青海省3次强震前地下流体短临异常的对比分析     

张敏  马延魁 《高原地震》2003,15(1):9-14

通过对发生于1999～2000年间库玛中东段地区3次5级以上地震前地下流体短临异常的分析对比，得出了该地区地下流体短临异常的时空强演化特征。  相似文献   

德令哈6．6级地震前地震活动及地震序列特征     

陈玉华马文静  崔国信 《高原地震》2003,15(3):1-8

德令哈6．6级地震发生在青海省地震局2003年度会商确定的应注意地区内，震前测震学出现多项中短期异常。该地震序列从其能量释放比、震级差均符合主震一余震型判断指标，为主震-余震型序列。序列跟踪工作总结出该序列早期阶段(20天内)预测强余震的几项指标。  相似文献   

Optimal Model for Geoid Determination from Airborne Gravity   总被引：2，自引：0，他引：2  

Novák  Pavel 《Studia Geophysica et Geodaetica》2003,47(1):1-36

Two different approaches for transformation of airborne gravity disturbances, derived from gravity observations at low-elevation flying platforms, into geoidal undulations are formulated, tested and discussed in this contribution. Their mathematical models are based on Green's integral equations. They are in these two approaches defined at two different levels and also applied in a mutually reversed order. While one of these approaches corresponds to the classical method commonly applied in processing of ground gravity data, the other approach represents a new method for processing of gravity data in geoid determination that is unique to airborne gravimetry. Although theoretically equivalent in the continuous sense, both approaches are tested numerically for possible numerical advantages, especially due to the inverse of discretized Fredholm's integral equation of the first kind applied on different data. High-frequency synthetic gravity data burdened by the 2-mGal random noise, that are expected from current airborne gravity systems, are used for numerical testing. The results show that both approaches can deliver for the given data a comparable cm-level accuracy of the geoidal undulations. The new approach has, however, significantly higher computational efficiency. It would be thus recommended for real life geoid computations. Additional errors related to regularization of gravity data and the geoid, and to accuracy of the reference field, that would further deteriorate the quality of estimated geoidal undulations, are not considered in this study.  相似文献   

Gravity variation before Kunlun mountain pass western Ms=8.1 earthquake     

祝意青王双绪  江在森朱桂芝李辉  张永志 《地震学报(英文版)》2003,16(3):304-311

The relation between the gravity variation features and Ms=8.1 earthquake in Qinghai-Xizang monitoring area is analyzed preliminarily,by using spatial dynamic variation results of regional gravity field from absolute gravity and relative gravity observation in 1998 and 2000.The results show that:1)Ms\8.1 earthquake in Kulun mountain pass westem occurred in the gravity variation high gradient near gravity‘s high negative variation;2)The Main tectonic deformation and emnergy accumulation before MS=8.1 earthquake are distributed at south side of the epicenter;3)The range of gravity‘s high negative variation at east of the MS=8.1 earthquake epicenter relatively coincides with that rupture region according to field geology investigation;4)Gravity variation distribution in high negative value region is just consistent with the second shear strain‘s high value region of strain field obtained from GPS observation.  相似文献   

地浸砂岩型铀矿床微磁异常研究及其找矿意义   总被引：4，自引：0，他引：4  

江民忠  李名松  谢迎春  石岩 《地质科技情报》2003,22(3):49-54

通过认真研究中国新疆某盆地410，411和412三个已知地浸砂岩型铀矿床的航磁资料，发现这些矿床上方均存在航磁微磁异常。根据地浸砂岩型铀矿的成矿地球化学机制，对航磁微磁异常的形成机理作了进一步探讨，结合试验区的实际预测成果指出，与氧化一还原过渡带有关的地浸砂岩型铀矿床上方存在微磁异常，高精度航磁完全能探测得到它。航磁微磁异常是此类矿床的特征异常之一，对此类铀矿床具有直接的指示意义，可以作为一种直接标志信息运用于前期成矿预测。  相似文献   

Continuous wavelet-like filter for a spherical surface and its application to localized admittance function on Mars     

Motoyuki Kido  David A. Yuen 《Physics of the Earth and Planetary Interiors》2003,135(1):1-16

We have developed a 2D isotropic continuous wavelet-like transform for a spherical surface. The transform is simply defined as the surface convolution between the original field and a kernel, based on the zeroth-order Bessel function with a spherical correction. This spherical correction violates the geometric similarity for the various scales of the kernels, which becomes more apparent at longer wavelengths. We found numerically that this transform is practically equivalent to a Gaussian bandpass filter in the spherical harmonic domain. We have applied this wavelet-like transform on the recently acquired Martian gravity and topography fields. Using a ratio constructed locally from these two fields, we have constructed a map describing the lateral variations of the localized admittance function on Mars.  相似文献   

The role of sediment specific gravity and availability on cluster evolution     

A. N. Papanicolaou  K. Strom  A. Schuyler  N. Talebbeydokhti 《地球表面变化过程与地形》2003,28(1):69-86

The objective of this experimental study was to account for the role of sediment availability and specific gravity on cluster formation and cluster geometric characteristics (spacing and size). To isolate the effects of sediment availability and specific gravity on cluster evolution, mono‐sized spheres were used to simulate the cluster evolutionary cycle. Overall, twelve experimental runs were carried out in the laboratory flume. Six of these tests were performed by using glass spheres (specific gravity, SG = 2·58) and the other six by employing an equal combination of glass and Teflon spheres (SG = 2·12) of the same diameter to evaluate the role of specific gravity on cluster evolution. The three sediment availability conditions that were investigated here simulated isolated gravel elements, pool–riffle sequences and densely packed gravel‐bed. An advanced image analysis technique was employed to track the evolution of cluster microforms and provide quantitative information about the size and shape of clusters and the number of clusters per unit area. The results of this study showed that: (1) sediment availability affects the architecture and size of cluster microforms; and (2) clusters consisting of mono‐sized sediments start disintegrating at twice the incipient conditions. By performing complementary tests for the isolated gravel elements case, it was found that the evolutionary cycle of individual clusters could be described as follows, in order of increasing stress: no cluster→two particle cluster→comet→triangle→rhomboid→break up. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

高精度推求正高的两种方法     

张赤军 《武汉大学学报(信息科学版)》2003,28(4):432-434,443

论述了高精度推求正高的两种方法 ,并对正高精度的推估及其在模型上的试算也作了讨论 ,对于海拔为 5 0 0 0m的高山 ,正高的误差一般不超过± 1 0cm ,这与距青岛水准原点达数千公里的西部高山 (原 )处正常高的精度也比较接近  相似文献   

深圳市1 km高分辨率厘米级高精度大地水准面的确定   总被引：56，自引：1，他引：56  

宁津生  罗志才  杨沾吉  陈永奇  张天纪 《测绘学报》2003,32(2):102-107

利用65个精度优于2 cm的GPS水准数据、5 213个实测重力点数据、100 m分辨率的数字地形模型和WDM94地球重力场模型,采用移去-恢复技术计算了深圳市1 km分辨率的大地水准面模型.将该模型大地水准面高与由29个GPS水准得到的大地水准面高进行比较,其差值的标准差为±1.4 cm.  相似文献   

给定内插高程异常值的精度时对GPS水准网格间距的考虑   总被引：7，自引：0，他引：7  

陈俊勇 《测绘学报》2003,32(2):130-133

在已布设GPS水准网的地区，若需内插其中任意一点的高程异常值时，应该了解该内插值的精度。导出了该内插点高程异常值的精度评定方法，并具体给出在我国C级GPS水准网中，该内插点高程异常推估值精度和该地区的地形和栅格重力异常分辨率的数学关系式和实例。在给定内插点高程异常值精度的局域大地水准面时，按不同地形和栅格重力异常分辨率的密度，根据这些数学关系式，可以设计间距合理的B级或C级GPS水准网。  相似文献