关于bem>值应用于地震趋势预测的讨论

在地震趋势的估计中，使用b值和使用Hurst指数是两种常用的方法．本文从地震序列的分形几何的角度，指出这两种方法之间具有一定的相关性．从分数布朗运动的角度看，b＞3/4与b＜3/4的地震序列具有不同的动力学性质．      

Rescaled range (R/S) analysis on seismic activity parameters

IntroductionSeismicity analysis is an important branch of seismology, which focuses statistically on the study of time, space and magnitude distribution of a group of earthquakes (FU, 1997). Earthquakes as instability phenomena of the lithosphere, however, involve very complicated mechanics. The seismic activity level is not steady, but fluctuating time by time, which shows the alternative change of periods of quiescence and activity (FU, 1986; Mogi, 1984; ZHANG, 1987). Because of such com…     

Fractal Analysis of the Gray-Scale Intensity Data of Finely Laminated Sediments from Bainbridge Crater Lake, Galápagos

The gray-scale intensity data of finely laminated sediments from Bainbridge Crater Lake, Galápagos, were analyzed in terms of Hurst exponent and fractal dimension. The sediment record preserved in this volcanic maar provides a continuous history of past El Niño/Southern Oscillation (ENSO) events over the last 6200 years. Accelerator mass spectrometry radiocarbon data show that sedimentation rate was not constant for whole core. To take into consideration this fact gray-scale intensity data from analyses of X-radiography images of a 4.1 m long core from this basin were divided into Data 1 and Data 2. Data 1 corresponds to the more recent part of stratigraphic sequence, which was deposited since 3000 yr BP; Data 2 is from the earlier part of record between 6200 and 3000 yr BP. A persistent behavior with a Hurst exponent of H = 0.88 and H = 0.8 was found by power spectrum analysis method for Data 1 and Data 2, respectively. The width method of analysis shows that ENSO fluctuation before 3000 yr BP had a persistent behavior on a time-scale up to 26 years, while the more recent El Niño occurrences have a persistent behavior on a time-scale up to 5.6 years.     

Statistical self-affinity, fractal dimension, and geologic interpretation

Properties of statistical self-affinity are explored and explained. Semi-variogram analysis can be used for identifying statistical self-affine behavior. This is, however, not the only method available for such an analysis. Some error and interpretation is involved; therefore, estimating the Hurst dimension (and from this the fractal dimension) from the semi-variogram can be misleading. Simulations based on statistical self-affine properties are alternatively used to develop an empirical approach to assessing statistical self-affine behavior. Analyzing simulations using semi-variograms, and comparing these semi-variograms to those from actual data, offers an alternate and perhaps superior approach to the understanding of the statistical self-affine properties of a geologic phenomenon. This empirical approach offers a method of reverse modeling for verifying estimates of Hurst dimension from semi-variograms.     

R／S方法分形对大华北地区地震时间间隔的时空扫描

用R/S分析方法研究了大华北地区地震发生时间间隔的统计分形问题。对大华北地区18个3°×3°的地理分区1970年1月—1993年7月M_L≥2.5的地震发生时间,以相同的工作窗长(100个相邻地震时间间隔)沿时序滑动进行R/S方法分析计算。结果表明,对所工作的时空范围内的18个M_L≥5.5地震,有12个地震在震前0.5—4年Hurst指数H值出现下降、下降-持续低值或稍有回升的异常变化。     

Conditioned ranges for independent symmetric three valued inflows

The paper considers, as inputs to a storage system, independent random variablesX ₁,X ₂,... which have a symmetric three-valued distribution. Expressions are obtained for the conditional expected values of (i) the adjusted range ofX ₁,...X _n, conditioned on the eventX ₁+...+X _n=0; (ii) the Hurst range ofX ₁,...,X _n , conditioned on essentially the same event. Numerical comparisons of these two conditioned ranges show that they are close in value unless the inputs have high kurtosis.     

塔里木盆地三源河年径流过程的非线形特征

This paper attempted to identify fractal and chaotic characteristics of the annual runoff processes in headwaters of the Tarim River. Methods of fractal analyses were used to explore several aspects of the temporal changes from 1957 to 2002. The main findings are as follows: (1) The annual runoff processes of the three headwaters of the Tarim River are complex nonlinear systems with fractal as well as chaotic dynamics. (2) The correlation dimensions of attractor derived from the time series of the annual runoff for the Hotan, Yarkand and Aksu rivers are all greater than 3.0 and non-integral, implying that all three rivers are chaotic dynamical systems that are sensitive to initial conditions, and the dynamic modeling of their annual runoff process requires at least four independent variables. (3) The time series of annual runoff in each river presents a long-term correlation characteristic. The Hurst exponent for the period of 1989 to 2002 suggests that we may expect to see an increasing trend in the annual runoff of the Aksu and Yarkand rivers in the years after 2002, but a decreasing tendency for the Hotan River in the same period. Foundation: Knowledge Innovation Project of CAS, No.KZCX2-XB2-03; Major Direction of Knowledge Innovation Project of CAS, No.KZCX2-YW-127; Shanghai Academic Discipline Project (Human Geography), No.B410 Author: Xu Jianhua (1965–), specialized in geographical quantitative methods and GIS.     

Geophysical characterisation of Carlo's V Castle (Crotone, Italy)

The Carlo's V Castle, located in Crotone Town, on the Ionian coast of the Calabria Region (Italy), date back to the 13th century d.C. (Fig. 1). During its long life, the building changed several owners and sustained the damages and the consequent reconstructions due to the innumerable naval battles. Moreover, the castle suffered the action of the earthquakes which always afflict the region.With the principal aim of detecting the location, depth and geometry of the rests of destroyed structures, a systematic Ground Penetrating Radar (GPR) survey was carried out in the area inside the boundary walls. The results are sixty-two one-meter-spaced, filtered and migrated radargrams arranged in four 3D data-sets. From each data-set, the most significant time-slice was extracted.To reduce the ambiguity in the GPR data interpretation, additional geophysical techniques, such as Magnetic (M), and Electrical Resistivity Tomography (ERT), were carried out with a partial superimposition with the GPR data. A comparison and a joint interpretation amongst different geophysical data pointed out some very remarkable features associated to buried remains and possible buried cannonballs.With the secondary aim to check the presence of an old military walkway linking two bastions a GPR profile was carried out on the sea side boundary wall. The GPR results are in agreement with an ERT survey carried out on the same profile and consistent with the presence of an underground passage.     

三维随机断裂带的航空时域电磁响应数值模拟

传统的均匀分布异常体模型,不能准确描述地下介质的不规则性变化,采用随机介质进行替代,将使电导率这一物性参数更加接近于实际的电导率分布.本文结合地质结构中断裂带特征,采用Von Kármán函数建立三维随机介质模型,通过讨论Hurst指数与自相关长度对三维随机电导率模型建模产生的影响,进行参数优化建立所需的随机介质模型.利用一维傅里叶变换建立三维随机变化的条状断裂带异常体,三维傅里叶变换建立三维随机变化的背景围岩,准确地表征了油气藏断裂带特征.基于时域有限差分方法,实现了磁源激励下的三维随机介质航空时域电磁响应数值模拟.采用均匀半空间模型验证了数值模拟的正确性,分析了随机断裂带与均匀断裂带的电磁响应特征,结果表明随机断裂带可以准确描述地下介质的分布特征,而且与断裂带垂直方向的电磁响应特征清晰地描述了断裂带的倾向、走向与位置,为断裂带结构探测提供了理论依据和技术指导,三维随机断裂带模拟方法同样适用于其它三维随机介质的数值模拟.     

Long-range dependence in the runoff time series of the most important Patagonian river draining to the Pacific Ocean

The Baker River is the largest free-flowing river in Chilean Patagonia. Long-range dependence (LRD), a recognised hydrological property of river runoff worldwide, was detected for the Baker River runoff time series. Analyses were conducted on a monthly scale between 1961 and 2015 using the fractal and multifractal detrended fluctuation analysis methodology. A long-range-dependent Hurst coefficient (H) equal to 0.94 was obtained. A scaling range, which is the signature of LRD, was detected for the Baker River runoff time series between 1 and 5.25 years. Baker River runoff showed a strong correlation (r?=?0.96) with the Antarctic Oscillation (AAO) Index during the 2007–2015 period. The high storage capacity of Lake General Carrera, the size of the Baker River basin area and the dynamics of AAO are proposed as main factors that contribute to the emergence of LRD in the Baker River runoff time series.