云南地区地震短临预报实践

１９９７年４－６月云南省地震局对滇西南重点监视区做了短临预报,但这期间未发生所预期的地震。而滇西南地区６级地震的背景和省内的前兆异常变化是明显的。为此,认为前兆异常是区域应力场增强的结果。异常与地震是相互伴生的兄弟关系,不是父子间因果关系,是造成地震虚报的主要原因。     

平行走滑断层相互作用的粘弹模型和减震作用

研究了二维粘弹性介质中平行走滑断层的相互力学作用及其地震活动性的影响。当一条断层发生滑动,将导致平行断层面上剪切应力减小,因此,可能推迟平行断层发生滑动,推迟时间在几年至几百年的范围内,这取决于发生滑动的断层与平行断层之间的距离,以及平行断层自身应力积累孕育地震过程经历的时间。     

我国电子政务建设的机遇挑战及其对策

通过对电子政务发展战略的深入分析 ,指出我国电子政务的建设正面临四个挑战 ,包括重复建设、无序操作、忽视应用、管理滞后等。面对重复建设、建设无序、忽视应用、管理滞后等问题 ,提出了迎接四个挑战的具体对策     

Study on a gravity precursor mode of the <Emphasis Type="Italic">M</Emphasis><Subscript>s</Subscript>=7.0 Lijiang earthquake

To study the seismogeny process or the precursory behavior of the 1976 M _S=7.0 Lijiang earthquake, we analyze the repeat gravity data with high precision from the Western Yunnan Earthquake Prediction Experiment Area (WYEPEA) and the related results of geology and geophysics survey in this paper. Considering the gross errors caused by observation data and model difference, we have firstly inverted the slip distribution of the main active faults with time based on the robust Bayesian least squares estimation and multi-fault dislocation model. The results show that the slip changes of the faults with time from 1990 to 1997 obviously reflect the preparation process of the Lijiang earthquake. The images of main precursor mode have the characteristic of main shock-after shock type, which is agreement to the model of coupling movement between crust density and crust deformation (DD mode of coupling movement).     

The Generating Region of Bidirectional Electron Beams in the Corona

Metric and decimetric type III bursts and microwave spike emissions with negative and positive frequency drift rates which were observed with radio spectrometers at Yunnan and Beijing Observatories are presented. The frequencies and heights at which the bidirectional electron beams originated are estimated. Three events reveal a separatrix frequency (at 250, 1300, and 2900 MHz) between normal- and reverse-drifting radio bursts, indicating a compact acceleration source where electron beams are injected in both upward and downward directions. These cases may indicate that the changeover frequencies of bidirectional electron beams are within a large band from 250 to 2900 MHz and the frequency bands of separatrices are in very small (4 to 100 MHz) and different bands. These type III bursts appear to be a plasma emission phenomenon from a beam of electrons which seem to have widely separated acceleration regions from the high to the low corona. These cases suggest that current sheets that separate open and closed magnetic fluxes in the low corona, and oppositely directed open field lines in the high corona are possible sites for bidirectional electron acceleration. The regions of magnetic topology from closed to open magnetic field structures should be very large (from about 20000 to 107000 km above the photosphere).     

Type III burst pair

We present a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0–2.0 GHz) of the Beijing Astronomical Observatory (BAO). Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. We call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is a nice interpretation of type III burst pair since the plasma beta 0.01 is much less than 1 and the beams have velocity of about 1.07×10⁸ cm s^–1 after leaving the reconnection region if we assume that the ambient magnetic field strength is about 100 G.     

"2006-2020年中国地震危险区与地震灾害损失预测研究"项目成果介绍

本文详细介绍了“2006~2020年中国地震危险区与地震灾害损失预测研究”项目的立项背景、目标、所开展的主要工作、取得的成果、研究成果的社会效益和对该领域研究未来工作的展望。     

Analysis on the noises from continuously monitoring GPS sites

In this paper,we analyze the time series of site coordinates of 27 continuously monitoring GPS sites covered bythe Crustal Movement Observation Network of China over the whole country.The data are obtained in the periodfrom the beginning of the observation to the November of 2005.On the basis of data processing,we analyze thepower spectrum density of coordinate component noise at each site and calculate the spectral indexes manifestingthe noise property of each component.The spectral indexes indicate that for most sites,the noise of time series ofeach coordinate component can be addressed by the model of white noise flicker noise;and for a small amountof sites,it can be described by the model of white noise flicker noise random walk noise.We also quantita-tively estimate each noise component in the model by using the criterion of maximum likelihood estimation.Theresult shows that the white noise in the time series of GPS site coordinates does not constitute the main part ofnoise.Therefore,the error estimation of site movement parameters is usually too small,or too optimistic if weconsider the white noise only.Correspondingly,if this factor is not fully considered in explaining these movementparameters,it might mislead the readers.     

Coregistration Based on Three Parts of Two Complex Images and Contoured Windows for Synthetic Aperture Radar Interferometry

The coregistration of complex image pairs is a very important step in synthetic aperture radar interferometry (InSAR) data processing. This letter proposes a novel coregistration method that only needs three arbitrary parts of the two complex images instead of four parts in the existing coregistration methods. This method constitutes an integrated three-part method for InSAR data processing with our contoured-correlation-interferometry method for phase-image generation. Saving one part transmission makes a significant advantage when processing SAR images on satellites. Furthermore, we demonstrate that, by means of using fringe contoured windows instead of squared windows, the accuracy of the coregistration for both the three-part coregistration method and the existing methods can be improved considerably     

3S集成技术在城镇土地利用变更调查中的应用研究

城镇地区由于建筑物密集、土地利用类型变化快、土地利用现状图比例尺较大等特点,土地利用变更调查主要依靠专业部门利用全站仪完成,但全站仪需要通视的特点限制了其工作效率。而采用3S集成技术进行城镇地区土地利用变更调查的技术方法,则可以相应提高工作效率。基于3S集成技术城镇地区土地利用变更调查的应用模式为:通过GPS接收机与笔记本电脑(已配置GIS软件系统)通讯,实现GPS与GIS的集成,并调用RS影像作为底图,既可实现实时的数据采集、存储和编辑。对于城镇地区部分GPS信号弱的地区,采用测边交会的方法则可以完成这些点的数据采集,克服了GPS使用盲区的限制。