Rupture nucleations in the 1995 Hyogo-ken Nanbu earthquake and its large aftershocks   总被引：1，自引：0，他引：1  

Bunichiro Shibazaki  Yasuhiro Yoshida  Mamoru Nakamura  Masao Nakamura  Hiroshi Katao 《Geophysical Journal International》2002,149(3):572-588

  相似文献   

Experimental and numerical study of current-induced artificial upwelling     

《Applied Ocean Research》2019

The aim of the current paper is to investigate hydrodynamic characteristics of the artificial upwelling induced by ocean currents. Experiments were performed in a flume at different density difference heads, horizontal current velocities and upwelling pipe diameters. A three-dimensional computational fluid dynamics (CFD) model was employed on wider range of parameters for further analysis. The performance of the numerical model has been confirmed by the experimental findings. The present results show that the volume flow rate of current-induced artificial upwelling is influenced by geometrical parameters and inclination angle of the pipe, the horizontal current velocity and vertical distribution of water density. In ideal two-layer density stratified water, the critical current velocity to generate upwelling linearly increases with the increase of the density difference, and the maximum rising height for upwelling is inversely proportional to the density difference. Feasibility analysis was taken by using current and density profiles of the East China Sea near Dongji Islands, which provides an useful reference for engineering practice.  相似文献   

秋刀鱼舷提网渔具性能模型试验与海上实测结果的比较评估   总被引：1，自引：0，他引：1  

石永闯  朱清澄  花传祥  张衍栋 《海洋学报》2019,41(2):123-133

舷提网是秋刀鱼（Cololabis saira）作业的主要方式之一,由于渔获率较高得到迅速推广。模型试验和海上实测是研究网具性能最为普遍的两种方式,两者试验结果的对比评估对于更好地测定网具作业性能具有十分重要的意义。根据2014年11-12月进行的秋刀鱼舷提网静水槽模型试验以及2015年7-10月和2016年6-10月在"鲁蓬远渔019"号船上进行的秋刀鱼舷提网网具性能测试试验测定的网具数据,采用多元线性回归方法,对网具的沉降深度和提升速度进行了标准化,并利用Bootstrap法分析了舷提网模型试验和海上实测试验结果。结果表明:（1）通过Bootstrap法得出标准化后的实测网最大沉降深度的均值分布范围为20.37~29.54 m,95%置信区间为21.76~28.13 m;模型网网具最大沉降深度均值的范围为26.42~37.58 m,95%置信区间为27.70~36.20 m。实测网网具中部最大沉降深度均值大约是模型网网具中部最大沉降深度均值的0.731~0.783倍。（2）通过Bootstrap法得出标准化后的实测网提升速度的均值分布范围为0.107~0.193 m/s,95%置信区间为0.111~0.191 m/s;模型网网具提升速度均值的范围为0.204~0.316 m/s,95%置信区间为0.207~0.312 m/s。实测网网具中部提升速度均值大约是模型网网具中部提升速度均值的0.591~0.611倍。（3）当假设海流速度为0时,求得实测网网具的平均沉降深度为29.14~41.21 m,约为模型网网衣中部最大沉降深度均值的0.751~0.807倍。（4）30 m和60 m水深的海流速度均对实物网网具中部的沉降深度有所影响,60 m水深的流速影响更加显著（P<0.05）。  相似文献   

Environmental responses of jellyfish polyps as drivers of medusa populations off the coast of Namibia     

L Ziegler  MJ Gibbons 《African Journal of Marine Science》2018,40(3):323-329

Jellyfish populations in the southeastern Atlantic off the coast of Namibia have increased subsequent to the decline of small pelagic fisheries at the end of the 1960s, although the environment there has also become warmer and the waters off Walvis Bay have become richer in zooplankton in recent years. Laboratory experiments were conducted with the scyphozoan jellyfish Chrysaora fulgida to investigate the effects of food density (0, 30, 70, 100 or 150 Artemia nauplii 200 ml^?1), feeding frequency (once daily or once every third day) and water temperature (12, 16 or 20 °C) on the asexual reproduction, growth and development of polyps. The results of a generalised linear mixed-effects model reveal that all variables impacted asexual reproduction, with greater polyp production attained at higher food concentrations, increased feeding frequencies and increased temperatures. The most common mode of asexual reproduction was by lateral budding. These laboratory results suggest that polyps of C. fulgida may have proliferated off Namibia in recent times, which would contribute to increased numbers of jellyfish there.  相似文献   

Effects of rising temperature on growth and energy budget of juvenile Eogammarus possjeticus(Amphipoda:Anisogammaridae)     

Suyan Xue  Yuze Mao  Jiaqi Li  Jianguang Fang  Fazhen Zhao 《海洋学报(英文版)》2021,40(9):82-89

Growth and energy budget of marine amphipod juvenile Eogammarus possjeticus at different temperatures(20°C,24°C, 26°C, 28°C, 30°C, 32°C and 34°C) were investigated in this study. The results showed that the cumulative mortality rate increased significantly with rising temperature(p0.01), and exceeded 50% after 24 h when temperature was above 30°C. With the temperature increasing from 20°C to 26°C, the ingestion rate and absorption rate increased, but decreased significantly above 28°C(p0.01), indicating a decline in feeding ability at high temperatures. The specific growth rate increased with rising temperature, but decreased significantly(p0.01) after reaching the maximum value at 24°C. Similarly, the oxygen consumption and ammonia emission rates also showed a trend of first increase and then decrease. However, the O:N ratio decreased first and then increased with rising temperature, indicating that the energy demand of E. possjeticus juvenile transferred from metabolism of carbohydrate and lipid to protein. In the energy distribution of amphipods, the proportion of each energy is different. With rising temperature, the ratio of the energy deposited for growth accounted for ingested gross energy showing a trend of decrease, while the energy lost to respiration, ammonia excretion, and feces accounted for ingested gross energy being showed a trend of increase. It seemed that rising temperature increased the metabolism and energy consumption of the amphipods and, meanwhile, decreased the energy used for growth, which may be an important reason for the slow growth and small body size of the amphipods during the summer high-temperature period.  相似文献   

Quantitative analysis of Arctic ice flow acceleration with increasing temperature     

Zemin Wang  Boya Yan  Songtao Ai  Kim Holmén  Jiachun An  Hongmei Ma 《海洋学报(英文版)》2021,40(1):22-32

This study explores the ice flow acceleration(21.1%) of Pedersenbreen during 2016–2017 after the extremely warm winter throughout the whole Arctic in 2015/2016 using in situ data and quantitatively analyses the factors contributing to this acceleration. Several data sets, including 2008–2018 air temperature data from Ny-?lesund,ten-year in situ GPS measurements and Elmer/Ice ice flow modelling under different ice temperature scenarios,suggest that the following factors contributed to the ice flow acceleration: the softened glacier ice caused by an increase in the air temperature(1.5℃) contributed 2.7%–30.5%, while basal lubrication contributed 69.5%–97.3%.The enhanced basal sliding was mostly due to the increased surface meltwater penetrating to the bedrock under the rising air temperature conditions; consequently, the glacier ice flow acceleration was caused mainly by an increase in subglacial water. For Pedersenbreen, there was an approximately one-year time lag between the change in air temperature and the change in glacier ice flow velocity.  相似文献   

从涨退水看鄱阳湖水位-湖面面积关系   总被引：1，自引：0，他引：1  

曾少龙  赖格英  杨涛 《水文》2019,39(3):46-51

鄱阳湖是我国最大的淡水湖,鄱阳湖水位-面积关系对研究鄱阳湖生态环境的变化具有重要意义。目前研究所建立的鄱阳湖水位-面积关系各异,存在一定的不确定性,其原因在于忽略了涨退水对鄱阳湖水位与面积的影响。在考虑鄱阳湖涨水与退水过程的基础上,利用鄱阳湖2000~2014年实测水位数据与对应的遥感影像数据,分析了鄱阳湖同一水位出现多个水面面积情况下湖泊不同面积的空间分布及其成因,并对鄱阳湖水面面积与水位关系的不确定性进行了分析。研究结果表明:(1)鄱阳湖水面面积与水位关系存在不确定性,主要受鄱阳湖涨水与退水过程中鄱阳湖水面比降不同的影响;(2)在同一水位条件下,涨水过程中鄱阳湖水面面积往往大于退水过程的水面面积,同时水面面积的增减变化与涨水退水的幅度变化趋势呈一致性;(3)涨水与退水过程对鄱阳湖水位与面积的影响主要表现在中低水位,随着水位增长到高水位时,这种影响会越来越小。  相似文献   

胶东地区玲珑双向变质核杂岩的均衡隆升：运动学涡度的指示     

吴晓冬  朱光 《地质学报》2024,98(1):31-49

在胶东半岛西北部,围绕着玲珑岩基所发育的早白垩世伸展构造,属于独特的双向变质核杂岩。这一变质核杂岩的东、西边界上,分别发育了倾斜相背的招平与焦家伸展拆离剪切带。双向变质核杂岩的剥露是否也有均衡隆升的贡献,一直没有明确的认识。本次工作以采自这两条边界拆离剪切带不同部位的糜棱岩样品为分析对象,分别应用刚性残斑长短轴比值法（具体又分别使用了Wallis投图法和刚性颗粒网格法）和石英c轴组构与主应变比值法对同一样品进行了运动学涡度测量。对于招平拆离剪切带,应用刚性残斑长短轴比值法获得的涡度值为0. 57~0. 73,而应用石英c轴组构与主应变比值法获得的涡度值为0. 80~0. 93。对于焦家剪切带,应用刚性残斑长短轴比值法获得的涡度值为0. 58~0. 74,而应用石英c轴组构与主应变比值法获得的涡度值为0. 79~0. 93。对于剪切带的同一样品,这两种测量方法给出的结果明显不同。应用刚性残斑长短轴比值法数据所获得这两条剪切带的减薄率,也明显高于应用石英c轴组构与主应变比值法数据的计算结果。理论分析与实例表明,刚性残斑长短轴比值法所获得的涡度值代表了剪切带的早期变形,而石英c轴组构与主应变比值法所得结果指示了晚期变形。由此表明,玲珑双向变质核杂岩边界拆离剪切带演化中,伴随着纯剪组分的明显降低,指示了剪切带产状的变陡,为均衡隆升的结果。均衡隆升发生在核杂岩演化的晚阶段,是早白垩世郭家岭期同构造花岗闪长岩侵位的响应。本文结果指示,双向与不对称变质核杂岩具有相似的演化规律,都经历过晚阶段均衡隆升,对中—下地壳的剥露具有重要的贡献。  相似文献   

渤海西岸致灾风暴潮的统计预报模型   总被引：2，自引：0，他引：2  

王月宾 《气象》2007,33(9):40-46

渤海西岸是风暴潮灾害多发区,1990年代以后发生几率和灾害损失明显增加。利用气象科学和海洋水文科学相结合的方法,依据黄骅港潮汐资料,对发生在渤海西岸的风暴潮进行统计分析。结果表明,台风和强冷空气配合气旋是造成渤海西岸风暴潮的主要天气系统,偏东大风增水和天文潮叠加是造成风暴潮的直接因素;风暴潮和天文潮汐都有半日潮现象。在此基础上,建立了渤海西岸风暴潮预报模型,通过台风或冷空气配合气旋影响时增水值的计算,结合天文潮汐资料,做出最高潮位预报。应用该预报方法对渤海西岸发生的7次风暴潮进行回报,预报值与实测值基本相当,是基层台站较实用的预报方法。  相似文献   

上海地区沿海岸线工程受相对海平面上升影响浅析     

丛林  许彰珉 《上海国土资源》2000,(1):6-10

由于受全球变暖和人类活动加剧的影响,预计到２０５０年上海地区海平原相对升高５０￣７０ｃｍ,这会给包括堤坝在内的沿海岸线工程带来新的危害：包括地下水位抬升引起浅基础承载力下降、砂土地震液化加剧和建筑物陷加重、堤坝标准、威胁堤坝安全等问题。从定量的角度研究分析上述危害的严重性,提出综合措施。  相似文献