Emergency Seismic Damage Assessment of the M_S8.0 Great Wenchuan Earthquake Based on Remote Sensing Imagery

The fast processing, seismic damage data extraction and loss evaluation from RS imagery acquired immediately after a destructive earthquake occurs, are important means for compen-sating the insufficiency of seismic damage information from ground-based investigations and provide an important basis for emergency command and rescue. The paper introduces the method of emergency seismic damage assessment using remote sensing data and its application to the great Wenchuan earthquake of magnitude 8.0 occurring in southwest Sichuan Province on May 12, 2008. The practical effectiveness of the method is also evaluated in the paper.     

Study on the Phenomenon of Geomagnetic Low-value Displacement before Moderately Strong Earthquakes in Gansu

This paper analyzes the distribution characteristics of geomagnetic low-value displacement in Gansu and its adjacent areas from 1995 to 2003 on the basis of the data of the daily amplitude minimum value time of the geomagnetic vertical component. It is shown that in addition to the changing rules of geomagnetic low-value displacement itself, there is a better correlation between geomagnetic low-value displacement and the occurrence of moderately strong earthquakes. There appeared to be geomagnetic low-value displacement before the moderately strong earthquakes in Gansu in the 9 years from 1995 to 2003. This result indicates that geomagnetic low-value displacement is of instructive significance for earthquake prediction to some extents.     

Validity of the Bouchet’s complementary relationship at 102 observatories across China

Bouchet in 1963 hypothesized that for large homogeneous land surface with minimum advection of heat and moisture, there exists a 1:1 complementary relationship of potential and actual evaporation coupled through land-atmosphere feedbacks. The complementary relationship has been widely used to estimate regional actual evaporation and explain the pan evaporation paradox. We examine the standardized potential evaporation (potential evaporation divided by wet environment evaporation) at 102 observatories at different elevations across China. Generally, the relationship is appropriate at the low elevations (<1000 m). With the increase of elevation, vapor transfer power becomes much less than radiation energy budget because of lower vapor pressure deficit and stronger global solar radiation. As a result, at the high elevations (over 1000 m), the excess energy resulted by limited moisture availability is not enough to be converted into drying power of the air. This result suggests that the complementary relationship is asymmetric at the high elevations. Supported by the Presidential Special Award Foundation, the Chinese Academy of Sciences (Grant No. O7R70020SD) and the National Key Technology R & D Program (Grant No. 2006BAC08B0408)     

Cropland cover change in Northeast China during the past 300 years

Land use/cover change induced by human activities has emerged as a “global” phenomenon with Earth system consequences. Northeast China is an area where the largest land cultivation activities by migrants have happened in China during the past 300 years. In this paper, methods including documentary data calibration and multi-sourced data conversion model are used to reconstruct historical cropland cover change in Northeast China during the past 300 years. It is concluded that human beings have remarkably changed the natural landscape of the region by land cultivation in the past 300 years. Cropland area has increased almost exponentially during the past 300 years, especially during the past 100 years when the ratio of cropland cover changed from 10% to 20%. Until the middle of the 19th century, the agricultural area was still mainly restricted in Liaoning Province. From the late 19th century to the early 20th century, dramatic changes took place when the northern boundary of cultivation had extended to the middle of Heilongjiang Province. During the 20th century, three agricultural regions with high ratio of cropland cover were formed after the two phases of spatial expansion of cropland area in 1900s–1930s and 1950s–1980s. Since 1930s–1940s, the expansion of new cultivated area have invaded the forest lands especially in Jilin and Heilongjiang Provinces. Supported by National Natural Science Foundation of China (Grant No. 40571165) and Innovation Foundation of Chinese Academy of Sciences (Grant No. KZCX2-YW-315)     

蒙城地震台地电阻率各向异性参量研究

地电阻率各向异性参量计算方法是由钱复业,赵玉林等研究出来的方法。我们试用该方法编制相应的计算机程序,对蒙城地震台1978～2008年地电阻率的数据进行处理;并结合震例进行对比分析,发现对于震中距300km内的中强震,与地电阻率各向异性参数的趋势性变化存在密切的关系;地电阻率各向异性参量特征可以反映孕震区地下介质的孕震信息,对未来地震的预测将起到一定作用。     

信息熵在水氡资料处理中的应用

在较大地震的孕育过程中,随着弹性应变能的不断积累,孕震区有可能从原来的无序状态转变为一种在时间、空间上的有序状态,与之相联系的各种信息量的有序程度都有可能增加。本文引入信息熵来描述信息量的有序程度,结果表明,在研究范围内的多数地震前出现了熵减的过程,说明地震前确实存在一个从无序状态向有序状态转化的现象。文中利用信息熵方法,对福建省4个水氡观测资料进行分析,认为该方法,对各台的映震效能不同,虽然都通过了R值检验,但由于漏报率、虚报率的差异,从而影响了各台的R值评分;另外,用该方法提取的异常所反映出来的特征也不相同,如各台的异常持续时间和异常幅度同闽台地震的关系存在差异。     

地电阻率观测中一类反常年变化的分析讨论

本文从理论和实际观测资料方面讨论了我国某些地电阻率台站出现的冬天低值、夏天高值的反常年变化,指出出现这类年变化的原因可能有三种,其中最主要的是在特殊地电断面上,由于表层介质电性变化对地电阻率测量以反向贡献所致,这是表层电阻率变动引起地下电流密度非线性变化在特殊地电断面上的反映。这种特殊地电断面的标志就是表层介质的响应系数出现负值。此外,本文还讨论了在资料处理时,这类年变的消除方法。     

新疆某些地震前地下水动态异常特征的分析

本文在清理乌鲁木齐小区域井网地下水位资料和新疆某些油井动态资料的基础上,通过对震例的分析,探讨了本区地震前地下水动态异常的基本特征。认为,地震前地下水动态短临异常是明显的;异常仅仅出现在震源附近的有限区域;异常形态大致可以分为两种类型,即下降型和喷涌型。最后,对在地震孕育过程中与地下水异常有关的几个问题进行了初步的讨论。     

Paleogeography of the North and South China blocks during the Cambrian

Paleomagnetic results demonstrate that during the Cambrian the South China block was close to the equator. We suggest that it was adjacent to North Australia. This reconstruction juxtaposes Cambrian marine basins in South China and Australia, explaining the affinity between Cambrian trilobites from the two areas, as well as the existence of phosphorite deposits in the Early and Middle Cambrian in Australia and in South China. The stratigraphic similarity between the late Precambrian Sinian System in South China and the Adelaide System in Australia, and the continuing fossil affinities from Cambrian through Ordovician of both areas suggest that the proposed geographic configuration lasted from the late Precambrian (800 Ma) to Early Ordovician (470 Ma). Paleomagnetic results from the Cambrian of North China indicate that it was in the southern hemisphere at that time. Based on the paleontological evidence, we suggest that the North China block was close to Tibet, Iran and northern India during the Paleozoic.     

地震空间分布的多分维谱探讨

本文首先介绍了计算地震空间分布多分维谱的方法,如推广G—P法、固定质量法和固定半径法,然后利用推广G—P法计算理论模型(如Henon映射、随机模型)的多分维谱并分析计算中有关参数的影响(如计算样本大小和标度区确定),结果表明:度量半径r应小于研究区域的直径的1/4以减小边界效应。最后计算并分析地震资料(如1976年唐山地震地区的地震目录)。