全息光弹法分析南天山东部地区构造应力场

本文根据活断层资料,在软材料实验基础上,用激光全息光弹实验法分析了南天山东段构造应力场特征,实验结果表明,本区现代构造应力场主压应力为近南北向。在水平挤压力作用下,近东西向构造明显呈挤压状态,北东、北西向断层呈左旋或右旋走滑。τ_(max)、σ_1、σ_2的分布相似,其高值区展布于断层端点、交汇区等特殊部位。提出塔格拉克、库车—轮台、库尔勒东南为应力集中区。     

山东半岛东部湿地生态系统服务评价及比较研究

以山东半岛东部的烟台市和威海市为例,利用层次分析和主成分分析方法对研究区各县市湿地服务进行评价,采用自然间断法的方式将各市县湿地生态系统服务等级进行划分。结果表明:两种方法的评价原理和结果虽有差异,但都将烟台市辖区、威海市辖区划分为高生态服务地区,将栖霞市和招远市划分为低生态服务区。上述两种方法虽然评价原理不一致,但通过互相验证,更能真实地反映研究区湿地生态系统服务状态。     

乌鲁木齐城市化进程对局地气候变化的影响研究

利用1976—2014年乌鲁木齐城区和郊区两个气象站的气温、降水、相对湿度和风速气象数据及1995—2014年乌鲁木齐市城市发展数据,运用线性趋势对比分析城区和郊区各气候要素的年际变化特征;采用相关分析法对城市化因子和气候要素进行了探讨。结果表明:城、郊区气温均呈明显的上升趋势,城区的年均气温高于郊区;城区降水量是郊区的3.93倍,增长速率是郊区的3.98倍;各年代城区相对湿度比郊区大,但呈下降趋势,郊区呈上升趋势;各年代郊区风速大于城区,郊区风速约为城区的2.35倍,均呈下降趋势。近20 a,乌鲁木齐城市化进程加快,对局地气候影响明显,其中对平均气温和相对湿度的影响最为显著。     

Compositional multivariate statistical analysis of thermal groundwater provenance: A hydrogeochemical case study from Ireland

Thermal groundwater is currently being exploited for district-scale heating in many locations world-wide. The chemical compositions of these thermal waters reflect the provenance and circulation patterns of the groundwater, which are controlled by recharge, rock type and geological structure. Exploring the provenance of these waters using multivariate statistical analysis (MSA) techniques increases our understanding of the hydrothermal circulation systems, and provides a reliable tool for assessing these resources.Hydrochemical data from thermal springs situated in the Carboniferous Dublin Basin in east-central Ireland were explored using MSA, including hierarchical cluster analysis (HCA) and principal component analysis (PCA), to investigate the source aquifers of the thermal groundwaters. To take into account the compositional nature of the hydrochemical data, compositional data analysis (CoDa) techniques were used to process the data prior to the MSA.The results of the MSA were examined alongside detailed time-lapse temperature measurements from several of the springs, and indicate the influence of three important hydrogeological processes on the hydrochemistry of the thermal waters: 1) salinity and increased water-rock interaction; 2) dissolution of carbonates; and 3) dissolution of sulfides, sulfates and oxides associated with mineral deposits. The use of MSA within the CoDa framework identified subtle temporal variations in the hydrochemistry of the thermal springs, which could not be identified with more traditional graphing methods, or with a standard statistical approach. The MSA was successful in distinguishing different geological settings and different annual behaviours within the group of springs. This study demonstrates the usefulness of the application of MSA within the CoDa framework in order to better understand the underlying controlling processes governing the hydrochemistry of a group of thermal springs in a low-enthalpy setting.     

The influence of petrophysical properties on the salt weathering of porous building rocks

The influence of pore structure, water transport properties and rock strength on salt weathering is evaluated by means of a thorough rock characterisation and a statistical analysis. The pore structure was described in terms of its porosity, pore size distribution (quantified by mean pore radius) and specific surface area, density and water transport was characterised by means of water permeability (saturated flow) and capillary imbibition (unsaturated flow); whilst the rock strength test was carried out using uniaxial compressive strength, compressional and shear wave velocities, dynamic elastic constants and waveform energy and attenuation were obtained from the digital analysis of the transmitted signal. A principal component analysis and a stepwise multiple regression model was carried out in order to examine the direct relationships between salt weathering and petrophysical properties. From the principal component analysis, two main components were obtained and assigned a petrophysical meaning. The first component is mostly linked to mechanical properties, porosity and density whereas the second component is associated with the water transport and pore structure. Salt weathering, quantified by the percentage of weight loss after salt crystallisation, was included in both principal components, showing its dependence on their petrophysical properties. The stepwise multiple regression analysis found that rock strength has a predominant statistical weight in the prediction of salt weathering, with a minor contribution of water transport and pore structure parameters.     

广东省及邻区活动断裂的实验研究

从实验应力分析和岩石力学的角度,综合其它学科的相关理论,给出了一种有别于传统的活动断裂的新定义及其判据。其定义为:在现代构造应力场中,存在沿原断裂面破裂和扩展的断裂。其判据为:①某断裂走向与主压应力1σ方向所夹的锐角0°≤β≤50°时,其为活动断裂;②β=25°的断裂为最活动的断裂。通过对广东省及邻区活动断裂的实验研究还得到其1σ方向分布图(广东省域从东到西,1σ方向大致为305°～360°～15°)、活动断裂或活动断裂分段的走向范围以及主要活动断裂分段内潜在的最大地震。大致为:①NW走向的断裂,除西部极少数外,全部是活动断裂。各断裂分段内潜在的最大地震在MS 5.1～7.4级之间:②研究区东部的近EW向断裂、西部NE向断裂的部分分段和SN向断裂,也是活动断裂。各分段内潜在的最大地震在MS6.8～7.5级之间。     

Spatiotemporal characteristics of the displacement field revealed with principal component analysis and the mode-rotation technique

Principal component analysis (PCA) was applied to the displacement field recorded at 147 GPS stations in the Kanto-Tokai district, Japan, for the period from January 1999 to February 2003. Some prominent geophysical events occurred during this period. Using PCA, we attempted to decompose the displacement field into some representative spatial modes and their corresponding temporal modes to quantitatively extract the primary geophysical events that have caused rapid crustal deformation in this region. The displacement field was roughly decomposed into modes corresponding to the following three major events: (1) The Miyake-Kozu volcanic event, which occurred in the region south of Tokyo in 2000. It included large-scale dyke intrusion and intensive earthquake swarm between the Miyakejima and Kozushima islands. (2) The Tokai slow-slip event, which is considered to have begun just after the Miyake-Kozu volcanic event and is ongoing as of November 2005. It occurred on the boundary between the subducting Philippine Sea Plate and the overriding Eurasian (Amurian) Plate in the Tokai district. (3) The Boso slow-slip event, which lasted for approximately 10 days in October 2002. It occurred on the boundary between the subducting Pacific Plate and the overriding North American Plate near the Boso Peninsula. In the decomposition process, we combined the mode-rotation technique with ordinary PCA. This is because PCA causes contamination between modes, i.e., a mode obtained with PCA is contaminated by other modes. For example, the first principal mode corresponding to the Miyake-Kozu volcanic event, which is by far the largest in magnitude, was clearly seen in many other modes. In order to remove such contamination, we applied the mode-rotation technique, in which the principal axes derived from PCA are rotated so as to minimize the correlation coefficients between different temporal modes for a time period in which some prominent change occurs. Combining the mode-rotation technique with PCA exhibited a better performance in separating the displacement field.     

冬季高度场主分量与正压能量转换的关系

对观测的34年北半球冬季500hPa月平均位势高度场作了经验正交函数分析，对前5个主分量与正压能量转换过程之间的关系作了统计分析。结果表明基本气流向低频扰动的正压能量转换，有利于主分量结构类型的低频环流异常的产生和维持，这一关系是明确的和显著的。     

El Nino的周期变化和空间特征——兼应用PC和CPC分析太平洋海温距平场

本文联合利用实主成分(以下简称PC)分析和复主成分(以下简称CPC)分析,探讨太平洋SST演变的时空特征.结果表明:这两种分析方法得到的第一个主成分都展示El Nino随时间周期性变化,在PC中表现为峰谷的变化,在CPC中表现为振幅和位相的变化;相应的荷载向量主要反映El Nino和La Nina事件时期空间分布特征,大振幅区域位于主要冷暖洋流活动中心.第一个复荷载向量可以认为在驻波上附加一个南北向传播的行波.第二个荷载向量为一驻波,第三个复荷载向量看上去像一个东西向传播的行波,后两个特征型各自强调不同El Nino和La Nina时期的空间特征.驻波峰、谷区域之间呈现反相关关系;这里虽然没有研究波群和群速度,但就行波而言,也初步看出能量传播的路径.与复荷载向量对应的实荷载向量仅显示驻波特征.