2019-12-26湖北应城M4.9地震强震动特征分析     

李恒  雷东宁  范珂显 《大地测量与地球动力学》2020,40(6):551-554

对2019-12-26湖北应城M4.9地震的强震加速度记录进行基线校正和滤波处理,分析地震动场的分布特征。结果表明,此次地震记录的峰值加速度（PGA）随距离衰减较快;场地效应、上盘效应和破裂方向性效应共同导致地震动产生巨大差异。对应城地震台的强震记录进行旋转,其顺断层方向记录与垂直断层向和垂直向记录差异明显,存在一段周期约为0.3 s的类简谐强震动,与以走滑为主的震源机制相吻合。  相似文献   

Spreading change of Africa–South America plate: insights from space geodetic observations     

Shuanggen Jin  J. Wang 《International Journal of Earth Sciences》2008,97(6):1293-1300

The results derived from geological data show that the half-spreading rate between the African and South American plates has remained relatively constant at 2 cm/year over the past 80 million years (Silver et al. in Science 279:60–63, 1998). In this paper, we have reestimated a new relative angular velocity of Africa–South America plates using the selected space geodetic station data through a new method. Our angular velocity estimates the spreading rates of Africa–South America plate over several years that are similar in azimuth but significantly slower in rate than the NUVEL-1A predictions averaged over the past 3 million years. The implied rates of deceleration coincide with longer-term trends over the past 35 million years and may reflect the effects of plate interaction and coupling of Africa–South America plates. An erratum to this article can be found at  相似文献   

Development of a geotechnical and geophysical database for seismic zonation of the Ankara Basin,Turkey     

Mustafa K. Koçkar  Haluk Akgün 《Environmental Geology》2008,54(1):165-182

The Kocaeli earthquake (M _w = 7.4) of 17 August 1999 occurred in the Eastern Marmara Region of Turkey along the North Anadolu Fault and resulted in a very serious loss of life and property. One of the most important geotechnical issues of this event was the permanent ground deformations because of both liquefaction and faulting. These deformations occurred particularly along the southern shores of ?zmit Bay and Sapanca Lake between the cities of Yalova and Adapazar? in the west and east, respectively. In this study, three sites founded on delta fans, namely De?irmendere Nose, Yeniköy tea garden at Seymen on the coast of ?zmit Bay, and Vak?f Hotel site on the coast of Sapanca Lake were selected as typical cases. The main causes of the ground deformations at these sites were then investigated. Geotechnical characterization of the ground, derivation of displacement vectors from the pre- and post-earthquake aerial photographs, liquefaction assessments based on field performance data, and analyses carried out using the sliding body method have been fundamental in this study. The displacement vectors determined from photogrammetric evaluations conducted at De?irmendere and Seymen showed a combined movement of faulting and liquefaction. But except the movements in the close vicinity of shorelines, the dominant factor in this movement was faulting. The results obtained from the analyses suggested that the ground failure at De?irmendere was a submarine landslide mainly because of earthquake shaking rather than liquefaction. On the other hand, the ground failures at the Yeniköy tea garden on the coast of Seymen and the hotel area in Sapanca town resulted from liquefaction-induced lateral spreading. It was also obtained that the ground deformations estimated from the sliding body method were quite close to those measured by aerial photogrammetry technique.  相似文献   

The analysis of ground vibrations induced by bench blasting at Akyol quarry and practical blasting charts   总被引：3，自引：0，他引：3  

Umit Ozer  Ali Kahriman  Mehmet Aksoy  Deniz Adiguzel  Abdulkadir Karadogan 《Environmental Geology》2008,54(4):737-743

Ground vibrations arising from excavation with blasting is one of the fundamental problems in the mining industry. Therefore, the prediction of ground vibration components plays an important role in the minimization of environmental complaints. In this study, 582 events were recorded during limestone production at a quarry (Akyol Quarry) during a period of time. The blasting parameters of these shots were also carefully recorded. During the statistical analysis of the collected data, three predictor equations proposed by the United States Bureau of Mines (USBM), Ambraseys–Hendron and Langefors–Kihlstrom were used to establish a relationship between peak particle velocity and scaled distance described by these prediction equations. As a result of this analysis, the most powerful relationship was determined and proposed to be used in this site. And also, this equation was used in the derivation of the practical blasting charts specific to this site as a practical way of predicting the peak particle velocity and maximum charge amount per delay for future blasting.  相似文献   

Frequency domain electromagnetic and ground penetrating radar investigation of ephemeral streams: case study near the Southern High Plains,Texas     

Jeffrey Burrell  Harold Gurrola  Kevin Mickus 《Environmental Geology》2008,55(6):1169-1179

A frequency domain electromagnetic (FDEM) and ground penetrating radar (GPR) study was conducted on an ephemeral stream in north-central Texas to determine if FDEM and GPR measurements can be combined to determine the electrical characteristics of current and ancient stream channels. GPR data were collected at several frequencies to image sedimentary structures of different scale lengths, and to determine the formation porosity and water content of stream sediments. FDEM measurements were collected using Geonics EM31 and EM34 loop–loop instruments on a profile along the current stream channel and five profiles perpendicular to the channel. The results indicate that the greater spatial resolution of the EM31 mapped the current and possible ancient channels better than the EM34, however, the EM34 provided depth information on the formations underlying the channel sediments that the EM31 could not image. GPR measurements taken along a point bar deposit with 200, 100 and 25 MHz antennae indicated that the higher frequency antenna better resolved channel structures including laminar bedding, trough scours and cross-bedding, however, lower frequency antenna (25 MHz) imaged sedimentary structures within the underlying channel sediments. Common midpoint GPR measurements collected along the point bar deposit were used to estimate the sediment formation porosity (26%) and the water content, during a dry period, of the unsaturated (12%) and saturated (26 or 100% of the pore space) sediments. The combined results indicated that the FDEM data should be collected first because of the speed and ease of measurements. The FDEM data (especially the EM31) pointed to the locations of possible sedimentary structures, which can then be resolved by using different frequency GPR measurements.  相似文献   

Reinforcing Coal Mine Roof with Polyurethane Injection: 4 Case Studies   总被引：2，自引：1，他引：1  

Gregory Molinda 《Geotechnical and Geological Engineering》2008,26(5):553-566

NIOSH has recently completed a study of the interaction between polyurethane (PUR) and coal mine roof in order to determine the mechanism of reinforcement, in both highly fractured rock and unfractured rock. Four case studies of PUR reinforcement are presented. At a West Virginia site, a borehole camera revealed the location of roof voids and guided the PUR injection. By injecting polyurethane into a zone from 0.6 to 1.8 m (2–6 ft.) high in the roof, a roof beam was created and ongoing intersection falls were halted. In another highly fractured roof in a western Pennsylvania mine, a total of 5.8 cm (2.3 in.) of rubbleized rock was found in a zone up to 3 m (10 ft.) into the roof. Untargeted PUR injection filled approximately 1/2 of the fractures. These two case studies showed that it is not necessary to fill up 100% of the void space to create stability. In the other two field sites, polyurethane was injected into weak, but unfractured roof. Post-injection video monitoring showed that weak bedding planes were hydraulically wedged open and polyurethane injected along bedding. The reinforcement value of this injection method is limited because of the wafer-thin layer of PUR introduced along bedding, and the lack of a PUR “webbing” which would serve as a structural framework to provide strength. It was determined that video inspection prior to PUR injection can aid in identifying the fracture zones to target, and minimize “blind” pumping and loss of PUR.  相似文献   

Variations in the accuracy of gravity recovery due to ground track variability: GRACE,CHAMP, and GOCE   总被引：4，自引：2，他引：2  

J. Klokočník  C. A. Wagner  J. Kostelecký  A. Bezděk  P. Novák  D. McAdoo 《Journal of Geodesy》2008,82(12):917-927

Following an earlier recognition of degraded monthly geopotential recovery from GRACE (Gravity Recovery And Climate Experiment) due to prolonged passage through a short repeat (low order resonant) orbit, we extend these insights also to CHAMP (CHAllenging Minisatellite Payload) and GOCE (Gravity field and steady state Ocean Circulation Explorer). We show wide track-density variations over time for these orbits in both latitude and longitude, and estimate that geopotential recovery will be as widely affected as well within all these regimes, with lesser track density leading to poorer recoveries. We then use recent models of atmospheric density to estimate the future orbit of GRACE and warn of degraded performance as other low order resonances are encountered in GRACE’s free fall. Finally implications for the GOCE orbit are discussed.  相似文献   

城市形态的分维估算与分形判定   总被引：3，自引：3，他引：0  

陈彦光 《地理科学进展》2017,36(5):529-539

城市形态的分形是城市发育到一定阶段涌现出的有序格局和复杂结构,其基本特征是空间分布的无尺度性质。当研究者基于某个显著性水平推断城市分维存在时,实际上就是基于相应的置信度判断分形特征。虽然分形城市研究已经多年,但大量有关维数测算的基础问题依然悬而未决。本文根据分形几何学的基本思想论证城市形态分维测算的若干问题。分维测量的准则是最佳覆盖——不多不少、恰到好处的覆盖。盒子覆盖是最容易理解的测量方法。采用盒子覆盖法测量城市形态分维时,应考虑三个标准：一是快速逼近,二是简便操作,三是稳定拟合。直观估计分维的办法是利用双对数坐标图。由于城市形态不是严格意义的分形,而是类似于文献中的“前分形”,测量尺度与相应测度的幂律关系通常仅在一定尺度范围内有效,从而形成所谓标度区。本文围绕城市形态的分维测量和分形判断开展一系列讨论,包括尺度选取、标度区识别和统计标准等问题,对今后城市分形研究具有理论启示和方法论的参考价值。  相似文献   

珠江三角洲晚第四纪垂直构造运动速率   总被引：8，自引：1，他引：8       下载免费PDF全文

陈伟光  赵红梅  常郁  卢邦华 《地震地质》2001,23(4):527-536

根据珠江三角洲 16 6个第四纪古三角洲沉积物的测年数据 ,在扣除了古海平面变化、沉积层的压实效应和地壳静力均衡沉降等非构造因素的影响后 ,估算出晚第四纪以来三角洲地区的垂直构造运动速率。估算按北东、近东西和北西向 3组断裂所切截的 11个断块构造区分别进行。结果表明 ,位于三角洲南部的斗门断块和中部的广州 -番禺断块的活动速率相对较高 ,这个特征得到了三角洲晚第四纪古地理演变、断层活动年代学和地震活动研究的初步验证  相似文献   

地震动加速度过程的小波模拟   总被引：3，自引：0，他引：3  

谢异同  张同亿  吴敏哲 《地震工程与工程振动》2001,21(2):19-23

本文应用基数B－样条小波模拟地震动加速度过程，将小波分析引入地震动加速度过程的研究，实现了地震动加速度的模拟，并可给出其解析表达式，便于设计地震动的调整及地震反应的求解。  相似文献