Characteristics of coseismic water level changes at Tangshan well for the Wenchuan MS_8.0 earthquake and its larger aftershocks     

Baojun Yin      Li Ma Huizhong Chen Jianping Huang  Chaojun Zhang  Wuxing Wang 《地震学报(英文版)》2009,(2):149-157

Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parameters(maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earth-quake parameters(magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from ...  相似文献   

Mean sea level trends around the English Channel over the 20th century and their wider context     

Ivan Haigh  Robert Nicholls  Neil Wells 《Continental Shelf Research》2009

This paper provides estimates of rates of change in mean sea level around the English Channel, based on an extensive new hourly sea level data set for the south coast of the UK, derived from data archaeology. Mean sea level trends are found to vary by between 0.8 and 2.3 mm/yr around the Channel. The rates of mean sea level change are calculated by removing the coherent part of the sea level variability from the time series of annual mean sea level before fitting linear trends. The improvement in accuracy gained by using this approach is assessed by comparing trends with those calculated using the more traditional method, in which linear trends are fitted directly to the original records. Removal of the coherent part of the sea level variability allows more precise trends to be calculated from records spanning 30 years. With the traditional approach 50 years is required to obtain the same level of accuracy. Rates of vertical land movement are approximated by subtracting the mean sea level trends from the most recent regional estimate of change in sea level due to oceanographic processes only. These estimated rates are compared to measurements from geological data and advanced geodetic techniques. There is good agreement around most of the UK. However, the rates estimated from the sea level records imply that the geological data suggest too much submergence along the western and central parts of the UK south coast. Lastly, the paper evaluates whether the high rates of mean sea level rise of the last decade are unusual compared to trends observed at other periods in the historical record and finds that they are not.  相似文献   

A complex geophysical observation station: Results of multiyear research     

S. V. Bekhterev  O. S. Kazantseva  A. B. Manukin  V. I. Rebrov  N. G. Sivodedova 《Seismic Instruments》2009,45(1):27-33

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小波变换在关中井水位资料分析中的应用   总被引：2，自引：0，他引：2  

邢西淳  毛娟  邵辉成  张世民 《高原地震》2009,21(4):1-8

利用小波变换和多尺度分析原理,对周至井、三原井7年的水位日均值序列进行了分析,将周至井、三原井水位资料中的不同周期成分进行了有效分离,小波变换分解结果能够更直观和显著地反映地震活动,特别是印尼8．7级、汶川8．0级特大地震及其中强余震异常显示明显。对甘东南地区的5级以上地震也有较明显的前兆反映,表明小渡分析在处理和分析水位资料方面是一种有效的方法。  相似文献   

Reconstruction of paleocoastlines for the northwestern South China Sea since the Last Glacial Maximum   总被引：1，自引：0，他引：1  

YanTao Yao  Jan Harff  Michael Meyer  WenHuan Zhan 《中国科学D辑(英文版)》2009,52(8):1127-1136

The range of relative sea level rise in the northwestern South China Sea since the Last Glacial Maximum was over 100 m. As a result, lowland regions including the Northeast Vietnam coast, Beibu Gulf, and South China coast experienced an evolution from land to sea. Based on the principle of reconstructing paleogeography and using recent digital elevation model, relative sea level curves, and sediment accumulation data, this paper presents a series of paleogeographic scenarios back to 20 cal. ka BP for the northwestern South China Sea. The scenarios demonstrate the entire process of coastline changes for the area of interest. During the late glacial period from 20 to 15 cal. ka BP, coastline slowly retreated, causing a land loss of only 1×10⁴ km², and thus the land-sea distribution remained nearly unchanged. Later in 15–10 cal. ka BP coastline rapidly retreated and area of land loss was up to 24×10⁴km², causing lowlands around Northeast Vietnam and South China soon to be underwater. Coastline retreat continued quite rapidly during the early Holocene. From 10 to 6 cal. ka BP land area had decreased by 9×10⁴km², and during that process the Qiongzhou Strait completely opened up. Since the mid Holocene, main controls on coastline change are from vertical crustal movements and sedimentation. Transgression was surpassed by regression, resulting in a land accretion of about 10×10⁴km². Supported by Key Laboratory of Marginal Sea Geology, Chinese Academy of Sciences (Grant No. MSGL0711), the Guangdong Natural Science Foundation (Grant No. 04001309) and Open Fund of the Key Laboratory of Marine Geology and Environment, Chinese Academy of Sciences (Grant No. MGE2007KG04)  相似文献   

ENSO signals and their spatial-temporal variation characteristics recorded by the sea-level changes in the northwest Pacific margin during 1965–2005     

LinWang Yuan  ZhaoYuan Yu  ZhiRen Xie  ZhiYao Song  GuoNian Lü 《中国科学D辑(英文版)》2009,52(6):869-882

Sea-level is closely linked to the Earth’s climate and its change is important as a metric for global and regional climate change. Identifying, extracting, and revealing such information through detailed analysis is the prerequisite for understanding the mechanisms of sea-level change. The monthly- average tide-change records reported and examined in this paper are from 10 tide gauge stations distributed in the northwest margin of the Pacific Ocean, registered during the period 1965-2005. In particular, we have utilized the Second Order Blind Identification (SOBI) method to identify and the Empirical Mode Decomposition (EMD) method to extract the El Niño-Southern Oscillation (ENSO) signals imprinted in those tide gauge records; and subsequently, we have investigated the spatial-temporal characteristics of the extracted ENSO signals using wavelet analysis methods. The following results are obtained: (1) the ENSO events recorded by each tide gauge series are of different types and intensity, which show considerable temporal-spatial variation characteristics, with sea-level responses to ENSO signals remarkably stronger in low latitude areas than in medium-high latitude areas; (2) due to the influences of ocean currents, topographical conditions, and other factors, there exist variations in the type of relationship between the sea-level changes and the recorded ENSO events at different latitudes; (3) sea-level changes can also denote scale-variation characteristics of ENSO events, and particularly, since 1980s, all the tide gauges located south of Kanmen show intense responses to ENSO and the timescale of ENSO events extended gradually from around 4 years to 2–8 years, reflecting variations in the intensity and frequency of ENSO events; and (4) reverse changes of certain scale were noted before and after strong ENSO events recorded by sea-level changes, supporting the research findings about the interaction (mutual coupling and superimposition) between the probability of occurrence of strong ENSO events and their time scale.  相似文献   

ENSO signals and their spatial-temporal variation characteristics recorded by the sea-level changes in the northwest Pacific margin during 1965-2005     

YUAN LinWang  YU ZhaoYuan  XIE ZhiRen  SONG ZhiYao & Lü GuoNian School of Geographical Science  Nanjing Normal University  Nanjing  China 《中国科学D辑(英文版)》2009,(6)

Sea-level is closely linked to the Earth's climate and its change is important as a metric for global and regional climate change. Identifying, extracting, and revealing such information through detailed analysis is the prerequisite for understanding the mechanisms of sea-level change. The monthlyaverage tide-change records reported and examined in this paper are from 10 tide gauge stations distributed in the northwest margin of the Pacific Ocean, registered during the period 1965-2005. In particular, we ha...  相似文献   

基于性能的结构抗风设计理论框架   总被引：2，自引：0，他引：2  

周云  汪大洋  陈小兵 《地震学刊》2009,(3):244-251

提出了基于性能的结构抗风设计理论框架,将风压强度划分为4个设计风压等级（弱风压、中风压、强风压及超强风压）,将人体振动舒适度划分为6个等级（无振感、轻微振感、中等振感、烦恼、非常烦恼和无法忍受）、三种振动水平（与人的舒适感相关的振动水平、与人正常工作和操作有关的振动水平、与人的生理健康直接相关的振动水平）。结合不同类别建筑物的性能需求及人体振动舒适度的要求,将结构风振性能水准划分为4种状态（性能健康、性能亚健康、性能病态及性能丧失）,将结构风振性能目标划分为5个等级（A、B、C、D、E）。提出了结构抗风概念设计与计算分析的一般原则,给出了结构性能抗风安全性评价及社会经济评价基本内容的建议。  相似文献   

地下流体水位观测地震前兆机理研究   总被引：2，自引：0，他引：2  

明成山  纪延辉  查楠  吕强 《东北地震研究》2009,25(2):41-50

本文主要研究锦州沈家台汤池子观测站地下流体数字化水位的年、月、日动态特征及数字化资料映震性能分析。检验理论固体潮与实际观测水位的潮汐因子、相对误差,排除气压对水位观测的干扰因素,识别水位观测水动态中较大幅度的脉冲和突变、阶变、潮汐畸变,水位上升打破年变等因素,提高利用地下流体观测地震前兆的监测效能。  相似文献   

Regional patterns of observed sea level change: insights from a 1/4° global ocean/sea-ice hindcast     

Alix Lombard  Gilles Garric  Thierry Penduff 《Ocean Dynamics》2009,59(3):433-449

A global eddy-admitting ocean/sea-ice simulation driven over 1958–2004 by daily atmospheric forcing is used to evaluate spatial patterns of sea level change between 1993 and 2001. In the present study, no data assimilation is performed. The model is based on the Nucleus for European Models of the Ocean code at the 1/4° resolution, and the simulation was performed without data assimilation by the DRAKKAR project. We show that this simulation correctly reproduces the observed regional sea level trend patterns computed using satellite altimetry data over 1993–2001. Generally, we find that regional sea level change is best simulated in the tropical band and northern oceans, whereas the Southern Ocean is poorly simulated. We examine the respective contributions of steric and bottom pressure changes to the total regional sea level changes. For the steric component, we analyze separately the contributions of temperature and salinity changes as well as upper and lower ocean contributions. Generally, the model results show that most regional sea level changes arise from temperature changes in the upper 750 m of the ocean. However, contributions of salinity changes and deep steric changes can be locally important. We also propose a map of ocean bottom pressure changes. Finally, we assess the robustness of such a model by comparing this simulation with a second simulation performed by MERCATOR-Ocean based on the same core model, but differing by its short length of integration (1992–2001) and its surface forcing data set. The long simulation presents better performance over 1993–2001 than the short simulation, especially in the Southern Ocean where a long adjustment time seems to be needed. In memory of my little brother Jean-Eudes, whose thirst for science filled out the rich discussions we had about my investigations and his job as user-service provider for MERCATOR-Ocean.  相似文献