共查询到19条相似文献,搜索用时 62 毫秒
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华北地区震前断层水平异常活动特征 总被引:4,自引:1,他引:3
分析了首都圈及邻近地区跨断层基线测量资料, 研究了唐山、大同及张北地震前后断层水平异常活动特征。结果表明, 震前在震中外围存在显著的断层水平异常活动, 监测断层水平活动是地震预测的有效手段; 同一测点震前断层水平异常活动具有相似性特征; 唐山地震前在震中附近一定范围内出现的断层水平异常活动, 具有断层预位移性质。 相似文献
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本文对《中国震例》系列书籍及期刊所记录的华北地区存在震前跨断层形变异常的震例进行了综述, 分析了华北地区不同区域跨断层前兆异常特征。 首都圈地区3次6级以上地震之前1~3年, 围绕震中会出现10~30项跨断层形变异常, 其中超过8成异常场地位于距震中100 km范围以外, 有7~8成的异常测项表现为趋势的加速或转折变化, 异常幅度集中在1~3 mm, 在异常发展过程中或者在加速达到峰值后恢复过程中发震。 随着震级的降低, 近场跨断层异常增加, 对于5~6级左右地震, 无论远场近场均会出现2~8项水准异常, 而5级以下地震前跨断层形变异常只有1~2项且主要分布在近场。 相似文献
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用DDA模拟华北地区的无震断层滑动和断块形变 总被引:6,自引:0,他引:6
华北地区的地质构造具有典型的断块系统特征。用非连续形变分析(DDA)方法模拟了该地区的长期形变,包括无震断层滑动和断块形变。通过模拟我们发现:(1)断层沿不同方向的滑动通常与ENE-WSW向的区域构造挤压一致。(2)如果沿主要活动断层的平均无震滑动速度与跨断层大地测量观测的结果一样是每年零点几毫米的量级,那么断块内的典型应变速率是10^-8/a或更小量级,所以一些小区域的观测报告所得的应变率10^-6/a就不能代表该地区的形变速率。(3)对一条断层,由相邻断块内刚体旋转引起的断层滑动方向可能与区域构造挤压引起的滑动方向相反。但由于由构造挤压引起的滑动量级远大于由断块旋转引起的断层滑动,因此,一般来讲,断层滑动图像总体上与这一地区构造挤压方向一致,也就是说,由区域挤压引起的滑动控制了整个滑动情况。(4)根据(3),某些观测到的与ENE构造挤压方向相反的滑动可能是由某些更为局部化的因素引起的,没有构造意义。 相似文献
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本文介绍了1987年2月17日江苏射阳5.1级地震的基本参数及中期预报。通过对射阳5.1级地震前短临异常的初步总结,发现短临异常在时间分布上具有阶段性、同步性和相关性,空间分布呈现“多源”前兆场特征。据此,探讨了预报江苏及南黄海的中强地震的可能性。 相似文献
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研究了华北地区几次大震周围的较小区域内和较大区域内的b值变化.发现了较小区域内的b值随时间先升高后逐步降低,直至最低值,震前又有所回升才发震;较大区域内的b值随时间的变化,在大震前有个明显的峰值期,其峰值期的长短与大震震级有关. 另外,研究了b值从大震震中向外随区域扩展的变化,发现b值从震中向外有逐步增高的趋势.在大震震中附近有个低b值区域,其外围有个高b值区域. 相似文献
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从断层相互作用研究华北地区未来的地震危险性 总被引:1,自引:0,他引:1
从应力释放角度研究断层相互作用,采用合应力描述已发震断层对相邻活断层稳定性的影响。研究认为,合应力为正的地区,未来发震的可能性增大;反之,发震的可能性减小。对华北地区1966 ̄1977年发生的14次6级以上地震进行了预测效能检验。结果表明,合应力为正值的地区与后继强震的相关达75%。将研究结果应用于华北地区给出了该地区2005年前可能发生强震的危险区,为中长期地震预报提供依据。 相似文献
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IntroductionThe research on stress field interior the Earth is an either relative old or young branch of geoscience. Early in the 20th century, in order to learn the state of inner stress field, a few scholars had used simple ideal model to analyze big scale tectonic conformations and activities according to tide, gravity, rotation and inner thermal materials. So far, lots of problems on the state of the Earth stress field have not been solved completely yet. The origin of stress field, the d… 相似文献
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By analyzing the relationship between ground water behavior and strong seismic activity during the past more than 20 years
in North China, we have found similar water level descending variation of a part of wells in the short-term stage before several
strong earthquakes. The characteristics of anomaly are: at the beginning, water level dropped abruptly or accelerated to drop;
then it turned to slow rising with a smaller amplitude than that of descending; earthquakes occurred during the slow-rising
process of water level, and at that time or before earthquake occurrence, water level rose with a large amplitude. Among more
than 100 wells in North China, the descending anomalies were not recorded for many times, but similar variation processes
of water level were noted at different wells before several strong earthquakes, which proves that seismic precursory anomalies
of ground water are of certain recurrence features, occurring repeatedly before different strong earthquakes. Therefore, it
is necessary to study the genesis of this type of anomaly and its relationship with strong seismic activity.
Foundation item: Key project of Ministry of Science and Technology during the Tenth Five-year Plan (2001BA601B 01-01-01). 相似文献
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Introduction The behavior of ground water is influenced by many factors, such as rainfall, exploitation ofground water, atmospheric pressure, tidal gravitation, ground stress variation, effect of surfacewater-body loads (or other loads) and other unknown factors. These factors change the dynamicstate of ground water to different extents and result in the diversification of ground water behavior.As for their mechanism, our knowledge is still superficial. Based on various images of water le… 相似文献
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Yang Guohua 《中国地震研究》2004,18(2):114-124
Based on high-precision data obtained in the past decade from GPS re-measurement in the North China Network, the Crustal Movement Observation Network of China (CMONOC) and GPS measurement along the Shanxi graben zone, the status and evolution of horizontal crustal movement in the North China region are analyzed. The results show that (1) the Yanshan tectonic zone (Zhangjiakou-Bohai Sea zone)is an active one with the largest horizontal strain in the North China region; The largest tendency differential movement of adjacent blocks is seen between the Yanshan block and the North China plain block; about 2mm/a (left lateral) ; (2)The significant horizontal differential movement along the boundaries of the North China region is characterized by right-lateral strike-slip movement at the middle-north segment on its west boundary (composed of Yinchuan and other active tectonic zones) and compressive movement at the south segment; while the Yinshan rift zone located along the west segment on its north boundary is dominated by tensile movement. Other boundaries and zones have no obvious differential movement; (3) On the whole, measurements of each period differ from one another, which might result from the nonlinear movement component as well as from the error effect. In the paper, results of the relative movement and strain in different periods are given for different blocks and boundary zones. 相似文献
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华北地区地震活动图象反映的地震构造特征 总被引:5,自引:0,他引:5
本文主要依据国家地震局分析预报中心出版的1:600万《中国地震震中分布图(M_L≥2,1970—1989)》,对华北地区地震活动基本图象进行了构造解释。由获取的中上地壳构造信息发现,本区具有清楚的共轭地震构造特征。并且指出,华北平原拗陷区的深、浅构造具有某些不协调特征。 相似文献
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本文根据地震和地震构造等资料,研究华北地区公元1300年以来MS≥6.5级地震的发震断裂的基本参数.利用1966年以来隆尧、海城、渤海和唐山等有仪器记录的地震的相关参数进行回归分析得出了地震烈度Ⅷ度区长轴长度与余震区长轴长度的回归关系式及震级与震源体破裂长度的回归关系式.用余震区长轴长度代替震源体的破裂长度,从而给出各次地震的震源断层破裂长度.利用地震测深的地壳结构构造剖面、地震序列的震源分布、壳内低速层和地壳上部的构造、盆地构造与居里面分布和已知地震震源分布等资料推断了震源破裂的上下界.基于一定的合理假定推导出了断层滑动角的估计方法,并应用于本研究区,得出了各次事件的断层滑动角. 相似文献
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