Checking the quality of restoration in the frequency domain of CDSN broad-band seismograms using modern control engineering

Incorrect results including false low frequency components may appear during the recovery of ground motion in the frequency domain. In order to check the quality of restoration in the frequency domain of CDSN broad-band seismograms, a digital model of the seismograph systems, based on modern control engineering, is presented and improvement of the method of restoration in the frequency domain is described. Examples shown in this paper demonstrate the effectiveness of the proposed approach in improving the restoration of true ground motion. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 90–99, 1992. The work is supported by the Chinese Joint Seismological Science Foundation.     

国家数字地震台网大震速报模式讨论

从大地震速报的科学意义和社会意义出发，论述了我国地震速报的现状．回顾大震速报的发展历程。以此为基础，讨论国家数字地震台网目前大震速报的模式，分析了在数字化代替模拟以后使用速度震级的可行性，以及量取20秒周期面波震级的必要性。从地震科研的发展方向构想我国未来地震速报的基本模式。     

超大功率振动源在首都圈地区地震监测预报中的应用研究

俄罗斯科学家西伯利亚分院研制了几种型号的超大功率振动源，其特点是功率大，信号传播距离远，探测深度大。目前，我国首都圈地区已建成由100多个子台组成的数字化地震台网。文章介绍了俄罗斯超大功率振动源及其在我国首都圈地区地震监测预报中的应用研究。     

宽频带数字地震记录仿真的应用

利用傅里叶分析法，把速度型宽频带数字地震记录变成台站人员所熟悉的长周期，中长周期模拟常规地震记录，分析人员能在仿真后的记录波形图上识别震相和计算震级。为地震台站用宽频带数字地震记录取代模拟记录提供了一种资料处理方法。     

Cyclic flank-vent and central-vent eruption patterns

 Many basaltic and andesitic polygenetic volcanoes have cyclic eruptive activity that alternates between a phase dominated by flank eruptions and a phase dominated by eruptions from a central vent. This paper proposes the use of time-series diagrams of eruption sites on each polygenetic volcano and intrusion distances of dikes to evaluate volcano growth, to qualitatively reconstruct the stress history within the volcano, and to predict the next eruption site. In these diagrams the position of an eruption site is represented by the distance from the center of the volcano and the clockwise azimuth from north. Time-series diagrams of Mauna Loa, Kilauea, Kliuchevskoi, Etna, Sakurajima, Fuji, Izu-Oshima, and Hekla volcanoes indicate that fissure eruption sites of these volcanoes migrated toward the center of the volcano linearly, radially, or spirally with damped oscillation, occasionally forming a hierarchy in convergence-related features. At Krafla, terminations of dikes also migrated toward the center of the volcano with time. Eruption sites of Piton de la Fournaise did not converge but oscillated around the center. After the convergence of eruption sites with time, the central eruption phase is started. The intrusion sequence of dikes is modeled, applying crack interaction theory. Variation in convergence patterns is governed by the regional stress and the magma supply. Under the condition that a balance between regional extension and magma supply is maintained, the central vent convergence time during the flank eruption phase is 1–10 years, whereas the flank vent recurrence time during the central eruption phase is greater than 100 years owing to an inferred decrease in magma supply. Under the condition that magma supply prevails over regional extension, the central vent convergence time increases, whereas the flank vent recurrence time decreases owing to inferred stress relaxation. Earthquakes of M≥6 near a volcano during the flank eruption phase extend the central vent convergence time. Earthquakes during the central eruption phase promote recurrence of flank eruptions. Asymmetric distribution of eruption sites around the flanks of a volcano can be caused by local stress sources such as an adjacent volcano. Received: 18 March 1996 / Accepted: 14 January 1997     

大丰地震台井下摆震级偏差及台站校正值

对大丰地震台井下摆1983-1992年的观测资料统计分析,发现井下摆测定的震级普遍低于江苏省地震局台网的平均震级,且和震中距有一定的关系。通过对震级偏差的计算得出大丰台的台站校正值。同时,对偏差的原因进行了探讨。     

763面波震级和大震速报

大量的观测资料表明我国大震速报台网与世界台网震级存在较大的偏差，而７６３面波震级与世界台网比较一致的事实，提出了将７６３面波震级用于大震速报的建议及其可行性。     

GDS-1000宽频带通用流动数字地震观测系统

GDS-1000宽频带通用流动数字地震观测系统主要用于大陆岩石层的人工及天然地震台阵研究、强震观测以及余震观测台网的临时布设。其主要技术指标为:动态范围120dB,前放增益1,16,128倍可调,高端频率6.25,25,45Hz可调,采样率25,100,200Hz可调,1MB固态数据存储器借助地震数据的压缩软件可以存储3MB以上的数据,工作温度范围-10-45℃,功耗小于3W。定时接受的BPM无线电授时信号可保证记录系统时钟校正误差小于10ms。其智能化地震触发系统可处于下列模态:近震触发,远震触发,近震和远震触发,任意地面运动信号触发,以及手动触发和定时触发。DSR-1000数字地震数据回收系统用于GDS-1000的参数预置、地震事件数据的转储和地震图的现场绘制。该系统在野外试验期间已取得大量近震、远震及核爆炸记录。     

DFS-Ⅴ型数字地震仪数字AGC的理论分析与探讨

数字AGC(自动增益控制)是数字地震仪中的关键部件之一。本文对DFS-V型数字地震仪中的数字AGC的基本理论进行了深入的理论探讨,建立了严格的工作流程图和工作方框图,对第一乘法器、第二乘法器、数字电平检测器、扩展和压缩发生器进行了深入的电路分析。最后结合主要的时序图,对DFS-V型数字AGC的整体工作过程进行了全面地评述。     

GDS－1000宽频带数字地震仪野外数据回收处理系统

在笔记本计算机上运行的ＧＤＳ－１０００宽频带数字地震仪地震数据回收处理系统软件，用于在野外条件下执行现场仪器参数设置、数据回收、数据解编及地震图的开窗显示等功能。近一年的野外实际应用结果表明，该系统软件具有数据通讯快速可靠、使用灵活方便等优点。