The Latest Research Progress on El Nino

Cold water in the deep Pacific can be drawn up to the surface (or west warm water drifts eastwards ) because strong tide increases the mixing of seawater both in vertical and horizontal. In this way greenhouse effect is decreased or increased by means of absorbing (or releasing) CO2. Therefore, La Nina cold event (or El Nino warm event) may occur,which is caused by wanning - up or cooling - down air above the ocean. Volcanic action at sea bottom is also controlled by strong tide.     

基于地面采样点的MODIS等效反射率计算与分析

本文介绍了等效反射率、平均等效反射率的概念及计算方法,以2006年10月在崇明东滩湿地采集的地面光谱反射率数据和MOD IS地面反射率产品为基础数据,计算了试验区等效反射率和平均等效反射率,开展了平均等效反射率与MOD IS反演反射率的比较分析,对MOD IS地面反射率产品精度作了分析和评价。     

地物波谱研究现状及方法的初步探讨

地物波谱特性是遥感技术应用的物理基础,是遥感定量分析的基础,地物波谱研究是遥感基础研究的重要内容。文中阐述了几种典型地物的波谱特征,介绍了测量方法及影响因素,并对国内外波谱数据库建设现状作了描述和分析,系统总结了前人研究成果后对地物波谱研究的发展方向提出了构想。     

A method to predict the group fissuring and faulting caused by regional groundwater decline

Ground fissuring is a recurrent problem in many countries where water extraction surpasses the natural recharge of aquifers. Due to differential settlement, the soil layer undergoes deformation and cracks with serious consequences for civil infrastructure. Here, we propose an approximate analysis of the fissuring process that can be used to predict the location of cracks, which increasingly affect some middle- and large-sized cities in the world. For that purpose, the ground loss theory is applied to sediments overlying a sinusoidal-shaped graben. This analysis shows the existence of a tensile zone at the border of the graben with maximal values on its shoulder where tension cracks are more likely to appear. It also shows that soil deformation under differential settlement may evolve into ground faulting if water withdrawal continues. Finally, when a crack has completely developed, the tensile zone shifts towards the center of the graben, creating a new area for potential cracking and faulting.     

基于高温高压岩石破裂实验结果对中强地震前震中附近区域部分地震学现象的初步解释

依据高温高压岩石破裂实验结果并结合理论分析，对 附近区域不同深度温压条件下岩石变形破坏性质及破坏失稳的力学行为进行了研究，在一次应力加载循环中，发生破坏的部位随时间具有向深部下迁的趋势。考虑到深度温压条件下岩石的渐进式破坏行为及突发失稳，对主震前震中附近区域小地震活动的增强、平静、活化等现象，以及b值等时间序列参数变化的可能机理进行初步探讨，并简单讨论了两类平静和两类b值变化的可能原因。     

Effect of asymmetry and irregularity of seismic waves on earthquake-induced differential settlement of buildings on natural subsoil

The effect of asymmetry and irregularity of the inputted seismic waves on the earthquake-induced differential settlement of the buildings on natural subsoil is investigated in terms of the earthquake damage phenomena, theoretical analyses, dynamic triaxial tests and shaking table tests. A conclusion can be drawn from the investigation results that, the asymmetrical and irregular character of the inputted seismic waves themselves may have a significant contribution to the differential settlement of subsoil and buildings in some cases, and this is a necessary factor to be considered in reasonable evaluation for the differential settlement and other problems relating to the soil deformation due to earthquakes.     

Seismic scattering at the top of the mantle Transition Zone

We document strong seismic scattering from around the top of the mantle Transition Zone in all available high resolution explosion seismic profiles from Siberia and North America. This seismic reflectivity from around the 410 km discontinuity indicates the presence of pronounced heterogeneity in the depth interval between 320 and 450 km in the Earth’s mantle. We model the seismic observations by heterogeneity in the form of random seismic scatterers with typical scale lengths of kilometre size (10-40 km by 2-10 km) in a 100-140 km thick depth interval. The observed heterogeneity may be explained by changes in the depths to the α-β-γ spinel transformations caused by an unexpectedly high iron content at the top of the mantle Transition Zone. The phase transformation of pyroxenes into the garnet mineral majorite probably also contributes to the reflectivity, mainly below a depth of 400 km, whereas we find it unlikely that the presence of water or partial melt is the main cause of the observed strong seismic reflectivity. Subducted oceanic slabs that equilibrated at the top of the Transition Zone may also contribute to the observed reflectivity. If this is the main cause of the reflectivity, a substantial amount of young oceanic lithosphere has been subducted under Siberia and North America during their geologic evolution. Subducted slabs may have initiated metamorphic reactions in the original mantle rocks.     

TRMM PR雷达与阜阳雷达降水资料的对比研究

选取了1998年与1999年HUBEX观测资料，将TRMM卫星上的星载降雨雷达PR与阜阳的713数字化天气雷达资料在以下3个方面做了比较：(1)强度场的分布；(2)平均反射率廓线；(3)灵敏度。分析、比较结果可知阜阳雷达在探测灵敏度和水平方向的分辨率要高于PR，但由于波束宽度、衰减和资料转化过程计算误差的原因，其远距离处的观测值与真实值有一定偏差。PR波长短，对衰减敏感，尤其是在垂直方向上经过强衰减后，订正值仍偏小。但由于探测方式的不同PR在水平方向上不存在衰减的问题，且其资料分布均匀，因此提出一种用PR资料来订正地基雷达资料的方法用以提高地基雷达探测的精确度。     

差异流动变形破坏研究

工程岩体出现许多流变现象, 它最突出的特点是差异流动变形破坏。本文从流变现象及变形量测结果论述差异流动变形破坏特征, 并且根据蠕变流动变形破坏与时间的关系进行了差异流动变形分类, 这些类型同时存在于一个岩体或岩块内。     

议京西大台地区的燕山运动

作者研究了京西大台地区的燕山运动，初步研究表明：这里不存在强烈的挤压变形迹象和显著的角度不整合．缺乏磨拉石建造。龙门组是厚度有限的河流相沉积，九龙山组是具有弱火山活动的湖相一滨湖相沉积。在隆起带和沉降带之间侏罗系地层显著的厚度变化率、大安山一斋堂滑覆构造及其派生的髫髻山断陷盆和大量高角度滑动面理，都显示了伸展构造背景下基底断块的差异升降。髫髻山组与壳幔相互作用有关的一套火山岩显示了上述运动的深部背景。