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1.
Seismicity in the western Himalayas is highly variable. Several historical and instrumentally recorded devastating earthquakes originated in the western Himalayas which are part of the Alpine–Himalayan belt. Earthquakes cause tremendous loss of life and to the built environment. The amount of loss in terms of life and infrastructure has been rising continuously due to significant increase in population and infrastructure. This study is an attempt to identify seismically susceptible areas in western Himalaya, using pattern recognition technique. An area between latitude 29°–36°N and longitude 73°–80°E was considered for this study. Pattern recognition starts with identification, selection and extraction of features from seismotectonic data. These features are then subjected to discriminant analysis and the study area was classified into three categories, viz., Area A: most susceptible area, Area B: moderately susceptible area, and Area C: least susceptible area. Results show that almost the entire states of Himachal Pradesh and Uttarakhand and a portion of Jammu & Kashmir are classified as Area A, while most of Jammu & Kashmir is classified as Area B and the Indo-Gangetic plains are classified as Area C. 相似文献
2.
笔者系统分析了1918—2005年间中国大陆及其周缘发生的3130个中、强地震的震源机制解,根据其特征进行了岩石圈应力场构造分区,首次得到区域应力场的压应力轴和张应力轴空间分布的统计数字结果。在此基础上研究了应力场的区域特征、探讨了其动力学来源以及构造运动特征。总体结果表明,中国大陆及其周缘岩石圈应力场和构造运动可以归结为印度洋板块、太平洋板块、菲律宾海板块与欧亚板块之间相对运动,以及大陆板内区域块体之间的相互作用的结果。印度洋板块向欧亚板块的碰撞挤压运动所产生的强烈的挤压应力,控制了喜马拉雅、青藏高原、中国西部乃至延伸到天山及其以北的广大地区。在青藏高原周缘地区和中国西部的大范围内,压应力P轴水平分量方位位于20～40°,形成了近NE方向的挤压应力场。大量逆断层型强震集中发生在青藏高原的南、北和西部周缘地区,以及天山等地区。而多数正断层型地震集中发生在青藏高原中部高海拔的地区,断层位错的水平分量位于近东西方向。表明青藏高原周缘区域发生南北向强烈挤压短缩的同时,中部高海拔地区存在着明显的近东西向的扩张运动。中国东部的华北地区受到太平洋板块向欧亚板块俯冲挤压的同时,又受到从贝加尔湖经过大华北直到琉球海沟的广阔地域里存在着的统一的、方位为170°的引张应力场的控制。华北地区大地震的震源机制解均反映出该区地震的发生大体为NEE向挤压应力和NNW向张应力的共同作用结果。台湾纵谷断层是菲律宾海板块与欧亚板块之间碰撞挤压边界。来自北西向运动的菲律宾海板块构造应力控制了从台湾纵谷、华南块体,直到中国南北地震带南段东部地域的应力场。地震的震源机制结果还表明,将中国大陆分成东、西两部分的中国南北地震带是印度洋板块、菲律宾海板块与太平洋板块在中国大陆内部影响控制范围的分界线。 相似文献
3.
Comparison of ionospheric characteristic parameters obtained by GPS and ionosonde with IRI model over China 总被引：1，自引：0，他引：1
Cheng Wang 《Journal of Earth System Science》2016,125(4):745-759
This paper presents a comparison of ionospheric characteristic parameters obtained by a GPS network and three ionosondes at Mohe (122.4°E, 53.5°N, dip angle 70.983°N), Zuolingzhen (114.6°E, 30.5°N, dip angle 46.350°N), and Fuke (109.1°E, 19.5°N, dip angle 27.083°N) located in China with an IRI model in the year 2011. Observed NmF2 and hmF2 values at the three stations are compared with IRI2007 and IRI2012 predictions, respectively. The results show that there are clear linear correlations between the observed values and the IRI model predicted values. The IRI model gives overestimations at the three stations mostly in 2011. For the NmF2 and hmF2 values, most of the results show that the IRI2012 predicted values are closer to the observed values compared with those of IRI2007. Additionally, the GPS TEC values derived from the Crustal Movement Observation Network of China (CMONOC) are compared with the IRI2012 predictions. From the results, it is evident that the IRI2012 model predictions follow the normal trend of diurnal variation of GPS measured TEC monthly means but do not reproduce the measured data well. The IRI2012 model overestimates electron density in the latter part of spring as well as the first half of autumn and winter and underestimates electron density in early spring and the latter part of autumn. Referring to GPS TEC, the precision of the IRI2012 model predicted TEC values is ～5 TECU over China. It may also be noted that there are two discontinuities of IRI-TEC monthly means appearing in November and December of the year 2011. This brings a bias of ～3 TECU of TEC values between two adjacent months. 相似文献
4.
Focal-mechanism solutions of four earthquakes in the eastern Himalayas and northern Burma are determined using the first motion of compressional waves. Two possible solutions thus obtained for each event reveal steeply dipping fault with predominantly strike-slip motion. The stress directions inferred from the focal mechanism solutions are interpreted in the light of predictions of the plate tectonics theory, viz., the underthrusting of the Indian plate in the Burma region in an easterly direction.Dynamic parameters (seismic moment, apparent stress and average dislocations) are obtained using the corrected spectra of Love waves. The earthquakes are found to possess low seismic moment and apparent stress values. A comparison of these estimates with values for intraplate earthquakes is given. It is suggested that these earthquake might be a consequence of a nonhomogeneous rupture process. 相似文献
5.
The M w 8.6 Indian Ocean earthquake occurred on April 11, 2012 near the NW junction of three plates viz. Indian, Australian and Sunda plate, which caused widespread coseismic displacements and Coulomb stress changes. We analyzed the GPS data from three IGS sites PBRI, NTUS & COCO and computed the coseismic horizontal displacements. In order to have in-depth understanding of the physics of earthquake processes and probabilistic hazard, we estimated the coseismic displacements and associated Coulomb stress changes from two rectangular parallel fault geometries, constrained by Global Positioning System (GPS) derived coseismic displacements. The Coulomb stress changes following the earthquake found to be in the range of 5 to ?4 bar with maximum displacement of ～11 m near the epicenter. We find that most of the aftershocks occurred in the areas of increased Coulomb stress and concentrated in three clusters. The temporal variation of the aftershocks, not conformed to modified Omori’s law, speculating poroelastic processes. It is also ascertained that the spatio-temporal transient stress changes may promote the occurrence of the subsequent earthquakes and enhance the seismic risk in the region. 相似文献
6.
本文系统解析并分析了1931年8月-2005年10月期间青藏高原及其周围发生的905个震级M4．5-8．5地震的震源机制结果,研究了青藏高原岩石圈的区域应力场与构造运动特征。结果表明,来自印度板块的北北东或北东方向的水平挤压应力控制了青藏高原及其周缘地区的岩石圈应力场。从喜马拉雅到贝加尔湖以南包括中国西部的广大范围内,主压应力P轴的水平分量位于近NE-SW方向,形成了一个广域的NE-SW方向的挤压应力场。特别是青藏高原周缘地区,除其东部边缘外,南部的喜马拉雅山前沿以及青藏高原的北部、西部边缘地区所发生的绝大部分地震都属于逆断层型或走滑逆断层型地震,表现出周缘地区的水平挤压应力更为强势。应力场特征充分表明, 印度板块的北上运动,以及它与欧亚板块之间的碰撞,所形成的挤压应力场是青藏高原强烈隆起的直接原因。在青藏高原周缘地区受到强烈挤压应力场控制的同时,有大量正断层型地震集中发生在青藏高原中部海拔4000m以上的地区,其中许多地震是纯正断层型地震。震源机制结果显示,近E-W向或WNW-ESE向的水平扩张应力控制着该区的岩石圈应力场;正断层型地震的断层走向多为南北方向,断层位错矢量的水平分量大体位于近东西方向。这表明青藏高原中部高海拔地区存在着近东西方向的扩张构造运动,且扩张构造运动是该区引张应力场的作用结果。其动力学原因可能与持续隆升的高原自重增大引起的重力崩塌及其周边区域构造应力状况有关。研究青藏高原存在挤压应力场与引张应力场及其构造运动的区域特征,对于认识青藏高原形成、发展的地球动力学机制,有着极其重要的意义。 相似文献
7.
刘宝珺 余光明 徐强 G. Einsele W. Frisch 刘光华 J. Wendt A. Wetzel L. Ratschbacher H. P. Luterbacher 《沉积与特提斯地质》1993,(1):32-49
通过对喜马拉雅三叠纪到第三纪区域沉积特征分析,阐明了雅鲁藏布喜马拉雅特提斯造山带从裂谷—被动大陆边缘—前陆盆地的沉积盆地演化史。随着以雅鲁藏布带为代表的喜马拉雅特提斯打开,三叠纪到早侏罗世为特提斯早期裂开的大陆边缘裂谷盆地。早期裂谷中心部位不是现在大陆缝合线的雅鲁藏布一带,而在低分水岭带。晚侏罗世到早白垩世,雅鲁藏布江南测为典型被动大陆边缘,其沉积盆地沉降、海平面变化与沉积作用相吻合。晚白垩世到第三纪为前陆盆地演化阶段,从沉积作用可以识别出晚白垩世晚期为造山第一暮,第三纪初为第二幕。 相似文献
8.
《Gondwana Research》2013,23(3-4):1068-1072
We analyze GPS data from 26 sites located on the Indian plate and along its boundary. The large spatial coverage of the Indian plate by these sites and longer data duration helped us in refining the earlier estimates of the Euler pole for the Indian plate rotation. Our analysis suggests that the internal deformation of the Indian plate is very low (< 1–2 mm/year) and the entire plate interior region largely behaves as a rigid plate. Specifically, we did not infer any significant difference in motion on sites located north and south of the Narmada Son failed rift region, the most prominent tectonic feature within the Indian plate and a major source of earthquakes. Our analysis also constrains the motion across the Indo-Burmese wedge, Himalayan arc, and Shillong Plateau and Kopili fault in the NE India. 相似文献
9.
Flexure of the Indian plate and intraplate earthquakes 总被引：2，自引：0，他引：2
The flexural bulge in central India resulting from India's collision with Tibet has a wavelength of approximately 670 km.
It is manifest topographically and in the free-air gravity anomaly and the geoid. Calculations of the stress distribution
within a flexed Indian plate reveal spatial variations throughout the depth of the plate and also a function of distance from
the Himalaya. The wavelength (and therefore local gradient) of stress variation is a function of the effective elastic thickness
of the plate, estimates of which have been proposed to lie in the range 40–120 km. The imposition of this stress field on
the northward moving Indian plate appears fundamental to explaining the current distribution of intraplate earthquakes and
their mechanisms. The current study highlights an outer trough south of the flexural bulge in central India where surface
stresses are double the contiguous compressional stresses to the north and south. The Bhuj, Latur and Koyna earthquakes and
numerous other recent reverse faulting events occurred in this compressional setting. The N/S spatial gradient of stress exceeds
2 bars/km near the flexural bulge. The overall flexural stress distribution provides a physical basis for earthquake hazard
mapping and suggests that areas of central India where no historic earthquakes are recorded may yet be the locus of future
damaging events. 相似文献
10.
We detect repeating earthquakes associated with the Philippine Sea plate subduction to reveal the plate configuration. In the Kanto district, we find 140 repeating earthquake groups with 428 events by waveform similarity analysis. Most repeating earthquakes in the eastern part of the Kanto district occur with a regular time interval. They have thrust-type focal mechanisms and are distributed near the upper surface of the Philippine Sea plate. These observations indicate that the repeating earthquakes there occur as a repetition of ruptures on the isolated patches distributed on the plate boundary owing to the concentration of stress caused by aseismic slips in the surrounding areas. This shows that the distributions of repeating earthquakes suggest the aseismic slips in the surrounding areas of small patches. We determine spatial distributions of repeating earthquakes in the eastern part of the Kanto district and find that they correspond to the upper boundary of the Philippine Sea plate, that is, the upper boundary of the oceanic crust layer of the Philippine Sea plate. The plate geometry around Choshi is newly constrained by repeating earthquake data and a rather flat geometry in the eastern part of the Kanto district is revealed. The obtained geometry suggests uplift of the Philippine Sea plate due to the collision with the Pacific plate beneath Choshi.Repeating earthquakes in the western part of the Kanto district have extremely shorter recurrence times, and their focal mechanisms are not of the thrust types. These repeating earthquakes are classified as “burst type” activity and likely to occur on the preexistent fault planes which are distributed around the “collision zone” between the Philippine Sea plate and the inland plate. The variation among the repeating earthquake activities in the Kanto district indicates that regular repetition of repeating earthquakes is possible only on the plate boundary with a smooth and simple geometry. 相似文献
11.
Laishram Sunil Singh V. K. Gahalaut Arun Kumar 《Journal of the Geological Society of India》2014,83(5):513-516
We report results of 9 years of GPS measurements of crustal deformation at Imphal, Manipur, a site located in the Indo-Burmese wedge of northwest Sunda arc. The analysis of these measurements suggests that the site moves at a rate of about 36.3±0.5 mm/year towards N55° in the ITRF2008. With respect to the Indian plate it moves at a rate of 16.7 mm/year towards N222°, i.e., predominantly towards southwest. The site is located about 15 km east of the Churachandpur Mao fault (CMF), which is reported to accommodate part of the India-Sunda motion. The site motion is not significantly affected by the earthquakes that occurred in the nearby region. However, the 2004 Sumatra-Andaman earthquake caused a coseismic displacement of ～ 3–5 mm predominantly towards southwest. The site motion is almost linear, with some seasonal variation, and does not show any evidence of accelerated slip or slow earthquake on the CMF or along the plate boundary. 相似文献
12.
David Denham Janet Weekes Clementine Krayshek 《Australian Journal of Earth Sciences》2013,60(3-4):323-332
Earthquakes in SE Australia are usually caused by compressive stresses acting in the crust, and are associated with steeply dipping faults. Sometimes the faulting is predominantly strike‐slip, as for the Bowning earthquakes of 1977 and some of the Dalton/Gunning earthquakes; and sometimes it is high‐angle thrust faulting, as for the 1961 Robertson and 1973 Picton earthquakes. No surface expression of the faults associated with any recent earthquakes in SE Australia has been reported. The directions of the pressure axes, from all the earthquakes for which focal mechanisms have been determined, do not form a consistent pattern. This suggests that the faulting associated with earthquakes in SE Australia is dominated by the geometry of pre‐existing crustal faults or zones of weakness. In situ stress measurements have not been made near the epicentral areas of the larger recent earthquakes, because of the absence of competent, near‐surface rocks coupled to the crust. However, in the western part of the Lachlan Fold Belt the in situ stress results indicate that the maximum pressure axis is approximately E‐W. The evidence from the focal mechanisms does not preclude the persistence of this stress regime farther to the east, and a regional compressive stress in the crust with an azimuth of about 120° is consistent with most of the earthquake focal mechanisms and the in situ stress measurements throughout SE Australia. 相似文献
13.
Cumulative and differential cumulative seismic strain release of shallow earthquakes during 1964 through 1972 show significant time-delayed correlation for many of the rises and/or sinks of tectonic plate boundaries for the Atlantic, Indian and Pacific oceans. For the Pacific, time delays are almost exclusively from areas of higher to areas of lower strain release, and could imply viscous stress relaxation along or near the lithosphere—asthenosphere boundary. Seismically determined slip rates for many of the subduction zones during 1964–1972 are lower than those of the preceding part of the century by a factor of 5. The significant correlation between many rises and sinks suggests worldwide interaction and coupling of plate motion. 相似文献
14.
Md. Afroz Ansari Prosanta K. Khan Virendra M. Tiwari Jayashree Banerjee 《International Journal of Earth Sciences》2014,103(6):1681-1697
Researchers ubiquitously noted that the common processes of partitioning oblique convergence in response to drag from the trench-hanging plate simultaneously produce radial slips, along-strike translation, and extension parallel to the deformation front. Here, we focus on the area between Nepal and Sikkim–Darjeeling Himalayas, and carry out gravity and finite-element stress modeling of the strike-orthogonal converging Indian lithosphere. We delineate the geometries of different layers and their interfaces through gravity modeling. The optimum model parameters along with rheological parameters of different layers are used for finite-element modeling. Finite-element modeling is done with boundary conditions of keeping the upper surface free and rigidly fixing the section of the northern boundary below the Main Himalayan Thrust. We impart on its frontal section an amount of 6 × 1012 N/m force, equivalent to resistive force of the Himalayan–Tibet system, and analyze the maximum and minimum compressive stress fields evolved in the lithosphere. We testify our observations with earthquake database and other geophysical and geological studies. We note that an increasing flexing of the Indian lithosphere beyond the Main Boundary Thrust becomes maxima between the Main Central Thrust and South Tibetan Detachment in both the areas; however, more steepening of the Moho boundary is identified in the Sikkim–Darjeeling Himalaya. This abrupt change in lithospheric geometry beneath the Greater Himalaya is likely correlated with the sharp elevation changes in the topography. Although the highest seismicity concentration is dominant in this zone, the Lesser and the Tethys Himalayas in Sikkim–Darjeeling area also record relatively fair seismic activity. More compressive stress field in different layers right within the sharp bending zone supports this observation. We thus propose that the sharp bending zone beneath the Greater Himalaya is suffering maximum deformation, and the deformation is continued in the mantle too. We also identify both right-lateral shear and radial vergence slip, which are presumably associated with the general dynamics and kinematics of the Himalaya. 相似文献
15.
本文按统一比例尺编制了印度-青藏地区1°×1°重力异常图和地形高程图,并用滑动平均方法得到了本区5°×5°重力异常图。用地改后的1°×1°重力异常,采用组合体模型人一机联作选择法,计算了横跨印度-青藏-蒙古长达4680km的岩石圈剖面,还给出了一个楔形体重力正演公式。基本结果有:(1)MBT、MCT的倾角为10°±5°,ITS、NS、KS的倾角为75°±5°;(2)地壳滑脱面的深度在青藏之下约20km,向高喜马拉雅、MCT、MBT抬升至15km;(3)青藏高原南、北边缘均为岩石圈结构的斜坡带,界面倾角由上向下而增大。在大、小喜马拉雅之下,壳内界面(Ⅰ、Ⅱ)的倾角约12°,Moho倾角为18°,岩石圈底面倾角约36°。在祁连山带所有界面倾角都小于喜马拉雅带,其中壳内界面倾角仅约1°,Moho倾角约2°,岩石圈底面倾角约12°;(4)岩石圈厚度由印度、蒙古向高喜马拉雅和祁连山带逐渐增加,与青藏岩石圈的边缘上翘形成主动俯冲和相对逆冲势态。印度岩石圈厚度(或上地幔顶部低密层埋深)不超过50km,蒙古高原(南)厚约70km,到高喜马拉雅和祁连山下分别增加至145和122km,青藏中心地带(怒江两侧)岩石圈厚135km,向南,北边缘各减小到120和90～102km,在高喜马拉雅和祁连山下面形成25和10km的断差;(5)在青藏Moho之下厚5km的高密薄层和软流层之间有一密 相似文献
16.
The Indian subcontinent is one of the most earthquake-prone regions of the world. The Himalayas are well known for high seismic activity, and the ongoing northwards drift of the Indian plate makes the Himalaya geodynamically active. During the last three decades, several major earthquakes occurred at the plate interiors and boundaries in this subcontinent causing massive losses. Therefore, one of the major challenges in seismology has been to estimate long recurrence period of large earthquakes where most of the classical Probabilistic Seismic Hazard Approaches fail due to short catalogues used in the prediction models. Therefore, during the past few decades, the Himalayan region has been studied extensively in terms of the present ongoing displacements. In this context the present study has been carried out to estimate the surface displacement in a seismically active region of the Himalaya, in between Ganga and Yamuna Tear, using multi-temporal Synthetic Aperture Radar (SAR) Interferometry. A displacement rate of 6.2–8.2 mm/yr in N14°E direction of the Indian plate towards the Tibetan plate has been obtained. It has been noted that the estimated convergence rate using Differential SAR Interferometry technique is relatively low in comparison with those obtained from previous classical studies. The reported low convergence rate may be due to the occurrence of silent/quite earthquakes, aseismic slip, differential movement of Delhi Hardwar ridge, etc. Therefore, in view of the contemporary seismicity and conspicuous displacements, a study of long-term observations of this surface movement has been recommended in future through a time-series SAR Interferometry analysis. 相似文献
17.
《Tectonophysics》1987,138(1):93-107
The Himalayan arc is a type of plate margin similar to an island arc and is a world-famous region of tectonic and seismic activities, where a series of large earthquakes have occurred in historical time. In this paper, the vertical deformation and horizontal displacement fields of the Himalayan arc are theoretically derived from the viewpoint of the collision between the Indian and Eurasian plates. In the light of the observed data, the seismicity, earthquake focal mechanism, seismotectonic and geomorphological features of the arc and its vicinity are reasonably explained. The characteristics of seismicity and the possibility of earthquakes with magnitude above 8 occurring in this region in the future are studied. 相似文献
18.
Longitudinal profiles along sixteen major transverse Himalayan rivers add important constraints to models of active continental subduction and its evolution. These profiles are characterized by a zone of relatively high gradient that cannot be associated with differential resistence to erosion in all cases. The base of the zone of increased gradients correlates with (1) the topographic front between the Lesser and High Himalayas, (2) the narrow belt of intermediate-magnitude thrust earthquakes, (3) the Main Central Thrust zone (MCT). These features define a small circle in the central portion of the Himalayan arc. These correlations suggest that the discontinuity in the river profiles and the other features are controlled by a major tectonic boundary between the rising High Himalayas and the Lesser Himalayas. No sharp increases in gradient are observed near the Main Boundary Thrust (MBT), except on a few rivers, such as the Jhelum or Kundar, where the MBT lies close to both the MCT and the seismic belt. Thus, it is unlikely that the MBT is a major tectonic boundary. The diversion of river courses along the MBT and around anticlines in the Sub Himalayas has probably been caused by aggradation near the rosion-deposition boundary, upstream of uplifts in the Mahabharat range and Sub Himalayas.A parallel is drawn between the Himalayas and New Guinea based on the hypothesis that continent-arc collision, of the type occurring in northern Australia, preceded continent-continent collision in the Himalayas. The present sedimentary/tectonic phase in New Guinea resembles the Subathu (Paleocene-Eocene) phase in the Himalayas. Incipient counterparts of the major Himalayan structures, including the MCT and the MBT, are recognized in New Guinea. The drainage patterns in the Himalayas and in New Guinea bear a similar relation to major structures. This suggests that (1) the tectonic evolution of the Himalayas has been rather uniform since early stages of collision, and (2) the Himalayan drainage was also formed at these early stages and is therefore antecedent to the rise of the High Himalayas. 相似文献
19.
印度—欧亚板块碰撞变形区的大地震时空分布特征与迁移规律 总被引：4，自引：4，他引：0
印度板块与欧亚板块在新生代期间的持续碰撞和挤压过程导致亚洲大陆发生了强烈的弥散式板内变形,并形成了一个以贝加尔湖为顶点,以喜马拉雅带为底边的近似三角形的变形区与强震活动区,即新-藏三角区。基于固体刚塑性变形平面结构,结合滑移线场网络模型,对该区历史强震活动的大范围离散式空间分布特点进行了分析解释。结合1505-1976年以来历史强震空间迁移的实例,归纳了该区历史强震活动与地震应变释放从印度板块边界→新-藏地块→两侧大陆的顺序性及定向性迁移特征,并根据对地震空间迁移规律的认识,进一步探讨了区域未来强震危险性问题。结果显示,从2000-2018年间,印度板块边界和新-藏三角区已多次发生M7.9~9.1大地震,但其东、西两侧的区域大陆地区却异常平静,没发生过7级以上大地震。依照区域强震活动的顺序性迁移特点,推测在未来几到几十年,亚洲大陆东部与中部以及喜马拉雅带东段等区域的大地震危险性较大。 相似文献
20.
The major earthquake-induced tsunamis reliable known to have occurred in and near Greece since antiquity are considered in the light of the recently obtained reliable data on the mechanisms and focal depths of the earthquakes occurring here. (The earthquake data concern the major shocks of the period 1962–1986.) First, concise information is given on the most devastating tsunamis. Then the relation between the (estimated) maximum tsunami intensity and the earthquake parameters (mechanism and focal depth) is examined. It is revealed that the most devastating tsunamis took place in areas (such as the western part of the Corinthiakos Gulf, the Maliakos Gulf, and the southern Aegean Sea) where earthquakes are due to shallow normal faulting. Other major tsunamis were nucleated along the convex side of the Hellenic arc, characterized by shallow thrust earthquakes. It is probably somewhere there (most likely south of Crete) that the region's largest known tsunami occurred in AD 365, claiming many lives and causing extensive devastation in the entire eastern Mediterranean. Such big tsunamis seem to have a return period of well over 1000 years and can be generated by large shallow earthquakes associated with thrust faulting beneath the Hellenic trench, where the African plate subduces under the Euroasian plate. Lesser tsunamis are known in the northernmost part of the Aegean Sea and in the Sea of Marmara, where strike-slip faulting is observed. Finally, an attempt is made to combine the tsunami and earthquake data into a map of the region's main tsunamigenic zones (areas of the sea bed believed responsible for past tsunamis and expected to nucleate tsunamis in the future). 相似文献