共查询到20条相似文献，搜索用时 15 毫秒
1.
F. Riguzzi S. Atzori F. Obrizzo G. Pietrantonio F. Pingue 《International Journal of Earth Sciences》2012,101(6):1661-1671
The Colli Albani volcanic complex (Rome, Italy) has been dominated by episodic eruptions commencing around 561?ka and ending with the most recent activity of the Albano maar phase (<70?ka). Earthquakes of moderate intensity, gas emissions and significant ground deformations are the recent evidences of a residual activity. Former geodetic data from leveling surveys, GPS stations and InSAR observations tracked ongoing significant uplift of the order of few mm/year near the Colli Albani western flank. Different uplift rates were detected by each technique in different time spans, suggesting also the possibility of sporadic recharge of the hydrothermal system. The renewed high precision leveling data from IGMI survey carried out in 1997/1999 and the last leveling survey carried out in 2006 show that the uplift along the route is currently significant at an average rate of ~3?mm/year. Radar interferograms from ALOS satellite show uplift rate of ~6?mm/year, southwest of the central sector of the leveling route. We have undertaken a joint inversion of the various geodetic data (vertical rates from leveling surveys, GPS site velocities and InSAR observations acquired by ALOS satellite) using a nonlinear inversion technique to estimate the parameters of a point-pressure source, possibly capable of explaining the ongoing deformation at Colli Albani volcano. 相似文献
2.
地表调查发现, 沿近南北向亚东-谷露裂谷中段的安岗地堑存在地震大滑坡、多世代断层崖和断层崩积楔等多种类型的史前大地震遗迹.进一步的观测和年代分析表明: 该区的古地震滑坡体至少存在新、老两期, 其中规模最大的"尼续大滑坡体"应该是最新一次大地震所形成.该区T1到T6各阶地的形成时代从新到老分别为7.7~2.1 ka、11.0~10.5 ka、17.6~12.1 ka、25.7~22.9 ka、58.4~70.6 ka和130~150 ka, 它们沿主边界正断层的平均垂直断距依次为2.8 m、6.1~7.9 m、10.3~12.5 m、16.6~19.0 m、28.0 m和76.0 m.其中T1和T2阶地上的断崖剖面揭示, 最近两次大地震发生在距今约5.8±1.0 ka和2.4±0.2 ka.综合分析认为: 安岗地堑的大地震活动具有较明显的丛集性特征, 并且在距今约23~26 ka以来一直处于大地震活跃期, 期间的断层垂直活动速率为0.8~1.3 mm/a, 大地震的原地复发间隔大致为3.3~3.6 ka, 特征地震的矩震级为7.0~7.2, 推算整个尼木地堑群的大震复发间隔最短可能只有约1.0~1.2 ka.研究结果指示, 藏南裂谷的大地震活动性明显比藏北的近南北向正断层更显著. 相似文献
3.
Wei-Chia Hung Cheinway Hwang Chung-Pai Chang Jiun-Yee Yen Chih-Hsi Liu Wan-Huei Yang 《Environmental Earth Sciences》2010,59(7):1535-1548
During 1992–2007, excessive pumping of groundwater caused large-scale aquifer-system compaction and land subsidence in the
Choshui River Alluvial Fan, especially in the area of Yunlin county. The subsidence impedes surface-water runoff and endangers
the operation of Taiwan High Speed Rail. Leveling, Global Positioning System (GPS), multi-level compaction monitoring well,
and Differential Interferometric Synthetic Aperture Radar (DInSAR) are used to study the extent of subsidence in Yunlin and
its mechanism. These sensors complement each other in spatial and temporal resolutions. A leveling network totaling 434 km
in length was deployed to derive subsidence at every 1.5 km along the routes, and the result is accurate to few mm and shows
a basin-like subsidence pattern centering at Tuku Township. Four multi-level compaction monitoring wells, co-located with
GPS pillars, detect compactions at different depths, showing that the aquifer-system compaction (the cause of subsidence)
occurs mostly below depths >200 m, where reduction of groundwater pumping is most needed. The vertical displacements from
GPS and leveling agree to within 1 cm, and are larger than the cumulative compaction detected by the compaction-monitoring
wells, suggesting that compaction also occurs below 300 m (the depth of the wells). The vertical displacements derived using
DInSAR and 8 ENVISAT SAR images agree with the leveling result to 1–2 cm. 相似文献
4.
青藏高原中部第四纪左旋剪切变形的地表地质证据 总被引：7，自引：5，他引：2
在青藏铁路的格尔木—拉萨段进行的活动断裂调查发现,在沱沱河—五道梁之间宽约150km的地段内发育了多条由北西西向次级断层左列分布构成的北西西向和北西向左旋张扭性断裂带,在断裂带之间则发育"S"型的北东向裂陷盆地和雁列分布的菱形裂陷盆地,盆地边界断裂也为左旋张扭性质。上述断裂带和裂陷带主要形成于第四纪,它们构成了宽约150km的不均匀的左旋简单剪切变形域,该变形域的整体活动性较弱,属于弱的不均匀剪切变形域。但其中的二道沟断陷盆地是个例外,该盆地边界断裂的垂直活动速率约为0 5mm/a,左旋活动速率介于0 8～1 0mm/a之间。而在整个左旋剪切变形带累计的左旋走滑速率不会超过6mm/a,它们所调节的昆仑山与唐古拉山之间的地壳南北缩短量也可能仅占总缩短量的15%～30%。上述弱剪切变形域与强烈左旋走滑的昆仑断裂系共同构成了高原中部的左旋剪切变形带,它们在印度板块与欧亚板块强烈碰撞的构造动力学背景下,起着调节青藏高原南北向缩短的重要作用。 相似文献
5.
青藏高原内部的近东西向伸展变形在藏南地区形成了一系列近南北向裂谷带,对其中最东端的错那-沃卡裂谷带南段错那-拿日雍错地堑调查结果表明,它是第四纪活动明显的半地堑式断陷盆地。控制该盆地发育的主边界断裂带是近南北走向、倾向东侧和长80～110km左右的盆地西缘正断层,是区域内N90°～92°E方向伸展变形的产物。断裂活动速率的多种估算结果表明,该断裂带百万年时间尺度的平均垂直活动速率介于0.2～0.9mm/a之间;MIS 8和MIS 6以来的断裂平均活动速率的合理估计值是0.6±0.2mm/a;但末次冰期盛冰阶以来的断裂平均活动速率明显增加,介于1.0～2.1mm/a之间,合理的估计值为1.3±0.3mm/a,末次冰盛期以来断裂垂直活动速率的增加极可能是该断裂带进入地震丛集期的反映。该地堑近于严格的南北走向及其与当雄-羊八井地堑相似的活动强度,指示了下地壳物质侧向流动所产生的纵向拉张作用最有利于该区近南北向裂谷带的形成。 相似文献
6.
It is obvious to anyone working on or dealing with underground mining operations, production gaps have to be opened in the ground during mining. The ground layers just above these gaps collapse toward production lines resulting in horizontal and vertical movements both inside and on the earth's surface. These movements are referred to as mining subsidence which eventually causes technical, economic, social and environmental hazards to natural and cultural structures on the surface. It is substantially crucial to the general and regional characteristics of these subsidence occurrences in the underground mining region so it can be possible to mitigate the subsidence induced damages and problems both in the ground and on the surface. Subsidence observations, thus, are conducted inside and on the ground by employing geodetic, geophysical and geotechnical methods with the aim to determine the characteristics and parameters of subsidence occurrence in a region evaluating these subsidence observations. The Zonguldak Hard Coal Basin and Kozlu Coal Production Region within the basin are places where urbanization and underground mining operations are intensively under way. Therefore it is vitally important to continuously monitor the horizontal and vertical displacements formed due to the underground mining in the basin and to determine the subsidence parameters so that it may be possible to forestall the subsidence induced issues that may occur in the near future. This study yields information and computations about the subsidence parameters determined under the light of three periods of geodetic observations carried out in the region. Using the three periods of GPS and precise leveling observations, the average slope angle values resulting from vertical displacements in the study region were obtained from the adjusted coordinates and height differences, and estimated as 16″.67 in positive (+) direction and 18″.03 in negative (−) direction. The horizontal unit deformation parameters, on the other hand, were computed as 0.28 mm/m for the extension parameter while 0.26 mm/m for compression parameter along the routes chosen in the Kozlu region. 相似文献
7.
We estimate interseismic coupling on the subducting plate interface in the Tokai area, central Japan, by inverting two geodetic data sets. The data record surface motion between March 1996 to May 2000; one represents vertical motion deduced from the leveling observations and the other is the horizontal velocity field deduced from GPS observations. In the inversion, we employed the analytical solutions of surface displacement due to a triangular dislocation element embedded in a homogeneous elastic half space in order to represent the curved plate interface. The vertical data show that the most strongly coupled portion of the subduction interface is concentrated beneath Omaezaki Cape, while the horizontal data show strongest coupling in the shallower region of the subducting plate interface. The estimated maximum value of coupling from the horizontal data is 40 mm/year, while that from vertical data is 25 mm/year. 相似文献
8.
A. Demoulin J. Campbell A. De. Wulf A. Muls R. Arnould B. Görres D. Fischer T. Kötter M. Brondeel D. Van. Damme J. M. Jacqmotte 《International Journal of Earth Sciences》2005,94(4):515-524
We present the HARD project of GPS monitoring of vertical ground motion in NE Ardenne and Eifel (western Europe). Its main purposes are to get a better insight into the present-day rates of vertical ground motion in intraplate settings and to identify the various causes of these motions. Since 1999, we have carried out yearly campaigns of simultaneous GPS measurements at 12 sites situated so as to sample the different tectonic subunits of the study area and especially to record potential displacements across the seismogenic Hockai fault zone. Five campaigns (1999–2003) have been processed currently. Key issues of the data processing with the Gamit software are discussed and first results are presented. Though temporally consistent in many cases, the obtained vertical motion rates are spatially highly variable. They are also much too high (several mm/year) to support a tectonic interpretation, and a long-term influence of groundwater level variations is proposed to account for the observed motions. This influence should be distinguished from seasonal variations and from inter-survey variations linked to the varying degree of soil and subsoil drying off during the successive spring surveys. 相似文献
9.
Precise levelling data are examined in the southern Black Forest massif by comparing them analytically along levelling profiles. Instead of generalizing regional vertical motion trends, the method emphasizes the current activity of accurately located individual structural elements. Measured recent crustal movement rates range from 0.2 to 1.1?mm/year for the 1930–1961 (1972) period, the inferred motions corresponding to aseismic fault creep. Based on the near infrared band image of a Landsat MSS scene, a lineament map of the study area is compared with the recent crustal movement (RCM) map. The Upper Rhine graben eastern border fault between Badenweiler and Freiburg displays the highest RCM: these displacements are consistent with the geological motion and the topographic expression of that structure. Within the massif, both the lineament map and the RCM map demonstrate the predominant role played by WNW/ESE- to NW/SE-striking structures in accommodating the deformation. Moreover, with the seismic dislocations in the southern Black Forest taking place also mainly on N120 and N20 faults, it is most probable that these active structures are deep-reaching zones of crustal weakness. To some extent, seismicity and RCM appear, however, to be mutually exclusive in their spatial distribution, the seismic Black Forest flexure and Dinkelberg block being opposed to the aseismically moving eastern and northern parts of the study area. 相似文献
10.
Kevin Burke 《Tectonophysics》1976,36(1-3)
Well over one hundred separate graben formed in association with ocean opening can be recognized around the shores of the Atlantic Ocean. The graben are linked forming an elaborate network of triple-rift systems. Some rifts developed to form ocean but many failed. The stratigraphie and structural history of these rift structures is varied and helps to illuminate the processes that operate at continental rupture. Rifting has been commonly accompanied by basaltic vulcanism and rapid accumulation of several kilometers of sediment. Horsts within the graben strongly influence early sediment distribution. Generally, rift faulting ceases about the time of onset of normal marine sedimentation but there are a few exceptions and some graben formed at ocean opening have influenced sediment distribution more than 100 m.y. later. Although tensional structures predominate strike-slip and compressional structures have developed locally in the graben. The rivers bringing the largest amounts of sediment into the Atlantic during the last 150 m.y. have prograded along failed rift arms formed at continental rupture. In some cases their deltas have come to lie on oceanic crust. 相似文献
11.
《Russian Geology and Geophysics》2014,55(3):376-389
The paper is focused on recent displacement rates in the Altai-Sayan region, obtained by hydroleveling, leveling, and satellite geodesy. Effective elastic moduli and viscosity parameters of the crust are used in the modeling of coseismic and tectonic processes. The elastic moduli are determined from measurements of periodic vertical displacements during seasonal loadings of the Sayano-Shushenskaya hydropower plant. We present the results of the modeling of coseismic displacements during the earthquakes of 10 February 2011 (M = 6.1) and 27 December 2011 (M = 6.7) in Tuva and West Sayan. The results of GPS determinations for postseismic displacements in the Chuya earthquake zone (Gorny Altai, 27 September 2003, M = 7.5) are analyzed; models for the geologic medium are selected; and its effective viscosity is estimated. The tectonic component of the recent crustal displacements in the Altai-Sayan region is defined. 相似文献
12.
13.
矿区GPS高程拟合精度和可靠性研究 总被引：1，自引：2，他引：1
根据矿区控制测量的特点，在矿区水准网基础上，用水准测量的方法联测数量足够、分布均匀的GPS点，然后用GPS高程拟合的方法确定其余大量GPS点的高程，建立矿区GPS高程控制网。结合实例论述了该拟合方法建立矿区GPS高程控制网的精度和可靠性，并分析了它的应用价值。 相似文献
14.
O. Dauteuil J. Bouffette F. Tournat B. Van Vliet-Lanoë J.C. Embry Y. Qut 《Tectonophysics》2005,404(3-4):203-216
In Iceland, the main deformation activity occurs not only in the active rift zone where volcanism and seismicity coexist in fissure swarms but also in the transfer zones (north and south) where the main part of the seismic activity is located. Many studies described extension and vertical displacement associated with rifting and magmatism inside this rift zone. They have classically assumed that no deformation occurs outside the rift zone. However, few studies have already been conducted outside the rift zone. This work focuses on an area west of the rift zone in the Akureyri area, which displays an anomalous topography. We illustrate an ENE tilting of 0.23° since approximately 17,000 years ago using ancient lacustrine shorelines mapped in detail with a differential GPS survey and analysis of SPOT images. This degree of tilting corresponds to a vertical displacement of 160 m, i.e., a deformation rate of 1 cm/year, which is close to values measured in the active zone. This long wavelength deformation is compatible both with (i) the topographic anomaly of the Akureyri area, and with (ii) the very diffuse microseismicity that affects northern Iceland. The origin of this tilting is discussed and the different hypotheses (glacial loading response, rift uplift, transform zone effect, thermal doming, local magmatic intrusion) are reviewed. Our results, structural data and the topography are more consistent with a local magmatic intrusion inducing local doming. This work is the first attempt at quantifying long-term deformation outside the rift zone in Iceland. 相似文献
15.
西藏错那-沃卡裂谷带中段邛多江地堑晚新生代正断层作用 总被引：3，自引：1，他引：2
遥感解译和地表调查结果显示, 位于西藏曲松县境内的邛多江盆地构成了藏南近南北向裂谷带最东端的错那-沃卡裂谷的中段。它是在该区近东西向逆冲构造带停止活动之后, 上地壳沿N108～115°E方向发生引张作用所形成的第四纪半地堑式断陷盆地。控制晚第四纪盆地发育的主边界正断裂带位于盆地西缘, 总体呈NNE走向, 向东倾, 长40 km左右。断裂活动位移测量和年代学测试结果表明, 该边界正断层带在5Ma左右就已开始活动, 总累计垂直位移量至少为2.6～2.8 km, 最小长期平均垂直活动速率约0.5mm/a。末次冰期盛冰期以来, 该断裂平均活动速率的最合理的估计值为1.2 ±0.6 mm/a。 相似文献
16.
Active horizontal and vertical deformation in western Washington is modeled using an inverse dislocation model. The modeling technique uses published horizontal crustal velocities, derived from campaign and continuous GPS data, and uplift rates, calculated from repeated historical leveling surveys. The plate interface is represented by both screw and edge dislocations divided into segments. The rate of slip deficit accumulation on each segment is estimated by inverting the surface deformation data using a linear least squares procedure. The model predicts the data well, with an overall RMS residual of 0.85 mm/year. The horizontal residual vectors show no discernable pattern and no significant uniform regional strain and rigid rotations can be identified. The estimated slip deficit accumulation rates suggest that the plate interface is locked in a broad region beneath the coastline and possibly partially locked further downdip. The maximum slip deficit rate was estimated at 32.1±1.9 mm/year or approximately 91% of the plate convergence rate. The partially locked zone appears to be accumulating slip deficit at 8.2±1.9 mm/year. 相似文献
17.
讨论了高精度GPS观测中的负荷效应问题。根据地表质量负荷理论的Green函数方法,计算了地球表面质量负荷（包括大气、非潮汐海洋和陆地水）对中国部分IGS台站垂直位移的影响。其中,大气负荷对各台站的影响比较一致,变化幅度约为20 mm,非潮汐海洋对沿海台站的负荷影响显著,其变化幅度达到10 mm,水负荷对各台站的影响差异较大,最大的变化幅度约20 mm;总的负荷效应达到厘米量级,与GPS观测结果的比较说明在高精度的GPS观测的时间序列中,存在明显的季节性变化,而该变化与表面负荷有着直接的关系。特别是对于房山和乌鲁木齐2个台站,GPS观测的垂直变化中的季节项基本上就是来自于地球表面的质量负荷;而昆明和拉萨这2个台站尽管位于板块运动活跃区域,垂直季节性变化也主要源于地表负荷。因此扣除这些负荷影响的GPS观测资料将更有利于研究地壳的运动特征。 相似文献
18.
D. Upadhyay M. M. Raith K. Mezger A. Bhattacharya P. D. Kinny 《Contributions to Mineralogy and Petrology》2006,151(4):434-456
The suture zone between the Bhandara craton and the granulite-facies rocks of the Eastern Ghats Province in SE India contains a number of deformed alkaline and tholeiitic intrusives. The Khariar alkaline complex is one of the several occurrences which intruded in the Mesoproterozoic (1,480±17 Ma, 2σ) and was deformed during the Pan-African tectonothermal event. The geochemical signatures indicate a rift-related setting for the magmatic activity. The nepheline syenite parent magma may have been produced by in-mantle fractionation of clinopyroxene and Ti-rich amphibole from a basanitic primary magma derived from an enriched spinel lherzolite mantle source in the sub-continental lithosphere. Geochemical variations in the Khariar alkaline suite can be modeled by the fractionation of clinopyroxene, amphibole, titanite, zircon, apatite and allanite. The Mesoproterozoic alkaline magmatism at Khariar marks the initiation of a NE-SW rift which formed several craton margin basins and opened an ocean towards the south. The sediments of the cratogenic basins and the Eastern Ghats Province were deposited in these rift-related basins. A K-Ar age of 1,330±53 Ma from glauconites in sandstone suggests that the NW-SE trending Godavari–Pranhita graben formed at approximately the same time as the rift at the craton margin. If the two are related, the Godavari–Pranhita graben may represent the failed arm of a rift system in which the NE-SW arm was the active segment. The granulite-facies deformation and metamorphism of the Eastern Ghats Province sediments may be related to an episode of Grenvillian basin inversion. The Mesoproterozoic rifting and Grenvillian basin closure may thus represent two well-defined parts of a Wilson cycle i.e. the opening and closure of an ocean. The Khariar and other alkaline bodies were, however, deformed during a Pan-African collisional event associated with the westward thrusting of the Eastern Ghats Province granulites over the cratonic foreland. 相似文献
19.
A number of flat hollow cylinders equal in weight to the replaced soil have been installed at different depths below the surface of a 47% slope. The slope was developed over Maestrichtian chalk overlain by a poorly sorted but rather homogeneous Upper Pleistocene cover. The displacements of the cylinders have been recorded for three years.
The design of the geodetical method of measurement and the results are discussed. The estimated error (twice the standard deviation) of the measurements regarding the horizontal component of the displacements appears to be less than 0.4 mm; the error regarding the vertical component less than 0.3 mm.
Significant displacements have been recorded so far only from the upper 20 cm. The measured movements are spasmodic and parallel to the slope. The mean velocity of the top soil amounts to 1 mm/year. The collected data are insufficient to investigate the applicability of viscous creep models. 相似文献
20.
东海瓯江凹陷早第三纪裂谷期盆地充填机制探讨 总被引：1，自引：0，他引：1
早第三纪东海瓯江凹陷曾是一个弧后拉张形成的裂谷盆地,拉张断裂在构造上控制了盆地地堑、半地堑地貌,从裂谷早期、中期到晚期,地层垂向演化表现出砂－泥－砂三重序列的充填型式,根据位于不同构造单元的SM－1、WZ6－1－1井为例证,从相对海平面、可容空间、物源供给诸方面探讨了地层成因机制。 相似文献