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1.
射频大地电磁法(RMT)是以潜艇天线发射的射线源等作为场源的一种地球物理勘探方法,目前被广泛应用于近地表工程和环境地球物理勘探.RMT数据解释常采用基于静态假设的大地电磁法(MT)程序,往往会反演出不真实的浅层目标体.为解决这一长期困扰RMT资料解释的问题,本文实现了考虑位移电流的RMT有限元数值模拟.为了处理任意复杂模型,如起伏地形,非结构的三角形网格被用于离散RMT模型.首先通过算例对比,验证了程序的正确性和可靠性.通过Dike模型讨论了空气层厚度对RMT数值解的影响,结果表明当空气层厚度大于1/4波长即可满足精度要求.以山脊模型为例计算了位移电流对RMT响应的影响,表明位移电流的影响会随着山脊高程的增加而增大.最后通过舒家店实际模型进一步验证了位移电流在RMT中的重要性. 相似文献
2.
2005珠峰高程测定的技术进展 总被引：2，自引：0，他引：2
2005年中国对珠穆朗玛峰高程进行了新的测定. 重点介绍了2005珠峰测高中大地测量数据获取和处理方面的技术进步: 其中峰顶GPS测量是整个珠峰测高中的关键, 总结了以往珠峰峰顶GPS测量的经验教训, 采取多种技术措施, 大幅度提高了峰顶GPS测量的精度; 增加地面测站对峰顶觇标的激光测距, 以提高测定珠峰觇标平面位置和高程的精度; 采用雷达探测结合GPS技术, 测定珠峰峰顶冰雪覆盖层的厚度, 提高了测量峰顶冰雪覆盖层厚度的精度和可靠性; 利用珠峰地区的重力、GPS水准和DTM资料, 结合不同的地球重力场模型, 计算了珠峰地区两种栅格(30"×30"和2.5′×2.5′)的重力异常, 精化了珠峰地区局域重力场和似大地水准面. 最后给出了2005珠峰测高的成果: 珠峰峰顶雪面正常高为8846.67 m, 珠峰峰顶雪面正高(海拔高)为8847.93 m, 珠峰峰顶岩面正高为8844.43 m, 珠峰峰顶冰雪层厚度为3.50 m. 相似文献
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4.
局部似大地水准面精化中需要进行GPS水准与重力两种水准面的拟合,其中两种观测量精度的权比确定是关键问题,本文提出基于方差分量估计的方法解决这一问题.根据此思路,文中还利用某给定区域的实际资料,对常用的几种似大地水准面拟合方法——多项式拟合、多面函数拟合以及曲面样条插值的函数模型按不等权拟合似大地水准面进行试验.通过某3... 相似文献
5.
尽管在城市中使用地球物理方法进行探测会受到复杂人文干扰、施工场地有限的挑战,但是相比于昂贵且具有破坏性的钻孔勘探,在城市采用无损的地球物理勘探带来的好处还是远远超出了其限制.本文以成都市天府新区独角兽岛为试验区,在提前了解其地质背景和研究区工况现状的前提下,采用地质雷达、高密度电阻率法组合地球物理方法,对试验区1 km2的面积开展了综合地球物理勘探,地质雷达主要用于30 m以浅的地质结构精细分层,高密度电阻率法重点对30～100 m深的地层进行约束分层.为了提高分层精度,测点及地表起伏形态通过RTK测量控制,最终通过综合地球物理信息、RTK测量信息和钻孔信息,快速获取了试验区100 m以浅的三维地质特征,为正在开展的独角兽岛地下空间规划及施工建设提供了重要的基础资料. 相似文献
6.
沉积相研究是盆地隐蔽油气藏勘探中重要的研究内容之一,综合利用地球物理方法有效识别构造、岩性或沉积相差异是盆地隐蔽油气藏勘探的前提.本文基于重力、航磁、地震等综合地球物理资料,通过重磁异常正演剥离和剖面正反演拟合技术研究了华南桂中地区海相地层的密度分布特征,预测了岩相、沉积相的变化规律.研究发现,本区中、下泥盆统海相地层存在横向的岩性、岩相变化,研究区西北、东南部的台地相区重力异常高、岩石拟合密度值高;中部“X”型台地边缘相区重力异常杂乱、岩石拟合密度变化范围大;东部台沟相区重力异常低、岩石拟合密度值低.利用综合地球物理方法预测沉积相为盆地岩性圈闭油气藏和生物礁油气藏勘探提供了新的研究思路,研究成果已得到初步检验,但还有待进一步完善与实践. 相似文献
7.
研究利用重力场模型直接进行GPS高程转换的方法,即模型高程异常法和模型重力位法.根据误差传播定律,导出了由重力场模型位系数方差计算模型高程异常以及模型正常高的误差公式,并对影响两种GPS高程转换方法精度的因素进行分析.利用具有代表性的EGM96、EIGEN-51C和EGM2008重力场模型及某线路GPS/水准数据对两种方法进行实验研究与精度分析,结果表明:理论公式及实验结果都显示两种高程转换方法是等价的,转换精度相当;两种方法使用过程中,均可能需要系统偏差校正;EGM2008重力场模型具有非常好的分辨率及精度,在局部区域,基于EGM2008模型的GPS高程转换精度有望达到cm级. 相似文献
8.
9.
某煤矿典型CSAMT法视电阻率曲线的一维模拟 总被引：6，自引：3，他引：3
了解煤矿开采区的地层地质情况,指明断层、破碎带、陷落柱等构造及其含水性,并分析其对开采过程中可能造成的安全威胁是煤矿安全生产的重要保证．可控源音频大地电磁测深(CSAMT)法是浅层地球物理勘探的一种有力的手段,可以用来探明从地表到地下1500米范围的地质情况．在开采区完成三维地震勘探,对构造有了较系统的控制后,利用电法CSAMT手段重点来分析构造及地层的含水及富水特性,是一种科学的工作流程．本文采用一维正演方法对该矿区典型的CSAMT视电阻率曲线进行模拟并与实际曲线进行了对比．通过大量的模型拟合,得到了较好的拟合效果,这对反演解释提供了有用信息。 相似文献
10.
“十三五”规划中桂地区页岩气基础地质调查地球物理勘探正有序开展。桂地区页岩油气地球物理勘探基础较薄弱，如何有效开展地球物理勘探是当前基础地质调查重要课题。着重阐述了桂周边地区页岩油气地球物理勘探研究现状，指出桂周边地区页岩油气地球物理勘探技术成熟并取得了进展性突破。基于桂地区与其周边地区页岩油气地质条件具有较好可比性，重点讨论了周边地区页岩油气地球物理勘探成功经验对桂地区页岩油气地球物理勘探工作开展的几点认识及展望。指出今后开展桂地区页岩油气地球物理勘探及评价项目中需要注意的几个研究方向，即稳健推广二维地震勘探、优先发展2.5维电磁勘探、加强系统物性测试与分析、重磁电震综合为终极目标，为实际勘探开展奠定理论基础。 相似文献
11.
J. F. Prieto P. J. González A. Seco G. Rodríguez-Velasco L. Tunini P. A. Perlock A. Arjona A. Aparicio A. G. Camacho J. B. Rundle K. F. Tiampo J. L. G. Pallero S. Pospiech J. Fernández 《Pure and Applied Geophysics》2009,166(8-9):1461-1484
We review the results of the geodetic and structural studies carried out on La Palma Island using geodetic and geophysical data during the period 1992–2007. InSAR and GPS observation techniques were applied to study the existence of deformation on the island and gravity observations were carried out for structural studies. Gravity data were inverted using a nonlinear three-dimensional gravity inversion approach to obtain the geometry of the anomalous bodies constructed in a random growth process with respect to an exponentially stratified background. The main structural feature is a large central body (under the Caldera de Taburiente) with high density, which was interpreted as the Pliocene-age uplifted seamount and a relatively dense intrusive plutonic complex/magma body. The Cumbre Vieja series is characterized by elongated minima distributed according to the rift structure. InSAR results show a clear subsidence located on the Teneguía volcano, where the last eruption took place in 1971. A thermal source is the most probable origin for this deformation. A GPS network composed of 26 stations covering the total island surface was set up. Vertical displacements determined comparing the GPS coordinates obtained in 2007 with coordinates determined in 1994 are consistent with the InSAR results obtained in the southern part of the island. This is not the case for the northern part. From the comparison of 2006 and 2007 coordinates it is clear that more time is needed to obtain significant displacements, but observed trends are also consistent with InSAR results. All the observed significant displacements are in stations located outside of the large high-density central body. 相似文献
12.
GPS观测得到的地壳形变场通常包含有构造形变与非构造形变二类信息, 去除其中的非构造形变信息对于有效运用GPS数据研究构造形变场至关重要. 本文运用国际卫星对地观测资料及各类地球物理模型, 定量计算海潮、大气、积雪和土壤水、海洋非潮汐4项负荷效应造成的地壳非构造形变, 并以此研究和修正这些非构造形变对中国地壳运动观测网络GPS基准站位置时间序列的影响. 研究发现此4项负荷效应, 特别是大气、积雪和土壤水, 对于测站垂向位置的影响显著. 通过模型改正可以使测站垂向位置的RMS降低～1 mm, 占其总量的～11％. 对于垂向时间序列的周年项部分, 这一改正可降低其振幅的37％. 研究还表明经过地球物理模型改正和周年、半周年谐波拟合改正的时间序列比起仅经过周年、半周年谐波拟合改正的时间序列更为平滑, 表明地球物理模型改正对于消除非构造形变场的作用不是周年、半周年谐波拟合改正所能替代的. 相似文献
13.
The continuous efforts on establishment and modernization of the geodetic control in Turkey include a number of regional geoid
models that have been determined since 1976. The recently released gravimetric Geoid of Turkey, TG03, is used in geodetic
applications where GPS-heights need to be converted to the local vertical datum. To reach a regional geoid model with improved
accuracy, the selection of the appropriate global geopotential model is of primary importance. This study assesses the performance
of a number of recent satellite-only and combined global geopotential models (GGMs) derived from CHAMP and GRACE missions’
data in comparison to the older EGM96 model, which is the underlying reference model for TG03. In this respect, gravity anomalies
and geoid heights from the global geopotential models were compared with terrestrial gravity data and low-pass filtered GPS/levelling
data, respectively. Also, five new gravimetric geoid models, computed by the Fast Fourier Transform technique using terrestrial
gravity data and the geopotential models, were validated at the GPS/levelling benchmarks. The findings were also compared
with the validation results of the TG03 model.
The tests showed that as it was expected any of the high-degree combined models (EIGEN-CG03C, EIGEN-GL04C, EGM96) can be employed
for determining the gravity anomalies over Turkey. In the west of Turkey, EGM96 and EIGEN-CHAMP03S fit the GPS/levelling surface
better. However, all the tested GGMs revealed equal performance when they were employed in gravimetric geoid modelling after
de-trending the gravimetric geoid model with corrector surface fitting. The new geoid models have improved accuracy (after
fit) compared to TG03. 相似文献
14.
Ali Kiliçoğlu Ahmet Direnç Hasan Yildiz Murat Bölme Bahadir Aktuğ Mehmet Simav Onur Lenk 《Studia Geophysica et Geodaetica》2011,55(4):557-578
Turkish regional geoid models have been developed by employing a reference earth gravitational model, surface gravity observations
and digital terrain models. The gravimetric geoid models provide a ready transformation from ellipsoidal heights to the orthometric
heights through the use of GPS/leveling geoid heights determined through the national geodetic networks. The recent gravimetric
models for Turkish territory were computed depending on OSU91 (TG-91) and EGM96 (TG-03) earth gravitational models. The release
of the Earth Gravitational Model 2008 (EGM08), the collection of new surface gravity observations, the advanced satellite
altimetry-derived gravity over the sea, and the availability of the high resolution digital terrain model have encouraged
us to compute a new geoid model for Turkey. We used the Remove-Restore procedure based on EGM08 and applied Residual Terrain
Model (RTM) reduction of the surface gravity data. Fast Fourier Transformation (FFT) was then used to obtain the residual
quasigeoid from the reduced gravity. We restored the individual contributions of EGM08 and RTM to the whole quasi-geoid height
(TQG-09). Since the Helmert orthometric height system is adopted in Turkey, the quasi-geoid model (TQG-09) was then converted
to the geoid model (TG-09) by making use of Bouguer gravity anomalies and digital terrain model. After all we combined a gravimetric
geoid model with GPS/leveling geoid heights in order to obtain a hybrid geoid model (THG-09) (or a transformation surface)
to be used in GPS applications. The RMS of the post-fit residuals after the combination was found to be ± 0.95 cm, which represents
the internal precision of the final combination. And finally, we tested the hybrid geoid model with GPS/leveling data, which
were not used in the combination, to assess the external accuracy. Results show that the external accuracy of the THG-09 model
is ± 8.4 cm, a precision previously not achieved in Turkey until this study. 相似文献
15.
Improved determination of heights using a conversion surface by combining gravimetric quasi-geoid/geoid and GPS-levelling height differences 总被引：2，自引：0，他引：2
The quasi-geoid/geoid can be determined from the Global Positioning System (GPS) ellipsoidal height and the normal/orthometric
heights derived from levelling (GPS-levelling). In this study a gravimetric quasigeoid and GPS-levelling height differences
are combined to develop a new surface, suitable for “levelling” by GPS. This new surface provides better conversion of GPS
ellipsoidal heights to the national normal heights. Different combining procedures, a four-parameter solution, linear and
cubic splines interpolations, as well as the least-squares collocation method were investigated and compared over entire Norway.
More than 1700 GPS-levelling stations were used in this study. The combined surface provides significant accuracy improvement
for the normal height transformation of GPS height data, as demonstrated by the post-fitting residuals. The best solution,
based on the least-squares collocation, provided a conversion surface for the transformation of GPS heights into normal height
in Norway with an accuracy of about 5 cm. 相似文献
16.
《Journal of Geodynamics》2006,41(4-5):494-501
We have processed all available DORIS data from all available satellites, except Jason-1 over the past 10 years (from January 1993 to April 2003). Weekly solutions have been produced for stations positions coordinates, geocenter motion and scale factor stability. We present here accuracy presently achievable for all types of potential geodetic products. Typically weekly stations positions can be derived with a repeatability of 1.0–1.5 cm using data from 5 satellites simultaneously, showing the significant improvement in precision that has been gained recently using the additional new DORIS satellites. As an example, we show how such new results can detect displacement from large magnitude earthquakes, such as the 2003 Denali fault earthquake in Alaska. Displacements of −5 cm in latitude and +2 cm in longitude were easily detected using the DORIS data and are confirmed by recent GPS determination. The terrestrial reference frame was also well be monitored with DORIS during this 10-year period. Other geodetic products, such as tropospheric corrections for atmospheric studies are also analyzed. Finally, we discuss here the possible advantages and weaknesses of the DORIS system as additional geodetic tool, in conjunction with the already existing GPS, VLBI and SLR services, to participate in an Global Geodetic Observing System (GGOS). 相似文献
17.
Transformation between gravimetric and GPS/levelling-derived geoids using additional gravity information 总被引：1，自引：0，他引：1
The transformation from the gravimetric to the GPS/levelling-derived geoid using additional gravity information for the covariance function of geoid height differences has been investigated in a test area in south-western Canada. A “corrector surface” model, which accounts for datum inconsistencies, long-wavelength geoid errors, vertical network distortions and GPS errors, has been constructed using least-squares collocation. The local covariance function of geoid height differences is usually obtained from residual values between the GPS/levelling and gravimetric geoid heights after the elimination of all known systematic distortions. If additional gravity data (in the form of gravity anomalies) are available, the covariance function of geoid height differences can be determined by the following steps: (1) transforming the GPS/levelling-derived geoid heights into gravity anomalies; (2) forming differences between the computed in step 1 and given gravity anomalies; (3) determining the parameters of the local covariance function of the gravity anomaly differences; (4) constructing an analytical covariance model for the geoid height differences from the covariance function of the gravity anomaly differences using the parameters derived in step 3. The advantage of the proposed method stems from the great number of gravity data used to derive the empirical covariance function. A comparison with the least-squares adjustment shows that the standard deviation of the residuals of the predicted geoid height differences with respect to the control point values decreases by 2.4 cm. 相似文献
18.
De Lacy M.C. Rodríguez-Caderot G. Marín E. Ruiz A. Borque M.J. Gil A.J. Biagi L. 《Studia Geophysica et Geodaetica》2001,45(1):55-66
Two new GPS surveys have been carried out to check the accuracy of an existing gravimetric geoid in a test area located in northern Andalusia (Spain). The fast collocation method and the remove-restore procedure have been used for the computation of the quasigeoid model. The Spanish height system is based on orthometric heights, so the gravimetrically determined quasigeoid has been transformed to a geoid model and then compared to geoid undulations provided by GPS and levelling at benchmarks belonging to the Spanish first-order levelling network. The discrepancies between the gravimetric solution and GPS/levelling undulations amount to ±2 cm for one survey and ±5 cm for another after fitting a plane to the geoid model. 相似文献
19.
The paper presents the testing of the possibility of determining the heights of GPS points in the homogeneous field in the
new Croatian Height Reference System (HVRS71) by using the method of height transformation. The testing was made in the area
of Zagreb. As part of the field works, normal orthometric heights of 27 GPS points were determined according to the new height
system, by transferring the benchmark heights using the geometric levelling method, thus obtaining GPS/levelling points of
known ellipsoidal and normal orthometric heights. The GPS/levelling points served as the basis for determining the transformation
models that enabled the computation of normal orthometric heights from ellipsoidal heights of any GPS point in the observed
area. The empirical data used for modelling were reduced undulation dN values of GPS/levelling points. As part of the dN modelling
with parametric functions, the approximation surfaces were obtained on the basis of three polynomials: FN310, FN312 and FN318.
The transformation models were also tested using non-parametric Watson and Loess algorithms. The FN318 and Loess models yielded
the best results. 相似文献
20.
《中国科学:地球科学(英文版)》2021,(8)
The ice flow velocity is a basic feature of glaciers and ice sheets. Measuring ice flow velocities is very important for estimating the mass balance of ice sheets in the Arctic and Antarctic. Traditional methods for measuring ice flow velocity include the use of stakes, snow pits and on-site geodetic GPS and remote sensing measurement methods. Geodetic GPS measurements have high accuracy, but geodetic GPS monitoring points only sparsely cover the Antarctic ice sheets. Moreover, the resolution and accuracy of ice flow velocities based on remote sensing measurements are low. Although the accuracy of the location data recorded by the navigation-grade GPS receivers embedded in short-period seismographs is not as good as that of geodetic GPS,the ice flow velocity can be accurately measured by these navigation-grade GPS data collected over a sufficiently long period. In this paper, navigation-grade GPS location data obtained by passive seismic observations during the 36 th Chinese National Antarctic Research Expedition were used to accurately track the movement characteristics of the ice sheet in the Larsemann Hills of East Antarctica and the Taishan Station area. The results showed that the ice sheet in the two study areas is basically moving northwestward with an average ice flow velocity of approximately 1 m mon-1. The results in the Taishan Station area are basically consistent with the geodetic GPS results, indicating that it is feasible to use the embedded GPS location data from shortperiod seismographs to track the movement characteristics of ice sheets. The ice flow characteristics in the Larsemann Hills are more complex. The measured ice flow velocities in the Larsemann Hills with a resolution of 200 m help to understand its characteristics. In summary, the ice flow velocities derived from GPS location data are of great significance for studying ice sheet dynamics and glacier mass balance and for evaluating the systematic errors caused by ice sheet movements in seismic imaging. 相似文献