强震时-空综合概率增益模型与中长期预测方法效能研究

本文在介绍强震时-空概率增益综合预测模型与单项地震预测方法效能评价指标的基础上，给出了各种中长期预测方法的概率增益统计值和预测效能R值。并对结果进行了讨论。     

Application of fluid mechanic principles to the study of geodynamic processes at trench-arc-back arc systems

Geological processes at trench-arc-back arc systems are some of the most complex tectonic processes in need of study. A large amount of data based on geological and geophysical observations has been accumulated. To synthesize these data, mathematical models have proven to be very useful. Because geological processes are directly related to the dynamical behavior of the solid earth, many of them can be investigated in terms of fluid flow models. Some applications of fluid flow principles in studying tectonic processes at convergent plate boundaries are discussed in this paper. When mantle processes are modeled as convective systems, they are found to have direct implications for the determination of slab dip angles. Additionally, they can also account for the high heat flows in the back arc basins, provide a mechanism for back arc opening, and resolve the question whether subducted oceanic crust can reach melting at shallow depth for island arc magma generation. Besides mantle processes, flow models can also be used to study surface processes. A simple one-parameter plane flow theory is used to model the evolution of trench geometries. This model is able to fit simulataneously the trench curvature and the differential paleomagnetic rotation between volcanic islands for the Mariana. Despite the simplicity of many of these models, their ability to synthesize geological and geophysical data at convergent plate boundaries is quite remarkable.     

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.     

随机共振新实例--卫星热红外温度异常点的发现及其意义

卫星热红外温度异常点是天线附近背景噪声与地球信息随机共振的结果。温度异常点是卫星热红外图像新的信息源，温度异常点在利用卫星热红外信息和研究地球脉搏方面可以发挥重要作用。卫星热红外温度异常点的发现开拓了随机共振应用的新领域。     

由甘肃宕昌好梯幔源包体推导的上地幔物质组成、热结构和流变学特征

新生代火山岩中的幔源包体可以提供有关上地幔的直接信息。通过对采自甘肃宕昌县好梯乡的幔源橄榄岩包体的详细研究 ,探讨该地区上地幔的热结构和流变学特征 ,并与华北地区进行对比。研究结果表明 ,该区自壳幔边界以下至 75km深处的上地幔主要由尖晶石二辉橄榄岩组成 ,75km以下则主要由石榴石二辉橄榄岩组成 ,方辉橄榄岩只占少数 ;与华北地区没有明显的差异。由包体平衡温度、压力建立的上地幔地温线低于华北地区地温线 ;确定的壳幔边界在 5 2km左右 ,莫霍界面附近为下地壳物质与尖晶石二辉橄榄岩的过渡带 ;岩石圈底界深度约为 12 0km左右。根据包体的研究结果建立了研究区上地幔的差异应力、应变速率和等效黏滞度剖面。结果表明 ,该区新生代时期存在软流层的底辟 ,以及相应的岩石圈的减薄 ,但其规模明显小于华北地区。这些结果表明该区处在中国东部大陆裂谷带和中国中部克拉通块体群的过渡带     

The changing malaria risk patterns in East-Central Europe and the North Balkans in the last 27 000 years

Southeast Europe has historically been at the crossroads of migration routes between Western Asia and Europe. In the Holocene, this area might have been home to malaria. However, it is questionable when malaria arrived in this area and whether it could persist continuously or not in the Holocene. To begin to answer these questions, the July potential generation number of two malaria parasites were modelled, based on the reconstructed mean July temperatures of 52 times in the last 27 000 years. The results indicate that in the late Pleistocene era (27–12 kya bp ), vivax malaria might have been present in the south-east Black Sea and Aegean Sea's coastal areas. Vivax malaria could also be present in the Pannonian Basin and the inner parts of the North Balkans at least from the mid-Greenlandian period (~10 kya bp ). Although it is questionable whether falciparum malaria could be endemic in the Pannonian Basin during the mid-Holocene climate optimum (~6 kya bp ), this malaria plausibly could be endemic from the Neolithic era (~12–6.5 kya bp ) in the major river valleys of the North Balkan region, millennia ahead of the Graeco-Roman times (8th century bce to 6th century ce ).     

Variation analysis of precipitation during past 286 years in Beijing area,China, using non‐parametric test and wavelet analysis

Non‐parametric methods including Mann–Kendall (M–K) test, continuous wavelet transform (CWT) and discrete wavelet transform analysis are applied in this paper to detect the trend and periodic trait of precipitation data series in Beijing area where the data set spans nearly 300 years from 1724 to 2009. First, the trend of precipitation variables is elaborated by the M–K test (Sequential M–K test). The results show that there is an increasing trend (the value of this trend is 1.98) at the 5%‐significance level and there are not turning points in the whole data series. Then, CWT and wavelet variance are used to check for significant periodic characteristics of data series. In the plots of wavelet transform coefficients and figure of wavelet variance, some periodic events affect the trend of the annual total precipitation series in Beijing area. 85‐year, 35‐year and 21‐year periodic events are found to be the main periodic series of long‐term precipitation data, and they are all statistically significant. Moreover, the results of non‐parametric M–K test are exhibited on seven different combinations of discrete wavelet components. D5 (32‐year periodicity) periodic component is the effective and significant component on data. It is coincident with the result (35‐year periodic event as one part of main periodicity) by using CWT analysis. Moreover, approximation mode shows potential trend of the whole data set because it is the residuals as all periodicities are removed from data series. Thus, the mode A + D5 is responsible for producing a real basic structure of the trend founded on the data. Copyright © 2012 John Wiley & Sons, Ltd.     

Advective flow in sediments under the influence of compaction

Abstract

Models on flow and transport in surface water sediments currently neglect compaction, although it is well understood that compaction is one of the major processes below the free fluid-sediment interface. Porosity changes in the sediment layers, as a result of compaction, are measured in almost all probes: porosity decreases with the distance from the surface water-sediment interface. This paper provides a rigorous derivation of basic flux terms for a frame of reference that is moving with the fluid-sediment interface. It is shown how burial rate, interface velocity, velocities of fluid and solid phase and porosity are connected—under steady-state conditions. It turns out that porosity and the velocities in a one-dimensional column can be directly computed from each other. These findings are important not only for the understanding of compaction-driven flow itself; they are crucial for all studies on storage and transport of chemical components in sediments. As mass fluxes across the sediment-water interface may be affected, there is an indirect link on surface water quality, making these findings relevant also for research on eutrophication of surface water bodies and/or on biogeochemical cycles.     

利用模式识别方法进行地震短期综合预报的初步探讨

以乌鲁木齐及其附近地区多项前兆监测手段的系统性震例总结资料为基础,根据地震短期综合预报的特点,对利用模式识别方法进行地震短期综合预报的可能性做初步探讨。结果表明,利用模式识别方法进行地震短期综合预报具有明显的现实意义。     

Baroclinic dynamics of wind-driven circulation in a stratified bay: A numerical study using models of varying complexity

The baroclinic response of a stratified coastal embayment (Lunenburg Bay of Nova Scotia) to the observed wind forcing is examined using two numerical models. A linear baroclinic model based on the normal mode approach shows skill at reproducing the observed isotherm movements and sub-surface currents during a time of strong stratification in the bay. The linear model also shows that the isotherm movement in Lunenburg Bay is influenced by the wind forcing and propagation of baroclinic Kelvin waves from neighbouring Mahone Bay. The effects of nonlinearity and topography are investigated using a three-dimensional nonlinear coastal circulation model. The nonlinear model results demonstrate that the nonlinear advection terms generate a gyre circulation at the entrance of Lunenburg Bay, and the slope bottom topography at the mouth of the bay strengthens the sub-surface time-mean inflow on the southern side of the bay. A comparison of model-calculated currents in different numerical experiments clearly shows that baroclinicity plays a dominant role in the dynamics of wind-driven circulation in Lunenburg Bay.