与现代农业和大生物学;6)大数据在科技发展进程中必须重视的几个问题.

In this research, the latest field gravity data along a 1010 km-long geophysical profile crossing the Ordos basin, Weihe basin, Middle Qinling orogen and eastern Sichuan basin are collected. Based on this gravity data set, the gravity anomalies in different tectonic units are analyzed, the crustal density model along this profile is constructed, and the undulation and cross difference of density interfaces in crust and the distributional characteristics of faults around this profile are discussed.The research results show that in the Ordos basin, the Bouguer gravity anomalies vary gently. The densities vary mainly in vertical direction. Interfaces are simple and smooth. And there are few faults. In the Weihe basin between the Qinling orogen and the Ordos basin, the Bouguer gravity anomalies are very low. There exists a gravity gradient belt corresponding to the big fault north of the middle Qinling oroge. The Moho interface uplift is about 10 km beneath this area. In the middle Qinling orogen, the Bouguer gravity anomalies vary strongly. Densities change in both lateral and vertical directions. The interfaces in crust are not so clear as those in its two sides. There are a lot of faults, and the Moho interface sinks a little. In the Sichuan basin, the Bouguer gravity anomalies vary smoothly. The density structure varies mainly in vertical direction. Interfaces are more simple and smooth, and there are few faults. These features are similar to those in the Ordos basin.According to our research, there exist obvious differences between the middle Qinling orogen, Ordos basin and Sichuan basin in Bouguer gravity anomalies, crustal density models, undulation of interfaces in crust, and distribution of faults.At last, this study suggests that the North Qinling fault and Ankang fault are the northern and southern contact zones of the middle Qinling orogen in the gravity profile. There exists a "basin-orogen-basin" distinctive tectonic system in the North China craton-middle Qinling orogen-Yangzi craton with its special resent characters of evolution.

The Qinling-Dabie orogenic belt traverses the central part of Chinese continent, dividing the eastern part of China into a north and a south part, that is, the North China craton and the Yangtze craton. Driven by the opposite movement force system, the orogen turns into an extremely complex composite superimposed tectonic belt, metallogenic belt and seismic active zone. Meanwhile, the force system also conduced the anomalies of sedimentary formation and strongly undulating crystalline basement in the region. However, it is not clear what is the geophysical boundary field response, abnormal changes of lithofacies and structure, in particular, the deep understanding of the dynamic processes on the response of basin-mountain coupling. The seismic detection and research have been done along the profile of Yulin-Tongchuan-Fuling which is about 1000 km long. And geological interpretation to these features is made. The result shows that the variation in thickness of sedimentary formation is 4-10 km and the crystalline basement is with the intense undulations by 4-6 km. The study area was cut into the southern Ordos Basin, Qinling north foreland basin, Qinling-Daba orogenic belt, south foreland basin and northeast Sichuan basin by a series of basement faults; in addition, the foreland basin including the Weihe river basin north of Qinling and the Tongjiang-Wanyuan basin south of Qinling. Qinling orogenic belt, an intracontinental rising mountain, was formed by the North China Craton pushing towards south while the Yangtze craton squeezing towards north. And the process formed the southern and the northern foreland basin. The south and north boundary of Qinling orogenic belt is not a boundary fault but a combination boundary belt including the foreland basin. Qinling and Daba arc-shaped mountain originated from the same deep crystalline basement, that is to say, they were born from the same root. The series of new knowledge has significant implications for deeply comprehending the deep dynamic process and evolution mechanism of Qinling-Daba orogenic belt and redefinition of the true north boundary of Yangtze craton.

在印度洋板块与欧亚板块的碰撞—挤压作用下,不仅形成了喜马拉雅弧形山造山带,而且导致其东部弧顶—东构造结似一尖楔沿NNE方向插入青藏高原的东北缘.造成了巴颜喀拉块体和龙门山断裂系深、浅部构造强烈活动和变形,并导致高原腹地壳、幔物质以大型走滑断裂为通道边界向E-ES方向运移.2008年5月12日汶川—映秀Ms8.0地震就发生在这相对活动的巴颜喀拉块体与相对稳定的四川盆地之间的龙门山断裂系辖区内.基于该区深部壳、幔结构和主震(Ms8.0)与7万多次余震震中位置与震源深度的展布研究表明,汶川—映秀Ms8.0地震的发震断裂不是震中在地表投影位置附近,而是龙门山断裂系3条以不同角度西倾、且向下在15土5 km深处汇聚的断裂带CF.该发震断裂带不是一条简单的线性断裂带,而是一半径为5 km左右的柱状震源体,沿NE向展布.在青藏高原东北缘深部物质向东与向东南运动过程中地壳各层整体逐渐抬升,且在龙门山断裂系地带为减薄的转折部位,而地壳低速层却在这里尖灭.在两陆-陆板块碰撞力系作用下,壳、幔介质以上地壳底部低速层(深20±5 km)为上滑移面,并与上地壳解耦,而在深处则以岩石圈底部漂曳的软流层顶部(深100±10 km)为下滑移,故下地壳和上地幔盖层物质才能同步运动.它们在四川盆地高速“刚性”壳、幔物质阻隔下,龙门山断裂系的3条向下汇聚的断裂带与下地壳和上地幔盖层物质同步沿龙门山断裂系的断层面向上逆冲,当向上与向下同步运动的固态壳、幔介质二者在15±5 km深处强烈碰撞时激发了这次Ms8.0地震和一系列强余震的发生和发展.基于上述可见,对强烈地震孕育,发生和发展的深部介质与构造环境,深部物质与能量的交换、运移和深层动力过程的研究乃核心所在.

It is obvious that the India-Eurasia collision has formed the giant arc-like Himalayan belt. At the eastern Himalayan syntaxis, the Indian subcontinent plunges into the Tibetan plateau in NNE direction. Not only resulted in the Bayan Har block and Longmenshan fault system strong tectonic activity and deformation, but also resulted in the material of the hinterland of the plateau crust and upper mantle in the E-ES direction of migration to large strike-slip fault boundary for the channel. The Wenchuan-Yingxiu M(s)8. 0 earthquake of 2008, occurred on the Longmenshan fault system which lies in between the relative activities of the Bayan Har block and relatively stable Sichuan Basin. In the light of the structure of the crust and upper mantle and the distribution of the epicenter and focal depth of the main shock and its more than 70000 aftershaks, the seismogenic fault of Wenchuan-Yingxiu M(s)8. 0 earthquake is not the pojection position of the epicenter in surface. Three westly-vergent thrust faults seen on the surface in the Longmenshan extend downward at different angles and converge at depth 15 +/- 5 km, so it produced the convergence fracture (CF). Therefore this shear fault zone is the real triggering seismic fault which is responsible for the M(s)8. 0 event. It is actually a column-shaped source body striking in NE with radius 5 km centered at depth 15 +/- 5 km. In the process of deep material eastward and southeastern movement, the whole curst gradually rising and the Longmenshan fault system thinned then crust low velocity layer pinched in the northeastern margin of Qinghai-Tibet Plateau. There are two detachment interfaces at depth in this region, one is the low-velocity layer at depth 20 similar to 25 km in the upper and middle crust, the other is the top of the astheonsphere. Along these two interfaces, the materials of the lower crust and the lid in the upper mantle simultaneously transfer toward east. Due to the covering strata hinder of the deep rigid substance below the Sichuan basin, the material of the lower crust and upper mantle moves upward (thrusts) at a steep angle along the Longmenshan. Under the intense exchange of matter and energy, the source medium ruptures suddenly at a large scale to release a huge amount of elastic strain, resulting in the Wenchuan M(s)8. 0 earthquake. Based on the above, it is the key that we study the strong earthquake preparation, occurrence and development for deep environment of medium and structure and deep material and energy exchange, migration and deep dynamic process.

The crust-mantle boundary (Moho) is not a 'rigid' interface in physics as evidenced by high-precision artificial source deep seismic sounding in the Tibetan Plateau. This interface is not only extremely uneven with large relief, but also cut by a series of deep faults with different sizes and different geometries. Therefore, it should have complex dynamic responses of material motion on the surface and in the deep subsurface. In the common channel flow model, the interface between the lower crust and upper mantle is assumed as a flat boundary, and simplified into a smooth constrained boundary in numerical simulation. This paper adopts 2-D viscoelastic models to simulate the response of the channel flow model by an undulating Moho interface. These models are based On the average velocities of the crust and upper mantle of the Tibetan plateau extracted observational data. The results shows that the effect of channel flow is limited to a small area. The changes of Moho relief can affect the channel flow. The undulating Moho interface enhances the synchronous motion of the lower crust and lithospheric mantle, but in a limited range. The changes of Moho shape produces different influences on horizontal displacements on the surface and the Moho interface. Where the Moho occurs dislocation, the horizontal displacement on the surface begins to significantly reduce, implying decoupling of displacement between the surface and subsurface. The deep dynamic effects of the model and the response of the surface are not of local characters, instead at least regional processes.

The three tectonic units, Qinling-Daba orogenic belt, North China craton and Yangtz craton, are very complicated in whether each tectonic unit system or each boundary structure. Restricted by many times of tectonic movements, the Qinling orogen and its adjacent areas have experiencedspecial orogenic processes of continental interior. Although some related work has been done in this area, there are little studies on the fine structure and deep dynamical processesin the crust and mantle and, particularly for the system coupling research of the North China craton, QinLing-Daba orogenic belt and Yangtze craton. In order to fill this gap, we deployeda high-precision wide-angle seismic reflection and refraction wave field exploration survey profile across this region. It began from Yulin north of Ningshan in the north and extended southward to Fuling with a length of 1000 km. Through high-resolution data acquisition, inversion and characterization of the crust and mantle fine velocity structure, we found the specific velocity structure of deep crust and mantle along the profile and obtain the following new knowledge. (1) With the same basement, the Qinling-Daba orogenic belt was resulted from the uplift of the crystalline basement. In other words, the formation of the orogen was only related to the forced deformation and the spatial state of the upper crust. The orogenic belt and its forelands of the both sides were the products of the same deep process in the intracontinental orogenic process, while local uplift of the Moho interface led to the extension of the foreland basin B-fc between the North China craton and Qinling orogen. (2) The continuous sedimentary formation, crystalline basement, upper crust, lower crust, interval velocity structure and block velocity structure of uppermost mantle, relief change and space state at each interface are first put forward along the 1000 km long profile. We define the partition zones among the North China craton, Qinling-Daba orogenic belt and Yangtze craton on the basis of the seismic wave boundary response. In this paper, we also discuss internal structures of the three tectonic units and the velocity variation features of the adjacent areas. (3) There are significant differences between the North China craton, Qinling-Daba orogen and Yangtze craton in velocity structure of the continental area, Q structure, distribution of different faults and sequences. The distribution of the faults with varied scales, depths and attitudes displays the marked differencesin theirformation, deformation behavior, mechanisms and constraints by tectonic movements.

Since the velocities in surrounding rocks of roof and floor are faster than those in coal seam,the total reflection takes place if the angle of incidence is greater than critical angle when the seismic waves are excited in coal seam.After multiple combination and superposition of total reflection,channel wave will generate in coal seam.Channel wave is a confined wave and has the dispersion phenomenon which is the most important feature.Besides,when propagating in coal seam,channel wave has other features including low speed and weak attenuation.So it can be used to detect voids,faults and other geological structures in coal seam.This paper describes the current research situation of In Seam Seismic,the formation of channel wave,channel waves' features,methods of In Seam Seismic exploration,example of application and so on,and make an expection about In Seam Seismic exploration according to its characteristics.

The Longmenshan orogenic belt is in a very non-isostatic state, which means its crust is in an unstable state. In this paper, 2-D Finite Element Method is used with viscoelastic model to study the geodynamical mechanism of gravitational isostasy through the profile across the Songpan-Garze block, Longmenshan faults and Sichuan basin. The results show that: (1) The motion mode of deep materials is much changed by the isostatic adjustment. The interaction effects of the India plate collision and the gravity potential energy cause the dynamics of the sub-vertical downward asthenospheric flow at the bottom of the Longmen.shan lithosphere, and lead to the exceptionally steep topography at the eastern Tibetan margin as a result of gravitational buoyancy. (2) The distribution of strain-energy, the rheological structure and other results are calculated numerically, which show that the sections with high risk factors coincide with the areas of the Wenchuan earthquake. The different geophysical structures, as well as the different rheological model on both east and west side of Longmenshan faults zone played important roles in the seismogenic mechanism of the Wenchuan earthquake. (3) We suggest that crustal shortening together with isostatic adjustment, including the rapid erosion-related unloading, is a key component of the geodynamic processes on the eastern Tibetan Plateau margin.