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301.
Real-time seismology for the 05/12/2008 Wenchuan earthquake of China: A retrospective view 总被引:2,自引:0,他引:2
Paul SOMMERVILLE 《中国科学D辑(英文版)》2009,52(2):155-165
The devastating 05/12/2008 Wenchuan earthquake (Mw7.9) in Sichuan Province of China showed very few precursory phenomena and occurred on a fault system once assigned to be
of moderate long term seismic risk. Given the existing coverage of seismograph stations in Sichuan Province, real-time seismology
could have been effective in avoiding some earthquake damage and helping post-earthquake emergency response. In a retrospective
view, we demonstrated that the epicenter can be located with 20 km accuracy using just two broadband stations with three-component,
which takes only about 10 s after the onset of the earthquake. Initial magnitude is estimated to be M7 with the Tc measurement
over first 4 seconds of P waves. Better magnitude estimate can be obtained within 2 min by modeling Pnl waves for stations
about 500 km away where the S waveforms are clipped. The rupture area is well revealed by teleseismically-recorded >M5 early
aftershocks within two hours after the mainshock. Within a few hours, teleseismic body waves were inverted to derive a more
detailed rupture process and the finite fault model can be readily used to calculate ground motions, thus providing vital
information for rescue efforts in the case where no real-time strong motion records are available.
Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-116-1) and National Key
Technology Research and Development Program of China (Grant No. 2006BAC03B00) 相似文献
302.
Evidence of multistage late Quaternary strong earthquakes on typical segments of Longmenshan Active Fault Zone in Sichuan,China 总被引:1,自引:0,他引:1
WaLi Jiang XinSheng Xie JinFa Zhang ChangBin Sun Wei Huang Qiang Sheng XiYing Feng 《中国科学D辑(英文版)》2009,52(9):1412-1425
Investigation of offset landforms and trench excavation are important means to acquire the evidence of multistage activities of active faults. Here we present the result of fault trough investigation in Beichuan County and the Pingtong Town of Pingwu County along the Longmenshan Central Fault Belt, as well as the result from trench excavation at the platform foreslope in Hanwang Town of Mianzhu County on the Longmenshan Front Range Fault Belt. These results show that at least three fault activity events, in... 相似文献
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305.
采用国家地震台网数十台地震仪的观测资料研究了汶川大地震和昆仑山大地震的“震前扰动”现象,结果表明,“震前扰动”现象与强台风的影响密切相关,适用于英国海洋学家Higgins的海浪非线性干涉理论中的“第二类脉动”.然而,通过对信号时频特征的细致分析后发现:“震前扰动”信号存在着明显的“时频偏移”现象,不完全符合“第二类脉动”的特征.因此本文认为,汶川大地震的“震前扰动”除了包含“第二类脉动”信号外,还可能存在着“第三类脉动”,这对强震短临前兆的研究有重要意义. 相似文献
306.
南北构造带天水、武都强震区地壳和上地幔顶部结构 总被引:1,自引:0,他引:1
利用两条相互垂直的高分辨地震折射/宽角反射剖面和相应的非纵观测的多个扇形剖面取得的人工地震资料, 研究天水和武都8级大震区的地壳和上地幔顶部结构和构造.二维剖面结果显示, 地壳沿垂向可分为上地壳和下地壳两大层.上地壳中部存在低速层, 层内介质速度比背景值低0.3~0.5km/s.莫霍面深度大约为46~48km.NE向的天水-武都剖面下地壳速度在横向上变化剧烈, NW向的成县-武山剖面, 在礼县以西, Moho面和C界面有被上涌物质改造过的迹象.三维速度成像显示, 在105°E附近, 从7至11km的深度范围内, 存在一条近NS向的断裂带, 在该带的两侧速度结构有明显的差异, 西侧为低速异常, 而东侧为高速异常, 这一近NS向的断裂带与二维剖面的下地壳深断裂在位置上很接近.该地区的几个8级大震均发生在105°E附近, 并且呈一近NS条带. 相似文献
307.
It is fact that the severe ground motions of shear waves have a strong effect on the dynamic behavior of buildings and civil structures. We simulate near source strong motions of a pure shear wave and synthesize small motions, using the parameters based on the recorded accelerograms at the site that is regarded as a base rock in the Osaka basin, Japan. By making use of a stochastic technique, we can easily introduce higher frequency contents in the motions and apply the technique to the synthesis of small waves regarding as a green function. We also introduce to the analysis the useful relationships among the time duration Td, the seismic moment M0, the corner frequency fc and the high cutoff frequency fmax which were regressed by a simple representation scheme. Considering two active faults that may affect severe damage on buildings and civil structures, we try to predict strong ground motions in Osaka basin and show the characteristics of them. 相似文献
308.
林爱兰 《热带气象学报(英文版)》2002,8(2):150-157
Reanalysis data from NCEP/NCAR are used to systematically study preceding signals of monthly
precipitation anomalies in the early raining season of Guangdong province, from the viewpoints of 500-hPa
geopotential height field, outgoing longwave radiation (OLR) field, sea surface temperature (SST) and fourteen
indexes of general circulation depicting atmosphere activity at high, middle and low latitutes. Being multiple
tools of information, a number of conceptual models are formulated that are useful for prediction of the
magnitude of monthly precipitation (drought, flood and normal conditionss). 相似文献
309.
互花米草盐沼潮沟地貌特征 总被引:18,自引:1,他引:17
互花米草是我国从国外引进的能在淤泥质潮滩的高潮带下部和中潮带上部生长的禾木科植物,由于其植株高大、群落盖度高、根系发达等生物学特性,其对潮流动力特征有显著的影响。本文通过对江苏省东台市笆斗垦区外互花米草盐沼地的潮沟形态调查,发现互花米草盐沼潮沟具有以下一些特征:潮沟密度大,可达50km/km2以上;潮沟的宽深比小,大多在8以下;沿岸堤发育,且多呈不对称状;一级主潮沟与主潮沟接头处普遍呈逆弧形;盐沼外侧边缘发育有明显的陡坎冲沟。分析认为这些特征主要与互花米草发达的根系和致密的植株等生物学特性有关,发达的根系增加了盐沼滩面的稳定性,而互花米草高大的植株增加了对潮水运动的阻力,提高了滩面落潮水的归槽水位,改变了潮流的泥沙沉积地点和涨、落潮流的流向,从而形成比较特别的互花米草盐沼潮沟特征。 相似文献
310.
通过对1998年4月19日发生在北海市银海区侨港、咸田、西塘等镇的一次飑线天气过境过程的大气环流特征风的垂直切变及物理量场、能量场的诊断分析,探讨这次强对流天气形成的原因。 相似文献