Evaluation of earthquake potential along the Northern Anatolian Fault Zone in the Marmara Sea using comparisons of GPS strain and seismotectonic parameters

Seismotectonic parameters including the Gutenberg-Richter b-value and multifractal dimensions D₂ and D₁₅ of seismicity patterns (both spatial and temporal) were compared to GPS-derived maximum shear and dilatation strains measured in the Marmara Sea region of western Turkey along the Northern Anatolian Fault Zone (NAFZ). Comparisons of seismotectonic parameters and GPS-derived maximum shear and dilatation strain along the NAFZ in the vicinity of the 1999 M7.4 Izmit earthquake reveal a positive correlation (r = 0.5, p = 0.05) between average dilatation and the Gutenberg-Richter b-value. Significant negative correlation (r = − 0.56, p = 0.03 and r = − 0.56, p = 0.02) was also observed between the spatial fractal dimension D₂ and GPS-derived maximum geodetic and shear strain. This relationship suggests that, as maximum geodetic and shear strains increase, seismicity becomes increasingly clustered.Anomalous interrelationships are observed in the Marmara Sea region prior to the Izmit event along a bend in the NAFZ near the eastern end of the Marmara Sea known as the Northern Boundary Fault (NBF). An asperity is located near the northwest end of the NBF. Along the 50-km length of the NBF, GPS strains become slightly compressive. The correlation between b-value and GPS-derived dilatation suggests that regions in compression have increased probability of larger magnitude rupture. The NBF appears to serve as an impediment to the transfer of strain from east to west along the NAFZ. Recurrence times for large earthquakes along the NBF are larger than in surrounding areas. Temporal clustering of seismicity in the vicinity of the NBF may represent foreshocks of an impending rupture.     

小波变换在SAR与TM图像的IHS变换复合方法中的应用

提出了一种改进的 IHS变换复合方法 ,即将小波变换与 IHS变换相结合的方法。它先将 SAR与 I进行小波融合 ,然后将融合数据代替 IHS反变换中的 I,最后进行 IHS反变换。文中对比分析了 4种复合方法 ,并且用熵、联合熵及平均梯度进行了定量评价。     

裂隙网络多标度分形计算机模拟

岩体裂隙网络是不均匀，非对称的复杂分形，用简单分数维不能刻画其特征，必须采用多标度分形来研究，才能全面客观地描述其本质。文中介质了隙网络多标度分形计算机模拟原理与方法。     

Using quartz grain size and shape analysis to distinguish between aeolian and fluvial deposits in the Dallol Bosso of Niger (West Africa)

Size and Fourier-shape characteristics of quartz sand grains were determined by computerized image analysis in order to distinguish between aeolian and fluvial soil parent materials in the Dallol Bosso in Niger. Factor analysis of grain-size distributions gave four sand end-members that can be related to fluvial transport dynamics operating when the sediments were initially deposited. The medium to fine (and more angular shaped) sand fractions are being reworked by wind. Aeolian deposits were well sorted whereas fluvial deposits were poorly sorted in both size and shape. Although gross-shape characteristics (lower harmonics of Fourier series expansion) indicated a common source rock for all sands, the aeolian sands were well rounded whereas the fluvial sands tended to be more angular (upper harmonics of Fourier series).     

天山地区地貌系统的自仿射分形与多重分形特征研究

利用标准偏差法和固定质量法，研究了新疆天山地区跨越多个不同构造地貌单元的两条地形剖线的自仿射分形和多重分形特征。结果表明：在所研究的标度范围内，两条剖线均表现出了不同特征的多度域分形性质，多重分形谱Dq的形态和值域范围也呈现出不同特征研究认为，地貌形态并不是完全随机的，而是一种确定性随机，不同标度区间的分维值表征了内外营力作用的方式，强度和空间尺度，同时提出地貌宏观与微观作用尺度的分界点在5km左右。这些结果对地貌动力学定量研究具有重要意义。     

Heat capacity and entropy of rutile (TiO<Subscript>2</Subscript>) and nepheline (NaAlSiO<Subscript>4</Subscript>)

 From heat capacities measured adiabatically at low temperatures, the standard entropies at 298.15 K of synthetic rutile (TiO₂) and nepheline (NaAlSiO₄) have been determined to be 50.0 ± 0.1 and 122.8 ± 0.3 J mol⁻¹ K, respectively. These values agree with previous measurements and in particular confirm the higher entropy of nepheline with respect to that of the less dense NaAlSiO₄ polymorph carnegieite. Received: 23 July 2001 / Accepted: 12 October 2001     

大震过程中地壳形变的混沌和多重分形特征及其预报意义

以地壳形变中倾斜观测为例,用常熟观测台石英摆地倾斜仪记录到的１９９５年７月１日至１９９７年６月３０日ＳＮ测向的观测数据作为研究的原始资料,采用时间延迟相空间重构法计算并研究了１９９６年１１月９日南黄海Ｍｓ６．１级地震前后地倾斜系统混沌吸收子的关联维数,Ｄ２二阶熵Ｋ２和最大Ｌｙａｐｕｎｏｖ指数λ１,并用推广ＧＰ法和数盒子法研究了地震前后系统多重分开遥广义维数谱Ｄ２和奇异性谱（α）研究结果表明,地倾斜     

基于"元素含量-面积"模型方法的地球化学场的多重分形模式分析

从多重分形理论出发,在赤峰地区的2个区域应用"元素含量-面积(C-A)"模型方法.对"元素含量-面积"双对数图的形态进行分析,将地球化学异常多重分形特征模式分为3种类型:模式Ⅰ为可拟合为2条直线段的简单多重分形模式,具有该模式的元素在研究区内没有成矿富集的趋势,不存在实质性的致矿异常;模式Ⅱ为可以拟合为3条直线段的高富集多重分形模式,它在模式Ⅰ的基础上叠加有高含量的异常场,具有该模式的元素在研究区内存在较强的局部富集,成矿的可能性很大;模式Ⅲ为可拟合成3条直线段的低富集多重分形模式,它在模式Ⅰ的基础上叠加的是较弱的异常场,具有该模式的元素在研究区内有较弱的矿化作用.在此基础上,分析了元素的成矿富集规律和空间分布特征,确定了区域异常和局部异常的异常下限,划分了地球化学背景、区域异常和局部异常.     

Hierarchical probabilistic regionalization of volcanism for Sengan region,Japan

A 1 km square regular grid system created on the Universal Transverse Mercator zone 54 projected coordinate system is used to work with volcanism related data for Sengan region. The following geologic variables were determined as the most important for identifying volcanism: geothermal gradient, groundwater temperature, heat discharge, groundwater pH value, presence of volcanic rocks and presence of hydrothermal alteration. Data available for each of these important geologic variables were used to perform directional variogram modeling and kriging to estimate geologic variable vectors at each of the 23949 centers of the chosen 1 km cell grid system. Cluster analysis was performed on the 23949 complete variable vectors to classify each center of 1 km cell into one of five different statistically homogeneous groups with respect to potential volcanism spanning from lowest possible volcanism to highest possible volcanism with increasing group number. A discriminant analysis incorporating Bayes’ theorem was performed to construct maps showing the probability of group membership for each of the volcanism groups. The said maps showed good comparisons with the recorded locations of volcanism within the Sengan region. No volcanic data were found to exist in the group 1 region. The high probability areas within group 1 have the chance of being the no volcanism region. Entropy of classification is calculated to assess the uncertainty of the allocation process of each 1 km cell center location based on the calculated probabilities. The recorded volcanism data are also plotted on the entropy map to examine the uncertainty level of the estimations at the locations where volcanism exists. The volcanic data cell locations that are in the high volcanism regions (groups 4 and 5) showed relatively low mapping estimation uncertainty. On the other hand, the volcanic data cell locations that are in the low volcanism region (group 2) showed relatively high mapping estimation uncertainty. The volcanic data cell locations that are in the medium volcanism region (group 3) showed relatively moderate mapping estimation uncertainty. Areas of high uncertainty provide locations where additional site characterization resources can be spent most effectively. The new data collected can be added to the existing database to perform future regionalized mapping and reduce the uncertainty level of the existing estimations.     

Evolution-EM signals before earthquakes in terms of mesomechanics and complexity

MHz-to-kHz electromagnetic (EM) anomalies have been detected worldwide over time intervals ranging from a few days to a few hours prior to near-surface earthquakes (EQs) that have occurred on land with magnitude approximately six or larger. The MHz radiation systematically appears earlier than the kHz. Laboratory experiments on rock samples reveal a similar change in the frequency content during progressive deformation, i.e. the emissions exhibit a frequency shift from MHz to kHz just before failure of the samples. Herein, we attempt to associate these consecutively emerging MHz and kHz modes of the pre-fracture EM emission with successive distinct stages of the fracture preparation process and the associated fracture mechanisms. We base our approach on synergetic principles of physical mesomechanics. A universal principle of physical mesomechanics is that the plastic deformation of a solid is related to its loss of shear stability at the micro-, meso-, and macroscale levels. Global fracture is determined by the mechanism controlling the development of macroscale bands of localized deformation associated with meso- and microscale relaxation processes. The major result we obtain is that the shift from MHz to kHz EM activity may signal the transition of plastic flow localization from the mesoscale to the macroscale, culminating in global fracture. A complexity measure (Approximate Entropy) and a persistency–anti-persistency measure (Hurst exponent) also give evidence of a two stage-model of EQ preparation process: significant complexity decrease and accession of persistency can be confirmed in the strong kHz EM activity that emerges in the tail of the pre-seismic EM activity. Laboratory experiments on rock samples reveal similar symptoms of an imminent global instability.