汶川地震给地震台网建设带来的启示

通过对紫坪铺水库数字遥测地震台网在汶川特大地震中的表现,分析通过特大地震洗礼的紫坪铺地震台网运行的经验和教训,提出遥测地震台网建设时观测仪器设备也应注意自身抗震的问题,并对今后地震台站观测仪器安装提出建议。     

操作CTM-DI磁力仪时应该注意的事项

本文介绍了CTM-DI磁力仪使用时应该注意的事项及维护方法。     

基于多尺度注意残差网络的地震波形分类研究

选用2010年2月—2016年12月发生在北京顺义及河北三河等首都圈邻近区域的117个地震事件(包括54个天然地震事件和63个非天然地震事件——爆炸事件)作为研究对象,利用文章所提出的多尺度注意残差网络对其中的天然地震事件和爆炸事件波形进行二分类。首先,对原始地震波形进行简单预处理并截取成相同长度的地震时序数据,直接将其作为网络模型的输入;其次,选用含有残差模块的深度神经网络作为基础网络,利用深度神经网络对特征的自动提取能力,省略了传统波形分类需要提前提取时域波形的特征作为分类算法输入的步骤;然后,融合通道注意力机制(ECA)并对其进行改进,将空间维度的信息融入通道信息,优化了网络对关键信息的关注,更好地聚焦重要特征;最后,使用空间金字塔池化代替最大池化进行多尺度特征融合,得到更多的特征信息,构成多尺度注意残差网络。实验结果表明,最高分类准确率为97.11%,平均分类准确率为96.53%,证明了多尺度注意残差网络在地震波形分类任务中的有效性,为震源类型识别工作提供了一种新的方法。     

震损快速识别算法在湖北应城M4.9级地震中的应用研究

针对基于人工检测方法存在效率低、实时性差等问题,提出了一种空间通道注意力机制改进的Faster RCNN的砌体结构震损图片快速识别算法。基于湖北省应城M4.9级地震现场调查获取的砌体结构震害图片,制作砌体结构门窗洞口和震损类型的数据集;通过Mosaic方法对数据集进行数据增强后,构建空间通道注意力机制改进的Faster RCNN模型提取震害图片高级语义特征;使用湖北应城M4.9级地震砌体结构震害调查数据集对模型进行训练及验证并确定最终的模型超参;最后基于改进的Faster RCNN对砌体结构门窗洞口和震损类型进行快速检测。实验结果表明,该改进的算法可以有效的识别出门、窗、剥落、裂缝,其检测精确分别为：93.1%、97.6%、74.8%、62.3%。此外,单张震害照片检测时间为60 ms,为砌体结构震害快速检测提供了新的思路。     

一条断层的活动性鉴定及其工程意义

拟建中的某工程场址经工程地质勘探和基础开挖发现一规模较大的北西向断层。本文通过对该断层的地貌形态、断层面宏观结构、断层带内物质的显微构造分析以及第四纪地层的^14C测年，对该断层进行了活动性鉴定，并提出了工程设计应注意的问题。     

基于对抗式残差密集深度神经网络的CT稀疏重建

针对计算机断层成像稀疏重建过程中产生条状伪影的问题,本文提出一种基于对抗式残差密集深度神经网络的CT图像高精度稀疏重建方法.设计一种耦合残差连接、密集连接、注意力机制和对抗机制的UNet网络,以含条状伪影图像和高精度图像作为训练样本,通过大规模训练数据,对该网络进行训练,使其具有压制条状伪影的能力.首先,利用滤波反投影...     

南通台核旋观测干扰的排除

针对南通地震台核旋观测的干扰，通过多种试验最终加以排除。这项工作表明，地震台站环境改造中要注意监测环境的保护，特别是铠装电缆的铺设要考虑到对磁、电观测的影响，并就如何进一步提高核旋的观测质量提出建议。     

对“地震学百科知识(三)——地震学反演问题”一文的更正

本刊2013年第4期(35-41页)的《地震学百科知识(三)——地震学反演问题》一文,40页第6行中的"设A为n×m的实矩阵"应改为"设A为m×n的实矩阵",敬请读者注意。     

地震绕射波弱信号U-net网络提取方法

绕射波携带大量小尺度非均匀地质体信息,对于提高地震勘探分辨率具有重要意义.绕射波能量远小于反射波,在地震记录中常被强反射波掩盖,因此分离并单独成像绕射波,为探测小尺度非均匀地质体的关键问题.传统绕射波分离方法受限于理论模型假设,对陡倾角反射波去除效果不佳,且易对绕射波造成损伤.基于经典编码-解码框架下的U-net网络和注意力机制,本文提出了一种绕射波智能分离方法,通过编码器自动提取地震数据中的绕射波特征,再由解码器恢复绕射波,从而隐性去除反射波.该方法作为端到端的机器学习,训练后的U-net网络可自适应地分离绕射波.本文通过数值模拟数据与实际数据构建训练数据集,利用训练后的U-net网络分离绕射波,并将结果偏移成像.数值模型测试和实际资料应用表明,融合了注意力机制的U-net网络能够有效压制反射波能量,保留绕射波动力学特征,克服了传统绕射波分离方法难以去除陡倾角反射的局限性,其提取的绕射波弱信号特征较为完整,能够进一步提高地震成像分辨率,在小尺度断裂刻画上具有优势.     

频率信号激励下岩石电性参数研究

物性实验是建立地质与地球物理关系的基础,同时也是对地球物理勘查资料进行合理解释的条件之一.本文通过总结以往的研究工作,对获取不同激发信号下电阻率值的实验装置、应注意的问题和应服从的模型进行分析,并针对Cole-Cole模型进行了理论计算与实际模拟电路的物理实验对比研究,提出了未来值得深入研究的几个方面.     

紧急救援有关问题的探讨与思考

首先简要回顾了紧急救援的发展过程；简述了与紧急救援有关的一些概念；讨论了城市搜索与救援、地震灾害紧急救援两个概念的由来和区别；回顾了国家地震灾害紧急救援队的设计并提出了地方救援力量建立的原则。最后是关于紧急救援未来发展的思考，并对保障措施提出了建议。     

物联网技术在地震受困人员应急搜救中的应用研究

为能在搜救地震受困人员时,实时监测灾区情况,增强实时性及降低搜救误差,研究物联网技术在地震受困人员应急搜救中的应用,设计基于物联网的地震应急搜救系统,采用RFID识读器将采集的数据通过互联网传输至数据处理中心服务器上,再反馈至灾区信息处理子系统中的监测防御模块中,若出现异常情况则开启射频模块,命令现场报警装置响应报警应急搜救信号;通过蚁群算法获取最优搜救路线,及时搜救地震受困人员。实验结果表明,设计系统可有效搜救地震受困人员,且系统的吞吐率高达90%,搜救准确率均值高达97.6%,耗时均值仅为0.88 h,具有较高的搜救准确率和搜救效率。     

On the ability of Moho reflections to affect the ground motion in northeastern Italy: a case study of the 2012 Emilia seismic sequence

It has been observed that post-critically reflected S-waves and multiples from the Moho discontinuity could play a relevant role on the ground motion due to medium to strong size earthquakes away from the source. Although some studies investigated the correlation between the Moho reflections amplitudes and the damage in the far field, little attention was given to the frequency content of these specific phases and their scaling with magnitude. The 2012 Emilia seismic sequence in northern Italy, recorded by velocimetric and accelerometric networks, is here exploited to investigate Moho reflections and multiples (SmSM). A single station method for group velocity-period estimation, based on the multiple filter technique, is applied to strong motion data to detect SmSM. Amplitude and frequency scaling with magnitude is defined for earthquakes from \(\hbox {Mw}=3.9\) to \(\hbox {Mw}=5.9\) . Finally, the ability of SmSM to affect the ground motion for a maximum credible earthquake within the Po plain is investigated by extrapolating observed engineering parameters. Data analysis shows that high amplitude SmSM can be recognized within the Po plain, and at the boundaries between the Po plain and the Alpine chain, at epicentral distances larger than 80 km, in the period range from 0.25 to 3 s and in the group velocity window from about 2.6 to 3.2 km/s. 5 % damped pseudo-spectral accelerations at different periods (0.3, 1.0 and 2.0 s), and Housner intensities, are obtained from data characterized by large amplitude SmSM. A scaling relationship for both pseudo-spectral accelerations and Housner intensities is found for the earthquakes of the 2012 Emilia seismic sequence. \(\hbox {I}_{\mathrm{MCS}}\) from VII to VIII is estimated, as a result of SmSM amplitude enhancement, at about 100 km for a maximum credible earthquake ( \(\hbox {Mw}=6.7\) ) in the Po plain, showing that moderate to high damage cloud be caused by these specific phases.     

The figure of the earth — Changes in concepts

The search for the Figure of the Earth is rooted in the age-old wonder about the world we live in. The ancient mythical notions have developed, under the tutelage of Greek systematic thought, into specific questions of the shape and size of the Earth. The history of these questions, now spanning more than two millenia, shows a continuous refinement in formulation, as each bona fide answer prompted refined measurements which, in turn, started a new round of problems. The change in concept of what one was looking for was, and still is, closely connected with the technical capability and its potential for further development. This change in concept is traced here from ancient times to the present throungh some of its milestones: Anaximander's partly invisible celestial sphere and Pythagoras' spherical Earth; Eratosthenes' exemplary combination of astronomy and land surveying for the dual purpose of determining the size of the spherical Earth and making a map of the habitable world; the identical dual purpose followed by the Académie Royale des Sciences in the 17th century, but on a more sophisticated technical level; the challenge to the spherical concept by Newton's gravitational theory and the absorption of that theory into a wider concept of the Figure of the Earth; the acknowledgment of the irregular geoid by Gauss, Bessel, and Helmert, and the changed significance of the ellipsoid; Heiskanen's and Vening Meinesz' ‘Basic Hypothesis of Geodesy’ concerning the hydrostatic equilibrium of the Earth, and O'Keefe's contradiction on the basis of satelite data; the dream of global surveys come true through satellite geodesy and the accompanying inclusion of the outer gravity field of the Earth into the concept of its Figure; and lastly, the present and projected capability of high precision measurement and the widening of the concept of the Figure of the Earth from 3-dimensional rigidity to 4-dimensional time-dependence.     

搜索理论与建筑物评估和标记问题的讨论

简述了救援支持系统的含义、搜索理论的发展及其在倒塌建筑物救援中的应用前景；分析了我国现有倒塌建筑物评估的现状，认为应当在适当时机开展这方面的研究；重点讨论了建筑物评估和标记，认为目前我国应当借鉴国外救援行动有关的建筑物评估与标记方法；讨论了建筑物倒塌救援的搜索方法和程序；介绍了国外建筑物倒塌救援标记的使用方法。     

Soufrière of guadeloupe 1976–1977 eruption — mass and energy transfer and volcanic health hazards

The Soufrière volcano in Guadeloupe island delivered a phreatic eruption that commenced on July 8th, 1976 and lasted until March 1st, 1977. This eruption was similar to the 1797, 1798, 1809 and 1956 outbreaks. Phreatic activity ejected blocks derived from the fissure walls and fine pyroclasts produced by hydrothermal alteration of the old dome’s rocks. Field observations and measurements allowed the present authors to calculate the mass and energy transfer of steam and ashes: 10⁷ tons of water (very low considering that on the mountain summit the annual precipitation is 10 tons m)²,10⁶ m³ of ashes. The most important energy transfers was thermal: about 5 × 10²⁰ ergs for each phreatic eruption. The total kinetic energy output was 2 × 10¹⁹ ergs for a total thermal energy output of 64 × 10²⁰ ergs. The gases and fine pyroclasts did pollute the atmosphere, waters and soils and consequently affected the population living on the slopes of the volcano.     

Evidence for an Independent 26-s Microseismic Source near the Vanuatu Islands

The 26 s peak in the ambient seismic noise spectrum is persistently excited and observed at stations globally. Using noise cross-correlation functions (NCFs), the location suggests that the source could be situated in the Gulf of Guinea and Fiji Basin. However, the Fiji Basin was proposed to be the mirror site (near antipode) of the Gulf of Guinea source instead of an independent source, assuming that the surface waves more efficiently propagate along the major-arc paths of oceanic movements. To investigate the propagation of the Rayleigh waves along continental and oceanic paths, we analyzed the surface wave data recorded from an earthquake near the Gulf of Guinea and found that Rayleigh waves travel along continental minor-arc paths more efficiently than along oceanic major-arc paths. We then located the source in the western Pacific Ocean from group velocities measured with earthquake data by using the travel time misfit in NCFs after calibration and concluded that the source is in the Vanuatu Islands. Moreover, the temporal variation of the 26 s microseismic peak observed in the western Pacific seismic stations is very different from that in stations near the Gulf of Guinea, which suggests that they are excited by independent sources. Therefore, the Vanuatu source should be an independent microseismic source. As it is close to volcanoes in the Vanuatu islands, the Pacific 26 s microseismic source might be excited by magmatic processes, which are also responsible for very-long-period volcanic tremors.     

Survey of Geomagnetic Observations Made in the Northern Sector of Russia and New Methods for Analysing Them

An overview of the geomagnetic observations made in the northern part of Russia is presented from a historical perspective. Several stations were deployed on the territory of the former Soviet Union during the International Geophysical Year, 1957–1958, with the active participation and guidance of the Interagency Geophysical Committee which is inherited by the Geophysical Center of the Russian Academy of Sciences (GC RAS). In the 1990s, the majority of these stations, especially those in the remoter regions, were closed. Nowadays, the geomagnetic network, including the observatories of the INTERMAGNET program, has been restored. Examples of high-latitude geomagnetic variations in the Russian longitudinal sector are shown, and maps and trends of the secular variation over the territory of Russia presented. Particular attention is paid to the automated processing of data and to the analysis methods used. To process the growing amount of high-resolution geomagnetic data, sophisticated mathematical methods based on the fuzzy logic approach and new discrete mathematical analysis algorithms have been developed. The formal methods and algorithms for recognizing both artificial and natural disturbances in the magnetograms are described.     

Expressions for the Global Gravimetric Moho Modeling in Spectral Domain

We apply a newly developed numerical method to improve the Moho geometry by the implementation of gravity data. This method utilizes expressions for the gravimetric forward and inverse modeling derived in a frequency domain. Methods for a spectral analysis and synthesis of the gravity field and crust density structures are applied in the gravimetric forward modeling of the consolidated crust-stripped gravity disturbances, which have a maximum correlation with the (a priori) Moho model. These gravity disturbances are obtained from the Earth’s gravity disturbances after applying the topographic and stripping gravity corrections of major known anomalous crust density structures; in the absence of a global mantle model, mantle density heterogeneities are disregarded. The isostatic scheme applied is based on a complete compensation of the crust relative to the upper mantle density. The functional relation is established between the (unknown) Moho depths and the complete crust-stripped isostatic gravity disturbances, which according to the adopted isostatic scheme have (theoretically) a minimum correlation with the Moho geometry. The system of observation equations, which describes the relation between spherical functions of the isostatic gravity field and the Moho geometry, is defined by means of a linearized Fredholm integral equation of the first kind. The Moho depths are determined based on solving the gravimetric inverse problem. The regularization is applied to stabilize the ill-posed solution. This numerical procedure is utilized to determine the Moho depths globally. The gravimetric result is presented and compared with the seismic Moho model. Our gravimetric result has a relatively good agreement with the CRUST2.0 Moho model by means of the RMS of differences (of 3.5 km). However, the gravimetric solution has a systematic bias. We explain this bias between the gravimetric and seismic Moho models by the unmodelled mantle heterogeneities and uncertainties in the CRUST2.0 global crustal model.