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张献兵
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类别: 科研

标题 北京大学第二届地球物理青年论坛邀请函  发布时间 2018年5月1日21时30分 星期二
    随着现代地球物理观测技术、理论研究以及计算能力的发展,地球物理学专业正在面临前所未有的机遇。当代地球物理学研究更需要交叉学科观测以及分析手段。北京大学理论与应用地球物理研究所是北京大学多学科教学与科研的一个窗口,也是中国教育界多学科研究的一个亮点。秉承创新引领发展的理念,未来几年,北京大学理论与应用地球物理研究所将致力于营造开放与自由的学术环境,吸纳全球顶尖的人才和技术,建设国际一流的科研团队、打造软硬件齐全的科研平台。愿有志加盟者共同筑梦未名湖畔。
    北京大学第二届地球物理青年论坛将于2018年7月25-27日在北京大学举办,旨在为地球物理学以及相关交叉领域的海内外青年学者提供高水平学术交流平台。值此北京大学建校120周年之际,诚邀海内外优秀青年学者相聚美丽的燕园,讨论前沿学术热点,增进交流与合作。
一、申请条件
在国内外知名大学或科研机构获得地球物理相关博士学位十年以内,或者未来一年内将获得博士学位,年龄不超过40岁。
二、支持方案
1、为部分受邀学者提供往返北京与现就职或求学单位的交通费用;
2、论坛举办期间提供受邀学者的食宿。
三、时间节点
1、参会申请:2018年5月20日前,提交申请材料:
   个人简历+研究陈述(中英文皆可)至 xbzhang@pku.edu.cn
2、主办方确认海外支持名单:2018年5月30号
3、 摘要截止:2018年6月30日
4、会议报到:2018年7月24日,报到地点:北京大学
5、会议时间:2018年7月25-27日
四、联系方式
联系人: 张献兵 邮箱:xbzhang@pku.edu.cn


北京大学地球与空间科学学院
理论与应用地球物理研究所
2018年5月2日

点击前往“青年论坛”

宁杰远
电话: 62765852
类别: 科研

标题 4月30日(星期一)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年4月27日17时25分 星期五
Title: Transient Pressure Surge in a Fluid-Filled Fracture
Presenter: Assistant Professor Yingcai ZHENG
Institution: Department of Earth and Atmospheric Sciences, University of Houston
Time: 20180430-15:00:00
Location: Room 2829, No. 2 Science Building.

Abstract: Weak dynamic seismic stress waves from distant earthquakes can abruptly change the fluid permeability of a hydrologic system, trigger seismicity, or cause liquefaction. Many proposed mechanisms to explain these phenomena require a large fluid pressure gradient to induce fluid flow during the passage of the waves, yet the exact mechanism as to how the fluid pressure can change is unclear. Using full-waveform numerical modeling, we found that the transient seismic-wave pressure in a fluid-filled fracture could increase more than 2 orders of magnitude relative to the incident pressure. We call this transient pressure surge (PS). This pressure increase could be much more pronounced for low - frequency transient waves than for high frequencies and could develop a large pressure gradient to drive the fluid to flow. This PS phenomenon may be important for understanding many natural phenomena in fluid‐fracture systems.

Biography: Yingcai Zheng is an Assistant Professor in seismic imaging and reservoir characterization, in the Department of Earth and Atmospheric Sciences, at University of Houston. He also holds a joint faculty appointment in the Department of Physics, UH. Prior to his joining University of Houston in 2014, he was a Postdoctoral Fellow and Research Scientist at Earth Resources Laboratory at Massachusetts Institute of Technology. He got his Ph.D. in Geophysics from University of California Santa Cruz in 2007 and B.S. degree (2001) from Peking University, Beijing. He is a recipient of the SEG's 2015 Karcher Award for his contribution in exploration geophysics.

Reference: Zheng Y. Transient Pressure Surge in a Fluid-filled Fracture[J]. Bulletin of the Seismological Society of America, 2018.

宁杰远
电话: 62765852
类别: 科研

标题 4月19日(星期四)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年4月17日13时0分 星期二
报告题目:1. Induced Seismicity and Groundwater Leakage in Oklahoma, USA ;2. 如何思考学术问题?
报告人:王其允 教授
报告人单位:加州大学伯克利分校
报告时间:20180419-15:00:00
报告地点:理科二号楼2829

报告内容简介:
Most aquifers are used as sources of fresh water, some aquifers are used for disposal of wastewater and other hazardous liquids. An example of the latter is the deep injection of massive amount of wastewater co-produced from hydrocarbon exploration, which has induced abundant earthquake in the mid-continental US such as the state of Oklahoma. Such earthquakes have the potential to cause aquifer leakage and release hazardous liquids into the environment.  Thus it is important to monitor the leakage of aquifers not only for the safety of water resources but also for the security of underground repositories. Traditional methods for detection of aquifer leakage are time consuming and are thus infeasible for continuous and long-term monitory. Here we propose to use the tidal response of water level in wells for such purpose. Quantitative interpretation of the tidal response of the hydraulic head of an aquifer has been made either with a model for perfectly confined aquifers or with that for purely unconfined aquifers. However, leaky aquifers are neither totally confined nor purely unconfined, but behave somewhere between the two end members at the frequencies of tidal loading. A model for the interpretation of the tidal response of such aquifers, however, is currently lacking. We derive a new model for the tidal response of a leaky aquifer and use the model to interpret the tidal response of water level in a USGS Oklahoma deep monitoring well installed in the Arbuckle aquifer. The analysis suggests that the Arbuckle aquifer is leaking significantly at this site. It also shows that Earth tide analysis of water level in wells may be useful for continuous monitoring of leakage of groundwater system, which bears on the safety of water resources, the security of underground waste repositories, and the outflow of wastewater during hydrocarbons extraction.

报告人简介:
• Education:
B.Sc. (Geology) Taiwan National University, June 1958
M.A. (Geological Sciences) Harvard University, June 1961
Ph.D. (Geological Sciences) Harvard University, May 1964
• Appointments:
Geophysicist, Smithsonian Astrophysical Observatory, 1964-1967.
Miller Fellow, University of California, Berkeley, 1968-1969.  
Assistant Professor, Associate Professor, Full Professor, UC Berkeley, 1967-2007. Professor of the Graduate School, UC Berkeley, 2007 – present.
• Current research focus:
Effects of earthquakes on groundwater
Effects of induced seismicity on pore pressure and crustal deformation
Effects of pore pressure on crustal strain and deformation


宁杰远
电话: 62765852
类别: 科研

标题 4月13日(星期五)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年4月9日9时2分 星期一
报告题目:结合矿物波速数据和地震学结果探索地球深部
报告人:吴忠庆 教授
报告人单位:中国科学技术大学
报告时间:20180413-15:00:00
报告地点:理科二号楼2829

报告内容简介:
地震学研究提供了大量地球内部的波速结构信息,为了解读这些地震学结果,更好地认识地球内部,获得地球内部温压条件下高质量的矿物波速数据是关键,我们用第一性原理计算的方法研究了多个地幔重要矿物的高温高压波速,利用这些数据,我们探讨了地幔楔低Vp/Vs的成因、地幔转换带顶部水含量、以及下地幔的成分。

参考文献:
[1]. Wu Z, Wentzcovitch R M. Quasiharmonic thermal elasticity of crystals: An analytical approach [J]. Physical Review B Condensed Matter, 2015, 83(18):772-772.
[2]. Qian W, Wang W, Zou F, et al. Elasticity of orthoenstatite at high pressure and temperature: Implications for the origin of low VP/VS zones in the mantle wedge [J]. Geophysical Research Letters, 2017.
[3]. Wu Z. Velocity structure and composition of the lower mantle with spin crossover in ferropericlase [J]. Journal of Geophysical Research Solid Earth, 2016, 121(4):2304-2314

报告人简介:
报告人1997年获四川大学水利系学士学位,2000年获浙江大学物理系硕士学位,2003年获清华大学物理系博士学位,2003起先后在清华大学高等研究院、明尼苏达大学化工材料系、和南加州大学化工材料系博士后,2010年起任教于中国科学技术大学,用第一性原理计算研究材料在高温高压下的物性,发展了一个计算高温弹性特性的方法,其所需的计算量不到常规方法的十分之一,利用该方法研究了地幔多个重要矿物的弹性特性,探讨这些结果对认识地球深部组分、温度和动力学结构的意义,已在Nature、PNAS、JGR等杂志发表论文50多篇。

报告人主页:http://ess.ustc.edu.cn/user/82

宁杰远
电话: 62765852
类别: 科研

标题 4月5日(星期四)下午4:00优赛科技北大地球物理学术报告会  发布时间 2018年4月3日22时19分 星期二
Title: Subject-oriented finite fault inversion: do you need a reason to burn CPUs?
Presenter: Prof. JI Chen
Institution: University of California, Santa Barbara
Time: 20180405-16:00:00
Location: Room 2829, No. 2 Science Building.

C.V.
Education:
B.S., Peking University, Beijing, 1991.
M.S., Institute of Geophysics, Chinese Academy of Science, 1994.
Ph.D., California Institute of Technology, 2002.

Research focuses on exploring the physical processes of large earthquakes with various modern geophysical observations, such as broadband seismograms, high-rate GPS, and radar interferometry.

Current research interests:
    Developing real-time finite fault inversion systems to quickly evaluate the catastrophic tragedies caused by large shallow earthquakes in regional and teleseismic distances.
    Globally surveying the seismic nucleation phases of great earthquakes
    Analyzing the uncertainties associated with the source models of large earthquakes
    Capturing the "early" post-seismic deformation following the large earthquakes by joint inverting the seismic and geodetic data
宁杰远
电话: 62765852
类别: 科研

标题 4月6日(星期五)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年4月1日14时40分 星期日
报告题目:环境地球科学之滑坡地震地质学
报告人:许冲 研究员
报告人单位:中国地震局地质研究所
报告时间:20180406-15:00:00
报告地点:理科二号楼2829

报告内容简介:
滑坡地震地质学是研究地震荷载下滑坡发生机理、分布与演化规律的学科;也是借助地震滑坡解决地震地质问题的学科。它是地质灾害学、地震地质学、工程地质学之间的一门交叉边缘学科。其也与固体地球物理学、构造地质学、构造地貌学、环境地质学、数值计算、地理信息系统、遥感、统计分析等学科密切相关。从科研层面与应用层面的分类大体构建了滑坡地震地质学的研究框架与体系。科研层面的目的是探索地震滑坡规律,应用层面的目的是地震滑坡防灾减灾。根据科研与应用层面的研究目的,将其研究内容大体分为两部分:(1)研究地震滑坡发生机制、分布样式、演化规律等;(2)建立地震滑坡与地震、发震构造、地震破裂过程等的关系式,进而利用地震滑坡解决地震地质问题,如地震问题(地震参数、地震动强度、地震烈度)、发震构造问题(性质、破裂过程)、地质问题(震区地貌演化)等。最后,从地震滑坡数据库,全球范围多震例的地震滑坡分析,地震滑坡与地震地质对象关联的机理研究,地震滑坡演化规律等方面对该学科进行了展望。

参考文献:
[1] 许冲. 2018. 环境地球科学之滑坡地震地质学[J]. 工程地质学报, 26(1): 207-222.
[2] Xu C, Xu X, Shyu J B H. Database and spatial distribution of landslides triggered by the Lushan, China Mw 6.6 earthquake of 20 April 2013[J]. Geomorphology, 2015, 248:77-92.
[3] Chong X, Xu X, Shen L, et al. Optimized volume models of earthquake-triggered landslides[J]. Scientific Reports, 2016, 6:29797.
[4] Xu C, Xu X. The spatial distribution pattern of landslides triggered by the 20 April 2013 Lushan earthquake of China and its implication to identification of the seismogenic fault[J]. Science Bulletin, 2014, 59(13):1416-1424.
[5] Xu C, Xu X, Yao X, et al. Three (nearly) complete inventories of landslides triggered by the May 12, 2008 Wenchuan Mw 7.9 earthquake of China and their spatial distribution statistical analysis[J]. Landslides, 2014, 11(3):441-461.

报告人简介:
报告人分别于2007年与2010年在西安科技大学与中国科学院地质与地球物理研究所获得硕士与博士学位,现为中国地震局地质研究所研究员。依托负责的3项国家自然科学基金(青年、面上、国际合作)与2项国家重点研发计划子课题等,发表论文多篇,被引3600多次。

宁杰远
电话: 62765852
类别: 科研

标题 4月5日(星期四)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年3月27日14时23分 星期二
Title: A new method to measure iron self-diffusion at high pressure and temperature
Presenter: Prof. Simon Clark
Institution: Australian Research Council Centre of Excellence for Core to Crust Fluid Systems (CCFS) and GEMOC, Department of Earth and Planetary Sciences, Macquarie University
Time: 20180405-15:00:00
Location: Room 2829, No. 2 Science Building.

Abstract
Diffusion plays a key role in planetary processes. It controls solid state fractionation which determines the distribution of elements and it is the rate limiting step for creep which determines the rheology.  Many processes occur deep within planetary bodies so we need to understand the effect of pressure on diffusion rates. Iron is abundant throughout the Earth so an appreciation of the self-diffusion rate of iron is of particular relevance. Previous studies [1,2] have focussed on determining diffusion coefficients in iron-nickel alloys. These studies determined diffusivities by placing two metals in contact (iron and nickel), pressurizing in a piston cylinder or multi-anvil high-pressure cell, heating, quenching and then cutting and polishing the sample before measuring concentration as a function of distance using an electron micro-probe. These studies successfully quantified the effect of temperature on the diffusion coefficient but were unable to detect any effect of pressure possibly due to the relatively low pressure range achievable using piston cylinder and multi-anvil devices. To extend the pressure range we need to move to diamond anvil high-pressure cells but the extremely small sample size (typically 20-50μm in diameter) makes the method of using the electron microprobe (with a beam size of around 5μm) infeasible. This limitation has now been overcome with the advent of new instruments such as the nano-SIMS with a beam size of around 100nm. We have therefore carried out a demonstration measurement of iron self-diffusion in the bcc phase of iron using samples prepared at high-pressure and temperature in a laser heated diamond anvil cell. Samples were prepared by taking a 6μm thick sheet of 56Fe and coating it on one side with a 70nm thick layer of 57Fe. 60μm diameter disks were cut from this sheet and loaded into a 60μm hole in a Re gasket in a diamond anvil cell together with a 60μm diameter, 10 μm thick disk of KCl on either side as insulating layers. The sample was then pressurized and the centre of the sample was heated using the laser heating system in the Department of Earth Sciences, Bristol University. The pressure was released, the samples recovered and the KCl insulating layers removed. Slices were cut from the centre of the sample using a Helios NanoLab G3 CX focused ion beam mill and the concentration of 56Fe and 57Fe measured using a Cameca NanoSIMS 50L. Both of these instruments are housed in the Centre for Microscopy, Characterization and Analysis at the University of Western Australia. Diffusion coefficients of 1.46x10-14 m2/s-1 at 43.6GPa and 2100 K and 9.92x10-14 m2/s-1 at 43.6GPa and 2000 K were determined. These were combined with the previous data [1,2] and found to give a satisfactory fit to the Sammis and Smith model [3] with an activation volume of 1.43 cm3/mol and an activation energy of 431 kJ/mol.

Reference
[1] Goldstein, J., Hanneman, R., and Ogilvie, R., 1965, Diffusion in the fe-ni system at 1 atm and 40 kbar pressure(Interdiffusion coefficients for Fe-Ni alloy as function of composition in alpha and gamma phases at 1 atm and 40 kbar pressure): AIME, TRANSACTIONS, v. 233, p. 812-820.
[2] Yunker, M. L., and Van Orman, J. A., 2007, Interdiffusion of solid iron and nickel at high pressure: Earth and Planetary Science Letters, v. 254, no. 1, p. 203-213.
[3] Sammis, C. G., Smith, J. C., and Schubert, G., 1981, A critical assessment of estimation methods for activation volume: Journal of Geophysical Research: Solid Earth, v. 86, no. B11, p. 10707-10718.

CV
• Education
1985 - 1992:  Department of Crystallography, Birkbeck College, University of London. PhD Crystallography.
1988 - 1983:  Department of Crystallography, Birkbeck College, University of London. MSc Crystallography.
1976 - 1980:  Chemistry Department, City University, London. BSc Industrial Chemistry.
• Work Experience
2012 - Present:  Lecturer, Dept. Earth and Planetary Science, Macquarie University, Australia.
2001 - 2012:    Staff Scientist, Advanced Light Source, Lawrence Berkeley National Laboratory, USA.
1987 - 2001:    Beamline Scientist, Daresbury Laboratory, UK.
• Adjunct Positions
2011:  Honorary Associate, Dept. of Earth and Planetary Sciences, Macquarie University, Sydney, Australia.
2006:  Associate Adjunct Professor, Dept. of Earth and Planetary Sciences, University of California, Berkeley, USA.
2005:  Associate Researcher, Dept. of Earth and Planetary Sciences, University of California, Berkeley, USA.
2000:  Honorary Professor Dept. of Earth Sciences, The University of Manchester UK.
1994:  Honorary Lecturer, Dept. of Earth Sciences, The University of Manchester, UK.
• Research
My research is based primarily around using x-ray scattering and diffraction to study interesting problems in materials and Earth science. The majority of my work has involved non-ambient conditions usually high-temperatures and high-pressures.  I started out doing neutron diffraction at the ILL and ISIS before moving to synchrotron radiation. My current interests include using scattering to determine the atomic structure of amorphous materials and melts and using a combination of diffraction and imaging to measure defect densities as a function of pressure and temperature.

Homepage
https://directory.science.mq.edu.au/users/sclark
https://sites.google.com/site/simonmartinclarkpersonalinfo/cv

宁杰远
电话: 62765852
类别: 科研

标题 3月30日(星期五)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年3月26日9时58分 星期一
报告题目:基于三维速度结构的全波形油、气田诱发地震定位及震源机制反演
报告人:李俊伦 青年千人
报告人单位:中国科学技术大学
报告时间:20180330-15:00:00
报告地点:理科二号楼2829

报告内容简介:
油气生产以及深地下工程引起的诱发地震由于和社会生活以及民众的生命财产安全密切相关,能够造成重大的社会影响,近期成为了地震研究中一个新热点。本次报告将介绍近些年来我在油气田诱发地震的震源定位和震源机制反演方面的工作。报告内容包括最新发展的快速对齐和匹配算法,及其在由于油气开采造成的地层下陷、区域地质应力改变,断层重新激活引起的油气田诱发地震的应用及解释结果。报告中介绍的反演算法和反演过程中的经验总结也可以应用到其他小地震的观测、解释之中。
应用最新提出的快速对齐和匹配算法,只需很少几个反演参数和人工干预,就可以有效的利用观测到的地震全波形信号,同时定征出小地震的震源位置和震源机制解。此算法可以有效地减少由于速度结构误差带来的理论波形和观测波形之间的匹配残差,并在反演之前产生一个约束参考解,从而能够定征出可靠、稳定的震源属性。

报告人简介:
报告人于2004年、2007年在南京大学获得学士和硕士学位,之后于2013年在麻省理工学院获得地球物理专业博士学位。毕业之后,报告人加入了美国壳牌国际勘探与开发公司,任地球物理研究员。报告人于2016年入选第13批青年千人计划,并于2017年底全职回国工作。
在博士学习和壳牌工作的10余年时间里,报告人一直致力于油气田开采导致的诱发地震以及水力压裂的微地震等方面的研究工作中。工作期间在水力压裂微地震和油、气田诱发地震等方面的研究中做出了非常重要的贡献,研究成果得到广泛应用,取得了重要的经济及社会价值,多次得到嘉奖。现致力于微地震、诱发地震各个方面的研究,以及将被动源方法应用于油气资源勘探,以及将勘探地震中的偏移成像方法应用于天然及诱发地震的研究中。

报告人主页:http://ess.ustc.edu.cn/user/503

宁杰远
电话: 62765852
类别: 科研

标题 5月24日(星期四)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年3月16日20时49分 星期五
Material and Stress Rotations: The Key to Reconciling Crustal Faulting Complexity with Rock Mechanics
Prof. AMOS NUR
Geophysics Department, Stanford University, Stanford, California
20180524-15:00:00
Room 2829, No. 2 Science Building
A perennial problem in fault mechanics is that the fault geometries in situ—especially of strike- slip faults—often contradict theoretical predictions. According to experimental and theoretical rock mechanics as captured by Coulomb’s law, fault directions and motions should correspond simply to stresses in the crust. However, the complex geometrical distribution and regional trends of observable faults in the crust often seem at odds with the regional state of stress. Fortunately, these discrepancies can be neatly reconciled with Coulomb’s law if we recognize that many faults did not form in their current orientations, but have rotated over time, and/or the stress field has rotated as well.
I describe a comprehensive tectonic model for the strike-slip fault geometry, seismicity, material rotation, and stress rotation, in which new, optimally oriented faults can form when older ones have rotated about a vertical axis out of favorable orientations. The model was successfully tested in the Mojave region using stress rotation and three independent data sets: the alignment of epicenters and fault plane solutions from the six largest central Mojave earthquakes since 1947, material rotations inferred from paleomagnetic declination anomalies, and rotated dike strands of the Independence dike swarm.
The success of the rotation model in the Mojave has applications well beyond this special region alone. The implication for crustal deformation in general is that rotations—of material (faults and the blocks between them) and of stress—provide the key link between the geology of faults and the mechanical theory of faulting. Excluding rotations from the kinematical and mechanical analysis of crustal deformation makes it impossible to explain the complexity of what geologists see in faults, or what seismicity shows us about active faults. However, when we allow for rotation of material and stress, Coulomb’s law becomes consistent with the complexity of faults and faulting observed in situ.

宁杰远
电话: 62765852
类别: 科研

标题 3月23日(星期五)下午3:00优赛科技北大地球物理学术报告会  发布时间 2018年3月16日20时45分 星期五
Full Waveform Seismic Tomography 101
Prof. Li ZHAO
Peking University
20180323-15:00:00
Room 2829, No.2 Science Building
Started in the final days of the last century as the so-called finite-frequency tomography, full waveform seismic tomography (FWST) is now one of the frontiers in seismological research. As a brand new approach to imaging the Earth structure, FWST has undergone a steady development in the past twenty years, and has been practiced in more and more investigations of the upper-mantle structures in regions such as southern Africa, East Asia, and Europe. Generally speaking, seismic tomography involves three crucial elements: measurement of data or modeling residuals, computation of structural sensitivity kernels, and solution of the inverse problem. For FWST in particular, accurate waveform modeling, such as the normal-mode method for one-dimensional Earth models and finite-difference method (FDM) or spectral element method (SEM) for two- or three-dimensional Earth models, is required to obtain full-wave data measurements and structural sensitivity kernels. In order to use the large amount of data to constrain regional and global structure, additional steps must be taken to improve the computational efficiency. We have developed the strain Green tensor (SGT) database approach in which the strain field from fundamental seismic sources are calculated in the reference Earth model beforehand and stored on disks. The SGT database can then be used in efficient calculations of all synthetic seismograms as well as structural sensitivity kernels of any data. Full waveform approach enables us to use any seismic waves including direct P and S waves, their surface reflections PP, SS, PPP, etc., surface waves, the 410-km and 660-km discontinuity reflections P410P, P660P, the CMB-reflected PcP, ScS, PcPPcP, etc., the CMB-diffracted Pdiff and Sdiff waves, and the core phases such as SKS and all the PKP branches. On the other hand, all these seismic phases can be used to constrain the Earth structures, including the isotropic, anisotropic, elastic, and anelastic velocity perturbations. In this talk, I will review the theoretical development of full waveform seismic tomography with an introduction of its basic formulation and exhibition of numerical examples.

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