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1.
陆地重力观测相较于航空和卫星重力观测,距离场源更近,观测精度相对较高,其静态异常和时变数据已广泛应用于研究多种地球动力学问题.21世纪以来,绝对重力观测技术发展迅速,陆地观测网络日益完善,高精度陆地重力观测数据产品逐渐丰富,基于这些产品的大地测量和地球物理研究不断取得新进展.本文总结了近十几年来高精度陆地重力观测数据在大地测量和地球物理领域的应用进展情况,包括基于重力异常数据构建重力场和大地水准面模型、建立地壳物性结构模型、反演Moho界面形态和估计岩石圈有效弹性厚度,以及利用时变重力数据构建时变重力场模型、探测微弱动力学信号、估计地壳构造变形速率和分析与火山、地震过程的可能关联,最后探讨分析了陆地重力测量的未来发展趋势,可为中国大陆重力观测系统建设与发展规划提供参考. 相似文献
2.
香山绝对点的重力非潮汐变化 总被引：15，自引：0，他引：15
1988年3月－2001年3月中国地震局和中国计量科学院合作用NIM－Ⅱ仪器在香山地震台进行58次绝对重力测量，其中44次同时量测了地下水水位。本文从角度研究了香山点重力变化的机理。主要结论：（1）地下水活动是重力变化的主要局部干扰源，它与重力观测值分段相关，可用一个5次多项式进行改正；（2）局部地壳形变的影响甚小，可略而不计；（3）地震活动导致重力值发生短期变化，最大幅度达0．333μms^-2;(4）1989－2001年重力值近于线性地下降了0．191μms^-2,平均速率为－0．0147μms^-2/a属全球性或区域性重力变化。 相似文献
3.
海底重力测量以其高精度、横向高分辨率等优势,完善了海洋勘探技术体系,为基础地质研究、资源勘查、重大工程建设、大地水准面精化等提供支持。通过在渤海海域开展海底重力测量,取得了约15 000 km2的重力数据,对海底重力测量精度的影响因素及评价方法进行了研究。海底重力测量精度相比于陆域存在诸多干扰因素,主要受水深、海底底质、海况、平面和高程测量精度、近区地形改正等因素的影响。本文以测点布格重力异常值为评价指标,研究分析各项因素对海底重力测量精度的影响。结果表明:①超浅水域,环境干扰对海底重力测量精度影响较大;②海底底质较硬区域,重力测量精度较高;③风力对海底重力测量精度影响较小,引起的海浪、海流会有限地影响观测精度;④平面定位精度对海底重力测量精度影响相对较小;⑤高程是海底重力测量精度影响最大的因素;⑥海底地形平缓区域、近区地形改正对重力精度的影响可忽略不计。同时评估了相对重力值法、布格重力异常值法、重力异常插值法3种质量检查方法,研究揭示以布格重力异常值为指标的评价方法更具合理性,符合海底重力测量的特点。 相似文献
4.
南海位于太平洋板块、印澳板块和欧亚板块交汇处,自晚中生代以来历经张裂作用、海底扩张以及印藏碰撞、菲律宾海板块西向运动等构造事件的叠加改造,不仅形成了复杂多样的构造格局,而且堆积了厚薄不均的沉积层.为了考察沉积层密度改正对利用重力资料分析南海不同尺度构造特征的影响,本文利用南海各区域不同深度沉积层的地震波速度及钻孔密度等数据,建立了沉积层与沉积基底密度差随深度变化的二次函数关系式,并基于该关系式,计算了南海沉积层相对基底密度低而产生的重力异常值.结果显示,南海沉积层的重力异常值在海盆区介于-40~-60 mGal,而在堆积巨厚沉积物的莺歌海盆地可达到-135 mGal;相对于空间重力异常、布格重力异常,经沉积层重力异常改正后的地壳布格重力异常更能突出深部不同尺度的密度结构和莫霍面的起伏特征,其总水平导数模更突显了南海西北部红河断裂带的海上延伸;利用谱分析技术估算岩石圈强度时,经沉积层重力异常改正的地壳布格重力异常数据获得的岩石圈有效弹性厚度值更为符合地质实际,特别是在长条形的巨厚沉积区如莺歌海盆地和马来盆地.分析表明,重力异常的沉积层密度改正对揭示南海构造特征具有重要的意义. 相似文献
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跨越中、印、缅三国交界的青藏高原东南的喜玛拉雅“东构造结”地区（92°E~97°E，26°N~30°N）一半以上的面积尚没有重力测点，是重力数据空白区,故无法直接研究其重力场特征与深部地壳结构（构造）.本文分析了卫星重力异常的特性，提出应用卫星重力异常作为近似空间重力异常，并作布格改正后，得到的布格重力异常具有与该地区地形高程呈镜像相关的特征，可用以研究深部地壳结构.据三条重力剖面计算得到该地区三个地壳深部结构剖面的结果，给出青藏高原地壳厚度>70 km；喜马拉雅造山带为55 km左右；布拉马普特拉河谷盆地为33~35 km；那加山山脉地区为40~45 km，显示出三者为三个不同的构造单元.同时给出布拉马普特拉构造单元为相对高密度的刚性物质构成，随着印度洋板块向北运移，在碰撞、挤压下，插入青藏高原东南缘一带.导致该地带的强烈构造运动，和频发大、小地震.最后提出了几点认识和建议. 相似文献
6.
连续重力观测和GPS的技术结合能够监测到物质迁移和地壳垂直形变之间的量化关系.和相对重力测量以及绝对重力测量技术相比,其避免了时间分辨率和观测精度低,无法精细描述观测周期内的物质迁移过程问题.本文利用武汉九峰地震台超导重力仪SGC053超过13000 h连续重力观测数据;同址观测的绝对重力仪观测结果;气压数据;周边GPS观测结果;GRACE卫星的时变重力场;全球水储量模型等资料,采用同址观测技术、调和分析法、相关分析方法在扣除九峰地震台潮汐、气压、极移和仪器漂移的基础上,利用重力残差时间序列和GPS垂直位移研究物质迁移和地壳垂直形变之间的量化关系.结果表明:在改正连续重力观测数据的潮汐、气压、极移的影响后,不仅准确观测到2009年的夏秋两季由于水负荷引起的约(6~8)×10-8m·s-2短期的重力变化.而且在扣除2.18×10-8(m·s-2)/a仪器漂移和水负荷的影响后,验证了本地区长短趋势垂直形变和重力变化之间具有一致的负相关性规律.同时长趋势表明该地区地壳处于下沉,重力处于增大过程,增加速率约为1.79×10-8(m·s-2)/a.武汉地区重力梯度关系约为-354×10-8(m·s-2)/m. 相似文献
7.
系统误差及传递误差对山东重力变化的影响分析 总被引：1，自引：0，他引：1
对2009年以来的重力资料采用新的8位点号平差程序,利用绝对重力控制的相对重力测量10期资料进行了经典平差计算和系统误差检验分析,揭示了经系统误差改正后的重力变化结果较小,基本符合山东正常重力变化幅度。另外,对测网的传递误差带来的影响进行了简单的讨论,从而基本去除无震异常值较大的弊端,为合理科学分析山东重力场变化特点提供了前提条件。 相似文献
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9.
重复水准测量提供了点位高程变化的重要几何信息,但水准测量本身又受地球重力场的影响,在水准观测值中同时含有重力场的信息．重复绝对重力测量或相对重力测量提供了丰富的局部重力场的信息,由于点的重力值随高程变化而变化,因此,它们同时也含有点位高程变化的信息．经典平差方法将两类观测值分别解算,将互补的信息作为干扰加以改正,或作为噪声处理,这不仅丢失了有用的信息,而且有损于成果的精度．
本文在整体大地测量框架内构制了这两类观测值的联合解算模型,给出了解算方法,研究了形变场的拟合和预测问题,并用实例进行了验证,得到了一些有益的结果．研究表明:联合解算可同时给出地面点的高程及其变化率和局部重力场的参数及其变化率,有利于信息的提取;联合解算的精度优于单独解算的结果;秩亏抗差解和拟稳抗差解分别优于相应的非抗差解;拟稳抗差解算方法自动选择拟稳点,有效地抵制了粗差和形变异常对起算基准的干扰;对于多期复测的资料,使用动态拟稳抗差估计,不仅能动态地寻找可靠的拟稳点,而且能保证动态变化参数免受或少受各历元观测粗差的干扰,可明显地提高动态参数的验后精度;当点位丰富时,建立形变模型并据此内插未测点的变形和推测某个时刻地壳的形变状态也是可行的． 相似文献
10.
《地震研究》2020,(4)
基于2002—2017年的ECMWF Interim三维大气再分析资料、GRACE时变重力场模型和GPS数据,分析了青藏高原南缘的拉萨、日喀则、仲巴、噶尔4个绝对重力测站的非构造重力效应。结果表明:ECMWF Interim大气负荷重力效应主要表现为季节性变化特征,最大周年振幅可达到1.4μGal;GRACE陆地水负荷重力效应和GPS地壳垂直位移引起的重力效应均存在较为明显的季节性及长期趋势变化特征,二者的最大周年振幅和长期趋势分别达到2.6μGal,-0.6μGal/a和1.8μGal,-0.3μGal/a;GRACE与GPS的比较分析结果表明青藏高原南缘的非构造重力效应会受到局部流体质量负荷的显著影响。 相似文献
11.
In Capital Circle area, there are three groups of repeated gravity measurements observed by different institutes using different instruments or methods. The simultaneous adjustment of absolute and relative measurements and the elimination of systematic error among the relative measurements have been carded out in this paper. Thus an unified temporal gravity change system with absolute reference has been established. On the basis of this, the crustal subsidence effect on gravity, which belongs to non-tectonic factor, is analyzed and the station displacement corrections are carried out, so that the long-wave disturbance is eliminated. So far our following aims are realized： the advantages of the absolute and relative measurement methods are complementary to each other; the contradiction and environment disturbance are eliminated; the amounts of information are enlarged; the sampling interval of time domain is compressed. In a word, the ability of identifying the tectonic activity process is enhanced. The results show that： there are systematic errors between the two groups of relative measurements and within the data of 10 campaigns ; the uneven local crustal subsidence in the southeast of the study area results in a linear rise of gravity value at 10 stations; they can be corrected by the regression analysis. The maps of revised temporal gravity change can obviously and integrally reflect the Ms=5.0 earthquake in Guye on October 6, 1995. 相似文献
12.
THE COMPREHENSIVE ANALYSIS AND RESEARCH OF RECENT GRAVITY AND CRUSTAL DEFORMATION IN NORTHEASTERN EDGE OF THE TIBETAN PLATEAU 
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下载免费PDF全文 ZHU Yi-qing LIANG Wei-feng HAO Ming ZHAO Ling-qiang HAO Qing-hua ZHANG Guo-qing LIU Lian 《地震地质》2017,39(4):768-780
In this study, we systematically analyzed the relationship between regional gravity changes, 3D crustal deformation, regional tectonic environment and strong earthquakes based on the relative gravity measurements(2011-2014), GPS data and the background vertical deformation from the leveling measurements conducted from 1970 to 2011. Subsequently, we further characterized the temporal-spatial patterns and discussed the mechanism of regional gravity changes and the crustal deformation. The results can be summarized as follows:1)The regional gravity changes, the GPS-derived horizontal deformation and the vertical deformational obtained from leveling data showed a close spatial relationship:The gravity increased along with the direction of horizontal movement, and the gravity decreased with the crustal uplift and vice versa, which reflects the inherited characteristics of neotectonic activities. 2)The crustal deformation was closely related to the active faults. The contour lines of gravity changes and vertical deformation were generally along with the Qilian-Haiyuan Fault(the strike is NWW), and the crustal horizontal deformation showed left-lateral strike slip motion near the Qilian-Haiyuan Fault. 3)The strong earthquakes usually occur in the active faults where intensive gravity change and vertical and/or horizontal deformation occurred. The extrusion deformation, surface compression rate and gravity changes were obvious near the epicenter of 2016 Menyuan earthquake. The 2013 Minxian-Zhangxian MS6.6 earthquake occurred in the direction-turning area of intense gravity gradient zone and the transitional area of surface compression and vertical deformation. The first author of this paper has made a medium-term forecast before the Minxian and Menyuan earthquakes, especially the location of the earthquake. Based on the above understandings, we emphasized that:there are still possibilities of strong or huge earthquakes within medium-long term in the areas of crustal deformation anomalies in the study region. 相似文献
13.
Variations in the gravity field are introduced by mass or density redistribution in the vicinity of the measuring point as well as far field or global effects but also any crustal process which involves a height variation has a direct implication on the temporal variation of the gravity field.The measuring techniques involved in the WEGENER project include absolute and high precision relative gravity measurements and stationary measurements with superconducting gravity meters. The state of the art for both techniques is discussed and shown that systematic errors or the measurement of their changes can be detected by inter-comparison with other absolute gravimeters and frequently repeated measurements at a reference station monitored by a superconducting gravimeter. In the combination of the available gravity techniques it is possible to achieve a precision at the micro-Gal level for secular trends and a higher accuracy for period events which enable improvements in the modelling of environmental effects induced by ocean, atmospheric and ground water loading effects from the long term processes. 相似文献
14.
F. Greco G. Currenti G. D’Agostino A. Germak R. Napoli A. Pistorio C. Del Negro 《Bulletin of Volcanology》2012,74(7):1745-1756
To achieve a balance between uncertainty and efficiency in gravity measurements, we have investigated the applicability of combined measurements of absolute and relative gravity as a hybrid method for volcano monitoring. Between 2007 and 2009, three hybrid gravity surveys were conducted at Mt Etna volcano, in June 2007, July 2008, and July 2009. Absolute gravity data were collected with two absolute gravimeters, which represent the state of the art in recent advances in ballistic gravimeter technology: (1) the commercial instrument FG5#238 and (2) the prototype instrument IMGC-02. We carried out several field surveys and confirmed that both the absolute gravimeters can still achieve a 10 μGal or better uncertainty even when they are operated in severe environmental conditions. The use of absolute gravimeters in a field survey of the summit area of Mt Etna is unprecedented. The annual changes of the gravity measured over 2007–2008 and 2008–2009 provide unequivocal evidence that during the 2007–2009 period, two main phenomena of subsurface mass redistribution occurred in distinct sectors of the volcano, accompanying different eruptive episodes. From 2007 to 2008, a gravity change of ?60?μGal was concentrated around the North-East Rift. This coincided with a zone affected by strong extensional tectonics, and hence might have been related to the opening of new voids. Between 2008 and 2009, a North-South elongate feature with a maximum gravity change of +80?μGal was identified in the summit craters area. This is interpreted to indicate recharge of a deep-intermediate magma storage zone, which could have occurred when the 2008–2009 eruption was still ongoing. 相似文献
15.
利用成都地区1996~2008年绝对重力和相对重力观测资料获得区域重力场时空动态变化结果,系统分析了龙门山断裂带重力场变化特征及其与汶川8.0级地震的关系.①重力变化与龙门山断裂构造活动存在密切空间联系,重力测量较好地反映了伴随活动断层的物质迁移和构造变形引起的地表重力变化效应.②成都地区重力场动态图像较完整地反映了2008年5月12日汶川8.0级地震孕育、发生过程中出现的流动重力前兆信息.③映秀及北川重力点值时序变化累积量达120×10-8m·s-2,较好地反映了汶川地震前映秀和北川两个极震区附近的重力测点随时间的剧烈波动性上升变化.④汶川地震前,龙门山断裂带东侧的四川盆地相对稳定,而较显著的重力变化发生在龙门山断裂带西侧的川西高原上. 相似文献
16.
Mean annual sea level (MASL) data for 25 Greek stations were analyzed for the time period 1969–1982. The data from 4 of these were unacceptably poor, and the record of 3 stations showed unexplained step functions that were interpreted as errors. Relative MASL between stations showed crustal stability at 10 of the 18 useful stations. The standard deviation from the long-term average of these stations was ±1.8 cm. We conclude that if station records are carefully kept in this area crustal movements in excess of 5 cm can be detected by relative MASL. A comparison of MASL data with gravity changes measured in the Peloponnese and Central Greece suggests that vertical movements occurred along a gradient equal to or larger than the free air gradient. We conclude that the gravity network should be reoccupied frequently such that the non-tectonic effects to be determined from the probable observed gravity changes, and the tectonic vertical movements may be better understood. A co-seismic subsidence of about 5 cm is inferred to have taken place near Korinth during the 1981,M s =6.8, earthquake, which occurred 20 km N of this tide gauge (Posidonia). During 2.5 years before the 1968 Thessaloniki,M s =6.6, earthquake, sea level was lower than average suggesting possible crustal elevation of 3.6 cm at about 28 km epicentral distance. Because of the small amplitude of this change we are not certain that it represents crustal uplift. At station Myrina (on Limnos) a strong and consistent trend of subsidence accumulated a 15 cm change between 1975 and 1980. Chios showed a trend of emergence (total accumulation about +5 cm), while Volos showed a trend of subsidence (approximately ?5 cm total). Kefalinia appears to have subsided about 10 cm during the data period. The six stations along the Hellenic arc plate boundary showed nearly constant MASL, suggesting that crustal stability existed there during the last 14 years. We conclude that MASL data in Greece can be useful for understanding tectonic processes, especially if these data are gathered carefully and at numerous locations, and are cross-correlated to high precision repeat gravity measurements, and geodetic releveling. Also, MASL data on active volcanic islands have excellent potential for detecting uplift before future eruptions. 相似文献
17.
V. Yu. Timofeev E. N. Kalish Yu. F. Stus’ D. G. Ardyukov M. G. Valitov A. V. Timofeev D. A. Nosov I. S. Sizikov E. V. Boiko P. Yu. Gornov R. G. Kulinich T. N. Kolpashchikova Z. N. Proshkina E. O. Nazarov V. G. Kolmogorov 《Izvestiya Physics of the Solid Earth》2018,54(3):430-443
The modern gravimetry methods are capable of measuring gravity with an accuracy of up to 10–10 of the normal value, which is commensurate with the accuracy of the up-to-date methods of displacement measurements by satellite geodesy. Significant changes, e.g., in the coseismic displacements of the Earth’s surface are recorded in the zones of large earthquakes. These changes should manifest themselves in the variations of gravity. Absolute measurements have been conducted by various modifications of absolute ballistic gravimeters GABL since the mid-1970s at the Klyuchi point (Novosibirsk) in the south of the West Siberian plate. Monitoring observations have been taking place in the seismically active regions since the 1990s. In this paper we consider the results of the long-term measurements of the variations in gravity and recent crustal displacements for different types of earthquakes (the zones of shear, extension, and compression). In the seismically active areas in the east of Russia, the longest annual series of absolute measurements starting from 1992 was recorded in the southeastern segment of Baikal region. In this area, the Kultuk earthquake with magnitude 6.5 occurred on August 27, 2008, at a distance of 25 km from the observation point of the Talaya seismic station. The measurements in Gornyi (Mountainous) Altai have been conducted since 2000. A strikeslip earthquake with magnitude 7.5 took place in the southern segment of the region on September 27, 2003. The effects of the catastrophic M = 9.0 Tohoku, Japan, earthquake of March 11, 2011 were identified in Primor’e in the far zone of the event. The empirical data are consistent with the results of modeling based on the seismological data. The coseismic variations in gravity are caused by the combined effect of the changes in the elevation of the observation point and crustal deformation. 相似文献
18.
自2006年起,北京地区一些流动重力测点测值在趋势变化的基础上加速变化,昌平和顺义等测点附近重力场非均匀性变化增强。以北京昌平重力观测点为中心增加2条重力剖面观测线,并进行3期观测,分析重力场演化特征,采用地下水重力效应经验公式、自由空气改正关系式,分别改正地下水位、地壳形变对重力典型变化点的影响。研究表明：重力变化是地下水位、地壳形变影响的结果,重力剖面观测区及附近重力变化比较平稳,变化均在误差范围内,排除该异常是地震前兆异常的可能。 相似文献
19.
Chihiro Hashimoto Toshinori Sato Mitsuhiro Matsu’ura 《Pure and Applied Geophysics》2008,165(3-4):567-583
Free-air gravity anomaly in plate subduction zones, characterized by island-arc high, trench low and outer-rise gentle high, reflects the cumulative effects of long-term crustal uplift and subsidence. In northeast Japan the island-arc high of observed free-air gravity anomaly takes its maximum about the eastern coastline. On the other hand, the current vertical crustal motion estimated from geological and geomorphological observations shows a gentle uplift in the land area and steep subsidence in the sea area with the neutral point near the eastern coastline. Such a discrepancy in spatial patterns between the free-air gravity anomaly and current vertical crustal motion can be ascribed to a change in the mode of crustal uplift and subsidence associated with the initiation of tectonic erosion at the North American-Pacific plate interface. We developed a realistic 3-D simulation model of steady plate subduction with tectonic erosion in northeast Japan on the basis of elastic/viscoelastic dislocation theory. Through numerical simulations with this model we found that simple steady plate subduction brings about the crustal uplift characterized by island-arc high with its maximum about the eastern coastline, while steady plate subduction with tectonic erosion, which is represented by the landward retreat of the plate interface, brings about gentle uplift in the land area and steep subsidence in the sea area with the neutral point near the eastern coastline. Therefore, if we suppose that tectonic erosion started 3–4 million years ago after the long duration of simple steady plate subduction, we can consistently explain both patterns of free-air gravity anomaly and current crustal uplift in northeast Japan. 相似文献