共查询到20条相似文献，搜索用时 132 毫秒
1.
地表的断裂分布具有复杂的几何结构,分形几何学是定量研究断裂的复杂性和破碎性的一种数学方法。利用分维的方法,在比例尺为1:20万的安宁河断裂北段(西昌以北)的断裂分布图上,对断裂带各段的长度进行了测量,得到了各段的分形维值。测量结果冕宁大桥附近还有较大的维数(D_0=1.42),断裂北端维数值则相对较低(D_0=1.15),礼州一带和大桥一带相近(D_0=1.39)。作为断裂带的一个特征参数,分形维值与断裂带的力学性质、断裂运动、地震活动等有密切的关系。不同的力学环境中形成的断裂段有着不同的 D_0值:逆冲为主的断裂段 D_0值较低。在复杂断层背景上发展起来的活动走滑断层段有较高的 D_0值。 相似文献
2.
通过对中国大陆及青藏高原、新疆、华北和东北各构造区的地震活动性的分析,论证了区域地震活动是一种自组织临界现象.利用分形理论中的粗视化网格法,研究了中国大陆以及各构造区断层系的分形特点和分形结构的跨尺度特征.开展了组构具有分形特点的沙堆模型实验.结合断裂力学理论,认为地震的自组织临界现象源于分形几何断层系的自组织临界性动力学过程,地震分维数和断层系分维数之间存在着一种正相关关系,明确了断层系分形和地震活动性分形之间的因果关系.在此基础上,提出了系统组构的分形是系统输出能量的分形的根源的观点,并进一步利用已有的观测资料进行了分析.最后,基于这个观点和区域断层分布可以通过常规的航卫片分析、地面调查和地质勘探等手段确定的事实,提出了利用断层的分维数与地震的分维数的相关关系,对区域地震的概率分布特征进行估计的观点,可为地震的预测预报提供参考. 相似文献
3.
本文利用box—Counting法讨论了新疆各主要断裂带的几何分形,得出了各断裂带的分维值。结合区域构造及地震活动性特点,分析讨论了断层分形几何学在判定强震危险区方面的应用前景。结果表明,相应于较大的断层分维数,则对应于较强的地震活动水平;相应于较小的断层分维值,则对应于较弱的地震活动水平。一方面,断裂分维值较高的断裂带,其构造也较复杂。因而,断层分维有可能作为判定活动断裂带地震活动水平的一种特征物理量。 相似文献
4.
5.
昌马断裂带的分维几何学特征 总被引：1，自引：0，他引：1
1.前言美国地震学者P.G.Okubo等人(1987)在帕克菲尔德—索尔顿湖长达近千公里的圣安德烈斯断裂带上,分六段对该断裂进行了分维解析,发现该断层具明显的分维结构,计算出六段的分维数为:1.12～1.43。研究结果表明,较大的分维数D值与断裂带上断层几何形态复杂的地段相对应,同时这些地段又是历史强震区。在国内,断层分维几何学研究也 相似文献
6.
7.
大地震活动的模糊时间分维特征 总被引：4，自引：0，他引：4
本文首先简要介绍了模糊分维的概念与确定方法。然后以中国华北、川滇、甘宁青地区,日本伊豆和日本海地区以及美国加利福尼亚地区的地震活动时间分布为例,研究了大地震活动的模糊时间分维特征,并用模糊分维划分强震活动的高潮期和探索强震前的中长期测震学前兆异常指标。结果表明,模糊分维数D_0呈趋势上升的时期为强震活动的高潮期;此外,据D_0随时间的变化曲线可以发现一些大地震前数年D_0先下降而后回升的中长期前兆异常变化。本文还研究了模糊集“大地震”的λ-截集的分维数D_0(λ),具体取λ=0.65和λ=0.8,并与模糊分维数D_0进行了对比分析。结果表明,D_0(λ)与D_0的总变化趋势相近,但一般说来D_0的应用效果更好。 相似文献
8.
从分形几何的新视角出发,分析近断层地震动的不规则性和复杂性.利用盒维数法计算了来自台湾集集地震和美国北岭地震的30条近断层地震动加速度时程的分形维数.计算结果表明,这些地震动加速度时程具有统计分形特征.近断层地震动运动特征对其分维数影响明显,滑冲效应脉冲地震动的分维数平均值最小,向前方向性效应脉冲地震动的分维数平均值居中,无脉冲地震动的分维数平均值最大,其波形不规则程度也最高.而且,地震动时程的分维数反映了其频谱特性,可作为频谱周期的表征参数.地震动的分维数D与特征周期Tc具有较强的负相关关系.最后,对于近断层地震动作用下单自由度(SDOF)体系的弹性和非弹性动力反应时程,应用盒维数法计算了其分形维数,考察了其分形性质. 相似文献
9.
本文提出形成地震序列的多分形断层模型并利用分形分维理论讨论该模型及其序列。给出本模型的震级—频度关系、余震序列中强余震预报公式和多分维D_q—q关系式,探讨了利用多分维预报地震的有效性。 相似文献
10.
断层系、地震及其关系的分形研究——以中国为例 总被引：3，自引：0，他引：3
运用分形理论以中国为例对断层系、地震及其关系进行了分形研究,探讨了断层系分维值D和地震活动分维值D的意义,并根据D,D的差异进行了断层系、地震综合关系的研究. 相似文献
11.
Yebang Xu 《地震科学（英文版）》1992,5(2):389-398
The research of the information dimension (D 1) in an active fault zone considers the contribution of each seismic event to information and reflects the characteristics of the temporal and spatial distributions of earthquakes from a new point of view, avoiding some short-comings of the research about the capacity dimension (D 0). The results of calculation show that the information dimension of the temporal distribution in Xianshuihe active fault zone before Luhuo large earthquake isD 1=0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions of the temporal distribution of the earthquakes in Anninghe active fault zone are respectivelyD 1(t N)=0.1363 (for the north section) andD 1(t S)=0.06710 (for the south section). The information dimensions of the spatial distribution are respectivelyD 1(K N)=1.053 (for the north section) andD 1(K S)=0.7758 (for the south section). The north section and the south section belong to two self-similar systems with different information dimensions respectively. The extent of the self-organization of seismic activity in the south section is higher than that in the north section. This is helpful for us to judge the major dangerous section in the key region of the seismic monitoring. The research about the information dimension of the temporal and the spatial distributions of earthquakes is significant for the exploration of active fault zones and seismic prediction. 相似文献
12.
In this paper we show evidences of the fractal nature of the 3-D inhomogeneities in the lithosphere from the study of seismic wave scattering and discuss the relation between the fractal dimension of the 3-D inhomogeneities and that of the fault surfaces. Two methods are introduced to measure the inhomogeneity spectrum of a random medium: 1. the coda excitation spectrum method, and 2. the method of measuring the frequency dependence of scattering attenuation. The fractal dimension can be obtained from the inhomogeneity spectrum of the medium. The coda excitation method is applied to the Hindu-Kush data. Based on the observed coda excitation spectra (for frequencies 1–25 Hz) and the past observations on the frequency dependence of scattering attenuation, we infer that the lithospheric inhomogeneities are multiple scaled and can be modeled as a bandlimited fractal random medium (BLFRM) with an outer scale of about 1 km. The fractal dimension of the 3-D inhomogeneities isD
3=31/2–32/3, which corresponds to a scaling exponent (Hurst number)H=1/2–1/3. The corresponding 1-D inhomogeneity spectra obey the power law with a powerp=2H+1=2–5/3. The intersection between the earth surface and the isostrength surface of the 3-D inhomogeneities will have fractal dimensionD
1=1.5–1.67. If we consider the earthquake fault surface as developed from the isosurface of the 3-D inhomogeneities and smoothed by the rupture dynamics, the fractal dimension of the fault trace on the surface must be smaller thanD
1, in agreement with recent measurements of fractal dimension along the San Andreas fault. 相似文献
13.
Fractal dimension of fault systems in Japan: Fractal structure in rock fracture geometry at various scales 总被引：18，自引：0，他引：18
Takayuki Hirata 《Pure and Applied Geophysics》1989,131(1-2):157-170
Based on fault maps, whether or not the fracture geometry of rocks is self-similar, was examined by using a box-counting algorithm. The statistical self-similarity (fractal structure) of the fault fracture systems holds well at the scale of about 2 to 20 km. The fractal dimension in Japan varied from 1.05 to 1.60. The fractal dimension is about 1.5–1.6 at the central part of the Japan Arc, and decreases with distance from the center. At a smaller scale, the fractal structure also holds well in the rock fracture geometry. The fractal dimension of the North Izu Peninsula fault system (branching faults) is 1.49 at the scale of 0.625 to 10 km, the fractal dimension of rock fracture geometry at the scale order of 10–1 to 10–2 meters is about 1.49–1.61. The upper limit of the fractal dimension of rock fracture geometry is about 1.6, judging from the estimation of fractal dimension on actual fracture geometry of rocks. This value may impose a restraint on modeling of faulting and the fracture process of rocks. 相似文献
14.
Yebang Xu 《地震学报(英文版)》1992,5(2):389-398
The research of the information dimension (D
1) in an active fault zone considers the contribution of each seismic event to information and reflects the characteristics
of the temporal and spatial distributions of earthquakes from a new point of view, avoiding some short-comings of the research
about the capacity dimension (D
0). The results of calculation show that the information dimension of the temporal distribution in Xianshuihe active fault
zone before Luhuo large earthquake isD
1=0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions of the temporal
distribution of the earthquakes in Anninghe active fault zone are respectivelyD
1(t
N)=0.1363 (for the north section) andD
1(t
S)=0.06710 (for the south section). The information dimensions of the spatial distribution are respectivelyD
1(K
N)=1.053 (for the north section) andD
1(K
S)=0.7758 (for the south section). The north section and the south section belong to two self-similar systems with different
information dimensions respectively. The extent of the self-organization of seismic activity in the south section is higher
than that in the north section. This is helpful for us to judge the major dangerous section in the key region of the seismic
monitoring. The research about the information dimension of the temporal and the spatial distributions of earthquakes is significant
for the exploration of active fault zones and seismic prediction.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 372–379, 1991.
This paper is sponsored by the Chinese Joint Seismological Science Foundation. The English version is improved by Zhenwen
An. 相似文献
15.
Characterization of Fault Zones 总被引：8，自引：0，他引：8
— There are currently three major competing views on the essential geometrical, mechanical, and mathematical nature of faults. The standard view is that faults are (possibly segmented and heterogeneous) Euclidean zones in a continuum solid. The continuum-Euclidean view is supported by seismic, gravity, and electromagnetic imaging studies; by successful modeling of observed seismic radiation, geodetic data, and changes in seismicity patterns; by detailed field studies of earthquake rupture zones and exhumed faults; and by recent high resolution hypocenter distributions along several faults. The second view focuses on granular aspects of fault structures and deformation fields. The granular view is supported by observations of rock particles in fault zone gouge; by studies of block rotations and the mosaic structure of the lithosphere (which includes the overall geometry of plate tectonics); by concentration of deformation signals along block boundaries; by correlation of seismicity patterns on scales several times larger than those compatible with a continuum framework; and by strongly heterogeneous wave propagation effects on the earth's surface. The third view is that faults are fractal objects with rough surfaces and branching geometry. The fractal view is supported by some statistical analysis of regional hypocenter locations; by long-range correlation of various measurements in geophysical boreholes; by the fact that observed power-law statistics of earthquakes are compatible with an underlying scale-invariant geometrical structure; by geometrical analysis of fault traces at the earth's surface; and by measurements of joint and fault surfaces topography.¶There are several overlaps between expected phenomenology in continuum-Euclidean, granular, and fractal frameworks of crustal deformation. As examples, highly heterogeneous seismic wavefields can be generated by granular media, by fractal structures, and by ground motion amplification around and scattering from an ensemble of Euclidean fault zones. A hierarchical granular structure may have fractal geometry. Power-law statistics of earthquakes can be generated by slip on one or more heterogeneous planar faults, by a fractal collection of faults, and by deformation of granular material. Each of the three frameworks can produce complex spatio-temporal patterns of earthquakes and faults. At present the existing data cannot distinguish unequivocally between the three different views on the nature of fault zones or determine their scale of relevance. However, in each observational category, the highest resolution results associated with mature large-displacement faults are compatible with the standard continuum-Euclidean framework. This can be explained by a positive feedback mechanism associated with strain weakening rheology and localization, which attracts the long-term evolution of faults toward progressive regularization and Euclidean geometry. A negative feedback mechanism associated with strain hardening during initial deformation phases and around persisting geometrical irregularities and conjugate sets of faults generates new fractures and granularity at different scales. We conclude that long-term deformation in the crust, including many aspects of the observed spatio-temporal complexity of earthquakes and faults, may be explained to first order within the continuum-Euclidean framework. 相似文献
16.
《Earth and Planetary Science Letters》2007,253(3-4):429-438
Slip and length measurements on earthquakes suggest large stress drop variability. We analyze an extended set of slip-length measurements for large earthquakes (M ≥ 6) to seek for the possible origin(s) of this apparent variability. We propose that such variability arises from earthquakes breaking a variable number of major fault segments. That number depends on the strength of the inter-segment zones, which itself depends on the structural maturity of the faults. We propose new Dmax–L parameterizations based on that idea of multiple segment-ruptures. In such parameterizations, each broken segment roughly scales as a crack, while the total multi-segment rupture does not. Stress drop on individual segments is roughly constant, only varying between 3.5 to 9 MPa. The slight variation that is still observed depends on fault structural maturity; more mature faults have lower stress drops than immature ones. The new Dmax–L functions that we propose reduce uncertainties with respect to available relationships. They thus provide a more solid basis to estimate seismic hazard by integrating fault properties revealed by geological studies. 相似文献
17.
Fractal research of fault gouge 总被引：1，自引：0，他引：1
ＦｒａｃｔａｌｒｅｓｅａｒｃｈｏｆｆａｕｌｔｇｏｕｇｅＳＨＵＮ－ＭＥＩＳＨＡＯ（邵顺妹）ａｎｄＪＩＮ－ＣＨＡＮＧＺＯＵ（邹瑾敞）ＥａｒｔｈｑｕａｋｅＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｏｆＬａｎｚｈｏｕ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａ... 相似文献
18.
19.
Fractals in geology and geophysics 总被引：21，自引：0，他引：21
Donald L. Turcotte 《Pure and Applied Geophysics》1989,131(1-2):171-196
The definition of a fractal distribution is that the number of objectsN with a characteristic size greater thanr scales with the relationNr
–D. The frequency-size distributions for islands, earthquakes, fragments, ore deposits, and oil fields often satisfy this relation. Fractals were originally introduced by Mandelbrot to relate the length of a coastline to the length of the measuring stick. This application illustrates a fundamental aspect of fractal distributions, scale invariance. The requirement of an object to define a scale in photographs of many geological features is one indication of the wide applicability of scale invariance to geological problems, scale invariance can lead to fractal clustering. Geophysical spectra can also be related to fractals; these are self-affine fractals rather than self-similar fractals. Examples include the earth's topography and geoid. 相似文献