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利用辽宁地区三期复测水准资料,计算得出1988—1998年和1998—2016年两个时段的地壳垂直形变速率, 并绘制相应的地壳垂直形变速率矢量图和等值线图.结合辽宁地区的区域地质背景及构造断裂活动性,分析了区域地壳垂直形变特征与地震活动性之间的相关性,明确了该区域的整体地壳垂直形变趋势及需重点关注的区域.结果表明:海城MS7.3地震后较长时间内,辽宁地区整体以继承性运动为主,辽东隆起和辽西隆起以上升为主,下辽河断陷带下沉;1998年后,辽宁地区整体形变差异量减小,该地区垂直形变正趋于稳态,垂直形变速率梯度高值区仍集中于下辽河断陷带与辽东隆起、辽西隆起的交界地带,因此该区域的潜在危险性较高,需要持续并重点关注. 相似文献
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结合GNSS和黑龙江地区定点形变观测,分析日本2011年3月11日Mw9.0地震对黑龙江地区地壳形变的影响.结果显示:日本Mw9.0地震引起哈尔滨站、绥阳站震后2年内运动速率明显增加(哈尔滨站增大4 mm/a,绥阳站速率增大6 mm/a);定点形变与GPS观测到的同震效应至少在4个台站多种仪器均具有较好的一致性;日本Mw 9.0地震不仅引起区域水平向应变变化,对垂直向也产生一定影响;长基线变化反映出日本Mw9.0地震引起的大空间尺度应变变化与黑龙江地区长期构造应力场背景一致,该地震对黑龙江地区地表应变积累可能有增强影响. 相似文献
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利用小波变换分析方法提取沂沭断裂带及其分支断裂跨断层流动短水准和长水准趋势变化成分, 计算分析不同断裂的垂直形变速率和受力状态, 结果表明: 沂沭断裂带及其北西向分支断裂近期垂直形变速率均较小, 没有明显的速率异常和受力状态改变; 同一断裂具有分段和分时活动特征, 断裂活动性质与地质考察结果基本一致; 大部分水准观测场地在1995年苍山5.2级、 2011年日本9.0级地震前后断裂垂直形变速率和受力方式发生了变化; 山东近几年出现的跨断层水准异常基本结束, 仅存的冯家坊子水准异常存在一定干扰, 沂沭断裂带及附近地区近期发生强震的形变背景尚不明显。 相似文献
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三峡地区水资源丰富,加上三峡水库蓄放水的影响,水动力环境复杂,对该区域陆地水负荷变化影响的研究还比较薄弱.本文基于CORS站网,辅以少量重力台站数据,采用负荷形变和重力场球谐分析方法,研究了三峡地区陆地水负荷对地壳形变和重力变化的影响.本文研究发现:①基于CORS站网能够监测陆地水负荷引起的地壳形变和地面重力时空变化.②陆地水负荷对垂直形变的影响达厘米级,对水平形变的影响较小,对地面重力的影响可达数百微伽.③2011年1月至2015年6月陆地水负荷对垂直形变影响的年变化趋于平衡,对地面重力变化影响主要集中在三峡水库和重庆市附近.④基于CORS站网确定的三峡地区陆地水地壳垂直形变,与GRACE卫星重力成果在分布规律和趋势上具有较高的一致性,但在部分区域存在差异.本文研究成果可用于水动力环境监测与水资源保护利用,为高程基准和重力基准的动态维护提供支持. 相似文献
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辽宁地区垂直形变场特征再研究 总被引：1，自引：1，他引：1
本文利用动态拟稳平差方法及经典平差方法分别处理了1956-1961年～1978—1983年、1982—1983年～1988年两组垂直形变资料,并绘出垂直形变图,用以分析、说明辽宁地区长趋势垂直形变场及辽南地区近期垂直形变场特征.得出:1.辽宁地区长趋势垂直形变场明显受区域地质构造单元控制.辽东台隆、燕山台褶带相对缓慢上升,下辽河断陷下降,三块主体构造单元均呈向渤海沿岸倾斜的趋势.2.海城地震发生在形变等直线发生转折,不同构造单元差异运动交界地带.3.辽南地区近期垂直形变场出现反向运动,并在岫岩县附近形成一条北北西向强烈挤压带. 相似文献
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垂直形变梯度能够有效反映区域构造运动的垂直差异变化程度。 我们利用长时间段的水准资料结合GPS资料计算垂直形变梯度值, 计算结果显示垂直形变速率梯度的空间分布与构造分布具有显著的相关性, 南北地震带垂直形变速率梯度异常最显著区域在鲜水河断裂带、 龙门山断裂带和小江—则木河断裂带附近, 其次是青藏高原东北缘地区的庄浪河断裂带与冷龙岭断裂带交会区域, 2016年门源6.4级地震就发生在这一异常区域内, 但是从垂直形变速率梯度的高梯度区域分布来看, 在天祝至景泰一带也有发生强震的背景。 三大断裂交会区域是整个南北地震带构造活动最为强烈的区域, 应该注意该地区未来强震发生的危险性。 相似文献
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丽江7.0级地震前形变场动态演化与孕震信息提取研究 总被引：1，自引：0，他引：1
本文用分段速率整体动态平差法，处理了滇西水准监测网８０年代以来的水准复测资料，并进行了形变速率多面函数拟合和垂直形变场信息分离。研究了１９９６年２月３日发生于滇西水准监测网北部的丽江７０级地震前，形变场动态演化和信息分离得到的垂直形变剪切变形、扩张变形、体积变化及准加速度等信息指标分布变化特征。结果表明：８０年代中前期，在滇西的丽江、永胜及其附近地区出现的大规模形变速率高梯度带和信息指标高值分布所反映的剧烈垂直差异运动，是丽江７０级地震前１０余年孕震应变能开始快速积累的显示；而１９８５～１９９２年形变场趋势转折与垂直差异运动显著减弱，可能意味着孕震能量积累到一定程度后，孕震区处于相对闭锁阶段。在此基础上，结合丽江７０级地震前区域地震活动分析和不同地区强震孕震形变对比，进一步研究了强震前形变场非均匀态特征和孕震信息的识别提取，得出了一些用大地形变进行强震中期预测的有益结果。 相似文献
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In this study, vertical deformation of different regions of Yunnan area in 1993-2013, 2001-2006, 2011-2017 is obtained using observational data of precise leveling. The results show that:1) In the whole, Yunnan area exhibits uplifting in the east of Yunnan and subsiding in the south of Yunnan, which is well consistent with the current horizontal velocity field obtained by GPS. In the east of Yunnan, southeastward horizontal velocity at the east boundary of Sichuan-Yunnan block is significantly decreased, which indicates extrusion deformation. This result is in accordance with the result that there is uplift in the east of Yunnan with precise leveling data. GPS velocity field rotates clockwise at Eastern Himalayan Syntaxis, therefore east-west extension is formed in central and southern Yunnan, which coincides with crustal subsidence observed by precise leveling. 2)The vertical movement in the northwest of Yunnan mainly exhibits the succession movement of basin subsidence and mountain uplift, in which, in the rift zone, Chenghai Basin, Qina Basin, Binchuan Basin and Midu Basin distributed along Chenghai Fault are all in the sinking state and the sinking velocity of Binchuan Basin located in the end of the sinistral strike-slip Chenghai Fault is the maximum. The sinking velocity of Dali Basin distributed along Honghe Fault is approximately 0.5mm/a and the sinking velocity of Midu Basin is approximately 1mm/a under the comprehensive action of right-lateral Honghe Fault and left-lateral Chenghai Fault. On the northwest boundary of the fault zone, the vertical movement of the basins (Lijiang Basin, Jiangchuan Basin)under the control of the nearby Lijiang-Jianchuan Fault is not obvious and the nearby mountain area exhibits uplift. 3)In the Honghe Fault, the southern region still possesses strong activity. Seeing from the leveling profile and vertical deformation field, the Honghe Fault still possesses the significance of block boundary fault and strong activity. GPS velocity field reveals that the southeast movement velocity of the Sichuan-Yunnan rhombic block is rapidly decreased near Xiaojiang Fault and the earth's crust is shortened and deformed. In the vertical deformation field, the uplift is formed near Xiaojiang Fault and there is obvious vertical deformation gradient. 4)Notably, deformation contour in the junction of Qujiang Fault and Xiaojiang Fault is characterized by four quadrant distribution, which indicates the possibility of earthquake. 相似文献
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Based on GPS velocity during 1999-2007, GPS baseline time series on large scale during 1999-2008 and cross-fault leveling data during 1985-2008, the paper makes some analysis and discussion to study and summarize the movement, tectonic deformation and strain accumulation evolution characteristics of the Longmenshan fault and the surrounding area before the MS8.0 Wenchuan earthquake, as well as the possible physical mechanism late in the seismic cycle of the Wenchuan earthquake. Multiple results indicate that:GPS velocity profiles show that obvious continuous deformation across the eastern Qinghai-Tibetan Plateau before the earthquake was distributed across a zone at least 500km wide, while there was little deformation in Sichuan Basin and Longmenshan fault zone, which means that the eastern Qinghai-Tibetan Plateau provides energy accumulation for locked Longmenshan fault zone continuously. GPS strain rates show that the east-west compression deformation was larger in the northwest of the mid-northern segment of the Longmenshan fault zone, and deformation amplitude decreased gradually from far field to near fault zone, and there was little deformation in fault zone. The east-west compression deformation was significant surrounding the southwestern segment of the Longmenshan fault zone, and strain accumulation rate was larger than that of mid-northern segment. Fault locking indicates nearly whole Longmenshan fault was locked before the earthquake except the source of the earthquake which was weakly locked, and a 20km width patch in southwestern segment between 12km to 22.5km depth was in creeping state. GPS baseline time series in northeast direction on large scale became compressive generally from 2005 in the North-South Seismic Belt, which reflects that relative compression deformation enhances. The cross-fault leveling data show that annual vertical change rate and deformation trend accumulation rate in the Longmenshan fault zone were little, which indicates that vertical activity near the fault was very weak and the fault was tightly locked. According to analyses of GPS and cross-fault leveling data before the Wenchuan earthquake, we consider that the Longmenshan fault is tightly locked from the surface to the deep, and the horizontal and vertical deformation are weak surrounding the fault in relatively small-scale crustal deformation. The process of weak deformation may be slow, and weak deformation area may be larger when large earthquake is coming. Continuous and slow compression deformation across eastern Qinghai-Tibetan Plateau before the earthquake provides dynamic support for strain accumulation in the Longmenshan fault zone in relative large-scale crustal deformation. 相似文献
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该文讨论地变率指标的概念。它是指在由发震构造引起的垂直运动为主的地表形变场中,水平方向上单位距离内垂向速率变化的物理量。笔者以华北地震区划为例,认为它可作为预测未来震情的一种有效的定量依 相似文献
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The vertical deformation gradient can reflect the rate of vertical change in unit distance, and the vertical deformation velocity gradient can reflect the strength of the earth''s crust tectonic activities. In this paper, using long period leveling data combined with GPS data, the vertical deformation gradient values are calculated. Leveling data and GPS data are two different means of monitoring deformation, but the result is approximately the same vertical deformation gradient. The results show that the spatial distribution of the vertical deformation velocity gradient and tectonic distribution has an obvious correlation. The most significant gradient anomalies along the North-South Seismic Belt are Xianshuihe fault, Longmenshan fault and Xiaojiang-Zemuhe fault, while the second gradient anomalies in the northeastern Qinghai-Tibetan plateau are Zhuanglanghe fault and Lenglongling fault. The Menyuan MS6.4 earthquake in 2016 occurred in this abnormal area. However, according to the vertical deformation high gradient area distribution, there is also the possibility of an earthquake occurrence in the Tianzhu and Jingtai area. The area of convergence of three major fault zones is the strongest tectonically active region of the North-South Seismic Belt. 相似文献
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为了研究与总结2008年5月12日汶川8.0级地震前GPS与跨断层资料反映的龙门山断裂带及其周边地区的运动、构造变形、应变积累演化过程,以及汶川地震临震阶段可能的物理机制,本文综合1999~2007期GPS速度场、1999~2008年大尺度GPS基线时间序列、1985~2008年跨断层短水准等资料进行了相关分析与讨论。结果表明:(1)GPS速度剖面结果显示,宽达500km的川西高原在震前有明显的连续变形,而四川盆地一侧和跨龙门山断裂带基本没有变形趋势,表明震前川西高原在持续不断地为已经处于闭锁状态的龙门山断裂带提供能量积累。(2)GPS应变率结果显示,震前龙门山断裂带中北段的NW侧EW向挤压变形明显,变形幅度从远离断裂带较大到靠近断裂带逐渐减小,而断裂带变形微弱;龙门山断裂带西南段周边形成了显著的EW向挤压应变集中区,应变积累速率明显大于中北段。(3)断层闭锁程度反演结果显示,除了汶川地震的震源位置闭锁相对较弱,且西南段有大概20km宽度断层在12~22.5km深度为蠕滑状态以外,震前整条龙门山断裂基本处于强闭锁状态。(4)大尺度GPS基线结果显示,跨南北地震带区域的NE向基线从2005年开始普遍出现压缩转折,反映NE向地壳缩短的相对运动增强。(5)跨断层短水准场地结果显示,震前年均垂直变化速率和形变累积率很低,表明断层近场垂向活动很弱、闭锁较强。通过以上分析认为,在相对小尺度的地壳变形中,震前龙门山断裂带深浅部均处于强闭锁状态,断裂带水平与垂直变形都很微弱,这可能经历了一个缓慢的过程,而且越是临近地震的发生,微弱变形的范围可能越大;在相对大尺度的地壳变形中,震前龙门山断裂带西侧的巴颜喀拉块体东部地区经历了地壳缓慢且持续的缩短挤压变形,为龙门山断裂带应变积累持续提供了动力支持。 相似文献
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利用小波分析对河西地区1971—1979、1979—1983年的地壳垂直形变场进行计算,结果表明:三阶以内的小波分解结果与地质构造走向基本一致,说明河西地区地壳垂直运动的短波主要反应的是断层活动;四阶小波变换结果为地壳垂直形变的低频部分,反映的是大区域地质构造运动所引起的地壳垂直形变。1971—1979年,门源南部的地壳垂直运动相对剧烈,而到了1979—1983年,门源地区地壳垂直运动主要活动区域由门源南部地区转移到门源附近区域,这可能与门源6.4级地震孕育的区域构造活动有关。 相似文献
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Field experiment of subgrade vibration induced by passing train in a seasonally frozen region of Daqing 总被引：1，自引：1，他引：0
Ling Xianzhang Zhang Feng Zhu Zhanyuan Ding Lin Hu Qingli . School of Civil Engineering Harbin Institute of Technology Harbin China . Institute of Subgrade Prevention Engineering China . Information & Engineering Technology College Sichuan Agricultural University Ya’an China . School of Architectural Engineering Heilongjiang University Harbin China Professor PhD Associate Professor 《地震工程与工程振动(英文版)》2009,8(1):149-157
The vibration characteristics and attenuation of the subgrade caused by passing trains in a seasonally frozen region of Daqing, China are investigated. Three field experiments were conducted during different times through the year, in normal, freezing and thawing periods, respectively, and the influence of the season, train speed and train type, is described in this paper. The results show that: (l) the vertical component is the greatest among the three components of the measured vibration near the rail track, and as the distance to the railway track increases, the dominant vibration depends on the season. (2) Compared with the vibration in the normal period, the vertical and longitudinal vibrations increase while the lateral vibration decreases in the freezing period. However, in the thawing period, the vertical and longitudinal vibrations decrease, and the lateral vibration increases. (3) As train speeds increase, the subgrade vibration increases. (4) The vibration induced by a freight train is greater than by a passenger train. These observations provide a better understanding of the vibration and dynamic stability of the subgrade and may be useful in developing criteria for railway and building construction in cold regions. 相似文献
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Measurements of surface velocity, ice deformation (at 42 and 89% ice depth) and proglacial stream discharge were made at Haut Glacier d'Arolla, Switzerland, to determine diurnal patterns of variation in each. Data are analysed in order to understand better the relationship between hydraulically induced basal motion and glacier ice deformation over short timescales. The data suggest that hydraulically induced localized basal ‘slippery’ spots are created over diurnal cycles, causing enhanced basal motion and spatially variable glacier speed‐up. Our data indicate that daily glacier speed‐up is associated with reduced internal deformation over areas previously identified as slippery spots and increased deformation in areas located adjacent to or down‐glacier from slippery spots. We interpret this pattern in terms of a transfer of mechanical support for basal shear stress away from slippery spots to adjacent sticky areas, where the resulting stronger ice–bed coupling causes increased ice deformation near the bed. These patterns indicate that basal ice is subjected to stress regimes that are variable at a high spatial and temporal resolution. Such variations may be central to the creation of anomalous vertical velocity profiles measured above and down‐glacier of basal slippery zones, which have shown evidence for ‘plug flow’ and extrusion flow over annual timescales. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献