西宁地震台地磁数字化与模拟记录对比分析

西宁地震台FHD数字化核旋仪从2006年10月安装以来,一直与模拟仪器并行工作。二者采样率不同,所测的量也不相同。在对西宁地震台磁变仪的记录图纸进行数字化转换、生成分钟值的基础上,对FHD仪和磁变仪的观测结果进行对比分析。结果表明:数字FHD仪比三分量磁变仪更加准确地记录了当地地磁场的变化,数字仪器的观测资料明显优于模拟仪器。     

64层CT血管造影在自发性蛛网膜下腔出血病因诊断的价值

目的:探讨64层CT血管造影在自发性蛛网膜下腔出血的病因诊断中的价值。方法:对2009年1～12月97位患有自发性蛛网膜下腔出血的病人行64层CT血管造影成像扫描,应用容积再现、最大密度投影、曲面重建、多平面重建等后处理技术显示血管,以明确病因。结果:64层CTA诊断12例正常,1例颈内动脉海绵窦瘘、9例动静脉畸形,75例动脉瘤,所有病例与数字减影血管造影和/或手术对比证实,其中12例正常病例行DSA检查,64层CTA漏诊1例,但其总的敏感性为98.7%,特异性为100%。结论:64层CT血管造影对自发性蛛网膜下腔出血的病因诊断准确性高,且简单、快速、微创、安全和经济,可作为自发性蛛网膜下腔出血病因诊断的首选检查方法。     

海南地区5口井水位对汶川地震的同震响应及其频谱分析

对比海南地震台网记录的汶川MS8.0地震的地震波形,分析了海南5口井的高采样率数字化水震波波形特征。采用傅立叶变换和小波分解方法,对海南前兆台网5个台水位仪在汶川MS8.0地震中记录到的高采样率数字化水震波进行了频谱分析,结果显示地震波的不同波组激发的水震波波组差别较大,5口井的水震波周期跨度很大,从10多秒到1000多秒,不同井孔的水震波幅度差别较大。同时还初步分析了水震波的形态和水震波各个频率组的形成机理。     

中国数字地震台网数字化地震资料使用指南

由于数字地震记录仪具有记录频带宽,分辨率高,动态范围大以及易于用计算机处理等优点,所以数字地震台网产出的数字地震资料成为地震活动性,震源机制,地球内部研究,地震监测及预报等的最基本数据源。     

Testing a model for predicting the timing and location of shallow landslide initiation in soil‐mantled landscapes

The growing availability of digital topographic data and the increased reliability of precipitation forecasts invite modelling efforts to predict the timing and location of shallow landslides in hilly and mountainous areas in order to reduce risk to an ever‐expanding human population. Here, we exploit a rare data set to develop and test such a model. In a 1·7 km² catchment a near‐annual aerial photographic coverage records just three single storm events over a 45 year period that produced multiple landslides. Such data enable us to test model performance by running the entire rainfall time series and determine whether just those three storms are correctly detected. To do this, we link a dynamic and spatially distributed shallow subsurface runoff model (similar to TOPMODEL) to an in?nite slope model to predict the spatial distribution of shallow landsliding. The spatial distribution of soil depth, a strong control on local landsliding, is predicted from a process‐based model. Because of its common availability, daily rainfall data were used to drive the model. Topographic data were derived from digitized 1 : 24 000 US Geological Survey contour maps. Analysis of the landslides shows that 97 occurred in 1955, 37 in 1982 and ?ve in 1998, although the heaviest rainfall was in 1982. Furthermore, intensity–duration analysis of available daily and hourly rainfall from the closest raingauges does not discriminate those three storms from others that did not generate failures. We explore the question of whether a mechanistic modelling approach is better able to identify landslide‐producing storms. Landslide and soil production parameters were ?xed from studies elsewhere. Four hydrologic parameters characterizing the saturated hydraulic conductivity of the soil and underlying bedrock and its decline with depth were ?rst calibrated on the 1955 landslide record. Success was characterized as the most number of actual landslides predicted with the least amount of total area predicted to be unstable. Because landslide area was consistently overpredicted, a threshold catchment area of predicted slope instability was used to de?ne whether a rainstorm was a signi?cant landslide producer. Many combinations of the four hydrological parameters performed equally well for the 1955 event, but only one combination successfully identi?ed the 1982 storm as the only landslide‐producing storm during the period 1980–86. Application of this parameter combination to the entire 45 year record successfully identi?ed the three events, but also predicted that two other landslide‐producing events should have occurred. This performance is signi?cantly better than the empirical intensity–duration threshold approach, but requires considerable calibration effort. Overprediction of instability, both for storms that produced landslides and for non‐producing storms, appears to arise from at least four causes: (1) coarse rainfall data time scale and inability to document short rainfall bursts and predict pressure wave response; (2) absence of local rainfall data; (3) legacy effect of previous landslides; and (4) inaccurate topographic and soil property data. Greater resolution of spatial and rainfall data, as well as topographic data, coupled with systematic documentation of landslides to create time series to test models, should lead to signi?cant improvements in shallow landslides forecasting. Copyright © 2003 John Wiley & Sons, Ltd.     

人工值守台数字化地震仪标定原理

推导了人工台数字化地震仪的分段标定公式，提出数字化记录系统的微分近似标定和拾震器阻尼衰减法标定的方法，并提供了不同短周期地震仪与数字化地震仪并行的藕合方式和标定计算公式。     

基于TCP/IP协议的地震波形数据实时传输技术在数字地震台网联网中的应用

介绍了TCP/IP传输协议及其在广东省数字地震台网联网中进行地震波形准实时传输应用的技术思路和解决方案.     

云南永胜期纳盆地的场地放大

根据2001年云南永胜Ms6．0地震的57个余震的304条数字地震记录,用线性反演法得出了期纳盆地相对于三道河台频率1．5～20Hz的S波场地放大。有实际放大作用的频率在10Hz以下,期纳台、半屏台和黄泥田台的放大峰值在4．5Hz处,糖厂台和龙门村台的放大峰值在7．5Hz处。所有台的峰值都约为三道河台的两倍。用永胜(基岩)区域数字地震台的记录作参考核算,10Hz以下,三道河台的场地放大约为1,其余台约为2,所以三道河台可作为基岩台看待。     

基于孔压静力触探试验的水运工程土分类方法研究

土的工程分类是工程勘察和设计应用的关键问题之一。基于孔压静力触探测试（piezocone penetration test,简称CPTU）原位测试参数进行土分类是高效实用的方法。国内外现有分类方法的名称及标准与我国《水运工程岩土勘察规范》（JTS 133－2013）不符合。因此,建立基于CPTU原位测试参数、符合我国行业标准的土工程分类方法具有重要工程意义。在收集大量国内外水运工程CPTU测试资料的基础上,对比分析了616个间距小于5 m的CPTU测试孔和相应钻孔取样与室内土工试验成果。选择国内外7种常用的CPTU土分类图进行应用比较,发现这些土分类图所采用的应力修正计算方法在考虑浅层土体的有效上覆应力修正时存在一定的缺陷,通过引入新的应力修正方法和修正土分类边界线,建立了适合我国水运工程的CPTU土分类方法。对比应用分析表明,该分类图能够准确地进行水运工程土类划分,尤其适合于软土、粉细砂和中粗砂的划分,可作为我国水运工程的土工程分类方法。     

大数据环境下数字填图数据集成服务技术

应用数字填图技术形成了大量地质填图图幅数据,这些数据空间结构化和非结构化特征并存,如何在网络环境下提供高效的数据服务是急需解决的一个难题。大数据技术的发展为数字填图、数据集成服务提供了一种新的途径。通过对数字填图数据特征的分析,在研究地质调查信息网格大数据处理框架的基础上,提出了结构化和非结构化数据相结合的有序化组织管理、发布与服务方法,并对关键技术进行了研究与试验,取得了良好的效果。