共查询到19条相似文献，搜索用时 807 毫秒
1.
利用转换函数的方法对临汾台1988年1月至1998年12月地磁资料进行了计算处理，用所得到的转换函数A、B的模|A|、|B|及总方差δz的月变化，来考察地震前后地下电性结构的变化。对1988年以来发生在临汾台周边地区的3次Ms4.0以上地震前后临汾台地磁转换函数的变化情况进行了研究。结果表明：不同周期的转换函数A、B以及总方差δz在震前有明显变化。 相似文献
2.
分析了江苏新沂地震台的短水准、地电阻率两种前兆资料的变化情况，研究了其与郯庐断裂带南段地震活动的关系。结果表明，新沂台前兆资料的变化能发现郯庐断裂带南段的强烈活动，对该断裂带上3．0级以上的地震有一定程度的反映。 相似文献
3.
吴海军 《地震地磁观测与研究》2002,23(5):66-68
引言 德都台偏角分量（D）基线值的月均值自1995年以来，一直有这样一种趋势：每年的3～7月份有一明显下降的变化，且有一低点在上述月份内，低点的两端呈漏斗状分布。这样的变化趋势和满洲里台、长春台在形态上基本一致，仅在幅度上明显大一些。在使用基线值处理观测年报时，使我台偏角分量的日均值差值曲线在每年的1月～3月和10月～12月与满洲里台、长春台的变化有很大差别。在2000年评1999年资料时发现了这一问题，确认我台的资料在冬季加温不正常，并指出前几年的资料也可能有问题。经地磁组确认是绝对观测仪器受温度变化的影响造成的… 相似文献
4.
地磁月均值的长期变化结果表明，1994年台湾海峡7．3级地震前4年，泉州台与仑坪台的X和Z分量均出现异常，X分量呈现负异常，Z分量呈现正异常，异常幅度达20－30nT.另外，地震前一年半，泉州台与通海台的视深比或仑坪台与通海台的视深比（周期为24h)都出现过先降后升的异常变化。 相似文献
5.
2021年5月21日云南漾濞县发生M_S6.4地震、5月22日青海玛多县发生M_S7.4地震,分别分析漾濞震中500 km内12个地电场台数据、玛多震中500 km内8个地电场台数据,获知:(1)漾濞地震周围罗茨等8台优势方位角在震前出现了异常变化,弥渡等4台看不出明显异常变化;盐源等7台相关系数在震前2～6个月出现了大幅度下降,元谋、苴林等5台相关系数看不出明显异常变化。(2)玛多地震周围门源等4台方位角在震前出现了异常变化,都兰等4台方位角看不出明显异常变化;门源等5台在玛多地震前2～6个月相关系数出现了大幅下降、变化范围明显变窄等现象,都兰、白水河、金银滩等3台优势方位角和相关系数都看不出明显异常变化。(3)两次地震分析中地电场优势方位角和相关系数异常变化在时间上皆具有同步或准同步性。 相似文献
6.
陈伯舫 《地震地磁观测与研究》2002,23(5):6-8
从太平洋4台的分析显示，APIA，GUAM和PAMATAI台Z分量的太阳黑子周变化与HONOLULU台的相位相反。可是，CANBERRA台的变化又和HONOLULU台同相。这种表现复杂的地方性差异，更反映出太阳黑子周变化源于外场之说的有问题的。 相似文献
7.
2001－03－09蒙城地震台地磁磁变仪CB－3（观测仪，备份仪）同时出现三个分量动线的跳动，分析表明蒙城地震台地磁总强度F，垂直强度Z发生变化，其原因可能是强电流作用下，地下介质电性变化所致。 相似文献
8.
本文利用北京地区的北京台（BJI）和北京十三陵台（BMT）的地磁场X、Y和Z分量时均值数据，研究了1960年至2013年期间该地区地磁场Sq强度的季节变化和长期变化.结果表明：（1）BJI台和BMT台的地磁场Sq不仅变幅相近，而且具有一致的地方时变化、季节变化、太阳活动周变化和长期变化.（2）BJI台和BMT台Sq强度的逐月变化，其中ASq（X）主要表现为春秋增强而冬夏减弱的季节变化.ASq（Y）呈现出夏季增强的半年变化.ASq（Z）变化较为复杂.虽然在5月和9月出现减小，但是总体来看，其变化曲线也具有夏季增强的半年变化特征.同时，Sq强度与太阳活动F107指数之间存在明显的正相关关系，具有一致的11年太阳活动周变化和长期变化，反映出了Sq与太阳活动之间的密切关系.（3）BJI台和BMT台Sq强度差值dASq表明，在大多数年份，两个台站的Sq强度之差一般不超过±2 nT，同时没有明显的季节或年周期变化特征.在2000年和2001年太阳活动高年，dASq出现显著增强，最大可达12.3 nT.反映出了北京地区Sq场强度梯度的剧烈扰动与太阳活动之间的密切关系，意味着在太阳活动高年，Sq电离层发电机电流的局部结构可能发生了明显的改变. 相似文献
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10.
应用差分法分析了新沂台与射阳台地磁垂直分量Z的变化，以加卸载响应比方法研究地磁场极值的变化，对这两台资料进行相关分析，研究发现，在中强震前新沂台的地磁场存在明显的异常变化。 相似文献
11.
利用球冠谐分析法对2009年我国35个绝对观测地磁台站的Sq太阳静日变化进行内外源场分离,反演得到三个劳埃德季节(冬季D,分点E,夏季J)相应的内、外源等效电流体系,结果表明Sq外源电流体系在该区域D、E、J三个季节的电流涡中心强度分别为56.2 kA、137.7 kA、137.9 kA,电流涡中心位置的地方时由冬季的1124LT前移至夏季的约1030LT;Sq内源电流体系在该区域D、E、J三个季节的电流涡中心强度分别为21.1 kA、63.4 kA、72.7 kA,电流涡中心位置的地方时由冬季的1100LT前移至夏季的约1000LT. 相似文献
12.
2000年Jerk存在吗 总被引：2，自引：0，他引：2
陈伯舫 《地震地磁观测与研究》2006,27(5):50-52
从分布在欧亚美太平洋几个质量较好的台站的dY/dt变化曲线看,2000年或2001年似乎没出现新的Jerk(Y)。 相似文献
13.
Wallace H. Campbell 《Pure and Applied Geophysics》1987,125(2-3):427-457
The electrical conductivity of the Earth's upper mantle can be inferred from geomagnetic quiet-day,Sq, variations recorded at the world's observatories using the, coefficients of a spherical harmonic analysis (SHA) that separate the external (source) and internal (induced) parts of the surface field. The conductivity profile determined from such an analysis can be sensitive to special characteristics of the quiet field itself as well as the separation techniques employed. This review of the Sq-analysis features critical to a conductivity derivation is pictorially presented along with the equations for application of theSchmucker (1970) technique to theSHA coefficients for a conductivity determination. Three examples illustrate the use of these equations with differentSq models. 相似文献
14.
S. S. Starjinsky 《Geomagnetism and Aeronomy》2008,48(2):265-276
Results of studying the lunar daily geomagnetic variations in the spectral and time regions at the network of observatories are presented. The seasonal variations in the amplitudes of the fundamental harmonic constituents of three lunar variation components have been revealed. The seasonal time variations have been analyzed using the digital bandpass filtering and harmonic synthesis based on the data of the Kakioka and Memambetsu geomagnetic observatories. The 11-year solar cycle and annual and semiannual periods have been distinguished in the seasonal variation spectrum. Studying the spectral singularities of the lunar daily variation at these observatories and the sea level variations in daytime and nighttime hours has made it possible to identify the contribution of the oceanic dynamo to the lunar variation vertical component. 相似文献
15.
An inspection of the long-term behaviour of the range of the daily geomagnetic field variation from comprehensive modelling 总被引：1，自引：0，他引：1
J. Miquel Torta Luis R. Gaya-Piqu Juan J. Curto David Altadill 《Journal of Atmospheric and Solar》2009,71(13):1497-1510
This paper attempts to reveal whether long-term trends in the ionosphere are reflected in the amplitude range of the geomagnetic daily variation recorded at ground level. The smooth and regular variation observed in the magnetograms on magnetically quiet days is induced by the ionospheric currents flowing in the dynamo region. So it is likely that trends in the conductivity or in the dynamics of this region could produce changes in the current densities, and consequently in the range of the geomagnetic variation. The crucial aspect is how to separate the changes produced by the geomagnetic activity itself, or by secular changes of the Earth's magnetic field, from the part of the variation produced by factors affecting trends in the ionosphere, which could have an anthropogenic origin. To investigate this, we synthesized for several geomagnetic observatories the daily ranges of the geomagnetic field components with a comprehensive model of the quiet-time, near-Earth magnetic field, and finally we removed the synthetic values from the observed ranges at those observatories. This comprehensive model accounts for contributions from Earth's core, lithosphere, ionosphere, magnetosphere and coupling currents, and, additionally, accounts for influences of main field and solar activity variations on the ionosphere. Therefore, any trend remaining in the residuals, assuming that all the contributions mentioned above are properly described and thus removed by the comprehensive model, should reflect the influence of other sources. Results, based on series of magnetic data from observatories worldwide distributed, are presented. Trends in the X and Z components are misleading, since the current system changes in form as well as in intensity, producing changes of the focus latitude in the course of a solar cycle and from one cycle to another. Some differences exist between the long-term trends in the Y component between the real and modelled ranges, suggesting that other non-direct solar causes to the amplitude changes of the solar quiet geomagnetic variation should not be ruled out. Nevertheless, the results also reflect some short-comings in the way that the comprehensive modelling accounts for the influence of the solar activity on the range of the daily geomagnetic variation. 相似文献
16.
Variations of geomagnetic components X, Y, and Z recorded in 19 Intermagnet European observatories in 2004 were analysed. The original data from all observatories were preliminarily
processed. In the first step, periods longer than three hours were filtered out. In the second step, variations of vertical
geomagnetic component Z were separated into external and internal parts. We introduced a non-dimensional index η defined as the square root of a ratio of the energy of the external part of the vertical component to that of the horizontal
components. Maps of the surface distribution of a new magnetic index η for the area of Europe at selected time periods were created, and their time changes are presented. The time changes of η for selected observatories are also shown. Moreover, we discuss a very interesting phenomenon we discovered, that has never
been described in geophysical literature. Namely, in the recordings of all the observatories we noticed the presence of very
regular variations, observed almost exclusively in the vertical component Z, which is quite unusual. These regular variations occur in the form of sinusoidal “wave packets”. The amplitudes of these
variations do not depend on the geomagnetic latitude and appear in the records of all the observatories we analyzed. They
occur in quiet days, which suggests that their source is in the ionosphere. 相似文献
17.
18.
陈伯舫 《地震学报(英文版)》1994,7(3):457-464
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19.
D. R. Barraclough T. D. G. Clark S. W. H. Cowley F. H. Hibberd R. Hide D. J. Kerridge F. J. Lowes S. R. C. Malin T. Murphy H. Rishbeth S. K. Runcorn H. C. Soffel D. N. Stewart W. F. Stuart K. A. Whaler D. E. Winch 《Surveys in Geophysics》1992,13(1):47-88
A joint Discussion Meeting of the Royal Astronomical Society and the Royal Irish Academy, held on January 11th, 1991, commemorated the establishment of some early magnetic observatories, discussed recent research using global geomagnetic data and described the present status of magnetic observatories in the United Kingdom. The observatory and instruments at the Dublin magnetic observatory; the origins of the Greenwich magnetic observatory, and why it eventually had to be resited; and the history of the Munich magnetic observatory formed the historical part of the proceedings. Current research topics discussed were the geomagnetic secular variation and deep Earth structure and dynamics; fluid flow patterns near the top of the core; the origin of the annual variation of the geomagnetic field; results of an analysis of monthly means from some British observatories; a new theory of the geomagnetic daily variation; and the interactions between ionospheric science and geomagnetism. The present-day observatory scene was described in terms of the information that can be derived from the almost 40 year series of data from Hartland magnetic observatory; of the methods used to process data from the three UK magnetic observatories, which nowadays are operated automatically and remotely; and (a look into the future) of a new project, INTERMAGNET, which aims to make available, in near real time, data from the world-wide network of magnetic observatories. 相似文献