Broadband synthetic aperture borehole radar interferometry   总被引：1，自引：0，他引：1  

I. Mason  N. Osman  Q. Liu  C. Simmat  M. Li 《Journal of Applied Geophysics》2001,47(3-4)

Trials in mines have established that wideband VHF borehole radars (BHR), working in the 10–100-MHz band, can be used to probe the rockmass between boreholes over ranges from <5 m to as much as 150 m with submeter resolution. There is evidence that ore bodies reflect these radar signals both specularly and diffusely, much as the ground/air interface does when overflown by synthetic aperture radar (SAR). In both SAR and BHR, multiple flight lines, together with diffuse reflections admit the possibility of developing interferometric 3D images of the object. This paper examines the possibility of imaging buried objects in three dimensions by interferometrically combining broadband VHF borehole radar profiles shot in adjacent pairs of boreholes. Broadbanding in BHR has the advantage of releasing the image from 2nπ phase ambiguities, but practically, interferometric borehole radar (InBHR) needs high signal-to-noise ratios (SNR) to avoid noise capture. This means that 3D InBHR is limited to ranges in wavelengths which are less than the rock's attenuation factor Q. Interferometric methods are developed which are capable of mapping ore bodies and other structures in three dimensions. Tangent plane migration methods are developed here in order to reconstruct surfaces that lie in the near-field of sparse interferometric arrays.  相似文献   

Study on the sources of some deep focus earthquakes in Northwest Pacific region     

An-Yi Li  Shao-Xian Zang 《地震学报(英文版)》1996,9(1):23-31

The sources for thirteen deep focus earthquakes ofm _b≥5.5 andh>400 km in Northwest Pacific region were studied using waveform fitting and shear fracture source model. The source parameters were obtained as follows: focal depth, faulting plane, slip direction, rupture velocity, rupture length, rupture direction and scalar moment tensor. It was found that all these earthquake sources can be interpreted as shear faulting and have simple source time functions. The strike direction of faulting plane for most deep focus earthquakes coincides with that of the subduction zone, especially in the deep part of the subduction zone, it results in the tendency of reducing the dip angle of the subduction zone. The multiple point source model was also used to study the source process. The waveform fitting is better than the shear fracture model, but the general rupture direction which coincides with that from unilateral shear source model can not be obtained from the multiple point source model. This study is supported by the National Science Foundation of China and the Chinese Joint Seismological Science Foundation.  相似文献   

从天津地区近十年的地下水位变化初探本区断裂活动的新动向     

吕惠琴  李朝弼 《华北地震科学》1996,14(3):38-47

在现有地震流体研究成果基础上，借地下水位的时空异常图象进行推测区域构造断裂活动的探索。通过对天津夺区１９８５至１９９４年地下水位异常的分析对本区的构造洗给出了以下推测；（１）１９８９年大同６．１级地震对地区构造活动显示出突出的调整性的变化。（２）沧东断裂带是本地区最活跃居主导活动地位的断裂。（３）沧东断裂带应力集中部位有同天津西南段向东北转移的迹象。  相似文献   

胶东金矿成矿构造──地球化学动力学研究   总被引：13，自引：4，他引：13  

赵伦山  吴悦斌 《现代地质》1996,10(2):213-217

通过对胶东区域断裂构造时空演化的分析，提出郯庐大断裂的次级断裂为胶东金矿的控矿构造，并为导矿构造。晚燕山期区域右行走滑断裂活动产生的浅部张剪裂隙为容矿构造，其张裂变形产生的扩容作用是“泵吸”深部矿液上侵充填的驱动力。张剪断裂以脉动方式释放构造应力，实测差应力值为１２０～４０ＭＰａ；从早到晚有衰减趋势。容矿断裂脉动活动可划分为脆性破裂和脆韧性扩张两种动力学状态或阶段，并制约着热液反应体系中成矿和控制反应进行的方向和强度，从而控制成矿元素的富集和分散。热液成矿反应体系的热力学演化与构造动力学条件的耦合是金富矿石形成的机制。  相似文献   

岩石蠕变破坏实验研究及其对地震预报的意义          下载免费PDF全文

赵阿兴 《地震地质》1992,14(1):89-95

通过对不同温度和围压条件下济南辉长岩的蠕变破坏实验结果和声发射特征分析,本文提出以岩石蠕变破坏应变做为岩石蠕变破坏判据。建立了岩石蠕变破坏应变的经验关系式。依据实验结果得到相应的济南辉长岩蠕变破坏应变参数,进一步探讨了预报岩石蠕变破坏和地震的方法  相似文献   

Influence of source region properties on scaling relations forM<0 events     

T. I. Urbancic  B. Feignier  R. P. Young 《Pure and Applied Geophysics》1992,139(3-4):721-739

Excavation induced seismic events with moment magnitudesM<0 are examined in an attempt to determine the role geology, excavation geometry, and stress have on scaling relations. Correlations are established based on accurate measurements of excavation geometry and methodology, stress regime, rock mass structure, local tectonics, and seismic locations. Scaling relations incorporated seismic moments and source radii obtained by spectral analysis, accounting for source, propagation, and site effects, and using Madariaga's dynamic circular fault model. Observations suggest that the interaction of stresses with pre-existing fractures, fracture complexity and depth of events are the main factors influencing source characteristics and scaling behaviour. Self-similar relationships were found for events at similar depths or for weakly structured rock masses with reduced clamping stresses, whereas a non-similar behaviour was found for events with increasing depth or for heavily fractured zones under stress confinement. Additionally, the scaling behaviour for combined data sets tended to mask the non-similar trends. Overall, depth and fracture complexity, initially thought as second order effects, appear to significantly influence source characteristics of seismic events withM<0 and consequently favour a non-similar earthquake generation process.  相似文献   

The experimental research on b value of AE for the rock specimens with pre-existing crack or notch under uniaxial compression     

Hong Li  Xiangchu Yin  Shiyu Li  Jihan Li 《地震学报(英文版)》1992,5(4):867-875

A lot of researches onb value have been made in seismology. Since the 1960’s Mogi, Scholz and others have studied AE of rock specimens in laboratory and discovered that it is related to natural earthquakes. All former researchers used integral specimens to studyb value in the laboratory. However a major earthquake is usually related to a existing seismic-fault in that area. For this reason, a series of fracture experiments with rock and glass specimens having pre-existing crack or notch is performed in order to examine the effect of preexisting crack tob value. The experimental results show that theb value begins to decrease as soon as the initiation of the crack and finally drop to a very low value when the specimen breaks unstably. Based on these, a brief discussion on the possible mechanism ofb value change for natural earthquakes is given. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,9, 393–400, 1987. Projects sponsored by the Chinese Joint Seismological Science Foundation.  相似文献   

断裂带热释光的初步研究     

谭凯旋  刘顺生 《矿物岩石》1992,12(2):16-20

本文对湖南水口山矿田断裂带岩石进行了热释光分析,断裂作用可对岩石的热释光特征产生显著变化。断裂带岩石天然热释光不存在250℃以下的低温峰;从围岩到断裂带中心,热释光峰值大幅度增加;同一断裂带从地表向深部热释光峰值增加。碎裂断裂带天然热释光峰值为10~3—10~4级,高峰温度位于290—310℃范围内;硅化断裂带的天然热释光峰值大多为10~2—10~3级,高峰温度多在330—350℃范围内。  相似文献   

四川省青川断裂的特征及形成的物理条件   总被引：3，自引：0，他引：3  

代建全 《四川地质学报》1992,(4)

本文详细地讨论了四川省青川断裂的断裂特征及形成的物理条件。对断裂构造岩的微构造和宏观构造进行了细致的描述分析,将断裂岩分为四个带。结合区域资料,讨论了断裂的形成时代及与邻区的关系。  相似文献   

非等间距序列的灰色预测模型及其在岩石蠕变断裂中的应用   总被引：3，自引：1，他引：3  

陈有亮  孙钧 《岩土力学》1995,16(4):8-12

给出了非等间距序列的灰色预测模型，讨论了该模型的灰色预测平面和最优预测函数。最一将该模型应用于符合Ｋｅｌｖｉｎ模型的岩石材料的蠕变断裂研究，给出了应用实例，并验证了该方法的可行性。  相似文献