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The Arica Elbow region represents that part of Andean South America where the azimuth of the strike of the Peru-Chile trench changes from 150° to 190°. The area under study is roughly bounded by latitudes 17 °S and 23 °S, The shape of the Wadati-Benioff zone was studied in terms of the distribution of ISC hypocentres dated between 1964 and 1993. A system of 22 vertical cross-sections, perpendicular to the trench axis, and a map of epicentres was used to derive the detailed shape of the Wadati-Benioff zone of the presently descending slab. The distribution of earthquake foci indicates a fingerlike shape of the lower part of the Wadati-Benioff zone beneath the aseismic gap. The slab length shows small changes around 350 km in the northern sections, pronounced length oscillations between 350 and 750 km in the neighbouring central sections and a constant value of 650 km in the southern sections. The dip and thickness of the Wadati-Benioff zone are practically constant in all sections. Fault plane solutions, separated spatially into three zones, were used to estimate the state of stress in the slab. 相似文献
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The regional stress field and seismic dynamics along the border zone between Fujian, Guangdong and Jiangxi Provinces are studied based on the seismo-geological data, GPS measurement, and seismicity. The results show that: (1) the principal compressional stress of the stress field is oriented in NW-SE direction and the principal extensional stress is in NE-SW direction; (2) the WNW-ward compression and collision of the Philippine Sea Plate to the eastern coast of Taiwan Island are the most direct and most important dynamic source for preparation and occurrence of strong earthquakes in the Taiwan area and along the border zone between Fujian, Guangdong and Jiangxi Provinces. 相似文献
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Xiang Hongfa 《中国地震研究》2005,19(2):125-138
INTRODUCTION TheRedRiverfaultinsouthwestChina,aboundaryfaultbetweentheIndochinaplateandthe Yangtzeplate,haslongbeenatopicofgeneralinterest.Manystudieshavebeendoneonthegenesis,evolutionandtectonicchangesinthehistoryoftheAilaoshan RedRivertectoniczoneinterm… 相似文献
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INTRODUCTIONManyhlstoric andrecent eaythquakes occurred along the Zhan9lakou-Penglal fanfaut zone situatedIn h。northern part of North China seismic regl()n(Fig.l),Including Sanhe-Pinggu MS.0 earthquakeonseptemberZ,1679 and Tangshan M7.8 eal’thquake on July28,1976.Afterthe Tangshanearthquake,a seismic quiescence along this zone lasted for 20 or more yeas without M 3 6.0eafthquake.Butonjanuary20,1998 theZhangbel M6.2 eafthquake occurred·Then the seismicactivity tends to … 相似文献
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Pull-apart Basins and the Total Lateral Displacement Along the Haiyuan Fault Zone in Cenozoic 总被引:2,自引:0,他引:2
INTRODUCTIONItisdebatedaboutthetotallateraldisplacementalongthemainboundaryfaultsofintraplateblocksineasternAsiacontinentinCenozoicera .Inthe 1 970sof2 0thcentury ,somescientistshades timatedlateraldisplacementbasedongeomorphicdata .Theyproposedthatthetotald… 相似文献
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Syuhada Syuhada Nugroho Dwi Hananto Chalid I. Abdullah Nanang T. Puspito Titi Anggono Tedi Yudistira 《Acta Geophysica》2016,64(6):2020-2049
We analyzed receiver function of teleseismic events recorded at twelve Indonesian-GEOFON (IA-GE) broadband stations using nonlinear Neighbourhood Algorithm (NA) inversion and H-k stacking methods to estimate crustal thickness, V p /V s ratios and S-wave velocity structure along Sunda-Banda arc transition zone. We observed crustal thickness of 34–37 km in Timor Island, which is consistent with the previous works. The thick crust (> 30 km) is also found beneath Sumba and Flores Islands, which might be related to the arc-continent collision causing the thickened crust. In Timor and Sumba Islands, we observed high V p /V s ratio (> 1.84) with low velocity zone that might be associated with the presence of mafic and ultramafic materials and fluid filled fracture zone. The high V p /V s ratio observed at Sumbawa and Flores volcanic Islands might be an indication of partial melt related to the upwelling of hot asthenosphere material through the subducted slab. 相似文献
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研究区位于华北盆地西北、近东西向的燕山台褶带、北东向的山西断隆接合部.该区域及其周围构造复杂并且地震活动频繁. 相似文献
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B. G. Gavrilov Yu. I. Zetzer V. I. Kurkin I. E. Markovich Yu. V. Poklad M. Parrot I. A. Ryakhovskii V. V. Yakim 《Izvestiya Physics of the Solid Earth》2012,48(4):354-362
Variations in the geomagnetic and electric fields and variations of the total electron content (TEC) of the ionosphere recorded
in the Baikal Rift Zone (BRZ) during the expeditions in 2009 and 2010 are analyzed. Synchronous bursts in the geomagnetic
field on the ground and in the ionosphere, which are caused by propagation of electromagnetic disturbances (spherics) generated
by the remote lightning discharges, are revealed. The analysis of the occurrence frequency of the electromagnetic disturbances
at an altitude of ∼700 km shows that there is a preferred region of predominant propagation of these disturbances from the
Earth-ionosphere waveguide to the upper ionosphere. When the ionospheric penetration point moves through this preferred region,
the frequency spectrum of TEC variations changes, and the northern boundary of the region of spectral alteration is located
at ∼54°N. The bursts in TEC that map on the zones of the main faults in the Tunka valley are identified. The results probably
suggest a relation between the electromagnetic phenomena in the ionosphere and the structures in the lithosphere. 相似文献
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基于太原市目标区交城断裂带的定量研究,特别是对活动断裂上的古地震资料进行的系统、详细的分析与总结,建立了反映该断裂地震地质特点和运动学属性的复发模式和概率模型.引入震级-地表破裂长度、震级-震源破裂长度、震级-断层破裂面积以及震级-地震矩的经验关系进行震级估计,最后进行综合评估以确定交城断裂带北段潜在地震的最大震级.复发模式的建立兼顾了泊松和准周期两种模式,利用专家意见法组合相应的Poisson模型和BPT模型,计算活动断裂最大潜在地震的复发概率.结果表明,交城断裂带北段潜在地震最大震级为Ms7.2级,而未来50a、100a、200a发生Ms7.2级地震的概率分别为2.1%、4.0%和7.9%. 相似文献
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鲜水河—安宁河断裂带磨西—冕宁段的滑动速率与强震位错 总被引:10,自引:1,他引:10
航片解译及野外地震地质考察结果表明,鲜水河-安宁河断裂带磨西-冕宁段存在明显的晚第四纪活动性,其以左旋走滑运动为主,并伴有显著的垂直滑动分量。晚第四纪以来的平均水平滑动速率在鲜水河断裂磨西以南段为6.0-9.9mm/a,安宁河断裂冕宁以北段为4.7-5.3mm/a。同震位错及地震地表破裂研究表明,A.D.1786年康定-泸定磨西73/4级地震的地表破裂可能南延至田湾以南;安宁河断裂冕宁以北段则具有蕴育71/2级左右地震的构造背景,最晚一次强震的地质记录极有可能是史料记载不全的A.D.1327年一次6级或6级以上地震的证据。 相似文献
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《Journal of Geodynamics》1988,10(1):25-41
The morphology of the Wadati-Benioff zone in the region of Kamchatka, the Kurile Islands and Hokkaido, based on the distribution of 6319 earthquake foci, has verified the existence of an intermediate-depth aseismic gap and its relation to active andesitic volcanism. It appeared that deep-focus earthquakes in this region belong to a paleosubduction zone activated by an intermediate-depth collision with the active subduction zone in the area of Hokkaido. A system of deep seismically active fracture zones was delineated in the continental plate and confirmed by the results of deep seismic sounding. Two of these fractures, dipping toward the subduction zone, may be considered as the principal feeding channels for active and Holocene volcanoes of the continental volcanic bels of Kamchatka. 相似文献
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Izvestiya, Physics of the Solid Earth - The approach is proposed for modeling deformations in the subduction zones from the surface displacement data recorded by the methods of satellite geodesy.... 相似文献
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On the Generation of ULF Magnetic Variations by Conductivity Fluctuations in a Fault Zone 总被引:1,自引:0,他引:1
G. D. Egbert 《Pure and Applied Geophysics》2002,159(6):1205-1227
v--vPrior to the October 18, 1989 Loma Prieta Ms 7.1 earthquake, Fraser-Smith et al. (1990) recorded a 10-100 fold increase in ultra-low frequency (ULF) magnetic fields near the earthquake epicenter. Several mechanisms for generation of these ULF fields by fluid flow in the earth have been advanced, but all appear to require unrealistic fluid velocities or hydraulic permeabilities to match the observations. As an alternative explanation, Merzer and Klemperer (1998) proposed that the increase in ULF magnetic fields could result from induced electric currents flowing in a fault-zone made temporarily much more electrically conductive by stress-induced reorganization of pore geometry. Using a numerical model we show that while this mechanism could produce a significant increase in ULF variations, mutual induction between the fault zone and the surrounding crust would probably limit the amplitude increase to levels well below those observed at Loma Prieta. We consider a variant on this quasi-static conductive fault zone model in which low frequency telluric currents are modulated by small higher frequency variations of bulk fault zone conductivity. We show that because the spectrum of natural EM variations is red, substantially larger relative increases in ULF magnetic fields could be produced by this mechanism with even small conductivity fluctuations at these frequencies. These variations would be easy to detect with a well-designed experiment, if they occurred. In principle this mechanism could explain the Loma Prieta ULF observations, however the magnitude of conductivity fluctuations that would be required to match the very large reported amplification factors still appears to be too large to be physically plausible. 相似文献
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Zhou Cuiying 《中国地震研究》2005,19(4):442-457
INTRODUCTIONThere exist many methods for studying recent crustal stress field.One of the most commonmethodsis to use focal mechanismsolution data of earthquakes to deduce the recent crustal stressfield.The method is simple and feasible and the data obtained is reliable.Yan Jiaquan,et al.(1979)usedthe method to study the recent tectonic stress field in China and its adjacent areas andgave a rough configuration and regional characteristics of the stress field.Li Qinzu(1980),WeiGuangxing,e… 相似文献
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The fault zone along the northern margin of West Qinling Range is a major active fault zonein the key seismic monitoring area in the southeastern part of Gansu Province.In order tostudy the current activity characteristics of this fault,GPS monitoring network has beenarranged along both sides of the fault and 3 measurements have been made from 1996 to1998.The result indicates that obvious differential movement exists along the north and southsides of the fault and the eastward movement on the south side is 3.8mm/a larger than thaton the north side.In the GPS network,the shortened side is generally in the trend of EW andthe extended side is basically NW to SE.The principal compressional stress trend in this areais about EW and the sinistral motion is obvious in the eastern part of the fault(nearWushan).The measured results also indicate that the displacement rate has decreased by50% and the compressional strain has increased by 100% as compared the data of 1997~1998 with those of 1996~1997,which shows t 相似文献
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Water Resources - The analysis of data on the space and time variations of the concentrations and element composition of organic matter dissolved in Caspian Sea water over 2010–2015 showed... 相似文献