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2010年9月3日16时35分46秒新西兰南岛Greendale附近发生了Mw7.0地震,震源深度约10.0 km.2011年2月21日新西兰南岛又发生了Mw6.1地震,为2010年Mw7.0主震后最大的一次余震,震源深度约5.0 km,发震断层为Christchurch南约9 km一条近东西走向逆冲的隐伏断层,该地震造成Christchurch城内多处建筑物严重损毁.本文分析了2010年新西兰地震事件Mw7.0主震与Mw6.1余震强地面运动的特征.新西兰Mw6.1余震近场强地面运动整体高于Mw7.0主震.将主震和余震的强震观测记录分别与新一代衰减关系(NGA)进行对比,发现余震强震观测数据整体高于其震级对应的NGA.分别选取距离主震和余震震中最近且强震观测记录最高的两个台站(GDLC台站和HVSC台站)作为参照台站,建立动态复合震源模型(DCSM)及有限断层随机振动模型(SFFM)进行强地面运动的模拟计算,分析两种模型的模拟结果并对比二者的优势及局限,以便在未来工作中更好地通过模型计算强地面运动特征,实现区域化特征快速、实时分析及局部重点、细致分析相结合的目标. 相似文献
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Assessing entrainment of bed material in a debris‐flow event: a theoretical approach incorporating Monte Carlo method
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Entrainment of underlying bed sediment by a debris flow can significantly increase the debris‐flow magnitude. To study this phenomenon, a theoretical approach to assessing bed‐sediment entrainment is presented. The approach is based on a static approximation that bed‐sediment entrainment occurs when the shearing stress of the flow is sufficiently high to overcome the basal resistance of the bed sediment. In order to delineate erodible zones in a channel, we analyze the critical condition of this static equilibrium model, and subsequently propose a new concept of a critical line to detect the entrainment reaches in a channel. Considering the spatial and temporal uncertainties of the input parameter, the approach is further incorporated within a Monte Carlo method, and the distribution of entrainment zones and post‐entrainment volumes can be analyzed. This approach is illustrated by back‐analysis of the 2010 Yohutagawa debris‐flow event, Japan. Results from 10 000 trials of Monte Carlo simulation are compared with the in situ surveys. It is shown that the present approach can be satisfactorily used to delineate erodible zones and estimate possible entrainment volume of the event. Discussion regarding the sensitivities and limitations of the approach concludes the paper. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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对大型湖泊盆地沉积物粒度组成进行研究,有助于解读全球致密油气和页岩油气勘探开发与其记录的古气候信息。
文章对青海湖沉积物粒度时空分布进行了详细的研究,通过采集覆盖大部分湖区的27根近现代沉积岩芯,并对湖心的三根
典型沉积岩芯进行了137Cs测定获取沉积岩芯的年龄;基于磁化率地层年龄模式,建立了整个湖区沉积岩芯的年代框架。粒
度分析结果显示,青海湖岩芯沉积物的粒度分布呈多峰,以细颗粒沉积为主,其中粉砂含量60%~70%,粘粒组分为10%~
35%,砂粒组分低于20%。青海湖沉积物的粒度变化在空间上相对较复杂,中值粒径呈现明显的砂岛附近、西部和西南湖
区高,其他湖区低的特征。在时间上,大体上自1960年到2017年呈现变粗的趋势,砂粒组分增多,粘粒组分减少。这些粒
度的时空变化可能是受风砂活动、流域土壤侵蚀、河流径流变化、湖平面变化和人类活动共同作用而成。 相似文献
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选取2010年3月24日西藏聂荣MS5.7和MS5.5地震前后的中国FY-2E静止气象卫星热红外遥感亮温和长波辐射数据, 对红外辐射数据采用阈值法进行去云预处理, 基于Morlet小波方法计算地震前后的红外辐射功率谱变化, 探讨地震前后红外辐射异常演变规律及特征。 研究结果显示, 西藏聂荣地震前出现了亮温和长波辐射异常增强现象, 并且其异常持续时间和主要异常区域基本一致, 但亮温的异常幅度大于长波辐射的异常幅度。 本研究对于该区域利用热红外遥感数据进行地震研究具有重要的参考价值和意义。 相似文献
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The published global ocean tide models show good agreement in deep oceans and exhibit differences in complex coastal areas, along with subsequent Ocean Tide Loading Displacement (OTLD) modeling differences. Meanwhile, OTLD parameters (amplitudes and phase lags) derived by Global Positioning System (GPS) Precise Point Positioning (PPP) approach need long time to converge to a stable state and show poor precision of S2, K1, and K2 constituents. Based on the fact that no constraint is imposed in the current kinematic solution, a new method is put forward, in which global ocean tide model predictions are taken as the priori information constraints to speed up the convergence rate and improve the accuracy of the GPS-derived OTLD parameters. First, the data of tide gauge from 01 January 2014 to 31 December 2016 are used to generate the harmonic parameters to evaluate the accuracy of six global ocean tide models and a regional ocean tide model (osu.chinesea.2010). Osu.chinesea.2010 model shows good agreement with the tide gauge results, while NAO99b model presents relatively large difference. The predictions from osu.chinesea.2010 and NAO99b model are employed as reference and the prior information, respectively. Second, continuous observations of 12 GPS sites during 2006–2013 in Hong Kong are collected to generate three dimensional OTLD amplitudes and phase lags of eight constituents using PPP with prior information constraints approach and harmonic analysis. Third, comparing the convergence time of eight constituents from PPP without and with priori information constraints approaches, the results show that the new method can significantly improve the convergence rate of OTLD amplitude estimates which obtain a certain level of stability seven years earlier than that derived by the PPP without priori information constraints. Precision of OTLD parameters derived by the new method is about 1 mm. By comparing with the precision of single PPP approach, the accuracy of eight constituents has been improved, especially for S2, K1, and K2 constituents. Finally, through comparing the different correction effects of OTLD estimates on the coordinates and their time series of the ground GPS stations, the results show that OTLD estimates derived by the new approach have similar influence as the osu.chinasea.2010 ocean tide model. The new method provides an effective means to improve the convergence and precision of the GPS-derived OTLD parameters, and achieve a similar correction as the high precision ocean tide model. 相似文献
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1981—2010年东海及毗邻的西北太平洋表层盐度的气候态分布特征 总被引:1,自引:0,他引:1
使用SODA表层盐度月平均数据,通过计算逐点逐年盐度均值、月际差,绘制等值线分布图,分析在新的30年气候基准期(1981—2010年),东海及毗邻的西北太平洋海域表层盐度场气候态分布特征,为进一步研究该地区长时间序列的气候变化奠定基础。结果表明:(1)在研究区表层平均盐度从西北到东南逐渐升高,形成3个明显的盐度特征场区:东海大陆架海区、东海黑潮海区以及西北太平洋海区;(2)研究区月际表层盐度存在明显的周期性变化,其中,盐度最小值的周期性规律最显著;(3)在月际变化中,1—4月为盐度高值季节,以3月份盐度最高,为27.5psu;5—8月为盐度低值季节,以8月份盐度最低,为22psu;9—12月为盐度上升季节;(4)依据盐度场的分布,结合地形、气候、海流等特征和前人研究,在研究区选取了22个特征点,从特征点看,位于西北太平洋海区的特征点盐度月振幅最小;位于长江入海口附近的D1和位于杭州湾南部的D2盐度月振幅较大,但D1与D2月际变化曲线呈现较为明显的反相关特征,这可能与长江冲淡水水舌夏季北移抑制苏北沿岸流南下和北上的台湾暖流夏强冬弱有关。 相似文献
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本文用中国地磁场复测点和地磁台站资料,建立了2000年代中国参考地磁场长期变化模型CGRF-SV2000.模型显示,中国地区地磁场变化比较平缓,X、Y、Z、H、D、I、F七个地磁要素的“无符号平均年变率”分别为12.2 nT/a、8.2 nT/a、43.8 nT/a、11.8 nT/a、0.96(′)/a、2.99(′)/a、22.4 nT/a,比国际参考地磁场IGRF给出的全球年变率约小1/3到1/2.各地磁要素的变化显示,地磁北极正在向中国移近,或者说,中国正在向高地磁纬度方向移动,平均移动速度约为3(′)/a.磁偏角变化还显示,中国地区东西部偏角差异继续扩大.作为检验和对比研究,本文利用第8代国际参考地磁场(IGRF)模型,分析了全球地磁场长期变化的时空特征,讨论了全球长期变模型IGRF_SV与中国长期变模型CGRF_SV的异同点.对比分析表明,中国地区地磁场的长期变化与全球长期变化总趋势基本符合,但是,CGRF_SV也表现出一些特有的局部异常特征. 相似文献
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阐述了美国2000—2010年古生物研究的4个主要方向: ①生物多样性的驱动机制,这些机制所适用的时空尺度;②主要的生物演变时、空分布的不均一性;③生物系统如何影响地表的物、化性质,生物地球化学循环如何随时间发生变化?④生物圈对区域尺度和全球尺度环境变化的反应,以及每一个方向包含的主要科学问题.。最后阐述了运用古生物知识认识当代环境变化。 相似文献
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