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本文回顾了中国地震信息系统的发展历程.1966年3月在我国河北邢台发生的灾害性地震的抗震救灾行动,不仅开辟了我国地震监测预报的先河,而且产生了中国地震信息系统.中国地震信息通信系统的前期是以传递地震观测信号和实时传递地震信号为起始,现在已经为地震观测服务发展成为具有全国规模的行业地震信息平台.全球进入21世纪的信息时代,我国信息技术和信息产业以惊人的速度迅猛发展,地震信息系统在我国信息基础设施发展的基础上,同样发展迅速.信息网络通达地震行业各个角落,地震各项工作无不以信息平台为基础.地震信息系统已经彻底改变了地震监测预报、震害防御和应急救援的工作方式、科研方式,同时促进了人们传统观念的变革,使我国地震事业进入了前所未有的蓬勃发展阶段. 相似文献
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叙述井分析了山西地震带地质构造特点和近期的中强地震及震群活动基本特征,在此基础上,与大同一阳高地震进行了分析对比,认为大同-阳高地震是山西地震带近期地震活动的继续,而山西地震带今后强震活动阶段的开始,其标志应是NVE向新生代断陷内的中强地震活动,因此在分析和预估山西地震带今后地震发展趋势时,应密切注视这一地带的地震活动。 相似文献
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研究了永登5.8级地震前地震活动异常特征,并应用秦保燕提出的地震动态空区的原理和地震频次起伏加剧,研究了1995年永登5.8级地震的孕震过程,对地震三要素进行了回顾性预报。结果表明,预测结果与实际地震发生的时间、强度和地点十分接近 相似文献
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渤海海域中小地震定量分析结果显示,渤海中存在多个地震密集区. 地震密集多呈NE向分布,但也确有NW向活动存在. 大致以39deg;N为界,渤海南部与北部的地震活动差异悬殊,几乎所有的强震和中小地震密集都集中于南部. 综合史料和中小地震密集特征, 对公元1548年震中位置进行了校订,对1888年地震的震级进行了讨论. 探讨了173年地震事件作为一次地震海啸的可能性. 对1597年地震事件作为一次渤海强震提出了质疑. 相似文献
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当测区噪声很强,采用组合震源工作仍然不能满足信噪比要求时,为进一步提高地震勘探信噪比,引入能形成定向地震波的相控震源.针对水平层状介质模型,对组合震源、相控震源地震进行了数值模拟,并定量计算了采用4,8,15,20单元的组合与相控震源地震数据的信噪比,同组合地震相比,相控地震使来自不同反射层的反射波信号的信噪比平均提高了154~990 dB.结果表明,相控震源地震得到的反射波信号信噪比高于组合地震,并且随着激震器数目增加,相控震源合成地震记录中的反射波地震数据信噪比明显提高. 相似文献
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本文从系统结构的概念出发,对短临前兆突变的特征和二维构模进行了讨论,利用层次分析法制定综合模式,对1991年7月22日云南施甸5.2级地震作出了较好的短临预报。 相似文献
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扬子地块古生代大地构造演化及古地磁学研究综述 总被引:5,自引:0,他引:5
本文简要地论述了扬子地块古生代大地构造研究现状,扬子与华夏地块之间的华南裂谷盆地于奥陶纪初发生收缩,直到加里东末期基本封闭,古生代扬子地块与华北地块之间的秦岭海槽以拉张为主,扬子地块西缘古生代期间处于相对稳定的构造环境,古生代末进入特提斯构造域,发生活化。 相似文献
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本文报导一例多次复发的囊性颅咽管瘤,应用^32P腔内放射治疗成功,随访4.5年无复发,生活自理,视力维持术前状态,复查CT囊腔缩小50%以上,可以认为立体定向腔内离疗是一种安全有效的方法,对于孤立的或多发的囊性颅咽管瘤病例应作为外科手术首选方法,但仍需进行深入的临床研究,以观察和确定疗效。 相似文献
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刘慧敏 《CT理论与应用研究》1997,6(1):15-17
胃癌病人有症状时往往已达进展期,欲行根治手术受到很大限制,部分探查术实际上相当于剖腹活检。因此,术前对病变大小、局部浸润及远隔转移准确判断非常重要。本文讨论了胃癌术前CT检查的TNM分期对手术切除可能性的评价 相似文献
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为适应洞室形变测量仪器网络化的发展及中国地震局“十五”前兆仪器总体设计的要求,高精度、智能化、网络化的应变仪应运而生。本文介绍了洞室定点高精度地应变仪网络化的实现过程,并给出了应用实例。 相似文献
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Field tests were conducted to determine representative total-intensity magnetic anomalies due to the presence of underground storage tanks and 55-gallon steel drums. Three different drums were suspended from a non-magnetic tripod and the underlying field surveyed with each drum in an upright and a flipped plus rotated orientation. At drum-to-sensor separations of 11 feet, the anomalies had peak values of around 50 gammas and half-widths about equal to the drum-to-sensor separation. Remanent and induced magnetizations were comparable; crushing one of the drums significantly reduced both. A profile over a single underground storage tank had a 1000-gamma anomaly, which was similar to the modeled anomaly due to an infinitely long cylinder horizontally magnetized perpendicular to its axis. A profile over two adjacent tanks had a smooth 350-gamma single-peak anomaly even though models of two tanks produced dual-peaked anomalies. Demagnetization could explain why crushing a drum reduced its induced magnetization and why two adjacent tanks produced a single-peak anomaly.
A 40-acre abandoned landfill was surveyed on a 50- by 100-foot rectangular grid and along several detailed profiles. The observed field had broad positive and negative anomalies that were similar to modeled anomalies due to thickness variations in a layer of uniformly magnetized material. It was not comparable to the anomalies due to induced magnetization in multiple, randomly located, randomly sized, independent spheres, suggesting that demagnetization may have limited the effective susceptibility of the landfill material. A different 6-acre site survey conducted on a 10- by 10-foot grid was analyzed to determine the maximum station spacing and line separation that could have been used. Essentially, all of the anomalies at this site would have been resolved by a survey conducted on a 20- by 20-foot grid and the larger anomalies would have been detected by a 50- by 50-foot grid. 相似文献
A 40-acre abandoned landfill was surveyed on a 50- by 100-foot rectangular grid and along several detailed profiles. The observed field had broad positive and negative anomalies that were similar to modeled anomalies due to thickness variations in a layer of uniformly magnetized material. It was not comparable to the anomalies due to induced magnetization in multiple, randomly located, randomly sized, independent spheres, suggesting that demagnetization may have limited the effective susceptibility of the landfill material. A different 6-acre site survey conducted on a 10- by 10-foot grid was analyzed to determine the maximum station spacing and line separation that could have been used. Essentially, all of the anomalies at this site would have been resolved by a survey conducted on a 20- by 20-foot grid and the larger anomalies would have been detected by a 50- by 50-foot grid. 相似文献
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J. R. Kayal 《Pure and Applied Geophysics》1980,119(2):349-355
The profile of temperature gradient versus depth (T-log) has been found to be very useful for correlation with electrical resistivity log (E-log) in coal-bearing formations. A positive correlation between electrical resistivity and thermal resistivity is observed in coal sections whereas a negative correlation is found in sandstone/shale beds, thus helping in coal prospect evaluation. T logs have been used to correct the location of coal bed which had apparently been misinterpreted by the E-log. Hole to hole correlation of T-log and E-log is found to be excellent and it is observed that thermal resistivity characteristics of given formations remain fairly uniform. A rough estimation of coal grade is possible from the detailed study of the T-logs. Abrupt changes of temperature gradient as also its reversals have been observed in burnt coal sections. 相似文献
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利用锁相环数字频率合成电路研制的质子磁力仪测程标定信号源,其频率准确度和稳定度都保证了维修和标定的要求,经实验证明,可靠性和抗干扰性强,解决了实际工作的需要。 相似文献