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1996年6~7月华北地区M_L≥3.0地震动态根据提供的资料,在华北地区(33.0~42.0°N,111.0~125.0°E)范围内,1996年6月份共发生ML≥3.0地震7次(见附表),无ML4以上地震发生。7月份共发生ML≥3.0地震6次(见附?.. 相似文献
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1994年8月华北M_L≥3.0地震动态1994年8月份在华北(33.0°─42.0°N,1111.0°─125.0°E)范围内共发生M_L≥3.0地震3次(见下表),无4级以上地震发生。本月华北地震活动水平偏低,三次地震全部发生在华北南部。山西和顺... 相似文献
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张北地震前地磁空间相关异常特征 总被引:2,自引:1,他引:1
应用地磁空间相关方法对华北地区1996年1月至1998年1月地磁核旋定点(北京时21h)观测数据的分析研究表明,1998年1月10日张北MS6.2地震和1996年5月3日内蒙古包头MS6.4地震前存在地磁空间相关低值异常。 相似文献
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马默斯莱克斯地区被更多的地震震动整个上周末一连串小地震震动了马默斯莱克斯地区,使地震学家提高了警惕,但科学家说也许没有即刻的危险。从星期五(1996年3月29日)开始,这个地区遭到了17次3级和3级以上地震的袭击。该震群最大的一次地震是4.3级,该地... 相似文献
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采用地磁加卸载响应比方法,对云南地区的数字化地磁垂直分量(W)日变幅值进行计算,研究2009年1月-2013年3月以来云南地区发生的8组MS≥5.0地震前的异常变化。结果显示,加卸载响应比值出现高值异常对云南地区短期内发生MS5.0以上地震有一定指示意义,尤其是MS5.5以上地震,对应效果较好。 相似文献
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《Advances in water resources》2005,28(7):701-710
The patterns of temporal variations of precipitation (P), streamflow (SF) and baseflow (BF) as well as their nitrate-nitrogen (nitrate) concentrations (C) and loads (L) from a long-term record (28 years) in the Raccoon River, Iowa, were analyzed using variogram and spectral analyses. The daily P is random but scaling may exist in the daily SF and BF with a possible break point in the scaling at about 18 days and 45 days, respectively. The nitrate concentrations and loads are shown to have a half-year cycle while daily P, SF, and BF have a one-year cycle. Furthermore, there may be a low-frequency cycle of 6–8 years in C. The power spectra of C and L in both SF and BF exhibit fractal 1/f scaling with two characteristic frequencies of half-year and one-year, and are fitted well with the spectrum of the gamma distribution. The nitrate input to SF and BF at the Raccoon watershed seems likely to be a white noise process superimposed on another process with a half-year and one-year cycle. 相似文献
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燕郊等测点迁移优化与地磁观测研究 总被引:1,自引:2,他引:1
为优化地磁观测条件,开展了燕郊、夏垫等测点迁移工作;按照测眯迁移原则与实施技术方案,完整地收集并整理了地质构造与地球物理等方面的基本资料;进行了野外实地勘察,磁场梯度的测量,确定了新测点,在新老测点上进行了较长时间的地磁场对比观测;应用多种方法分析研究了地磁对比观测资料,结果表明,新老测点与有关测点的地磁变化具有良好的一致性,并得到了新老测点之间的地磁数据的按点差。 相似文献
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We rederive and generalize hyperbolic moveout formulae for the common-midpoint (CMP) gather and for the zero-offset (ZO) section that can be efficiently used for macro-model-independent reflection imaging in two-dimensional media. The hyperbolic moveout formulae for the common-midpoint gather are obtained from different Taylor series expansions of a particular parametric moveout surface defined in the multicoverage data space. Such a moveout surface involves three kinematic wave-field attributes of two hypothetical waves, which have to be determined by a coherency analysis. By using hyperbolic moveout curves in the CMP gather and in the ZO section one can determine these attributes in two steps. The relationships between the local shapes of the interfaces and the attributes of the hypothetical wave-fields attributes are considered by means of geometrical optics. The determination of these attributes allows to perform a macro-model-independent ZO simulation and a subsequent inversion. 相似文献
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Vindell Hsu Charles E. Helsley Eduard Berg David A. Novelo-Casanova 《Pure and Applied Geophysics》1984,122(6):878-893
A close correlation in spatial distribution of local seismic activity and energy release patterns before and after the 1979 Petatlan, Mexico earthquake suggests heterogeneity within the fault plane of this major low-angle thrust event associated with subduction along the Middle America Trench. A simple two-asperity model is proposed to account for the complexity. Foreshocks and aftershocks of the neighboring 1981 Playa Azul earthquake showed a similar pattern. As both events occurred at the junction of the Orozco Fracture Zone and the Middle America Trench, we speculate that the observed complex fault plane is caused by subduction of the rugged ocean floor of the Orozco Fracture Zone. Short-term precursory seismicity prior to the Petatlan earthquake can be explained by using the asperity model and migration of a slip front from the south-east to the north-west across the main shock source region. 相似文献
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Summary This paper discusses the influence of system stiffness on the dynamic instability of fault surfaces under laboratory conditions for a number of test modes. In conjunction with shear load stiffness, the normal load stiffness, often neglected, is shown to have a considerable effect on the stick-slip process —its presence or absence and its characteristics. Also appropriate stiffnesses are suggested for an earthquake sequence modeled as a growing dislocation. 相似文献