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101.
Ikeya Motoji 《中国地震研究》1998,(3)
We present an electromagnetic model of a fault using the piezoelectric effect and the elastic dislocation theory to investigate theoretically the spatial distribution of the stress-induced charges associated with faulting. The relevant seismic electric field associated with these induced charges can be estimated quantitatively. Therefore, this simple model would provide a solid framework for additional theoretical developments on the explanations of the anomalous seismoelectric signals. The spatial distribution of the stress-induced charges around a vertical rectangular fault showed complicated characteristics. The estimation of the electric field associated with the stress-induced charges during the 1995 Kobe earthquake was consistent with the previous investigation from some reported anomalous seismic phenomena. 相似文献
102.
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104.
On May 2, 1993 more than 200 seismic events from an underground mine in Tyrol/Austria were recorded with short-period seismometers of a local seismic network which was introduced in the late 1980s to monitor the tectonic seismicity in Tyrol in greater detail. The cause of this series of mining-associated events has become the subject of intensive investigations — as it was associated with a subsidence affecting an area of 10.000 m2. Underground observations revealed a number of discontinuities along which the rock mass was able to move. Seismic recordings of the close-by seismic stations revealed two types of mechanisms: One mechanism seems to be associated with pure block-sliding along several discontinuities, while other signals indicate additional collapse. The consideration and combination of several seismological principles made possible the construction of a model of the mine collapse. 相似文献
105.
洛川黄土序列时间标尺的初步建立 总被引:10,自引:0,他引:10
对厚140m的洛川坡头黄土剖面黄土层以5cm,古土壤层以3cm系统采样,全部样品进行了室内磁化率测量。以黄土序列磁化率变化作为古季风气候变化的代用指标,根据第四纪冰期的Milankovitch理论,利用轨道调缠绵的方法初步建立了洛川黄支的时间标尺。通过古地磁场倒转时间的检验以及与宝鸡黄土序列时间标尺对比,表明本文所论述的时间标尺适用于该地区古环境演化的研究。 相似文献
106.
本文简介了黄赤交角、偏心率、岁差等地球轨道三要素和米兰柯维奇理论。概述了第四纪及前第四纪沉积物中与地球轨道三要素有关的周期性沉积记录,指出对旋回沉积的研究,可望为地层划分与对比提供一个标尺。 相似文献
107.
M Okuda N van VugtT Nakagawa M IkeyaA Hayashida Y YasudaT Setoguchi 《Earth and Planetary Science Letters》2002,201(1):143-157
The Marathousa Member, Middle Pleistocene strata in the fluvio-lacustrine Megalopolis basin, southwest Greece, displays distinct but complicated lithological cycles comprising first-order alternation of lignites and detrital muds and second-order alternation expressed by frequent intercalation of organic layers. Palynological evidence indicates that the lithological cycles are driven by the Earth’s orbital forcing. All the lignite seams yield temperate oak forest whereas the detrital beds provide semi-arid steppe mainly of Artemisia. This means that the first-order lithological cycle represents the glacial/interglacial cycle (i.e., the 100-kyr eccentricity cycle), providing a timescale of at least 350 kyr to the Marathousa Member. Pollen also detects smaller-scale climate fluctuations in many of the subordinate organic layers, with the total number of fluctuations being five in a complete lignite-detritus couplet. This means that the second-order lithological cycle reflects the 21-kyr insolation cycle. A tentative phase relation between the lithological cycles and the astronomical cycles is shown based on palynostratigraphy and electron spin resonance dating. Lacustrine environments with increased water tables are implied for the glacial periods sedimentologically, in contrast to local swamp vegetation for the interglacial periods. The subordinate organic layers were formed under intermediate environments (climate, water depth, etc.) between full glacials and interglacials. 相似文献
108.
气候演变中的冰和碳 总被引:18,自引:0,他引:18
地质历史上充满着冰盖消长 (“暖室期”和“冰室期” ,“冰期”和“间冰期”)与大气CO2 增减的周期性变化 ,而两者之间的关系并不清楚。由于冰盖变化的地质标志比大气CO2 变化的标志容易认识 ,长期以来古气候研究侧重“冰” ,而对“碳”即碳循环的研究不足 ,通常将碳循环的变化解释为冰盖变化的结果。近年来越来越多的发现表明 ,单纯用水循环的物理过程不能解释冰盖演变的许多现象 ,而且大气CO2 变化往往领先于冰盖。揭示碳循环变化对冰盖演变的影响 ,认识生物地球化学过程在冰期旋回中的作用 ,将不同纬区对地球轨道驱动全球气候的影响区分开来 ,才有可能正确预测未来气候的演变方向。 相似文献
109.
Two linear-hysteretic-damping models that provide energy dissipation independent of the deformation frequency, are studied in this paper: a hysteretic Kelvin element and a hysteretic Maxwell element. Both models use the Hilbert transform and yield integro–differential equations for the equations of motion of structures when real-valued signals are utilized in the formulation. It is shown that the use of analytic (complex-valued) signals allows the transformation of these integro–differential equations into differential equations with analytic input signals and complex-valued coefficients. These differential equations show both stable and unstable poles. A technique for the solution of these differential equations is presented; it consists of a conventional modal decomposition of the state-space equations and the integration of the differential equations forward in time for the modal co-ordinates associated with stable poles, and backwards in time for the modal co-ordinates associated with unstable poles. Some numerical examples are presented to illustrate the characteristics of the models and the proposed analysis technique. 相似文献
110.
为了提高GPS软件接收机信号捕获的速度,提出了一种GPS卫星C/A码信号捕获的新方法(这种方法具有Gold码的性质)。并证明了多颗卫星信号的相关性可以在同一次相关性计算过程中同时处理完成,在一次捕获卫星信号过程中可同时捕获多颗卫星信号。 相似文献