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1.
Yu. O. Kuzmin 《Izvestiya Physics of the Solid Earth》2009,45(11):973-986
Important problems of tectonophysical analysis of observational results in recent geodynamics are considered. The paradox
of low rates of recent horizontal deformations of the Earth’s surface is formulated. This paradox states that, according to
GPS measurements, the annual mean rates of relative deformations are 10−9–10−10 per year, whereas, according to ground-based geodetic and deformographic observations, the rates of recent horizontal deformations
of the Earth’s surface are on the order of 10−5–10−6 per year. This paradox is shown to appear as a result of the application of the procedure of averaging to the displacements
obtained on large measuring bases with a low degree of details of the time of observations.
It is established that, according to multiyear (over 40 years) data, the annual mean rate of deformation processes in the
Kopet Dagh seismically active region is 4 × 10−8 per annum along the vertical and 3.2 × 10−8 per year along the horizontal. 相似文献
2.
Yu. O. Kuzmin 《Izvestiya Physics of the Solid Earth》2018,54(6):886-903
The results of the analysis of extensive data about the local anomalies of recent surface displacements in the fault zones estimated from repeated geodetic observations in seismically active and weakly seismic (platform) regions are presented. It is shown that the local, symmetric sags of the Earth’s surface in the vicinity of the faults are the predominant type of anomalies. The simultaneous recording of the vertical and horizontal displacements shows that the local subsidence is accompanied by horizontal deformations of elongation along the lines that are orthogonal to the fault’s strike. Different kinematic types of faults are considered, and it is shown that the revealed anomalies correspond to the recent activation of the local joints within the fault zones resulting in the subsidence of the Earth’s surface. Three variants of the models describing the formation of the joint-type anomalies are considered: the block model, the dislocation model, and the parametric model. The comparison of the calculated distributions of the horizontal and vertical displacements in the vicinity of the fault with the observations shows that the parametric model fits the field data best. The parametric model describes a fault as a zone with varying internal parameters in two variants: as an inhomogeneity with a reduced stiffness or as an inclusion with anomalous strain according to the terminology of John D. Eshelby. By the example of regularly shaped objects, the equivalence of both approaches is demonstrated. 相似文献
3.
The time series of the uniquely long geodetic observations of recent geodynamic processes in the Kopet-Dag region are analyzed. The regional observations of contemporary vertical movements cover a 75-year period; the zonal and local systems of leveling measurements, which provide an increased degree of spatiotemporal detail (the distance between the benchmarks is less than 1 km and the measurements are repeated with a frequency of once per month to two times per annum), have been functioning for 50 years. It is shown that during the last 40–50 years, the regional stress field in the forefront of the Main Kopet-Dag thrust and collision zone of the Turanian and Iranian plates is quasi static. The annual average trend rate of strains estimated from a set of the time series of uniquely long geodetic observations is (3–5) × 10?8 yr?1, which is only one to two amplitudes of tidal deformations of the solid Earth. The local deformations in the fault zone reach the rates that are by 1.5–2 orders of magnitude higher than in the block part of the region. It is found that the segments of the Earth’s surface within the axial part of the depression experience persistent uplifting, which indicates that they do not follow the scheme of inherited evolution characteristic of the fault-block structures of the region. It is demonstrated that these anomalous uplifts can be caused by the variations in the weak seismicity in the zone of the North Ashgabat Fault. 相似文献
4.
Yu. O. Kuzmin 《Izvestiya Physics of the Solid Earth》2017,53(6):825-839
The comparative analysis of the Earth’s surface deformations measured by ground-based and satellite geodetic methods on the regional and zonal measurement scales is carried out. The displacement velocities and strain rates are compared in the active regions such as Turkmenian–Iranian zone of interaction of the Arabian and Eurasian lithospheric plates and the Kamchatka segment of the subduction of the Pacific Plate beneath the Okotsk Plate. The comparison yields a paradoxical result. With the qualitatively identical kinematics of the motion, the quantitative characteristics of the displacement velocities and rates of strain revealed by the observations using the global navigational satellite system (GNSS) are by 1–2 orders of magnitude higher than those estimated by the more accurate methods of ground-based geodesy. For resolving the revealed paradoxes, it is required to set up special studies on the joint analysis of ground-based and satellite geodetic data from the combined observation sites. 相似文献
5.
E. A. Rogozhin 《Izvestiya Physics of the Solid Earth》2013,49(5):643-652
The seismotectonic, seismological, macroseismic, and geodetic investigations carried out by different authors provided the idea about the size and structure of the sources of the largest Simushir earthquakes that occurred on November 15, 2006 and January 13, 2007. Sound conclusions concerning the character of dislocations arising in the epicentral area of strong submarine seismic events are drawn from the detailed analysis of GPS-based geodetic observations of surface deformations on the islands and in the southern Kamchatka. The focal mechanism solutions for two of the strongest quakes, together with the hypocentral positions of their aftershocks, are used for identifying the fault plane and reconstructing the pattern of the slip on it. 相似文献
6.
V. E. Levin 《Journal of Volcanology and Seismology》2009,3(3):200-209
This is a review of the geodetic monitoring of the horizontal component of recent crustal movements (RCMs) in Kamchatka and the Commander Islands for the period 1979–2007. Examples are provided of the RCMs recorded in Kamchatka and the Commander Islands for the period 1997–2007 by the Kamchatka regional GPS network (KAMNET) set up by workers at the Kamchatka Branch of the RAS Geophysical Service (KB GS RAS) in collaboration with the Institute of Volcanology and Seismology of the Far East Division of the Russian Academy of Sciences to study the geodynamic processes that are occurring in the Kamchatka subduction zone. An interpretation of examples of recorded RCMs is given. 相似文献
7.
8.
岩石圈流变学结构是控制不同构造环境下岩石圈形变的关键因素之一. 随着空间大地测量观测技术的发展, 基于空间大地测量数据的震后形变研究对揭示断裂带内的力学性质和区域性岩石圈流变学结构已成为可能. 该文首先基于岩石力学的摩擦和流变学实验, 对余滑和分布式韧性流的构造物理背景进行了分别阐述, 并介绍了震后形变数值模拟中本构关系和数值模型的发展. 数值模型主要有解析、 半解析和纯数值3类, 涉及的本构关系包括基于速率-状态摩擦准则的余滑以及分布式韧性流中常用的线性流变学模型(麦克斯韦尔体和标准线性固体)和瞬态流变学模型(宏观经验性的伯格斯(Burgers)体和微观幂律流变律). 然后以美国南加州1992年Landers MW7.3地震和1999年Hector Mine MW7.1地震震后形变研究为例, 介绍了震后形变的研究进展. 最后回顾了大陆岩石圈流变学结构的研究进展, 并以震后形变研究中的流变学结构(“三明治模型”和“焦糖布丁模型”)存在的争议为例, 说明了岩石圈流变学结构研究所具有的挑战性. 相似文献
9.
A local geodetic network of 20 points was established in 1988 around the Seiyal fault for monitoring lateral movements. Two levellinglines, crossing the fault, were prepared for monitoring vertical movements. The initial horizontal geodetic measurements were carried out in March 1989. The measurements were repeated twice a year. The initial vertical geodetic measurements (levelling) were carried out in November 1989 and repeated in November 1990.Four horizontal geodetic measurements and two levelling measurements were analysed. The results revealed remarkable horizontal and vertical changes during the period of measurement. 相似文献
10.
The resurvey of both a geodetic network and a levelling net was carried out in June 1981, 8 months after the Ms = 7.3 El Asnam earthquake of 10 October 1980. Previous seismological and neotectonic studies indicate that this event results from a north-east-trending overthrust complex fault of about 40-km length, which shows at least three principal segments with slightly different directions.Vertical movements, evaluated by means of a trigonometric levelling method show an uplift of the thrust fault of about 5 m and a depression of the southeastern edge of about 1 m. These movements are progressively attenuated away from the fault trace (see fig. 1). Horizontal movements have been evaluated by a classical first-order triangulation method. (see fig. 2 and table 1).The resulting mean strain tensors, calculated for different triangles of the geodetic network, indicate a shortening of about 2.50 m which is consistent with the SE-NW direction of compression determined from neotectonic evaluations and focal mechanisms (see fig. 3). Dislocation models are used to explain and discuss the observed deformations in the light of the seismological data and the observed ground breakages. Five segments are required to explain both horizontal and vertical deformations. The magnitude of vertical displacement (about 6 m) at the junction between the southwest and the central segments of the fault argues for the breaking of this area during the main shock and for a slip vector of about 8 m, at least in the central segment.In such circumstances where the first field observations show that a strong coseismic movement has taken place, the best methodology to be used seems to be:
- • - to resurvey as quickly as possible the widest acceptable zone of the old existing geodetic network, without special attention paid to the precision of these measurements.
- • - to set up as soon as possible a small aperture geodetic network of high accuracy in order to monitor the possible postseismic readjustments.
11.
12.
Based on the horizontal movement velocities and their error estimations of 144GPS stations in North China de-duced from the results obtained from multiple GPS measurements carried out in the period of 1992-2001,the horizontal deformation in the area is stuklied.The movements,entire deformations,local deformations,activeity patterns and intensities along the boundary zones are derived.And then the risk of strong earthquake in the area is estimated.In the research,the horizontal displacement observations can be considered as the sum of three parts.The first part is the entire motion following Eurasian plate,which can be derived from NUVAL-IA model;the second part is the relative motions and deformations between the sub-tectonic blocks in the studied area,which can be derived from a set of displacement observations determined by the expanded QUAD method in the paper;the third part is the local deformations and errors in the sub-tectonic blocks,which can be described as the inhomoge-neous strains of the block.The method and results are introduced in detail in the paper. 相似文献
13.
E.A. Fin'ko 《Journal of Geodynamics》1992,15(3-4)
The geodetic data on recent vertical crustal movements within the Kazakh shields is in good correlation with its development in the Holocene (according to a study of juvenile river terraces); they point to gradual transition of the shield to the platform morphostructures of Western Siberia and a contrasting joining with the Central Asia orogenic belt. Small gradients of recent vertical movements dominate the shield. Moderate gradients are typical of local structures, whereas increased and extremely high gradients belong to active deep fault zones. 相似文献
14.
Geodetic deformation vs. seismic strain deduced by historical earthquakes across the Alborz Mountains 总被引：1，自引：0，他引：1
Mohammad Reza Zolfaghari 《Journal of Seismology》2009,13(4):647-663
Historical seismicity is used in order to map spatial distribution of seismic moment released by past earthquakes and to compare
strain rate deduced from seismicity to those measured by geodetic GPS survey. Spatial analyses are performed on the seismicity
of northern boundary of Central Iranian Block which coincides with the Alborz Mountains. This belt has been responsible for
several catastrophic earthquakes in the past. In this study, the records of historical and instrumental earthquakes in the
Alborz Mountains are used to calculate and plot geographical distribution of seismic moment released in time. A two-dimensional
distribution function is proposed and used here to spread seismic moment along causative tectonic features. Using accumulated
seismic moment, average slip rates across active faults are estimated for 32 sub-zones along the Alborz Mountains and western
Kopet Dag. Seismic moment released by historical and recent earthquakes on this belt accounts for slip rate of 3–5 mm/year
which is in good agreement with the geodetic vectors recently deduced from GPS survey in this region. The study also reveals
geographical variations of slip rates along some 900 km length of this zone based on seismic history. The results are compared
against finding from similar study in this region. Portions of Central and Eastern Alborz show lower seismic strain rate which
could imply aseismic motion or overdue earthquakes. Completeness of historical earthquake catalogue and its reliability with
regard to earthquake magnitudes, locations, and rupturing systems are among many plausible factors controlling the credibility
of such results. Therefore, any conclusions derived from these results remain as reliable as the data and assumptions used
for the analyses. 相似文献
15.
V. A. Sankov A. V. Lukhnev A. I. Miroshnitchenko A. A. Dobrynina S. V. Ashurkov L. M. Byzov M. G. Dembelov E. Calais J. Déverchère 《Izvestiya Physics of the Solid Earth》2014,50(6):785-794
The contemporary horizontal movements and deformations in the central and southern parts of the Baikal depression are analyzed, and their relationship with contemporary seismicity is studied. Based on the long-term measurements by the Baikal geodynamical GPS monitoring network, the refined estimate is obtained for the velocity of the divergence of the Siberian and Transbaikalian blocks, which is found to occur in the southeastward direction (130°) at 3.4 ± 0.7 mm per annum. This agrees with the parameters of the long-term extension component estimated from the geological data and with the direction of extension determined from the seismic data. The distribution of the displacement velocity across the strike of the rift, which gradually increases from one block to another, suggests a nonrigid behavior of the continental lithospheric plates at the divergent boundary. About 30% (1.0–1.5 mm per annum) of the total increase in the velocity is accommodated by the Baikal Basin. The strain rate within the trough reaches 3.1 × 10?8 yr?1 and decreases on either side across the structure. The character of distribution of the horizontal displacement velocities on the Baikal divergent boundary between the Eurasian and Amurian plates favors the model of passive rifting. The zones of highly contrasting topography and increased seismicity are localized within the area of contemporary deformations, and the seismic moment release rate directly depends on the strain rate. Here, the rate of the seismic moment release rate makes up a few percent of the geodetic moment accumulation rate calculated by the approach suggested by Anderson (1979). Based on the coherence between the graphs of the rates of geodetic moment accumulation and seismic moment release rate by the earthquakes with M ≥ 5.0 during the historical and instrumental observation periods, the contemporary seismic hazard for the South Baikal Basin could be assessed at a level of seismic event with M = 7.5–7.6. 相似文献
16.
2001年MW7.8昆仑山地震是近半个世纪以来青藏高原发生的最大震级地震。同震破裂产生的巨大应力扰动驱动控制着显著震后形变。二十年尺度的大地测量数据记录了地震后长时间、大范围、时空依赖的震后形变演化过程及差异,揭示了昆仑山地震破裂段复杂的断层分段震后运动学特征、分段摩擦性质差异和青藏高原中北部岩石圈流变性质/结构横向各向异性。本文简要回顾昆仑山地震后基于二十年尺度时序InSAR和GPS的震后形变观测方法和时空特征,特别是时空密集的InSAR观测,是该构造区震后GPS观测的重要补充及其不可替代的观测手段;总结大范围震后形变模拟方法及其揭示的震后运动过程、多种动力学机制及其关系。最后总结提出昆仑山地震震后形变20年研究取得的科学认识及尚待深入研究的科学问题,一方面要持续性地对东昆仑断裂带大范围地表形变进行观测研究;另一方面,要不断更新震后形变模型,进一步深化对该断裂带地震周期形变、区域构造对周期形变控制作用、复杂断层运动时空演化机制的认识。 相似文献
17.
Eric O. Lindsey Valerie J. Sahakian Yuri Fialko Yehuda Bock Sylvain Barbot Thomas K. Rockwell 《Pure and Applied Geophysics》2014,171(11):2937-2954
We investigate interseismic deformation across the San Jacinto fault at Anza, California where previous geodetic observations have indicated an anomalously high shear strain rate. We present an updated set of secular velocities from GPS and InSAR observations that reveal a 2–3 km wide shear zone deforming at a rate that exceeds the background strain rate by more than a factor of two. GPS occupations of an alignment array installed in 1990 across the fault trace at Anza allow us to rule out shallow creep as a possible contributor to the observed strain rate. Using a dislocation model in a heterogeneous elastic half space, we show that a reduction in shear modulus within the fault zone by a factor of 1.2–1.6 as imaged tomographically by Allam and Ben-Zion (Geophys J Int 190:1181–1196, 2012) can explain about 50 % of the observed anomalous strain rate. However, the best-fitting locking depth in this case (10.4 ± 1.3 km) is significantly less than the local depth extent of seismicity (14–18 km). We show that a deep fault zone with a shear modulus reduction of at least a factor of 2.4 would be required to explain fully the geodetic strain rate, assuming the locking depth is 15 km. Two alternative possibilities include fault creep at a substantial fraction of the long-term slip rate within the region of deep microseismicity, or a reduced yield strength within the upper fault zone leading to distributed plastic failure during the interseismic period. 相似文献
18.
大地测量技术观测的震后变形是地壳和地幔岩石对同震应力扰动的变形响应,震后变形的强度及时空演化特征主要受断层面的摩擦性质、下地壳及上地幔岩石的流变参数等控制。震后大地测量被广泛用于研究断层及深部岩石的流变性质及其动力学过程,是对岩石力学实验、冰后回弹等手段探测结果的检验和补充。本文回顾性地总结了中国及邻域中强地震震后变形监测成效,这些震例主要集中在青藏高原内部和边界带。通过对包括昆仑山口西地震、汶川地震和尼泊尔地震在内的发生在青藏高原及周缘的强震震后变形机制、岩石圈流变参数约束等方面的研究,大大提升了对青藏高原不同区域深部岩石流变结构和性质的认识,为研究地震周期变形、地震危险性、青藏高原的形变模式、高原演化动力学提供了观测依据和定量参数。同时,指出进一步约束青藏高原深部岩石流变参数,一方面需要进一步提高西部地区连续GNSS监测能力,另一方面需要与地球物理成像技术进行融合。 相似文献
19.
V. E. Levin V. F. Bakhtiarov N. N. Titkov S. S. Serovetnikov M. A. Magus’kin A. V. Lander 《Izvestiya Physics of the Solid Earth》2014,50(6):732-751
The works on geodetic monitoring of the contemporary crustal motions (CCMs) in the region of the Kamchatka Peninsula and Komandor Islands for the 40-year history of instrumental observations are reviewed. The examples of CCM recording by the classical geodetic methods and, since 1996, by the Global Positioning System (GPS) are presented. The deployment of the regional network for GNSS observations by the Kamchatka Branch of the Geophysical Survey of the Russian Academy of Sciences (KAMNET) made it possible to study the geodynamical processes at the junction of three major plates (Eurasian, North American, and Pacific) and smaller plates (Okhotsk and Bering). The interpretation of the examples of recorded CCMs is presented. The prospects of further development in the field of studying the geodynamics of the Koryak-Kamchatka region are outlined. 相似文献
20.
唐山及大同－阳高地震大地形变与重力前兆综合研究 总被引：1，自引：0，他引：1
本大概还了近年来利用大地形变及重力复测资料研究唐山及大同－阳高地震的丰富成果，对这２次地震震前大地形变及重力前兆综合研究认为：震中区震前呈现闭锁状态；断层蠕滑及深部物质的运移，是震前的显著标志；地震成因的组合模式可以较好地解释唐山及大同一阳高地震的机制；跟踪监测形变场、重力场及断层活动时空演化特性，是利用大地形变及重力测量手段进行地震预测的基本出发点。 相似文献