Seismological Approaches to Earthquake Prediction     

Zhang Guomin  Li Li  and Jiao MingruoCenter for Analysis  Prediction  CSB  Beijing  China 《中国地震研究》1999,(2)

Seismological approaches used in earthquake prediction involve many subjects. To predict large earthquakes from small to moderate foreshocks has a clear meaning in physics. Some of the main methods of earthquake prediction used in China are outlined in this paper. According to the anomalies used for earthquake prediction, seismological approaches can be divided into two groups: those that use the anomalies in seismic patterns, including the increase and decrease in regional seismicity, the appearance of seismic gaps, seismic belts, seismic swarms, and foreshocks and those that use anomalies in special values and in seismic waves, such as the anomalies in b values and f values, in the Vp/VS ratio, Q values, stress drop, and shear stress.  相似文献   

西沙永兴岛附近海域沉积物的环境质量评价     

徐阁  王德鸿  王诗文  石军  袁超  韩留玉 《海洋学报》2022,44(1):137-146

根据2009-2017年9个航次对西沙永兴岛附近海域共6个站位的沉积物重金属监测结果,应用数理统计法估算了该区域7种重金属元素的背景值,分析了重金属的含量及年际变化,采用单因子标准指数法和潜在生态危害指数法对其重金属含量进行了评价.结果表明:研究区域沉积物重金属具有低背景值,均符合海洋沉积物质量第一类标准,沉积物质量为...  相似文献   

On calculating the Earth's C21 and S21 gravity coefficients in the IERS terrestrial reference frame     

S. M. Kudryavtsev 《Journal of Geodesy》1999,73(9):448-451

Modern models of the Earth's gravity field are developed in the IERS (International Earth Rotation Service) terrestrial reference frame. In this frame the mean values for gravity coefficients of the second degree and first order, C ₂₁(IERS) and S ₂₁(IERS), by the current IERS Conventions are recommended to be calculated by using the observed polar motion parameters. Here, it is proved that the formulae presently employed by the IERS Conventions to obtain these coefficients are insufficient to ensure their values as given by the same source. The relevant error of the normalized mean values for C ₂₁(IERS) and S ₂₁(IERS) is 3×10⁻¹², far above the adopted cutoff (10⁻¹³) for variations of these coefficients. Such an error in C ₂₁ and S ₂₁ can produce non-modeled perturbations in motion prediction of certain artificial Earth satellites of a magnitude comparable to the accuracy of current tracking measurements. Received: 14 September 1998 / Accepted: 20 May 1999  相似文献   

天然石材的放射性评价   总被引：6，自引：0，他引：6  

王南萍  王玉和  张明 《现代地质》1998,12(2):277-282

摘 要　 天然石材用作饰面材料时,应按 《天然石材放射防护分类控制标准》（犑犆５１８—９３） 进 行放射性评价。在石材矿山和石材产品放射性评价中,可采用核地球物理中地面 γ能谱和γ 总量 （照射量率） 检测方法,γ照射量率检出上限为５ ２狀犆／犽犵·犺。石材产品按内外照射限制 值 犆 犚犪 和 犆犲犚犪 的高低分为犃、犅、犆３大类。犆犲犚犪 超过１０００犅狇／犽犵的石材不可用作饰面材料。  相似文献   

滇东北山区坡耕地土壤可蚀性因子   总被引：8，自引：1，他引：7  

杨子生 《山地学报》1999,17(Z1):1

通过对滇东北山区坡耕地３类代表性土壤———红壤、黄壤和紫色土建立标准试验小区并进行连续３年实测,建立起计算滇东北山区坡耕地土壤Ｋ值的修正诺模公式;在确定各个土壤参数基础上,计算了滇东北山区坡耕地主要土壤的Ｋ值,为建立坡耕地土壤流失方程、进行土壤侵蚀预测预报、制定水土保持措施奠定了可靠的基础。  相似文献   

基于二次重现期的多变量洪水风险评估   总被引：4，自引：2，他引：2  

黄强  陈子燊 《湖泊科学》2015,27(2):352-360

由于洪水是一种具有多个特征属性的随机事件,频率分析成为洪水风险评估的一种有效手段,多变量重现期与设计值的定义与计算则是洪水频率分析中的重点和难点.本文通过构造洪水历时、洪峰与洪量的联合分布,介绍了一种新的多变量重现期定义——二次重现期,并探讨了"或"重现期、"且"重现期和二次重现期对安全与危险域识别的差异性,以及在洪水风险管理与工程设计中的合理性与可靠性.传统的"或"和"且"多变量重现期对安全与危险域的识别存在局限性,利用Kendall函数定义的二次重现期则提供了更加合理的安全与风险域识别,避免了对安全事件与危险事件的错误判定,更有利于指导洪水风险的管理.在给定的二次重现期条件下,依据出现概率最大原则推算的历时、洪峰与洪量设计值组合可以满足工程设计以较低成本承受较大风险的追求,相比于单变量设计值,考虑了洪水多个属性联合特征的多变量设计值提供了更加全面和可靠的参考信息.  相似文献   

利用Stao模型研究上海地区中小地震尾波     

刘菲  任烨  李贞 《华北地震科学》2019,37(4):60-64

利用2011—2017年上海台网记录的上海及周边50km内的地震事件,使用Stao模型,计算了东滩台、大洋山台、佘山台、天平山台、秦皇山台所在地区的尾波值,结果显示:上海及邻近地区整体呈现西高东低的分布,在东部沿海地区较低,浦西地区较高;根据上海台网的地震事件记录,发现上海地区地震虽然基本呈现弥散性分布,并没有出现沿断裂分布趋势,而整体分布为东部沿海地区及海域多于浦西地区;结合上海地区尾波值分布规律分析表明,所得值数据能够较好地反映该区域地震活动性。  相似文献   

What do Δ14C changes across the Gerzensee oscillation/GI‐1b event imply for deglacial oscillations?     

C. S. Andresen  S. Bjrck  O. Bennike  J. Heinemeier  B. Kromer 《第四纪科学杂志》2000,15(3):203-214

High‐resolution studies were performed on late‐glacial sediments from a small lake in western Denmark with respect to lithology, geochemistry, stable isotopes, pollen stratigraphy and radiocarbon dating on terrestrial macrofossils. One purpose was to detect the so‐called Gerzensee oscillation, or the GI‐1b event, in the later part of the Allerød warm period, and to describe the environmental impact of this short cooling. The other aim was to test the hypothesis that considerable Δ¹⁴C changes occur over this time, which can be related to ocean ventilation/thermohaline circulation changes. We find that the GI‐1b event had a major impact on both terrestrial and limnic ecosystems: large vegetation changes, increased soil erosion and lowered aquatic production. By correlations to events in the GRIP ice‐core and ¹⁴C patterns in the Cariaco basin we also transformed our ¹⁴C dated record into calendar years to calculate Δ¹⁴C values. The ¹⁴C dates show that the GI‐1b event both preceded, and was part of, the 11 400–11 300 ¹⁴C yr BP radiocarbon plateau, and was followed by the 11 000–10 900 ¹⁴C yr BP plateau; thus the later part of the event coincides with a distinct age decline. This delayed age drop (Δ¹⁴C rise) in relation to the hypothetical triggering mechanism behind the event, decreased ocean ventilation, could be explained by redeposited macrofossils at the onset of GI‐1b. This phenomenon, also seen at the onset of Younger Dryas, may also reflect increased soil erosion and redeposition at the start of cold periods. The independent Cariaco Basin record, however, implies that the very end of the cool GI‐1b event is related to a distinct rise in Δ¹⁴C. Likewise, the ¹⁰Be record from GISP2 shows a distinct rise in the middle of the event, precluding decreased solar forcing as the trigger of the climate event, but making it likely that high cosmic ray flux (low solar activity) may be the cause of the rising atmospheric ¹⁴C content. We thus conclude that the Δ¹⁴C changes over the Gerzensee oscillation (GI‐1b), being one of several coolings during the Last Termination, does not seem to be related to ocean ventilation changes. The reason behind this lack of coincidence between rising Δ¹⁴C and a fairly distinct Northern Hemisphere cooling may be due to the fact that the oceanic changes during some of these coolings are too subtle to give an atmospheric ¹⁴C imprint, or that an anti‐phase relationship between the two hemispheres blurs the Δ¹⁴C signal, or, finally, that a partly unknown mechanism may lie behind such coolings. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

海泡石化学成分分析标准物质研制   总被引：2，自引：0，他引：2  

魏双  王家松  徐铁民  方蓬达  王力强  王娜 《岩矿测试》2021,(5):763-773

海泡石是一种十分重要的非金属矿，被广泛应用于航空、畜牧、化工环保等领域中，贸易活动十分活跃。鉴于中国一直没有海泡石标准物质，国际上的海泡石标准物质定值组分少，为了满足相关研究需求，本文研制了湖南湘潭的海泡石标准物质（GBW07138）。对Ba、Be、Bi、Cd、Ce、Co、Cr、Cs、La、Li、Lu、U、Nb、Nd、Ni、Pb、SiO₂、Al₂O₃、Fe₂O₃、MgO、CaO、Na₂O、K₂O、TiO₂共24种组分进行均匀性和稳定性检验。针对不同含量、不同性质的组分，采用合理的国家标准方法检验了20种组分的RSD小于3%，其余4种组分Bi、La、Lu、Mo的RSD略大于3%，方差检验的F值均小于列表临界值[F_0.05（29，60）=1.65]，表明该标准物质均匀性良好。在稳定性考察期内，24种组分的含量无统计学上的明显变化，表明该标准物质稳定性良好。由9家实验室采用重量法、容量法、X射线荧光光谱法、电感耦合等离子体质谱法等传统化学分析方法和现代仪器分析方法协作定值，最终定值组分63种，涵盖了主量、微量及全部稀土元素，其中海泡石特征组分MgO和烧失量（LOI）的含量分别为18%±0.2%和8.55%±0.19%，这两种组分与现有的标准物质形成一定阶梯性，能够更好地满足海泡石成分分析测试需求。该海泡石标准物质可用于地质找矿、地球化学调查、地质矿产产品测试以及其他行业相关领域样品测试的质量监控标准。而且在研制该标准物质过程中，改良或开发的一些新方法可为后续开发海泡石标准物质提供技术支持。  相似文献   

基于SPSS的数理统计方法在海洋重金属环境背景值计算中的应用   总被引：1，自引：0，他引：1  

王秋璐  周燕遐  陈斐  东成 《海洋通报》2011,30(1):100-103

讨论并计算了海水中重金属的含量值域.基于SPSS的主成分分析方法,将Cu,Pb,Zn,Cr,Hg,As,Cd7类重金属构成3个主成分,再通过主成分权重值作图划分调查海域的环境统计单元.对重金属进行异常值判定和分布类型检验,最终得到重金属的环境背景值.  相似文献