人工爆炸地震野外数据处理装置

1988年底在华南地区连县-港口近400km的测线上,首次使用了中国科学院地球物理研究所研制的人工爆炸地震野外数据处理装置.该装置由AT型微机及必要的接口板和外围装置组成,能在野外条件下把模拟或数字记录仪记录结果以数字数据形式输入计算机,并进行显示、打印、存储等操作.由于成功地解决了诸如磁带信号直接屏幕扫描搜寻,时间信号自动识别、解码,钟差和零时信号屏幕光点比测,采样率随磁带速度自动调节,多通道长时间信号连续存储,数字滤波和再采样,用普通打印机快速打印高分辨率图形等技术问题,我们在野外记录后2-3天内即能绘出全测线120道记录的剖面图,达到了前所未有的高速度.     

Linking variable explosion style and magma textures during 2002 at Stromboli volcano,Italy

Microtextural characteristics of fresh ejecta from Stromboli volcano were examined from three periods of differing eruption style and intensity in 2002. Activity shifted from relatively weak and infrequent ash-charged explosions during January through May into two broad cycles of waxing activity in June through late September, and late September through December, followed by the onset on 28 December of the 2002/2003 effusive eruption. Analyzed sets of lapilli from May, September/October, and 28 December show contrasts in the physical properties of magma resident in the shallow conduit during this range of activity. Three distinct textures are observed among the analyzed pyroclasts: low density (LD) with an abundance of subspherical bubbles, the presence of large, irregularly shaped bubbles, and a light-to-transparent glass matrix; transitional texture (TT) with an intermediate number of subspherical bubbles, a high frequency of large, irregularly-shaped bubbles, and a honey colored glass matrix; and high density (HD) with sparse relatively small bubbles, conspicuous large irregular bubbles, and a dark glass matrix. Observational and quantitative data (density, vesicle size) indicate that these textures are linked through variable residence time in Stromboli’s shallow conduit, with an ongoing evolution from LD to HD magma. Calculations suggest that residual LD magma will evolve to HD texture in a period of hours to days. Contrasting amounts of the LD, TT, and HD magmas are present in each sample, with the most TT in May, the most LD in September/October, and the most HD in December. This implies that the shallow magma had a different rheology at each collection period. The viscosity of LD and HD magmas are calculated to be in the range of 2,000 to 2,600 and 3,000 to 5,000 Pa s, respectively, which, with their changing proportions, must have implications for rates of bubble slug ascent and processes of fragmentation. This study suggests that an increasing maturity of magma in Stromboli’s shallow conduit (with resultant increase in viscosity) feeds back to reduce the intensity of explosions, whereas a steady flux of LD magma favors more powerful explosions.     

浅层人工地震的断层识别

在工程地质问题中,用浅层地震折射法识别断层,是地震勘探为工程地质服务的主要项目之一.本文讨论了通过正确设计观测系统,合理控制炸药量,正确掌握地震折射资料的解释方法,是正确识别断层的有效途径.     

远程事件次声监测中的信号参数二维子空间计算方法

越来越多的观测发现,在地震、火山爆发、泥石流等重大自然灾害发生前,常产生异常的次声信号,这为地震及其他自然灾害的预报工作增加了一种可能的信息;同时,次声还是监测大气层、浅地表爆炸的有效手段.在自然灾害和爆炸事件次声监测中,慢度和方位角等参数对于源信号传播、定位以及源性质识别等工作具有重要意义.然而,目前的慢度和方位角等参数的算法--频率波数（FK）分析法,尚存在精度和分辨率不高等问题,特别是对多源次声信号的识别能力较差.为提高次声信号的监测精度,基于次声信号和噪声的子空间不相关性,构建了次声信号慢度和方位角二维子空间计算模型,并在此基础上提出了一种高分辨率次声信号二维子空间算法,仿真实验和实际数据的对比分析结果表明：本文提出的方法在精度和分辨率方面明显优于FK法,且能够更好地分离多源次声信号.

     

Probabilistic analysis of crushed zone for rock blasting

Transmission of explosion waves through a rock medium causes a severe vibration that stimulates the mechanical behavior of rock mass. This stimulation imposes highly concentrated stresses on the ends of existing fine joints and depending on the toughness of the rock, causes them to propagate rapidly. Consequently, the propagation and joining of cracks form a crushed zone around the blast hole. Several studies are available in the literature to estimate the radius of crushed zone, deterministically. In this paper, however, a probabilistic approach has been adopted. This is because the initiation and propagation of cracks have a probabilistic nature, and neither the initial state of the rock nor the explosion load could be expressed in a fully deterministic way. Thus, after generating random values for involved parameters, including explosive density, detonation velocity, dynamic Young’s modulus, dynamic Poisson’s ratio, uniaxial compressive strength, and borehole radius, the Monte-Carlo sampling method was adopted to calculate the exceeding probability of the crushed zone radius from desired values. The results showed that the exceedance probability for the growth of cracks falls sharply by the increase in the crushed zone radius so that the probability of crushed zone radius longer than 0.5 m is less than one percent. The results of this study, compared to the deterministic models, provide advantages in that they are not only limited to a certain value for the crushed zone radius and show the probability of exceedance for any desired radius.     

Application of Explosion Method to Soft Foundation Treatment of Great-West Dyke,Lianyungang Port

Explosion for the treatment of underwater soft foundation is a technique newly developed in China. This paper describes the application of the method of explosion to underwater soft foundation treatment of the Great-West Dyke, Lianyungang Port, including the technical characteristics and the effect, selection of explosion parameters, workmanship of construction, requirements of quality and inspection, and the like.     

基于非线性时频分析的地震和爆破识别

利用非线性赵-阿特拉斯-马克斯(Zhao-Atlas-Marks)时频分析方法对地震和爆破进行分析,结果显示:爆破的时频谱的时频聚集性比地震的时频聚集性较好;地震P波的平均频率大于爆破P波的平均频率;地震S波的平均时频中心相对于爆破分布在时间—频率面左上角。     

Spatiotemporal variability of ocean chemistry in the early Cambrian,South China

Following the Ediacaran metazoan radiation, the “Cambrian Explosion” set up the major framework of todays’ animal phyla as well as modern marine ecosystem. Here, we present a preliminary investigation on the temporal and spatial (from shallow to deep waters) variations of the early Cambrian ocean chemistry in South China through analyzing a Fe-S-C systematic dataset integrated from literature. Our investigation indicates that the early Cambrian deep ocean in South China was still anoxic and Fe²⁺-enriched (i.e., ferruginous) although its surface was oxic, and in between a metastable euxinic (anoxic and sulfidic) water zone may have dynamically developed in anoxic shelf waters with an increasing weathering sulfate supply. Furthermore, accompanying marine transgression and regression cycles in the early Cambrian, such a “sandwich” structure in ocean redox chemistry demonstrates five evolutional stages, which can be well correlated to the spatiotemporal patterns of fossil records in South China. The good correlation between metazoan fossil occurrences and water chemistry in South China suggests that early animals possibly possessed ability to inhabit anoxic but generally not euxinic environments as free H₂S was fatal to most eukaryotes. This view can well explain why those small shell fauna and sponges disappeared from shelf to slope areas where sulfidic Ni-Mo-rich shales were widely deposited. Thus, we conclude that the spatiotemporal variations of ocean chemistry and its biological effects probably played a key role in the phased animal radiations and “extinctions” in the early Cambrian.     

乌拉特前旗爆破与地震识别

2004年1～5月，内蒙古乌拉特前旗一带出现中小地震记录明显增多现象，在此期间，该区高速公路施工，新增许多爆破点。选取1～5月乌拉特前旗发生的45次地震事件，通过对模拟地震波形与数字地震波形对比和爆破与地震的震相分析，共识别出爆破5次，占该区地震总数的11．1％，排除人工爆破导致乌拉特前旗“窗口”中小地震记录增多的可能性，表明地震“窗口”中小地震活动明显增强。     

Reviewing pre-TRANSALP DSS models

The interpretation of DSS (deep seismic soundings) profiles in Central and Eastern Alps is recalled in the paper and the models of the lower crust and Moho proposed several years ago are compared to the results of the TRANSALP seismic reflection profile. This evaluation highlights a good agreement as far as the geometry of the deep crustal structure is concerned. Therefore, the reliability of the interpretative models, previously exclusively based on DSS profiles, becomes improved. The deep structure beneath the whole Alpine range is examined reconsidering the map of the Moho boundary and the structural model already proposed for the central-eastern sector. Five main interpretative transects are put side by side, starting from the Western Alps and moving eastwards to the Swiss–Lombardian Central Alps (“European Geotraverse”), to the cross section from southern Bavaria to the Euganei Hills, to the TRANSALP profile, and finally to the easternmost profile available so far (southern Bavaria–Trieste). The comparison outlines lateral variations of the deep crustal structure as well as a sharp contrast between the Adria and the European lower crust and Moho. The transition from the Adria plate to the Dinaric domain remains, up to now, undefined.