Thermal omens before earthquakes

IntroductionTopredictwherethedisastrousearthquakeoccursisoneofthegreatestproblemswhichconcernsthepublicmostandisdifficulttoresolvebythescienceandtechnologyoftoday.Inordertoresolvetheproblemandreducethelossofanearthquake,aseriesofobservationsystemshavebeeninstalledaroundtheworldtoattempttofindsomeomenbeforeaneanhquake.Butmostoftheearthquakepredictionsarefailedbecauseof"lookonewayandrowanother".Itshowsthatthecapabilityoftheobservationsystemofthestress-strainfieldandotherphysicparameterfields,whi…     

地形效应校正的遥感地热异常提取

在山地复杂地形条件下,利用热红外遥感获得的地表温度分布显著受到地形的影响,真实的地热异常信息往往难以识别,热红外遥感应用于山区地热勘探受到极大限制。以广东龙川地热勘查区为研究区,初步探讨了山地环境中如何抑制地形效应,以有效提取地热异常。首先,基于Landsat ETM+遥感数据反演地表温度,分析坡向和坡度两个地形因子与地表温度的关系;然后,在此基础上,将研究区的地表温度按坡向分成3个子区(阳坡、过渡坡和阴坡),根据阳坡地表温度与坡向的线性拟合关系将其校正到水平坡度上;最后,结合地质构造分布和地表覆被情况,在3个子区识别了4处地热异常,并与已知地热点进行比较验证。结果表明:坡向分区和阳坡坡度校正能够有效抑制地形效应,提高遥感地热异常识别精度,为山区地热资源的预测评价提供新思路。     

Socio-structural forces predicting global water footprint: socio-hydrology and ecologically unequal exchange

ABSTRACT

Growth in water use and threatened shortages of water have become increasingly important in the modern world system. Natural resources are exploited extensively by capitalist interests in industrially advanced nations, while the lower strata of the world system, the underdeveloped societies, are left with limited access to natural resources for their productive processes, particularly water resources. We contribute to socio-hydrological research by examining underlying socio-structural factors that play a part in the process of deteriorating conditions of global water resources. Drawing on a world-systems perspective, this study examines how socio-structural forces – world-system position, per capita beef consumption, per capita energy consumption, and urbanization – affect per capita water footprint, which includes an accounting of “virtual water” consumption. We find that per capita beef consumption and per capita energy consumption have significant positive direct effects, and the world-system position has a significant indirect and total effect on per capita water footprint.     

构造热演化的数值模拟方法

对模拟构造热演化的二维和三维非稳态热传导-平流微分方程的数值求解进行了研究.在空间和时间上分别应用有限单元法和差分法进行离散化处理;推导了非稳态热传导-平流有限元方程.在求解技术上发展了“迎风”权函数方法,将有限元法、有限差分法和“迎风”权函数法结合起来,使用变网格、变结点方法对地质体的运动介质、运动边界、多热源的非线性、非稳态的构造热演化进行了模拟.并对各种热源体的处理、初始条件和边界条件的处理进行了分析.     

Mathematical simulation of geotemperature field and thermal stress field in Sanjiang region of Yunnan

By the mathematical simulation of geotemperature field, deep quasi-stable thermal state and shallow thermal characteristics are reproduced in Sanjiang region of Yunnan. Faults are treated in two ways, 1) as constant heat source in terms ofq=μτ, that is, the quantity of frictional generated heat is constant, in order to simulate frictional heat generated by fault moving; 2) as heat conduits with high thermal conductivities to simulate such a phenomenon that there exist thermal fluids (for example, magma) in fault zones during tectonic movement. And then, through the simulation of thermal stress, the quantity (several bars to hundred bars) and the pattern of thermal stress vectors are obtained, which provides a new clue to the explanation and prediction of earthquakes. And larger tensional and shear stresses occur where the variation of geotemperature and the thickness of thermal lithosphere gradient belt. The stresses are concentrated in the temperature gradient belt. The shear belts of studied area are temperature gradient belts where the variation of the lithosphere thickness is larger and deep heat flow is high and thermal stresses concentrated. All of these may explain the facts that most of the earthquakes, hot springs occur along the fault zones. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 313–321, 1993. The study was financially supported by Chinese Natural Sciences Funds Item Ancient Tethys Tectonic Evolution in Western Yunnan and by centre for Remote sensing, Ministry of Metallurgy.     

Influence of hydrolysis on the sorption of metal cations by smectites: Importance of edge coordination reactions

A comparison was made between the adsorptive behaviors of Cd²⁺ and UO ₂ ²⁺ relative to two smectites that differed in their ratio of edge sites to fixed-charge sites. Adsorption varied with both pH and ionic strength, consistent with sorptive contributions of ion exchange and coordination reactions to edge hydroxyls. Both clay minerals exhibited a greater affinity for UO ₂ ²⁺ than for Cd²⁺, and the clay with a higher proportion of edge sites retained both ions more strongly. A computational model including fixed-charge sites and edge hydroxyls resulted in a good prediction of overall UO ₂ ²⁺ and Cd²⁺ uptake to both smectites.     

Bottom currents induced by baroclinic forcing in Lake Banyoles (Spain)

Because of the difference in morphometry and in the underground heating of the two lobes of Lake Banyoles there is a differential cooling that causes a density current — the denser water of the shallower lobe plunging into the deepest lobe forming a bottom current — which redistributes water between the lobes and replaces that of the northern lobe about every 5 days. This current has been studied during the mixing periods of the years 1989–1991 from temperature and current measurements and it has been found that it increases or slows down depending on the direction of the wind. Furthermore, it is observed that it mainly flows along the west shore of the lake, deflecting towards the right as an effect of the bottom morphometry. However, due to the long time scale of the density current the influence of the earth's rotation should not be neglected in advance. Finally, a simple numerical model has been used to corroborate the magnitude of this current — whose velocity has been directly measured — which is found to be the most important in the lake during the mixing period and so, it dominates the lake-wide circulation     

青海当金山口—四川黑水大地热流研究

在青海当金山口－四川黑水剖面（ＧＧＴ）区带内大地热流测量的基础上，采用布拉德数值分析法对地温梯度进行了三维地形校正，对中－新生代孔隙岩石热导率样品进行了饱水校正，取得了满意的效果，获得了１０个可信的大地热流值。青藏高原北部平均热流值为５１ｍＷ．ｍ＾－２，变动于３５～７８ｍＷ．ｍ＾－２，柴达木北缘构造带和巴颜喀拉构造带处于二者之间，平均为４９ｍＷ．ｍ＾－２。这种分布不均７２ｍＷ．ｍ＾－２，柴达木北缘