On estimating frequency-magnitude relations from heterogeneous catalogs     

Stefano Tinti  Rossella Rimondi  Francesco Mulargia 《Pure and Applied Geophysics》1987,125(1):1-18

The paper studies the effect of magnitude errors on heterogeneous catalogs, by applying the apparent magnitude theory (seeTinti andMulargia, 1985a), which proves to be the most natural and rigorous approach to the problem. Heterogeneities in seismic catalogs are due to a number of various sources and affect both instrumental as well as noninstrumental earthquake compilations.The most frequent basis of heterogeneity is certainly that the recent instrumental records are to be combined with the historic and prehistoric event listings to secure a time coverage, considerably longer than the recurrence time of the major earthquakes. Therefore the case which attracts the greatest attention in the present analysis is that of a catalog consisting of a subset of higher quality data, generallyS ₁, spanning the interval T ₁ (the instrumental catalog), and of a second subset of more uncertain magnitude determination, generallyS ₂, covering a vastly longer interval T ₂ (the historic and/or the geologic catalog). The magnitude threshold of the subcatalogS ₁ is supposedly smaller than that ofS ₂, which, as we will see, is one of the major causes of discrepancy between the apparent magnitude and the true magnitude distributions. We will further suppose that true magnitude occurrences conform to theGutenberg-Richter (GR) law, because the assumption simplified the analysis without reducing the relevancy of our findings.The main results are: 1) the apparent occurrence rate exceeds the true occurrence rate from a certain magnitude onward, saym _GR; 2) the apparent occurrence rate shows two distinct GR regimes separated by an intermediate transition region. The offset between the two regimes is the essential outcome ofS ₁ being heterogeneous with respect toS ₂. The most important consequences of this study are that: 1) it provides a basis to infer the parameters of the true magnitude distribution, by correcting the bias deriving from heterogeneous magnitude errors; 2) it demonstrates that the double GR decay, that several authors have taken as the incontestable proof of the failure of the GR law and of the experimental evidence of the characteristic earthquake theory, is instead perfectly consistent with a GR-type seismicity.  相似文献   

Numerical Modeling of the Ston-Slano (Croatia) Aftershock Sequence     

Herak  Marijan  Herak  Davorka  Markušić  Snježana  Ivančić  Ines 《Studia Geophysica et Geodaetica》2001,45(3):251-266

The rate of aftershock occurrence after the M6 Ston-Slano (Croatia) earthquake is modeled as the Epidemic Type Aftershock Sequence (ETAS). Increase of the modeled cumulative number of aftershocks with time was fitted to observations by the least-squares criterion using the combined grid-search and Monte-Carlo approach. This enabled not only the estimation of the most probable ETAS parameters, but also the determination of their confidence limits, as well as the estimation of the bias between them. It has been found that the bias is significant for some of the parameter pairs, regardless of the threshold magnitude assumed. Residual analyses revealed that all strong aftershocks (M _L 4.5) occurred during the periods of normal to high aftershock activity. There were two periods of quiescence in the sequence, both of which were followed by a strong aftershock.  相似文献   

The Privatization of the Oceans by Rognvaldur Hannesson     

Henry Frew 《The Professional geographer》2007,59(1):156-156

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Physics of basic motions in asymmetric continuum     

Roman Teisseyre  Marek Górski 《Acta Geophysica》2007,55(2):119-132

We consider the advantages of a formalism based on concept of the asymmetric continuum and we present some equivalence theorems relating it to the asymmetric elasticity and to micropolar and micromorphic theories as founded by Nowacki, Cosserats and Eringen. We consider the basic processes in an asymmetric continuum which could be reduced to the point basic motions/deformations. The co-action of spin and shear motions is assumed to play the main role in fracturing process, while the constitutive relation between the antisymmetric stresses and rotations replaces the friction constitutive law.  相似文献   

我国春玉米水分供需状况分析   总被引：4，自引：1，他引：4  

李应林  高素华 《气象》2002,28(2):29-33

论述了作物需水量的概念及其计算方法，利用最新的气候和作物资料，计算了我国春玉米的作物需水量，分析其时空分布特征，并利用水发订正系来评价春玉米需水量的满足程度。计算分析结果表明，气候条件对我国在玉米生产是有利的，但在播种期、出苗期及拔节期（4－6月份），存在明显的水亏缺现象，这一时期应采取相应的栽培技术及节水灌溉、人工增雨等措施来缓解旱情。  相似文献   

淮南矿区潘三矿构造发育规律定量研究   总被引：1，自引：0，他引：1  

周云霞  曹代勇等 《中国煤田地质》2002,14(3):4-6

本文采用煤层构造形态空间分析、断裂要素数理统计分析等方法,并引入断裂分形维数指标作为刻划断裂构造发育强度的指标之一,对准南矿区潘三矿地质构造进行了定性—定量分析,揭示了矿井地质构造发育的南北分带性和东西分区性特征。  相似文献   

熵气象学是动力气象学     

赵佩章  赵文桐 《沙漠与绿洲气象(新疆气象)》2001,24(4):9-9,12

论证“熵气象学”就是应用热力学第二定律的动力气象,是不足是统计出来的规律，所以它是气象学的发展。  相似文献   

内蒙古胜利煤田锗矿床赋存规律及找矿方向   总被引：5，自引：0，他引：5  

秦胜利 《中国煤田地质》2001,13(3):18-19

胜利煤田首次发现全国最大的锗矿床，其储量占全国30％以上，且赋存条件好，宜于大型露天开采。研究了其赋存规律，指明了今后找矿方向。  相似文献   

内蒙古呼伦贝尔盟北部砂金矿成矿规律          下载免费PDF全文

张振强 《地质找矿论丛》2001,16(3):192-196

呼伦贝尔盟北部地区由于新构造运动含金地质体长期风化剥蚀，促使金的活化。河流及其2－3级支流发育，流域广，水流充足，有利于砂金矿的迁移、富集。现代的乐山丘陵、宽阔沟谷有利于砂金的保存。该区已发现数十个砂金矿，多为河谷型，主要含金层为含粘土砂层或砂砾层。砂金富集与河谷地貌关系密切，河床弯曲的凸岸、变异部位、关门咀、迎门山等地貌是砂金富集有利部位。该区金直接来源于加里东和华力西花岗岩。结合金的来源、矿床的分布特征和富集规律，指出了该区今后砂金找矿方向。  相似文献   

八家子银多金融矿矿田成矿规律与成矿预测   总被引：3，自引：0，他引：3  

潘厚满 《矿产与地质》2001,15(5):320-323

八家子矿田由NW、NE向两组断裂带与孤形推覆构造交织，控制构成银铅锌、银铁矿床成矿系列，基成矿组份具有组合分带特征。预测东山－冰沟银、铅、锌、炉沟钼和冰沟里银多金属找矿区，经验证，获得找矿成效。  相似文献