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许康生 《地震地磁观测与研究》1992,13(2):15-19
地震泼由多种频率成份组成,在其传播过程中。由于地球介质的滤波作用,随着传播距离的增大。高频成份逐渐被衰减。周期越大的成份传播越远。因此,在地震观测上,不同频带的地震仪用于观测不同震中距范围的地震,使仪器较好地响应,就我国台网而言,短周期仪用于地方震、近震的监测,中长周期仪和长周期仪用于远震,极远震的监测,其中长周期仪偏重于记录极远震。但作者在实际分析工作中注意到,短周期仪的记录应用于远震,极远震的分析,显示出独特的作用,充分挖掘和利用短仪资料,将会更加丰富远震、极远震的震相资料。本文以高台地震台的资料为依据,从震中距和震级角度,与中长仪和长仪作比较,对短仪记录远震、极远震的震相及特征作了统计分析与初步探讨,并对新疆地区“影区”地震S波的记录、日本地区地震_PPcP等震相的出现提出了现象的存在,给出了相应的观测结果,以待步一步研究。 相似文献
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对2007年8月15日秘鲁近海MW8.0地震在全球数字地震仪台网(GSN)83个台的宽频带数字记录进行分析,在短周期(SP)、中长周期(SK)和长周期(LP)记录上均识别出在震源破裂过程中由主要破裂激发出的破裂震相。由破裂震相分析结果可以看出:该地震是一个由4次主要破裂构成的地震事件,第2次破裂、第3次破裂和第4次破裂与第1次破裂之间的时间间隔平均约9.1 s、48.5 s和63.3 s,与震源破裂时间函数的结果一致。4次主要破裂激发的破裂震相在GSN台站可识别的震中距范围为1.4°—153.8°。本文给出的破裂震相记录特征,为分析识别其他地震的破裂震相提供了参考。从地震记录图上直接识别破裂震相有助于快速判断震源破裂过程,有助于快速判断震灾损失。 相似文献
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采用黑龙江地震台网记录的地震波形,基于sPn震相,计算2005—2021年黑龙江省区域内发生的11次M≥4.0近震的震源深度。分析发现,在研究区域内,可精确识别单台震中距在3°—7°范围内的地震记录波形的sPn震相。计算多台站震源深度,发现其平均值与黑龙江地震台网采用HypoSat方法测定的震源深度结果基本一致,仅3个地震的误差较大。分析认为,采用sPn震相方法测定黑龙江地区近震的震源深度准确度较高,可为日常跟踪分析工作提供依据。 相似文献
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以河北台网记录到的地震数据为基础,根据sPn震相所具有的特征对该震相进行精确识别,计算出2001年以来河北地震台网记录的2个代表性地震的震源深度,为了得到更加准确的震源深度,采用sPn震相计算出多个台站震源深度的平均值,将结果与中国地震台网中心给出的震源深度进行比对,2个地震的震源深度误差均比较小,说明该方法在日常工作中可以得到应用,为地震科研工作提供有利的依据. 相似文献
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所谓PKP的前驱波,即位于核震相PKIKP之前的一个波列,其振幅较弱,并且在震中距离为125~0～143~0间普遍能观测到.首先观测到这个震相的是B.Gatenberg和C.F.Richter(1934).尔后,随着地震记录技术的改进,许多地震学家对这个震相进行了精确的分析和认真的研究.我国地震台网对于发生在中美洲的危地马拉、巴拿马一带的大地震,往往能记录到发育较好的PKP的前驱波,如图1、2所示.由此可见,PKP的前驱波作为出现在地震图上的一个震相是勿容置疑的. 相似文献
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《内陆地震》2021,(3)
选取2014年1月～2019年3月M_S≥4.0的新疆地震台网速报地震,通过标注初至震相Pg、Pn震相,对震中位置达到最大包围后,再标注续至震相Sg、Sn震相,分析增加Sg、Sn震相对新疆及相邻地区速报地震定位的影响。结果表明:网内地震,除了西昆仑和阿尔金山地区,新疆其他地区均可只标注Pg、Pn震相定位震中位置,且与中国地震台网中心统一目录的震中偏差不超过10 km;西昆仑及阿尔金山地区,标注3～5个Sg、Sn震相时,最接近中国地震台网统一目录的结果。网缘或网外地震,在最大空隙角超过180°时,就可能会出现震中反向。当出现震中反向结果时,标注Sg、Sn震相≥3个时,就能避免震中反向。当Sg、Sn震相标注3～7个时,与中国地震台网中心统一目录结果最接近。 相似文献
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通过对中国数字地震仪台网(CDSN)11个台1993—2012年间30个极远震记录的分析,识别出了PKP波入射到内外核界面(ICB)上的衍射波PKPdif波。PKPdif波在震中距120°左右时出现在PKIKP波之前,在震中距150°以后出现在PKIKP波之后,是一个长周期波。为了解释PKPdif波超前于PKIKP波的原因,设想在距地面约5 156.1～5 372.2 km的深度,即内外核界面下有可能存在一个PKIKP波的低速层(厚度约216.1 km)。该设想符合Jeffreys速度模型,给出的PKPdif波在震中距119.4°～176.1°间的走时表填补了目前使用的《IASPEI1991地震波走时表》的空白。讨论PKPdif波的运动学特征有助于对内外核界面物理性质的认识,有助于提高分析震相的水平和积累震相分析经验。 相似文献
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成都遥测台网速报和极远震的难点及对策 总被引：1，自引：1，他引：0
苏国君 《地震地磁观测与研究》1999,20(2):107-110
中国地震局要求各遥测台网速报７级以上的极远震。可是,成都遥测台网以短周期的速度量和位移量记录为主,只有两套千倍级电容延长周期的中长周期地震仪,没有各基准台为分析处理远震,极远震而配备的７６３地震仪。因此,速报极远震一直是成都遥测台网速报工作中的一个困... 相似文献
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The determination of the coefficient of viscosity of eruptive products gives useful elements to the knowledge of possible variations of composition and physical conditions of the magmas. 相似文献
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As is known, the secular deceleration of the Earth's diurnal rotation is explained mainly by the tidal friction in the ocean. Below we consider this mechanism in some detail, taking into account also elastic deformations of the mantle under the action of ocean loading and the interaction between the tide-generating body, ocean tidal wave, liquid outer core, and solid inner core. It is shown that elastic displacements of the core-mantle boundary under the action of ocean loading are of about the same amplitude and phase as the elastic loading displacements of the Earth's outer surface. As a result, side by side with the mechanism of secular deceleration of diurnal rotation of the mantle, there are also (1) the opposite mechanism of secular acceleration of diurnal rotation of the outer liquid core and of the solid inner core and (2) the mechanism of excitation of differential rotation in the liquid core. Taking these effects into account, we compare theoretical and modern observed data on the eastward drift of the solid inner core. It is shown that the best agreement may be obtained if the turbulent viscosity of the liquid core is about 2 × 10
3
Poise 相似文献
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The nutations of the planets Mars andEarth are investigated and compared. Alarge number of interior structureparameters are involved in the nutationcomputations. The comparison between the observations and the computationsprovides several constraints on these parmeters andtherefore allows a better understanding of the physics of the interior of theplanet. For the Earth, the high precision of the observations of the nutationshas led to a very good determination of interior properties of the planet. ForMars, observations of nutations are not yet available, and we review how theamplitude of the Martian nutations depends on the hypotheses consideredfor its interior. Although Mars is very similar to the Earth, its interior is not well known;for example, we don't knowif its core is liquid or solid. Only if the core is liquid,the Free Core Nutation (FCN) normal mode exists and can alter the nutationswhich are close to the resonance. From the observed geoids, it is known thatboth planets are not in hydrostatic equilibrium. The departure is larger forMars than for the Earth, and consequently, the implication of considering a convective mantle instead of a mantle in hydrostatic equilibrium described byClairaut's equation for the initial equilibrium state of the planet is largeron the Martian nutations than on the Earth nutations. The consequences of theuncertainty in the core dimensions are also examined and shown to be of a veryhigh influence for Mars if the core is liquid, due to the potential changes inthe FCN resonance. The influence of the presence of an inner core, which isknown to exist for the Earth, could be more important for Mars than for theEarth if the inner core is large. Due to the presence of Tharsis on Mars, thetriaxiality of this planet has, additionally, larger effects than on Earth. 相似文献
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Studia Geophysica et Geodaetica - 相似文献
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地震激励下处于深水中的桥墩和周围水体的相互作用将对桥梁结构的动力响应产生较大影响。首先对地震作用下水-桥墩的相互作用理论做了概括,给出了动水压力对桥墩的作用效应及各自的适用范围;对主要的三种考虑流固耦合效应的分析方法做了对比,探讨了地震作用下影响水-结构相互作用的主要因素,并对今后的研究提出了建议。 相似文献
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Geomagnetism and Aeronomy - The magnetic evolution of the active region of the Sun at the level of the photosphere has been studied. Magnetic synoptic maps of the 2007 Kitt Peak Observatory were... 相似文献
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V. E. Pavlov T. Yu. Tolmacheva R. V. Veselovskiy A. V. Latyshev A. M. Fetisova I. V. Bigun 《Izvestiya Physics of the Solid Earth》2017,53(5):702-713
Until recently, the existing data prevented the geophysicists from accurately dating the Bysy-Yuryakh stratum, which outcrops in the middle reach of the Kotuy River, constraining the time of its formation to a wide interval from the end of the Late Cambrian to the beginning of the Silurian. The obtained paleomagnetic data unambiguously correlate the Bysy-Yuryakh stratum to the Nyaian regional stage and constrain its formation, at least a considerable part of it, by the Tremadocian. This result perfectly agrees with the data on the Bysy-Yuryakh conodonts studied in this work and yields a spectacular example of the successful application of paleomagnetic studies in solving important tasks of stratigraphy and, correspondingly, petroleum geology. Within the Bysy-Yuryakh stratum, we revealed a large normal-polarity interval corresponding to the long (>1 Ma) period when the geomagnetic reversals were absent. This result, in combination with the data for the Tremadocian and Middle–Upper Cambrian sequences of the other regions, indicates that (1) the rate of occurrence of the geomagnetic reversals on the eve of the Ordovician Moyero superchron of reversed polarity was at most one reversal per Ma; (2) the superchron does not switch on instantaneously but is preceded by a certain gradual change in the operation conditions of the dynamo mechanism which, inter alia, manifests itself by the reduction of the frequency of geomagnetic reversals with the approach of the superchron. This finding supports the views according to which a process preparing the establishment of the superchrons takes place at the core–mantle boundary. 相似文献
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Ivanka Jakubcová Věra Marvanová Miloš Pick Antonín Novotný Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1982,26(2):193-196
Summary The results of two different methods of the determination of the non-linearity of the gravimeter scale are compared; the economy is discussed as well. 相似文献