各向同性膨胀点源模拟长白山火山区岩浆囊压力变形源   总被引：2，自引：1，他引：1       下载免费PDF全文

朱桂芝  王庆良  石耀霖  崔笃信 《地球物理学报》2008,51(1):108-115

2002～2003年长白山火山区的水平运动缺乏中心对称性分布特征,本文采用同一深度沿三个互相垂直方向拉张的点源模式模拟了长白山火山区的岩浆囊压力变形源. 在介质参数为V_p＝6.700 km/s,V_s＝3.8700 km/s,ρ＝2900 kg/m³的均匀弹性半空间中, 联合利用2002～2003年长白山火山区的GPS观测数据和水准数据, 结合PSGRN/PSCMP代码和遗传算法反演长白山火山区的压力变形源特征. 反演结果表明,由三个垂直的不等量扩张方向确定的椭球状点源模型可以较好地模拟长白山火山区岩浆囊压力变形源. 岩浆囊深处9.2 km,在走向为34.4°,倾角为82.2°的断层面的法向方向体积扩张量最大,达到7000000 m³;在走向为3028°,倾角为78.5°的断层面的法向方向体积扩张量次之,达到6598071 m³;在走向为337.7°,倾角为14.0°的断层面的法向方向体积扩张量最小,达到5220160 m³.  相似文献   

基阶与高阶瑞利波联合反演研究   总被引：9，自引：3，他引：6       下载免费PDF全文

罗银河  夏江海  刘江平  刘庆生 《地球物理学报》2008,51(1):242-249

研究了六层层状介质模型瑞利波基阶和高模式波相速度对横波速度、深度的敏感性,结果表明：基阶波较高模式波对7 m以内浅部地层的横波速度更敏感,敏感性频带在10～25 Hz范围内,峰值频带集中在18 Hz左右;高模式波较基阶波对深部地层的横波速度更敏感,敏感性频带宽,峰值分散.基阶波对浅层的敏感性和高模式波穿透深度更深的特点为近地表岩土层二维横波速度结构的联合反演提供了前提条件.利用阻尼最小二乘SVD（Singular Value Decomposition）算法联合基阶与高模式波对理论模型和实例数据进行横波速度反演,反演结果表明联合反演增强了反演的稳定性,提高了反演的精度.  相似文献   

A new combination of conditional environmental distributions     

《Applied Ocean Research》2018

  相似文献   

锚杆对节理围岩稳定性影响的离散元研究   总被引：13，自引：1，他引：12  

谭云亮  姜福兴  范炜林 《工程地质学报》1999,7(4):361-365

本文针对巷道围岩多被节理切割的特点,利用离散元研究了全长锚杆对节理围岩稳定性的影响。结果表明,尽早锚固,有利于围岩的稳定;同时,巷道各部位围岩的变形与破坏具有明显协同性或关联性,应预以系统考虑对围岩的加固。  相似文献   

3D joint inversion of magnetotelluric and airborne tipper data: a case study from the Morrison porphyry Cu–Au–Mo deposit,British Columbia,Canada          下载免费PDF全文

Benjamin M. Lee  Martyn J. Unsworth  Juliane Hübert  Jeremy P. Richards  Jean M. Legault 《Geophysical Prospecting》2018,66(2):397-421

Z‐axis tipper electromagnetic and broadband magnetotelluric data were used to determine three‐dimensional electrical resistivity models of the Morrison porphyry Cu–Au–Mo deposit in British Columbia. Z‐axis tipper electromagnetic data are collected with a helicopter, thus allowing rapid surveys with uniform spatial sampling. Ground‐based magnetotelluric surveys can achieve a greater exploration depth than Z‐axis tipper electromagnetic surveys, but data collection is slower and can be limited by difficult terrain. The airborne Z‐axis tipper electromagnetic tipper data and the ground magnetotelluric tipper data show good agreement at the Morrison deposit despite differences in the data collection method, spatial sampling, and collection date. Resistivity models derived from individual inversions of the Z‐axis tipper electromagnetic tipper data and magnetotelluric impedance data contain some similar features, but the Z‐axis tipper electromagnetic model appears to lack resolution below a depth of 1 km, and the magnetotelluric model suffers from non‐uniform and relatively sparse spatial sampling. The joint Z‐axis tipper electromagnetic inversion solves these issues by combining the dense spatial sampling of the airborne Z‐axis tipper electromagnetic technique and the deeper penetration of the lower frequency magnetotelluric data. The resulting joint resistivity model correlates well with the known geology and distribution of alteration at the Morrison deposit. Higher resistivity is associated with the potassic alteration zone and volcanic country rocks, whereas areas of lower resistivity agree with known faults and sedimentary units. The pyrite halo and ≥0.3% Cu zone have the moderate resistivity that is expected of disseminated sulphides. The joint Z‐axis tipper electromagnetic inversion provides an improved resistivity model by enhancing the lateral and depth resolution of resistivity features compared with the individual Z‐axis tipper electromagnetic and magnetotelluric inversions. This case study shows that a joint Z‐axis tipper electromagnetic–magnetotelluric approach effectively images the interpreted mineralised zone at the Morrison deposit and could be beneficial in exploration for disseminated sulphides at other porphyry deposits.  相似文献   

数据域初至波走时与成像域反射波走时联合层析速度建模方法          下载免费PDF全文

张兵  王华忠 《地球物理学报》2019,62(7):2633-2644

复杂地表探区,尤其是盆山过渡区的油气勘探是我国也是世界上油气勘探的重点区域,但是此类区域油气地震勘探中满足精确地震成像的速度建模一直是个没有很好解决的问题.本文提出了一种综合性的数据域初至波走时与成像域反射波走时联合层析复杂地表浅中深层速度建模方法,并针对联合层析速度反演解的非唯一性问题,深入地分析了层析反演中正则化的本质意义,指出了建立构造特征正则化方法的具体技术路线,提出了联合层析的实现流程及策略.理论和实际数据试验表明,本文提出的数据域初至走时与成像域反射走时联合层析浅中深层速度建模技术避免了常规建模方法中浅层速度模型与中深层速度模型的融合问题,较好地解决了传统成像域反射层析对近地表模型的不可控更新问题,整体提升了深度域浅中深层速度模型的建模精度,进而提高了复杂地表、复杂构造区的地震成像质量.  相似文献   

3D <Emphasis Type="Italic">v</Emphasis><Subscript>P</Subscript> and <Emphasis Type="Italic">v</Emphasis><Subscript>S</Subscript> models of southeastern margin of the Tibetan plateau from joint inversion of body-wave arrival times and surface-wave dispersion data          下载免费PDF全文

Lina Gao  Haijiang Zhang  Huajian Yao  Hui Huang 《地震科学（英文版）》2017,30(1):17-32

A new 3D velocity model of the crust and upper mantle in the southeastern (SE) margin of the Tibetan plateau was obtained by joint inversion of body- and surface-wave data. For the body-wave data, we used 7190 events recorded by 102 stations in the SE margin of the Tibetan plateau. The surface-wave data consist of Rayleigh wave phase velocity dispersion curves obtained from ambient noise cross-correlation analysis recorded by a dense array in the SE margin of the Tibetan plateau. The joint inversion clearly improves the v _S model because it is constrained by both data types. The results show that at around 10 km depth there are two low-velocity anomalies embedded within three high-velocity bodies along the Longmenshan fault system. These high-velocity bodies correspond well with the Precambrian massifs, and the two located to the northeast of 2013 M _S 7.0 Lushan earthquake are associated with high fault slip areas during the 2008 Wenchuan earthquake. The aftershock gap between 2013 Lushan earthquake and 2008 Wenchuan earthquake is associated with low-velocity anomalies, which also acts as a barrier zone for ruptures of two earthquakes. Generally large earthquakes (M ≥ 5) in the region occurring from 2008 to 2015 are located around the high-velocity zones, indicating that they may act as asperities for these large earthquakes. Joint inversion results also clearly show that there exist low-velocity or weak zones in the mid-lower crust, which are not evenly distributed beneath the SE margin of Tibetan plateau.  相似文献   

一种高效的基于交叉梯度结构约束的三维地震走时与直流电阻率联合反演策略          下载免费PDF全文

高级  张海江  方洪健  李楠 《地球物理学报》2017,60(9):3628-3641

基于交叉梯度结构约束的不同数据的联合反演可以提高地球物理成像的可靠度,但是由于不同观测数据对地下介质的灵敏度不同以及不同反演系统灵敏度矩阵元素的数值可能存在较大的差异,导致构建和求解联合反演系统存在很大的挑战.针对以上问题,本文提出一种新的基于单独反演模型更新量与交叉梯度结构约束相结合的联合反演策略.该策略利用单独反演系统分别确定出各个模型的更新量,然后利用它们约束交叉梯度系统的反演,得出新的模型更新量.通过这样的方式,有效实现了数据拟合与结构约束的平衡,实现了基于交叉梯度联合反演的目标.新的联合反演策略不需要对原来单独反演程序修改即可实现联合反演,减小了联合反演实现的难度,极大地提高了联合反演的易实现性,而且避免了联合反演矩阵存储及结构过于复杂难以求解的问题.基于新的策略,本文首次实现了基于交叉梯度结构约束的三维地震走时与直流电阻率联合反演.合成模型测试表明,与单一成像相比,联合成像减少了地震走时反演中出现的干扰异常并提高了电阻率反演的分辨率.  相似文献   

Cross double‐difference inversion for simultaneous velocity model update and microseismic event location          下载免费PDF全文

Xiao Tian  Wei Zhang  Jie Zhang 《Geophysical Prospecting》2017,65(Z1):259-273

Microseismic monitoring is an approach for mapping hydraulic fracturing. Detecting the accurate locations of microseismic events relies on an accurate velocity model. The one‐dimensional layered velocity model is generally obtained by model calibration from inverting perforation data. However, perforation shots may only illuminate the layers between the perforation shots and the recording receivers with limited raypath coverage in a downhole monitoring problem. Some of the microseismic events may occur outside of the depth range of these layers. To derive an accurate velocity model covering all of the microseismic events and locating events at the same time, we apply the cross double‐difference method for the simultaneous inversion of a velocity model and event locations using both perforation shots and microseismic data. The cross double‐difference method could provide accurate locations in both the relative and absolute sense, utilizing cross traveltime differences between P and S phases over different events. At the downhole monitoring scale, the number of cross traveltime differences is sufficiently large to constrain events locations and velocity model as well. In this study, we assume that the layer thickness is known, and velocities of P‐ and S‐wave are inverted. Different simultaneous inversion methods based on the Geiger's, double‐difference, and cross double‐difference algorithms have been compared with the same input data. Synthetic and field data experiments suggest that combining both perforation shots and microseismic data for the simultaneous cross double‐difference inversion of the velocity model and event locations is available for overcoming the trade‐offs in solutions and producing reliable results.  相似文献   

基于重磁震资料的南海新生代盆地分布综合研究   总被引：3，自引：1，他引：2       下载免费PDF全文

冯旭亮  张功成  王万银  赵志刚  邱之云  谢晓军  纪晓琳  鲁宝亮  宋双 《地球物理学报》2018,61(10):4242-4254

作为西太平洋最大的边缘海,南海分布有30多个新生代沉积盆地,其蕴含着丰富的油气资源.但由于资料的限制,南海存在不同区域盆地研究程度不同,不同区域盆地面积差别较大,部分盆地只是坳陷而没有达到盆地的级别以及盆地外围可能存在凹陷等问题.南海新生代盆地分布问题制约了其油气分布规律、储量等基础地质问题的研究.本文以地震剖面数据为约束,以重力资料为主、辅以磁力资料,研究了南海新生代盆地分布及构造区划.通过提取新生代盆地及其构造单元引起的重力异常,结合地震剖面等资料反演了新生界底界面深度及新生界厚度.在充分调研已有盆地和构造单元划分方案的基础上,根据南海的地质及地球物理特征,确定了盆地及构造单元划分标准.以新生界厚度为基础并结合重、磁、震、地质等资料,进行地质-重磁震联合解释,将南海原有的36个盆地重新划分为24个盆地,盆地总面积扩大了约15万km².研究表明,南海新生代盆地沉积层厚度在1.5~16 km之间,有6个北东东/北东向沉积坳陷带、2个近南北向沉积坳陷带以及1个三角沉积坳陷区;盆地展布方向主要为北东和北东东向,其次为北西和近南北向,呈现"南三北三"的分布特征.  相似文献