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1.
1960-2008年冬季期间,中国南方发生了23次低温冰冻(冻雨)天气事件,其中满足站日数大于10的事件有11次.2008年初中国南方发生了一场影响巨大的区域持续性低温冻雨天气事件,2011年初再次发生了类似的区域持续性低温冻雨事件.提前5天预报这类极端事件是国内外大气科学面临的难题.利用去逐日气候变化后的逐日850 hPa温度扰动,可以提前3~10天发现中国南方持续低温雨雪冰冻(冻雨)事件发生的信号.2008年初和2011初,影响中国南方的850 hPa冷空气扰动具有源地和路径相似性,它们都来自北非-中东并绕过青藏高原北侧到达中国南方,在对流层大气中形成"冷-暖-冷"的温度垂直结构.通过对欧洲中期天气预报模式产品中850 hPa温度扰动的相似性分析,成功地提前4~9天实际预报出了2011年初的中国南方低温冻雨天气过程. 相似文献
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Taketo Shimano Takeshi Nishimura Nobuyuki Chiga Yoshinobu Shibasaki Masato Iguchi Daisuke Miki Akihiko Yokoo 《Bulletin of Volcanology》2013,75(12):1-7
We develop an automatic system for the sampling of ash fall particles, to be used for continuous monitoring of magma ascent and eruptive dynamics at active volcanoes. The system consists of a sampling apparatus and cameras to monitor surface phenomena during eruptions. The Sampling Apparatus for Time Series Unmanned Monitoring of Ash (SATSUMA-I and SATSUMA-II) is less than 10 kg in weight and works automatically for more than a month with a 10-kg lead battery to obtain a total of 30 to 36 samples in one cycle of operation. The time range covered in one cycle varies from less than an hour to several months, depending on the aims of observation, allowing researchers to target minute-scale fluctuations in a single eruptive event, as well as daily to weekly trends in persistent volcanic activity. The latest version, SATSUMA-II, also enables control of sampling parameters remotely by e-mail commands. Durability of the apparatus is high: our prototypes worked for several months, in rainy and typhoon seasons, at windy and humid locations, and under strong sunlight. We have been successful in collecting ash samples emitted from Showa crater almost everyday for more than 4 years (2008–2012) at Sakurajima volcano in southwest Japan. 相似文献
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以2009-2010年发生在中国西南地区的持续性干旱事件为例,通过干旱和大气变量的物理分解得到了一些干旱事件发生的新认识.气象干旱多为年循环的气候干季与干旱扰动的叠加所致.一次干旱扰动大约为30-50天,而一次持续性干旱事件是由几次干旱扰动组成的.大气高度场和风场中存在三种时间尺度的扰动.一种是年际行星尺度的大气扰动,与ENSO冷暖事件有关,起源于赤道并传播到中高纬度地区需要2-4年.另一种是季节内行星尺度的大气扰动,与来自赤道地区的30-50天振荡有关.此外,大气中还存在天气尺度的扰动.利用行星尺度大气扰动向赤道外传播与天气尺度扰动的叠加,区域持续性干旱事件能够找到前期预报信号. 相似文献
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汶川地震与松潘地震前异常现象分析比较 总被引：1，自引：0，他引：1
分析了1976年松潘7.2级地震和2008年汶川8.0级地震前异常现象。汶川8.0级地震为地震活跃期的首发大地震,震前区域性中小地震相对平静,区域地震活动b值为0.77;松潘7.2级地震是活跃期间发生的地震,震中附近地区地震活动密集,曾发生松潘黄龙6.5级地震,震前区域地震活动b值为0.62;汶川地震前区域主压应力方位与错动类型总体上与8.0级地震给出的解大体一致,这与松潘7.2级地震前的情况有显著差异,震前地震与余震震型有差异。根据观测数据的分析和异常判定结果认为,松潘地震与汶川地震前的观测异常没有一个台项是重复出现的,短临异常数前者显著多于后者。松潘地震与汶川地震前的宏观异常现象差异极大,更未出现火球、地光临震异常现象。这说明,已有的短临前兆观测异常的出现仅有个案特征,而无普适意义。 相似文献
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分析后认为,从1999年开始龙门山断裂带上地震活动增强,并持续到2008年5月12日汶川8级地震发生前一个多月。地震活动的增强主要以最大地震的震级为3、4级的小震群活动的方式表现。2006年至2008年3月间,有两个小震群出现在汶川8.0大震震中附近。小震群地震震源机制的结果表明,随时间接近汶川8.0级大震发生,小震群的震源机制趋向一致,这些在空间分布不均匀的密集小破裂逐渐成定向有规律地排列,有利于裂隙的进一步扩展贯通,形成大破裂。 相似文献
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The 2008 M w 7.9 Wenchuan produced a ～285–300-km-long coseismic surface rupture zone, including a 60-km-long segment along the Qingchuan fault, the northeastern segment of the Longmen Shan Thrust Belt (LSTB), Sichuan Basin, central China. Field investigations, trench excavations, and radiocarbon dating results reveal that (i) the Qingchuan fault is currently active as a seismogenic fault, along which four morphogenic earthquakes including the 2008 Wenchuan earthquake occurred in the past ca. 3500 years, suggesting an average millennium recurrence interval of morphogenic earthquakes in the late Holocene; (ii) the most recent event prior to the 2008 Wenchuan earthquake took place in the period between AD 1400 and AD 1100; (iii) the penultimate paleoseismic event occurred in the period around 2000 years BP in the Han Dynasty (206 BC–AD 220); (iv) the third paleoseismic event occurred in the period between 900 and 1800 BC; and (v) at least three seismic faulting events occurred in the early Holocene. The present results are comparable with those inferred in the central and southwestern segments of the LSTB within which the Wenchuan magnitude earthquakes occurred in a millennium recurrence interval, that are in contrast with previous estimates of 2000–10,000 years for the recurrence interval of morphogenic earthquakes within the LSTB and thereby necessitating substantial modifications to existing seismic hazard models for the densely populated region at the Sichuan region. 相似文献
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Abstract Rome has been plagued by flooding since its foundation, and, in December 2008, the largest flood event over the past 20 years caused a fatality and more than €150 million in economic damage. Meteorological conditions associated with the December 2008 flooding are shown to be typical of flooding in the Tiber. The long record of discharge measurements of the Tiber River at the Ripetta station in downtown Rome was used to examine flood frequency for the Tiber, including assessment of the return interval of the December 2008 flood. Particular attention is given to examination of the stationarity assumption for flood peaks through change-point and trend analyses, quantile regression, and statistical modelling of the flood-peak distribution. Once anthropogenic changes linked to reservoir regulation of the Tiber River have been accounted for, the stationarity assumption holds and can be used for flood frequency analysis. We highlight the difficulties in detecting departures from the stationarity assumption due to climate change. In the current regime, the December 2008 flood event has a return period of the order of 10–20 years. Citation Villarini, G., Smith, J.A., Napolitano, F. & Baeck, M.L. (2011) Hydrometeorological analyses of the December 2008 flood in Rome. Hydrol. Sci. J. 56(7), 1150–1165. 相似文献
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A preliminary report on the Great Wenchuan Earthquake 总被引：11，自引：2，他引：9
Zifa Wang 《地震工程与工程振动(英文版)》2008,7(2):225-234
The May 12, 2008 Great Wenchuan Earthquake has resulted in more than 68,858 deaths and losses in the hundreds of billions RMB as of May 30, 2008, and these numbers will undoubtedly increase as more information becomes available on the extent of the event. Immediately after the earthquake, the China Earthquake Administration （CEA） responded quickly by sending teams of experts to the affected region, eventually including over 60 staff members from the Institute of Engineering Mechanics （IEM）. This paper reports preliminary information that has been gathered in the first 18 days after the event, covering seismicity, search and rescue efforts, observed ground motions, and damage and loss estimates. The extensive field investigation has revealed a number of valuable findings that could be useful in improving research in earthquake engineering in the future. Once again, this earthquake has shown that the vertical component of ground motion is as significant as horizontal ground motions in the near-source area. Finally, note that as more information is gathered, the numbers reported in this paper will need to be adjusted accordingly. 相似文献
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The study investigates the capability of coarse resolution synthetic aperture radar (SAR) imagery to support flood inundation models. A hydraulic model of a 98‐km reach of the River Po (Northern Italy) was calibrated on the October 2000 high‐magnitude flood event with extensive and high‐quality field data. During the June 2008, low‐magnitude flood event a SAR image was acquired and processed in near real time (NRT) in order to provide adequate data for quick verification and recalibration of the hydraulic model. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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地震预警作为一种能够有效减轻地震灾害的手段已经被世界上越来越多的国家和地区所研究,并在实际应用中取得了显著的减灾实效.利用汶川主震及其余震的强震观测记录研究了特征周期τc与震级的相关性、位移幅值Pd与峰值速度PGV的相关性以及τc和Pd的乘积与震级的关系.统计结果表明,τc与震级以及Pd与PGV之间都有较好的相关性,验证前人的统计结果.另外,τc和Pd的乘积与震级的关系也与台湾地区的结果一致.最后,研究结果被应用到了两款不同的仪器中,形成一套现地地震预警系统. 相似文献
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逆冲滑动是汶川地震的初始和主要震源过程,其破裂滑动量随断层深度的分布形态与多数板内逆冲强震不一致.本文用摩压比值来表征断层沿线的局部破裂危险程度,通过数值实验讨论了底部破裂源、近地表倾角和无地表破裂的前期地震等对铲形逆冲断层的破裂危险分布和破裂滑动分布的影响.有限元数值模拟结果显示,在巴颜喀拉块体对龙门山断裂带的高强度挤压下,上陡下缓近地表陡倾角的铲形断层形态使得汶川发震断层近地表对逆冲破裂和滑动有一定的阻碍作用;破裂滑动量集中于发震断层中部的前期逆冲地震是造成汶川MS8.0地震逆冲滑动分布异于板内逆冲强震滑动分布现象的一个可行解释. 相似文献
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2008年5月12日四川省汶川县发生了MS8．0特大地震（本文震级均为MS）,该地震是中国大陆内部活动地块边界带的特大地震,它发生在青藏、华南一级活动地块区边界交汇部位的龙门山断裂带。本文结合活动地块划分结果阐述了汶川8．0级特大地震前7级强震格局,探讨了该特大地震前可能的动力学变化过程;以中国大陆地区为研究对象,分析... 相似文献
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The 2008 Wenchuan earthquake has a significant impact on the seismicity of nearby regions. The Longnan earthquake which occurred on September 12,2008 in Gansu Province was out of the aftershock zone. Reliable source parameters are essential for understanding the seismogenic process of this earthquake. Therefore,three approaches are adopted to study the source parameters of this event. The focal mechanism is obtained with the g CAP method that takes non-Double-Couple(non-DC)component into account. The two fault planes are NP1:150°/45°/81° and NP2:342°/45°/98°,while the non-DC component is about 53%. The focal depth is 1. 6 km,which indicates the Longnan earthquake is a shallow event. Furthermore,this result is also in good agreement with results obtained with two other approaches:amplitude spectra of Rayleigh wave and surface displacement from In SAR measurement. To analyze the cause of the event,coulomb failure stress change caused by the Wenchuan earthquake on the Longnan earthquake fault plane is calculated. The result shows that coulomb stress change is 30 k Pa around the Longnan earthquake hypocenter,which exceeds the typical triggering threshold of 10 k Pa. The research indicates that the Wenchuan earthquake probably promote the happening of the Longnan earthquake. 相似文献
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THE 2008 AND 2009 QAIDAM,CHINA EARTHQUAKES:INSAR ANALYSIS FOR COSEISMIC DISPLACEMENTS AND INVERSION FOR FAULT MODELS 
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下载免费PDF全文 XU Xiao-bo SHAN Xin-jian QU Chun-yan ZHANG Guo-hong MA Chao SONG Xiao-gang ZHANG Gui-fang WEN Shao-yan 《地震地质》2017,39(3):485-496
This study focuses on four moderate-sized earthquakes in the northern margin of the Qaidam Basin, northeastern Tibet Plateau, China, of which one occurred in 2008, and three in 2009, respectively. We obtain coseismic displacement fields of these four events using Envisat descending ASAR data and D-InSAR technology. The results show that the 2008 earthquake has only one deformation center and the 2009 earthquakes have three deformation centers in their fields. The maximum displacement of 2008 and 2009 earthquakes are 0.097m and 0.41m in the LOS(line of sight), respectively. We invert ground displacements of these earthquakes based on elastic dislocation models to estimate slip distribution on fault planes. For the 2008 event, using a one-segment fault model, the inversion reveals peak slip of about 0.47m occurring at a depth of 19km. For the 2009 earthquakes, the ground displacement pattern observed by InSAR can be fitted by a three-segment fault model with smallest RMS of residuals. The three sectional fault model is considered the most reliable. 相似文献
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2008年冬季（1月和2月）和2012年冬季均发生了较强的拉尼娜事件,但欧洲气候,尤其是西欧在这两年差异较大,2008年异常偏暖,而2012年却出现了极寒事件.诊断表明,大气环流异常是造成气候差异的直接原因.2008年冬季,北大西洋上空大气环流异常呈正位相的北大西洋涛动,有利于欧洲异常偏暖;2012年冬季,北大西洋和欧亚高纬阻塞的长期维持是西欧发生极端严寒的重要原因.通过数值试验,研究了前期海表热状况异常对大气的影响.结果表明：北大西洋海温异常能在一定程度上解释这两年欧洲各自的气候异常;尽管热带海温异常对2012年冬季的北大西洋环流形势和欧洲气候异常起一定的贡献,但不能解释2008年的情形;靠近欧洲的北极海冰异常偏少使得欧洲气候偏冷,对2008年的偏暖气候贡献为负,对2012年则有正贡献. 相似文献
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为了了解2008年5月12日四川汶川MS8.0地震发生的地震活动背景,本文综合历史与现代地震资料,从南北地震带中段及其邻区的视野研究了汶川地震前1~2千年的强震活动性,以及震前20年的地震活动性背景.结果主要表明：（1）至少在2008年之前的1100~1700年中,龙门山断裂带未发生M≥7的地震,相对其南、北两侧的其他活动断裂带（或段）形成一个地震空区,2008年汶川MS8.0地震发生在该空区中;（2）17世纪以来,在由龙门山断裂带大部分地区、川北岷江-虎牙断裂带以及甘南文县-武都断裂带组成的巴颜喀拉块体东边界上共发生了12次M=6.5~8.0地震,显示出一个已持续了近400年、逐渐加速的应变能释放过程,2008年汶川MS8.0地震属于该过程中两次巨大地震之一;（3）汶川地震前20年,龙门山断裂带中、南段不存在背景地震活动的平静,反而显示出比曾经发生过1879年MS8地震的甘南文县-武都断裂带还略高的地震活动背景水平;（4）2008年汶川地震的强度远远超出龙门山断裂带的历史最大地震,说明仅基于数百年至一、两千年的历史地震记载,远不足以正确评估较低滑动速率的、大型活动断裂带的潜在地震危险性. 相似文献
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《Journal of Atmospheric and Solar》2005,67(15):1403-1410
The time separations between events in an extended list of occurrence times may reveal recurrence patterns of predictive and interpretive value. A strategy for extracting the period and amplitude of cyclic or recurrent phenomena from lists of event times is developed and applied to 119 years of geomagnetic storm data. The ensemble of time intervals separating pairs of sudden commencement geomagnetic storms (SSCs) differs significantly from that expected for randomly occurring events, permitting the detection of preferred intervals between event occurrences and a determination of the strength and significance of recurrence patterns. Through 11 sunspot cycles, SSCs show persistent nonrandomness at the solar rotation period and its low multiples. The recurrence period is shorter on descending cycle phase than on the ascending phase. The strength of SSC recurrence near 27 days is comparable on ascending and descending phases, in contrast with the behavior of gradual commencement storms triggered by corotating solar wind streams. 相似文献
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在离散波数法基础上计算2008年3月21日新疆于田MS7.3地震造成的近场区域完全库仑应力变化, 分析该变化对余震发生所产生的影响, 得到了此次地震在2008年10月5日乌恰MS6.8地震震中处所产生的动态库仑破裂应力变化. 计算结果表明, 该地震近场区域库仑应力变化图像演化大概持续了60 s, 库仑应力变化对余震的触发率达到90%以上, 其中动态库仑应力变化图像更好地解释了余震的分布. 余震震中处的完全库仑应力变化计算结果表明, 其动态库仑应力变化远远大于静态库仑应力变化. 于田MS7.3地震在乌恰MS6.8地震震中处造成的最大动态库仑应力变化为0.12 MPa, 说明后者可能受到了于田MS7.3地震的动态应力触发作用, 但不显著;而静态库仑应力则对其影响很小. 相似文献