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统计地震学的基本问题 总被引：3，自引：0，他引：3
"统计地震学"决不仅仅是统计学在地震研究中的简单应用.对这一点的忽视常常导致对"统计地震学"意义的低估.经过几十年的发展.现在是系统讨论"统计地震学"基本问题的时候了.这种讨论不仅对.统计地震学"自身的发展,而且对与地震预测预报相关的交叉学科的研究都是有益的.本文的注意力集中于"狭义的""统计地震学",即以地震预测预报为目标的、针对地震现象(主要是地震活动性)的统计研究.我们把"统计地震学"基本问题归纳为7个方面:①地震活动的统计规律及其独立性问题;②长期地震预测的统计方法的有效性问题;③中期时间尺度地震活动的"异常"问题;④可能的地震前兆和地震预测预报方法的统计显著性问题;⑤地震的物理可预报性问题;⑥地震预测预报的地震活动性方法的能力和限度问题;⑦地震活动的物理模型的"真实性"问题.本文的目的不是对"统计地震学"提出一个"希尔伯特问题"的框架,而是试图引起更多的讨论,特别是引起人们对超越争论、超越算法的基本问题的关注. 相似文献
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以晋、冀、内蒙交界区４次中强震为研究对象,通过多项预报方法对震例的统一检验,找出了４次地震前地震活动异常的共性特征,以此为统计对象,制定了该区域的地震学预报指标。 相似文献
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在滇西北地区(25°~28°N,99°~101.5°E)用不同的统计窗长和滑动步长,对当前常用的地震学参数进行分析研究,最终确定了6个预报指标:频度N、缺震、能量E、断层总面积ΣE、空间集中度C值、地震活动度S值。这6项指标对滇西北地区及周边区域1990年发生的M≥5.0地震有较好的短期映震能力,但丽江7级地震前,6个指标只有缺震出现了明显异常,达到预报指标,其余5个指标都无异常显示。这种结果一方面说明6项指标对6级左右地震有较好的对应关系,但对6.7级以上地震没有控制能力;另一方面也说明,丽江7.0级地震最显著的特征是短期阶段孕震区中小地震活动异常平静。因此,仅仅依靠地震学指标实现短临预报是不够的,还应结合其它方法和手段。 相似文献
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刘文龙与笔者已在“地震学预报方法深入攻关的建议”(国际地震动态,1990,9)一文中,较全面地提出了今后几年值得深入研究的预报地震的地震学方法的某些课题。本文仅就应用非线性动力学的研究成果,如何推进地震学预报方法的定量化方面,发表一些浅见。 1.地震学预报方法的基础是来自地震事件的记录,包括地震目录、地震波记录和地震波的传播。它 相似文献
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地城学预报方法在博克图5.6级地震研究中的应用 总被引：1，自引：0，他引：1
应用国家地震局８５－０４－０１课题提供的部分地震学预报地城方法对１９８０年和１９８１年博克图地震进行了研究。结果表明,该地震前后某些地震学预报项目出现了明显的异常变化。这些可作为监视该区地震活动的判定指标。 相似文献
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根据 198 8年以来全国地震趋势会商会 (NMSC)所提出的各类地震学异常资料 ,研究每一年异常与下一年大陆地震的对应关系 .9a内 46种地震学方法所提出的93 2项异常资料表明 :在 1989～ 1993年间 ,用地震学预报地震方法的数量有一个增大过程 ;各种方法所提出的异常对应地震的比率在 0～ 48%之间 ,平均为 2 8%左右 ,这也与我国地震预报中预报区数的成功率相当 ;统计预报、区域应力场增强、地震条带、小震调制比和b值等方法有较高的地震对应率 ,而地震活动异常平静、分数维、异常震群、c值和地震窗等方法要差一些 ;用地震学方法预报地震最成功的年份为1989年 ,最差年份为 1990年 ;与预报区数的成功比率一样 ,其地震的对应比率并未随时间的推移而有所提高 .各种地震学方法的物理内涵及其与地震孕育的内在联系及各种地震学方法间相互关联问题是今后用地震学方法预报地震的研究课题 . 相似文献
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本文把模糊数学中的模糊模式识别的直接方法、模糊聚类分析方法、模糊信息检索方法和新近提出的模糊分维方法应用到以地震活动性和地震前兆为基础的首都圈地震监测预报当中,分析研究了发生在这一地区的两次大地震,即1976年唐山7.8级和1989年大同6.1级地震前用模糊数学方法识别出的地震学前兆和非地震学前兆,并对这一地区大地震的长期和中短期模糊预报方法与途径进行了简要的讨论。 相似文献
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把用来分析地震波波形的时间线性度和空间线性度两种方法，应用到地磁资料分析当中，具体分析处理了１９７６年７月２８日唐山Ｍｓ７．８地震和１９８９年１０月１９日大同Ｍｓ６．１地震前后地磁场资料，并对这两次地震前后地磁时空线性度变化情况进行了研究。所得结果表明：①较大地震前地磁场的时空线性度均可能呈现出较明显的下降异常变化，有些在震前回升，②各分量的时空线性度呈现异常的时间基本上同步，并与波速异常发展趋势基本相符。 相似文献
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The spatial and temporal variability of groundwater recharge in a forested basin in northern Wisconsin 总被引：1，自引：0，他引：1
Recharge varies spatially and temporally as it depends on a wide variety of factors (e.g. vegetation, precipitation, climate, topography, geology, and soil type), making it one of the most difficult, complex, and uncertain hydrologic parameters to quantify. Despite its inherent variability, groundwater modellers, planners, and policy makers often ignore recharge variability and assume a single average recharge value for an entire watershed. Relatively few attempts have been made to quantify or incorporate spatial and temporal recharge variability into water resource planning or groundwater modelling efforts. In this study, a simple, daily soil–water balance model was developed and used to estimate the spatial and temporal distribution of groundwater recharge of the Trout Lake basin of northern Wisconsin for 1996–2000 as a means to quantify recharge variability. For the 5 years of study, annual recharge varied spatially by as much as 18 cm across the basin; vegetation was the predominant control on this variability. Recharge also varied temporally with a threefold annual difference over the 5‐year period. Intra‐annually, recharge was limited to a few isolated events each year and exhibited a distinct seasonal pattern. The results suggest that ignoring recharge variability may not only be inappropriate, but also, depending on the application, may invalidate model results and predictions for regional and local water budget calculations, water resource management, nutrient cycling, and contaminant transport studies. Recharge is spatially and temporally variable, and should be modelled as such. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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分析了乌恰5．7级地震前喀什-乌恰地区的地震活动情况和地震学参数异常过程。研究认为，5．7级地震发生在1996年9月以来形成的喀什西南4．0级以上地震空区的边缘，此次地震的活动间隔时间为1980年以来之最；震前有6项地震学参数空间扫描和5项地震学参数时间进程存在中短期异常；震前3级地震活动强度有多次起伏。 相似文献
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Alba Sanmiguel-Vallelado Juan I. López-Moreno Enrique Morán-Tejeda Esteban Alonso-González Francisco M. Navarro-Serrano Ibai Rico J. Julio Camarero 《水文研究》2020,34(10):2247-2262
Snowpacks and forests have complex interactions throughout the large range of altitudes where they co-occur. However, there are no reliable data on the spatial and temporal interactions of forests with snowpacks, such as those that occur in nearby areas that have different environmental conditions and those that occur during different snow seasons. This study monitored the interactions of forests with snowpacks in four forest stands in a single valley of the central Spanish Pyrenees during three consecutive snow seasons (2015/2016, 2016/2017 and 2017/2018). Daily snow depth data from time-lapse cameras were compared with snow data from field surveys that were performed every 10–15 days. These data thus provided information on the spatial and temporal changes of snow–water equivalent (SWE). The results indicated that forest had the same general effects on snowpack in each forest stand and during each snow season. On average, forest cover reduced the duration of snowpack by 17 days, reduced the cumulative SWE of the snowpack by about 60% and increased the spatial heterogeneity of snowpack by 190%. Overall, forest cover reduced SWE total accumulation by 40% and the rate of SWE accumulation by 25%. The forest-mediated reduction of the accumulation rate, in combination with the occasional forest-mediated enhancement of melting rate, explained the reduced duration of snowpacks beneath forest canopies. However, the magnitude and timing of certain forest effects on snowpack had significant spatial and temporal variations. This variability must be considered when selecting the location of an experimental site in a mountainous area, because the study site should be representative of surrounding areas. The same considerations apply when selecting a time period for study. 相似文献
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Spatial variability in streambed hydraulic conductivity of contrasting stream morphologies: channel bend and straight channel 
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下载免费PDF全文 Streambed hydraulic conductivity is one of the main factors controlling variability in surface water‐groundwater interactions, but only few studies aim at quantifying its spatial and temporal variability in different stream morphologies. Streambed horizontal hydraulic conductivities (Kh) were therefore determined from in‐stream slug tests, vertical hydraulic conductivities (Kv) were calculated with in‐stream permeameter tests and hydraulic heads were measured to obtain vertical head gradients at eight transects, each comprising five test locations, in a groundwater‐dominated stream. Seasonal small‐scale measurements were taken in December 2011 and August 2012, both in a straight stream channel with homogeneous elevation and downstream of a channel meander with heterogeneous elevation. All streambed attributes showed large spatial variability. Kh values were the highest at the depositional inner bend of the stream, whereas high Kv values were observed at the erosional outer bend and near the middle of the channel. Calculated Kv values were related to the thickness of the organic streambed sediment layer and also showed higher temporal variability than Kh because of sedimentation and scouring processes affecting the upper layers of the streambed. Test locations at the channel bend showed a more heterogeneous distribution of streambed properties than test locations in the straight channel, whereas within the channel bend, higher spatial variability in streambed attributes was observed across the stream than along the stream channel. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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有害蓝藻释放微囊藻毒素（MCs），严重威胁饮用水源地用水安全.为了解巢湖MCs污染状况及其异构体组成对水质的影响，于2012年夏季（8月）和秋季（11月），2013年冬季（2月）和春季（5月）进行采样分析，研究了巢湖水体中胞内微囊藻毒素（IMCs）和胞外微囊藻毒素（EMCs）异构体的时空分布及其与环境因子的关系.结果发现，IMCs和EMCs的平均浓度变化范围分别为0.12~6.45 μg/L和0.69~1.92 μg/L.在3种常见的异构体中，MC-RR和MC-LR比例较高，MC-YR最低，MC-RR和MC-LR是巢湖水体中MCs的主要异构体类型.IMCs和EMCs的异构体浓度及其比例呈现不同的时空分布特征.微囊藻生物量、水温、总磷浓度是影响IMCs和EMCs异构体浓度及其组成变化的关键环境因子.本研究表明巢湖富营养化严重的西湖区夏季能合成更多的MC-RR异构体，而秋、冬季节偏向于释放生理毒性更强的MC-LR异构体.了解MCs异构体组成变化及其关键影响因素，有助于预测预警水体MCs污染状况和评估饮用水源地MCs风险. 相似文献
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ＰｒｅｌｉｍｉｎａｒｙｌｏｃａｔｉｏｎｏｆｍｉｃｒｏｃｒａｃｋｓｉｎｓｅｖｅｒａｌｒｏｃｋｓｐｅｃｉｍｅｎｓｕｎｄｅｒｔｒｕｅｔｒｉａｘｉａｌｃｏｍｐｒｅｓｓｉｏｎＺｈａｏ－ＹｏｎｇＸＵ（许昭永），Ｓｈｉ－ＲｏｎｇＭＥＩ（梅世蓉），Ｃａｎ－ＴａｏＺＨ... 相似文献
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利用Arc GIS空间插值的方法,通过2013年逐月监测(12个月)36个站点水量及不同形态磷浓度,揭示滇池水体磷浓度和磷负荷的时空变化,并探讨不同形态磷负荷的组成贡献,旨在为进一步实施滇池水污染治理及污染负荷控制提供依据.结果表明:滇池水体总磷(TP)浓度在0.13~0.46 mg/L之间,其中颗粒态磷(PP)浓度占TP浓度的72.6%,溶解性活性磷(SRP)浓度占TP浓度的12.8%,溶解性有机磷(DOP)浓度占TP浓度的14%;2013年水体TP负荷为251 t/a,其中PP负荷为190 t/a,SRP负荷为26 t/a,DOP负荷为34 t/a;滇池水体PP负荷对TP负荷的贡献最大,为76%,其次为DOP和SRP,贡献分别为13%和10%;TP及不同形态磷浓度与其负荷在季节分布上差异显著,负荷随季节变化呈现秋、冬季较高,春、夏季较低,而浓度呈现夏、秋季较高,冬、春季相对较低的趋势.定量评估滇池水体不同形态磷负荷及其组成贡献,对进一步揭示滇池藻源和泥源内负荷对水污染的贡献具有重要意义. 相似文献
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Yebang Xu 《地震学报(英文版)》1992,5(2):389-398
The research of the information dimension (D
1) in an active fault zone considers the contribution of each seismic event to information and reflects the characteristics
of the temporal and spatial distributions of earthquakes from a new point of view, avoiding some short-comings of the research
about the capacity dimension (D
0). The results of calculation show that the information dimension of the temporal distribution in Xianshuihe active fault
zone before Luhuo large earthquake isD
1=0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions of the temporal
distribution of the earthquakes in Anninghe active fault zone are respectivelyD
1(t
N)=0.1363 (for the north section) andD
1(t
S)=0.06710 (for the south section). The information dimensions of the spatial distribution are respectivelyD
1(K
N)=1.053 (for the north section) andD
1(K
S)=0.7758 (for the south section). The north section and the south section belong to two self-similar systems with different
information dimensions respectively. The extent of the self-organization of seismic activity in the south section is higher
than that in the north section. This is helpful for us to judge the major dangerous section in the key region of the seismic
monitoring. The research about the information dimension of the temporal and the spatial distributions of earthquakes is significant
for the exploration of active fault zones and seismic prediction.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 372–379, 1991.
This paper is sponsored by the Chinese Joint Seismological Science Foundation. The English version is improved by Zhenwen
An. 相似文献