多元统计组合模型在地震综合预报中的应用

针对目前地震综合预报中的一些问题，利用近30年来迅速发展的多元统计分析中主成分分析、判别分析组成多元统计组合模型，在众多的地震预报指标（预报因子）中采用信息最大化方法，选择对中期预测信息累积贡献率大于90%地震预报指标，分别进行相关分析、预测、检验，最终应用马氏距离判别作外推综合预报；并以华北地区（30~42N，108~125E）为例进行模型的应用检验，初步研究已取得了较好的效果.      

Radar remote sensing for monitoring of dynamic ecosystem processes related to biogeochemical exchanges in tropical peatlands

Peatlands are an important multipurpose ecosystem, supporting huge quantities of biomass and peat soil carbon. A time series of Japanese Earth Resource Satellite-1 (JERS-1) L-band Synthetic Aperture Radar (SAR) data was employed to monitor two dynamic ecosystem processes; deforestation and inundation patterns. Using a change detection analysis for three images acquired during dry seasons of 1994, 1997 and 1998, we detected the deforestation that has occurred in the region due to the anthropogenic and natural causes. At a threshold of ±2 dB change in backscattering response, an area of about 98 km² of these forests was found to have been cleared during 1994–1997 for conversion to cultivatable lands. However, the agricultural crops miserably failed to grow on these cleared lands because of the adverse water and soil chemistry conditions. The deliberate draining of these lands, by laying and extension of a huge network of canals, created congenial ecological conditions for the spread of forest fires, particularly during the 1997 El Niño period. An area of 250 km² of forests was thus detected to have been destroyed by these fires between September 1997 and January 1998. These deforested lands are rapidly regenerating since their abandonment and the regenerating carbon stocks were simulated using the CENTURY ecosystem dynamics model. Furthermore, the L-band SAR was able to detect the pixel-wise seasonal and spatial inundation information for particular forest types where the transmissivity of the L-band SAR signals was quite significant. These forest types corresponded to comparatively low biomass areas. The SAR derived information about these two important dynamic processes would be useful for improving the accuracy of modelling the spatial and temporal distribution of the carbon and other trace gases in these ecosystems.Edited by D. Boyd     

Towards Operational Repeat-Pass SAR Interferometry at Active Volcanoes

Measurement of volcanic surface movement is an operational technique at many volcano observatories to help understand internal processes and to aid in eruption forecasting. The potential of differential radar interferometry (DInSAR) to map patterns of surface deformation on volcanoes is well-proven. However, the technique has not yet become operational, partly because current spaceborne radars were not designed for the task. We discuss the limitations of the European Space Agency's ERS SARs for this purpose in terms of: radar system constraints, volcano surface characteristics, interpretational uncertainties and the operational context. We illustrate the drawbacks at typical stratovolcanoes in South America, chosen to represent a range of conditions. For non expert users of DInSAR, knowing how well DInSAR will work on a particular volcano is important. Freely-available global datasets of vegetation cover and atmospheric water vapour content can be used as proxy measures of coherence and path delay effects, which are the two main determinants of data quality. Operational volcano DInSAR is still years away, but many of the characteristics of such a system can be specified based on the experience learned from earlier radars.     

Vertical accuracy of the SRTM DTED level 1 of Crete

A reference digital elevation model (DEM), produced from contour lines digitization, from topographic maps at scale 1:250.000 is used in order to assess the vertical accuracy of the SRTM DTED level 1 in Crete Island in Southern Greece. The error image interpretation revealed three types of systematic errors: (a) stripping, (b) large voids and (c) those errors resulted from the mis-registration of the Shuttle Radar Topography Mission (SRTM) imagery to the local datum. Terrain was segmented to plane regions and sloping regions. Sloping regions were segmented to aspect regions (aspect being standardized to the eight geographic directions defined in a raster/grid image). Error statistics was computed for the study area as well as the individual terrain classes. Vertical accuracy was found to be terrain class dependent. Sloping regions present greater mean error than the plane ones. Statistical tests verified that the difference in mean error between aspect regions that slope in opposite geographic directions is statistically significant. The greater mean error is observed for SW, W and NW aspect regions. The additional finishing steps applied to the SRTM dataset were not sufficient enough for the systematic errors and the terrain class dependency of the error to be corrected. The observed root-mean-square error (RMSE) for the SRTM DTED-1 of Crete do not fulfil the 16 m RMSE specification for the SRTM mission while the USA national map accuracy standards for the scale 1:250.000 are satisfied.     

Resolution tests of global geodynamic models by travel-time tomography

This study presents results of a 2-D tomographic inversion of synthetic data that examines the ability of seismic tomography to reveal structures created by mantle dynamic processes. Our seismic velocity anomaly model is based on the density heterogeneities obtained from models of thermal and thermo-chemical convection. Both layered and whole-mantle models are employed to produce the synthetic input anomalies. We investigate the resolving power of the inversion of P and pP arrival times, and assess the influence of parameterisation and regularisation (damping). We show that the effect of regularisation is substantial and that the optimum damping depends upon the wavelength of the input structures. The resolution of the inversion decreases considerably at depths greater than 1000 km, therefore the ability of the kinematic inversion to distinguish between whole-mantle and layered flows (coupled via thermal coupling) may be limited.     

时间域内有限地震断层的反演问题

为了解决有限地震断层破裂过程研究中的正演和反演问题，本文提出：（1）用广义反射、透射系数矩阵和广义射线理论计算上地幔及远场范围体波理论地震图的混合方法．同时采用格林函数的一种新的组合方式，可节约1／3计算机内存．（2）采用基于模拟退火的热浴算法进行全局搜索反演，不仅提高了在计算过程中新模型被接收的可能性，而且使得在时间域内目标函数的计算速度提高了近二个数量级．对1994年台湾海峡地震震源破裂过程的研究结果表明，这次地震的破裂过程相对比较简单．在前4．0s内地震断层的破裂相当剧烈，错动距离的平均值随着破裂时间增加而迅速减少．开始时破裂速度较高，前4．0s的平均值为3．1km／s，之后逐渐降至2．2km／s．错动方向随破裂的变化不大．     

资源危机矿山综合信息成矿预测

本文在阐明了资源危机矿山综合信息成矿预测基本概念和特点的基础上，探讨了资源危机矿山综合信息成矿预测基本方法问题，初步建立了资源危机矿山综合信息成矿预测的系统方法，并介绍了资源危机矿山综合信息成矿预测系列图件的编制方法。     

人造卡邦金刚石生长特性

人造卡邦金刚石生长受成压力、温度等条件的直接影响，从触媒金属向石墨中浸渍，石墨向金刚石结构转化、金刚石子晶生长三个方面讨论了人造卡邦金刚石的生长特性，根据人造卡邦金刚石生长规律，研究用不同的工艺方法，设计生长具有不同特点和用途的人造卡邦金刚石聚晶体。     

超高压金刚石研究的新进展

从金刚石单晶的生长、同位素金刚石及非金属触媒三个方面对目前金刚石研究状况作了介绍。