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利用2011年至2013年上海及邻近地区的常熟地震台、金泽地震台、佘山地震台记录的ML2.0以上地震波资料,基于Sato模型,采用不同的流逝时间,计算该区域的尾波Q值。结果表明:该区域为低Q值、高频率依赖性区域;不同流逝时间下同一个地震的Q值是不同的,流逝时间越长Q值越大;在2012年7月20日江苏宝应ML5.0级地震发生前,尾波Q值存在增大现象。 相似文献
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选取2011年1月~2012年12月上海台网数据库中记录的37次ML≥2.0地震的数字地震波资料,利用单次散射的Aki模型,计算上海及邻区尾波Q值,拟合Q值对频率的依赖关系,结果为Q(f)=(176.2±87.26)·f0.898 4±0.290 8。与国内其他区域相比,本区域Q值偏大,对频率依赖性低。结合上海及邻区地质特征及同期小震空间分布特点,将研究区域划分为以下4个小震密集区:苏中沿海区域、南黄海区域、苏州—东海区域、宁波—舟山区域,分区进行Q值统计分析,表明尾波Q值数据能够较好地反映该区域地震活动性。 相似文献
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建立在用来解释地方震和区域地震的尾波散射模型的基础上,用云南短周期区域台网12个台站的 VGK 地震仪记录的68个禄劝地震的余震序列尾波观测资料,分六个时间段估算了尾波 Q 值.发现在所观测的频率范围内(0.40——1.65Hz),Q 值与频率有关,估算的 Q 值在80——240之间,频率相关值=0.45.对表示散射强度的波源因子 B(fp)的估算结果多数在10-23——10-24量级,低 Q 值地区表现出激发强度高.值得注意的是禄劝地震前后,离震中区较近的台站所测得的 Q 值发生了明显变化,有的变化达2.0倍以上.Q 值随时间的区域变化,这在地震预报中也许有重要的实际意义.此外,测定了余震震源参数.对震源参数间的定量关系的讨论结果给出:IgE=1.59ML+11.335;E=(2.1010-5M0;在3.0ML5Pa,一个显著的特征是应力降与地震震级不存在明显的线性关系. 相似文献
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利用Sato模型研究宁夏及邻区尾波Q值分布特征 总被引：3，自引：3，他引：0
《地震地磁观测与研究》2016,(1)
利用Sato模型,选取2008年1月至2013年12月宁夏地震台网记录的波形清晰、噪声水平满足计算条件的ML≥2.0地震,计算宁夏及邻区各区域尾波Q值,与前人研究结果进行对比,得到研究区尾波Q值的分布特征。结果表明:宁夏及邻区尾波Q值整体呈北高南低分布;吴忠、灵武地区尾波Q值相对较高,与该区域存在高速区相对应;阿拉善左旗西南尾波Q值较低;盐池地区尾波Q值相对较高,对应该区稳定的地质构造;中卫、海原及附近地区尾波Q值相对较高,认为与该区域地壳深部的高温度与高热流值有关。 相似文献
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从2008年1月至2013年12月宁夏地震台网记录的665次ML≥2.0地震的数字地震波形资料中,选取波形记录清晰、噪声水平满足计算条件的数字地震波形记录,利用Aki模型,计算宁夏及邻区各区域尾波Q值,并与前人已有结果进行对比,得到该区尾波Q值的分布特征。结果表明:宁夏及邻区尾波Q值整体呈北高南低分布;吴忠、灵武地区该值相对较高,与该区域存在高速区相对应;阿拉善左旗西南该值较低;中卫、海原及附近地区该值相对较低,认为与该区域地壳深部的高温度与高热流值有关。 相似文献
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Q值的动态变化能够反映地壳应力、裂隙、地下流体等的变化趋势,为进一步理解地震的孕育发生提供证据.文中尝试将选自中国地震年报、四川省地震台网观测报告及云南省地震台网观测报告的数据分成6个时间段,分别对每个时间段的数据进行成像,来获得Q值的动态变化图像.首先选择一个具有超过14000条射线数据的时间段,通过原始数据加噪音的方法和Bootstrap方法对ML振幅成像的结果进行误差和可信度分析,然后在误差可接受的基础上,再对每个时间段的数据进行成像.研究结果发现:(1)原始数据的观测误差和忽略震源辐射花样对成像结果的影响比较小,40%的噪音所造成的结果误差最大不超过6%.(2)用Bootstrap方法获得的结果最大误差不超过平均Q值的8%,说明振幅层析成像方法在川滇地区的应用因采用大量数据所获得的结果是稳定可靠的,误差是比较小的.(3)分辨率测试发现,川滇地区在射线超过50条的区域,分辨率能够达到20'.(4)分别对每个时间段进行成像,从而获得Q值变化的动态图像.每个时段的区域平均Q值与中强地震的个数有明显的正相关关系,即地震个数越多,则区域平均Q值越大,这可能是区域整体应力变化的结果.通过分析地震的分布和Q值动态变化的关系还发现,大多数中强地震不是分布在Q值变化最大的区域,而是分布在Q增加和降低最大区域之间的过渡区域,这可能是由于差应力变化在过渡区最大,更容易触发地震造成的. 相似文献
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准确的Q值参数是地震衰减相关研究的基础,而如何准确地获得Q值一直是地震衰减研究中的一个难点。本文针对地震物理模拟屮不同Q值测量方法求取Q值存在较大差异的问题,通过标准样品实验和地震物理模型实验,分析了不同Q值测量方法的影响因素、稳定性和测量精度;并针对脉冲透射法测量精度差的问题提出了改良方法,即选择与测试样品声学特性相近的样品作为参考样品;讨论了各种测量方法应用于Q值定量分析研究的可行性。实验研究发现,利用脉冲透射法求取样品Q值时会受到较强的衍射效应影响,衍射效应引起的误差最高可达50%以上,而改良后的脉冲透射法(有机玻璃为参考样品)测量结果的相对误差保持在10%左右。通过对数据进行理论方法衍射校正及实验方法的改良,能够保障不同测量方法测量结果之间的差异保持在10%以内,从而实现利用地震物理模拟进行Q值定量分析的相关研究。 相似文献
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M. N. French R. L. Bras W. F. Krajewski 《Stochastic Environmental Research and Risk Assessment (SERRA)》1992,6(1):27-45
A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities. 相似文献
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《地震工程与工程振动(英文版)》2014,(4)
正This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to attract a balanced number of papers between Chinese and 相似文献
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George W. Housner 《地震工程与工程振动(英文版)》2008,7(2):I0001-I0001
Destructive earthquakes have caused great damage in China and the United States and collapsing buildings havecaused many deaths and injuries. The field of earthquake engineering studies earthquake hazards, the occurrence ofearthquakes of various magnitudes, the nature of the ground shaking during an earthquake, the vibration of structuresduring earthquakes, the strengthening of existing structures and the design of new structures to be earthquake resistant,and finally, how to cope with earthquake damage and restore a city to normal functioning. Such efforts are in progressin both countries, but unfortunately, the language barrier interferes with the free flow of information between China andthe Untied States. It would be mutually beneficial if some means could be developed to promote the exchangeof information across the Pacific Ocean. This new journal has been established for this purpose and its success willbe an important step in promoting earthquake engineering in China and the United States. 相似文献
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《国际泥沙研究》2014,(4)
正President:Giampaolo Di Silvio,Italy Vice Presidents:Ulrich C.E.Zanke,Germany Zhao-yin Wang,China The World Association for Sedimentation and Erosion Research(WASER),inaugurated on Oct.19,2004,is an independent non-governmental,non-profit organization.The mission of WASER is to promote international co-operation on the study 相似文献
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JianCheng Shi 《中国科学:地球科学(英文版)》2014,57(10):2281-2282
正Global Change includes climate change and other environmental changes caused by the joint interaction among various layers of Earth. From the positive side, global change provides new opportunities to human and other living forms on Earth. In the meantime, it creates tremendous challenges and negative impact. At present, the negative impacts have reached all primary processes of the global ecosystem and every aspect of human society, especially causing degradation of the ecosystem. For instance, intensive deforestation causes decline of biodiversity; global warming causes sea level rise and increases 相似文献
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Dissolved total carbohydrates (DTCH), dissolved free monosaccharides (DFMS), dissolved organic carbon (DOC), biodegradable DOC (BDOC), and humic substances (HS) were measured in White Clay Creek (WCC), a stream in southeastern Pennsylvania Piedmont, USA. Samples were collected over different seasons and under baseflow and stormflow conditions. DOC concentrations ranged from 1.0 to 12.8 mg/L C with the highest concentrations associated with stormflows. Carbohydrates ranged from 0.42 to 12.4 μM and accounted for 2.9 to 12.7% of the DOC. Humic substances represented the major DOC fraction, accounting for 55 to 72% of the DOC pool under all flow conditions. The humic fraction had a lower carbohydrate content (4.4%) than the non-humic fraction of DOC (7.2%). Stormflow DOC was enriched in carbohydrates relative to baseflow DOC, but the percentage of humic-C changed little. Carbohydrates were primarily present as dissolved polysaccharides (55%), but a significant fraction was bound to humic substances (40%), while a small proportion was present as monosaccharides (5%). The major monosaccharides in stream water, listed in order of decreasing concentration, included glucose, galactose, rhamnose, xylose, arabinose, mannose, and fucose. On average (30.6 ± 7.4)% (n = 44) of the stream water DOC was biodegradable, and carbohydrates accounted for 9.9 to 17.7% of the BDOC. 相似文献