CTS-1甚宽频带地震计

新建国家数字地震台网所使用的CTS-1甚宽频带地震计是一种具有甚宽频带、大动态范围、高灵敏度负反馈地震计。介绍了地震计的系统组成及工作原理。用多种方式给出了系统的传递函数，描述了仪器设计要点和系统测试，对仪器工作环境给予了特别的注意。最后简要介绍了地震计的应用情况。     

闪电起始过程时空特征的宽带干涉仪三维观测

闪电的起始位置和起始阶段发展速度是闪电研究中的重要问题。2010年夏季,使用架设在广州市从化区的两套甚高频 (VHF) 宽带干涉仪对闪电的起始阶段放电过程进行三维定位观测。对观测数据给出的地闪和云闪的起始高度分布特征以及起始阶段击穿过程的时空发展特征进行统计和对比分析,结果表明:闪电的起始高度分布呈双峰值特征,分别在5.0 km和8.8 km有两个明显的分布峰值,符合雷暴云三极性总体电荷结构的描述。对起始阶段闪电放电发展速度的计算表明,云闪和地闪在起始阶段的前15 ms内的平均发展速度均在104~105 m·s-1量级之间;多数云闪、地闪起始阶段前15 ms内的平均发展速度表现出减速趋势,但云闪个例中起始阶段前10 ms存在减速趋势的比例更高,且其中在前15 ms一直保持减速趋势个例所占比例也大于地闪。云闪和地闪的起始阶段放电过程的发展方向有向上、向下和水平发展3种情形,可用于指示闪电始发位置的环境电场方向。     

“孤石”精细探测物探方法研究 ——以福州滨海快线为例

孤石在我国南方花岗岩地区普遍存在,其发育无规律性,埋藏及分布较为随机;城市地铁盾构施工孤石探测是公认的技术难题。以福州滨海快线（机场—大鹤站）区间孤石分布区为研究区开展了微动、等值反磁通瞬变电磁、高密度电法、探地雷达探测方法综合勘察试验,从抗干扰能力、施工效率和探测效果方面进行了对比分析,发现因浅表存在高阻砂层屏蔽,高密度电法在15 m以浅具有较高勘察精度、受地下线网影响明显,探地雷达在砂层中的有效勘察深度仅4 ～ 5 m;优选出对于孤石体精细探测的物探方法,“微动 + 等值反磁通瞬变电磁”的组合方法具有抗干扰、较好探测效果,与钻孔验证结果吻合。     

Temporal observations of a seasonal snowpack using upward‐looking GPR

An increase of the spatial and temporal resolution of snowpack measurements in Alpine or Arctic regions will improve the predictability of flood and avalanche hazards and increase the spatial validity of snowpack simulation models. In the winter season 2009, we installed a ground‐penetrating radar (GPR) system beneath the snowpack to measure snowpack conditions above the antennas. In comparison with modulated frequency systems, GPR systems consist of a much simpler technology, are commercially available and therefore are cheaper. The radar observed the temporal alternation of the snow height over more than 2·5 months. The presented data showed that with moved antennas, it is possible to record the snow height with an uncertainty of less than 8% in comparison with the probed snow depth. Three persistent melt crusts, which formed at the snow surface and were buried by further new snow events, were used as reflecting tracers to follow the snow cover evolution and to determine the strain rates of underlaying layers between adjacent measurements. The height in two‐way travel time of each layer changed over time, which is a cumulative effect of settlement and variation of wave speed in response to densification and liquid water content. The infiltration of liquid water with depth during melt processes was clearly observed during one event. All recorded reflections appeared in concordance with the physical principles (e.g. in phase structure), and one can assume that distinct density steps above a certain threshold result in reflections in the radargram. The accuracy of the used impulse radar system in determining the snow water equivalent is in good agreement with previous studies, which used continuous wave radar systems. The results of this pilot study encourage further investigations with radar measurements using the described test arrangement on a daily basis for continuous destruction‐free monitoring of the snow cover. Copyright © 2010 John Wiley & Sons, Ltd.     

昆明地震台地面与井下地震计地震记录震级偏差

选取昆明基准地震台观测山洞内放置的宽频带地震计BBVS-60及井下放置的GL-S60B深井宽频带地震计记录资料,采用新的震级国家标准（GB17740-2017）,对地面及井下地震记录计算M_L、m_b、m_B（BB）、M_S、M_S（BB）等5种震级,得到2种地震计的震级偏差。结果显示,M_L平均偏差0.18,m_b、m_B（BB）平均偏差0,M_S平均偏差-0.02,M_S（BB）平均偏差-0.01。     

THE DELINEATION OF THREE-DIMENSIONAL SHALLOW GEOMETRY OF ACTIVE FAULT BASED ON TLS AND GPR: A CASE STUDY OF AN NORMAL FAULT ON THE NORTH MARGIN OF MAOYABA BASIN IN LITANG,WESTERN SICHUAN PROVINCE

It is crucial to reveal the surface traces and activity of active faults by obtaining high-precision microtopography and three-dimensional shallow geometry. However, limited by the traditional geological investigation methods in the field and geological condition factors, the measurement method on microtopography and shallow geometry of active fault is badly insufficient. In this study, the TLS and GPR are firstly used comprehensively to delineate the microtopography and shallow geometry of the normal fault scarp on the north margin of Maoyaba Basin in Litang. Firstly, the vertical displacements of two landforms produced by the latest two periods of normal faulting and the two-dimensional GPR profiles are obtained separately. Secondly, the three-dimensional measurement method of active fault based on TLS and GPR is preliminarily established. On this basis, three-dimensional model of fault scarp and three-dimensional images of subsurface geometry are also obtained. These data all reveal a graben structure at normal fault scarps. Thirdly, the fusion and interpretation of three-dimensional data from the surface and subsurface are realized. The study results show:1)the vertical displacements of the T₁ and T₂ terraces by the normal fault movement is 1.4m and 5.7m, the GPR profile shows a typical fault structure and indicates the existence of small graben structure with a maximum width of about 40m in the shallow layer, which further proves that it is a normal fault. 2)the shallow geometry of the normal fault scarp can be more graphically displayed by the three-dimensional radar images, and it also makes the geometry structure of the fault more comprehensive. The precise location and strike of faults F₁ and F₂ on the horizontal surface are also determined in the three-dimensional radar images, which further proves the existence of small graben structure, indicating the extensional deformation characteristics in the subsurface of the fault scarps. Furthermore, the distribution of small graben structure on the surface and subsurface is defined more precisely. 3)the integrated display of microgeomorphology and shallow geometry of normal fault scarp is realized based on the three-dimensional point cloud and GPR data. The fusion of the point cloud and GPR data has obvious advantages, for the spatial structure, morphological and spectral features from the point cloud can improve the recognition and interpretation accuracy of GPR images. The interpreted results of the GPR profiles could minimize the transformation of the surface topography by the external environment at the most extent, restore the original geomorphology, relocate the position and trend of faults on the surface and constrain the width of deformation zones under the surface, the geological structure, and the fault dislocation, etc. In a word, the TLS and GPR can quickly and efficiently provide the spatial data with multi-level and multi-visual for non-destructive inspection of the microgeomorphology and shallow structure for the active fault in a wide range, and for the detection of active fault in the complex geological environments, and it is helpful to improve the accuracy and understanding of the investigation and research on microtopography and shallow geometry of active faults. What's more, it also offers important data and method for more comprehensive identification and understanding of the distribution, deformation features, the behaviors of active faults and multi-period paleoseismicity. Therefore, to continuously explore and improve this method will significantly enhance and expand the practicability and application prospects of the method in the quantitative and elaborate studies of active faults.     

甚宽频带地震计噪声与环境耦合研究

首先以甚宽频带地震计为研究对象,分析垂直向的片簧系统理论模型,探讨气压变化对仪器的LP噪声影响;通过理论分析,得出垂直向的片簧系统受气压变化影响较大。根据片簧系统的理论模型,设计一种密封安装方法,通过实验探讨地震计噪声与环境耦合关系(气压、温度和底座变形的关系)。最后对实验数据进行功率谱噪声分析,结果显示抽真空后地震计三个分向的噪声均降低,其中在100 s处垂直向、东西和南北向分别降低了10 dB、5 dB和6 dB。     

易县台BBVS-120地震计记录重力固体潮能力分析

以河北省易县台BBVS-120甚宽频带地震计为研究对象,验证其垂直向地震记录波形中包含的长周期成分为重力固体潮,并运用小波变换方法提取地震记录中的固体潮信息;同时,通过对提取的固体潮信息进行Venedikov调和分析证明,易县地震台BBVS-120甚宽频带地震计可以记录重力固体潮信息。     

人工挖孔桩桩底探测方法与应用

在石灰岩地区的建筑基础设计为挖孔桩时,需进行桩底岩溶探测。本文介绍了3种可行的桩底探测方法,主要对地质雷达法与地震反射波法两种物探方法的基本原理及具体探测技术进行了介绍,通过对物探方法与传统钻探法进行有效组合可以提高人工挖孔桩桩底探测的效率和准确性。     

地质雷达在三峡工程施工应用研究

长江三峡工程施工阶段面临众多复杂的工程地质问题和施工技术难题,寻找一种快捷、高分辨无损探测手段查明施工中出现的隐蔽的地质缺陷或质量问题,无疑对施工进度和施工质量起到保证作用,采用地质雷达手段,探明了开挖过程中花岗岩体不均匀风化分布范围：圈定出较大断层及风化夹层的延伸范围和产状：并进行了专用高速公路质量检查等,文章结合三个实例介绍应用情况。经现场验证,探测结果与实际情况吻合,应用效果显著。