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221.
222.
Outgoing long wave radiation variability from IR satellite data prior to major earthquakes 总被引:12,自引:1,他引:12
Dimitar Ouzounov Defu Liu Kang Chunli Guido Cervone Menas Kafatos Patrick Taylor 《Tectonophysics》2007,431(1-4):211
Our analysis of the continuous outgoing long wave earth radiation (OLR) indicates anomalous variations prior to a number of medium to large earthquakes. The most recent analysis of OLR is from the M9.0 Sumatra Andaman Islands mega trust event. We compared the reference fields for December 2001 to 2004 and found OLR anomalous values, > 80 W/m2, (2σ) within the epicentral area on Dec 21, 2004, 5 days before the event. We used the NOAA/IR daily (one degree) and monthly (two and half degree) gridded data to differentiate between the global and seasonal variability and the transient local anomalies. The cause of such anomalies is not fully understood; one possible explanation is the existence of thermal outgoing radiation as a result of near ground air ionization and latent heat change due to change of air humidity and temperature. This phenomenon is hypothesized to be part of a relationship between tectonic stresses, electrochemical and thermodynamic processes in the atmosphere and increasing mid IR flux, all part of a family of electromagnetic (EM) phenomena related to earthquake activity. The time scale of the observed variations is a few weeks before the onset of the seismic event. In comparison with several years of data, the observed time-series preceding the earthquake had unusually high OLR. The OLR anomaly corresponds to a large area of ground coverage and coincides with the main epicentral zone. The significance of these observations is explored using data from most recent East Asian earthquake swarm of December 2004 and three other earthquakes. 相似文献
223.
HAN Kunying ZHANG Heng DING Xiaozhong REN Liudong SHI Chenglong PANG Jianfeng 《《地质学报》英文版》2020,94(4):1093-1116
On the southwestern margin of the Yangtze Block, the Dongchuan Group consists of slightly metamorphosed sedimentary rocks, including silty slate, argillaceous slate, clayey slate, arkose, dolomite, and minor volcanic rocks. To date, it is still a controversy over the depositional age and stratigraphic sequence of the Dongchuan Group. In this study, we analyzed five samples of meta-sedimentary rocks and one sample of meta-tuff from the Yinmin, Luoxue and Etouchang Formations of the Dongchuan Group in the Yuxi region for detrital zircon U-Pb ages and Lu-Hf isotope. The detrital zircon ages of the meta-sediments vary from 3073 to 1703 Ma, mainly clustered at three periods, from 1889 to 1840, 2490 to 2008 and 2878 to 2844 Ma. The youngest age peak of all the samples is ~1859 Ma, with the εHf(t) values of the zircons ranging from-20.3 to +4.3 and more than 90% being negative, indicating that the Paleoproterozoic crustal accretion on the southwestern margin of the Yangtze Block was dominated by reworking of the ancient crustal materials involved in the assembly and breakup of the Columbia supercontinent. Another important age range is between 2490 Ma and 2008 Ma, with εHf(t) values from-14.7 to +8.9 and 70% of them are negative, suggesting that the magmatism in the source area was also dominated by reworking and recycling of the ancient crustal materials, with minor juvenile mantle substances added. The detritus was probably derived from the Paleoproterozoic crystalline basement in the southern Yuxi region. The oldest peak age is ~2847 Ma and the εHf(t) values are from-7.7 to +7.0 with 50% of both positive and negative values, demonstrating a possible ~2.85 Ga ancient continental nucleus on the southwestern margin of the Yangtze Block and substantial growth in juvenile crust materials during this period. Besides, the weighted average age of the zircons from the meta-tuff of the Etouchang Formation is 1677 ± 14 Ma. Combining the previous research data and this study, we can constrain the depositional age of the Dongchuan Group in central Yunnan Province to the period from the late Paleoproterozoic to early Mesoproterozoic, slightly earlier than that of the Dongchuan Group in the Dongchuan area near to the southwestern Sichuan Province. The depositional age of the Dongchuan Group is older than that of the Kunyang Group. 相似文献
224.
油气成藏流体动力系统分析原理及应用 总被引:24,自引:1,他引:23
阐述了油气成藏流体动力系统分析的基本原理,把油气成藏流体动力系统分为重力驱动型、压实驱动型、滞流型和封存型四种类型。结合国内外的研究实例,分析了不同类型流体动力系统油气藏形成和分布的规律,强调在不同类型的流体动力系统中,油气藏形成的机理不同,在成藏动力学研究中有不同的侧重点。加强重力驱动型和封存型流体动力系统动力系统油气成藏条件研究对我国南方海相盆地和其它勘探程度较高的盆地深部的油气勘探具有重要意义。 相似文献
225.
震后灾害损失盲场快速评估的技术方法及其计算机软件系统可在确定地震震级、震中位置和发震时间等参数后,在人员未到地震现场的情况下,快速给出该次地震对一个区域造砀 经济损失和人员伤亡的初步评估结果。选择鲁南地震重点监视防御区为评估区域,并使用该软件系统对1995年9月-20日发生在苍山的5.2级地震进行了灾害损失快速评估的实际检验。从检验结果可看出 ,用固定资产损失率矩阵计算经济损失,获得基础资料方便, 相似文献
226.
对1997年9月23日和26日两次三水有感地震的特征进行了初步分析,认为这两次地震具有震前和震后地震活动水平低、面波发育和低震级高烈度等特性;震区的主压应力为北北西方向,两震的受力方向基本一致,但断层面解明显不同。 相似文献
227.
库车坳陷地质结构及油气带预测 总被引:3,自引:2,他引:1
利用油气地震勘探成果和露头的岩性资料 ,对库车坳陷地震层序进行划分 ,初步认为第三系膏盐层和三叠 -侏罗系煤层及泥岩是分布比较稳定的区域性软弱层 ,构成了区域内的主要滑脱面。将库车坳陷划分 6个构造带 ,对库车坳陷的构造样式进行归纳总结 ,并结合典型实例 ,采用平衡地质剖面技术对重要剖面进行地质平衡解译 ,使库车坳陷地质结构更加清晰。结合该区油气成藏的地质条件 ,划分出若干油气聚集带 ,对各油气聚集带进行分别评价 相似文献
228.
SummaryLocked in Stresses, Creep and Dilatancy of Rocks, and Constitutive Equations A micro rheological analysis is presented of the deformation characteristics of rocks based on the multi mineral and polycrystalline structure of igneous metamorphic and some sedimentary rocks; in addition the polygranular structure of sandstone-type rocks is also considered. Due account is taken with the history of rock formation and tectonics.Torsional creep test results on Ichang sandstone are presented and analysed. A new method of testing is introduced whereby the sample is subjected to a step wise loading function and the deformation measured as a function of the time. In this manner the creep as a function of stress and time can be obtained very easily from tests on only one sample.A hypothesis is presented on the origin and formation of locked in stresses the release of internal strain energy is studied at the hand of some typical test results. The practical importance of these stress pockets is discussed and it is stressed that creep and locked in stresses are fundamental factors in the behaviour of rocks which must be carefully studied in practice.On the basis of experimental results and physical reasoning constitutive equations are set up, which are three dimensional generalisations of the experimental Griggs equation: =a +b logt +ct, whereby the material parameters are scalar functions of the stress invariants.
With 8 Figures 相似文献
ZusammenfassungRestspannungen, Kriechen und Dilatation von Gesteinen, und Ausgangsgleichungen Es wird eine Analyse der rheologischen Verformungseigenschaften von Fels gezeigt, die auf dem Mineral- und Kristallgefüge von metamorphen Erstarrungs-und einigen Sedimentgesteinen beruht; außerdem wird das Korngefüge von Gesteinen mit einem Aufbau ähnlich dem von Sandsteinen berücksichtigt. Ebenso werden Gebirgsbildungsvorgänge und Tektonik beachtet.Ergebnisse von Torsionskriechversuchen an Ichang-Sandstein werden vorgelegt und analysiert. Eine neue Versuchsmethode wird vorgestellt, wobei der Probekörper einer stufenweise gesteigerten Belastung unterworfen wird und die Verformungen als Funktion der Zeit gemessen werden. Auf diese Weise wird durch Versuche mit nur einem Probekörper das Kriechen als Funktion der Belastung und der Zeit ermittelt.Es wird eine Hypothese über den Ursprung und die Bildung von Restspannungen vorgelegt. An Hand von typischen Versuchsergebnissen wird die Freiwerdung von innerer Verzerrungsenergie untersucht und die praktische Bedeutung von Kriechvorgängen und Restspannungen betont.Basierend auf Versuchsergebnissen und physikalischen Gesetzen werden Ausgangsgleichungen aufgestellt, die Verallgemeinerungen der experimentell von Griggs gefundenen Gleichung =a +b logt +ct in 3 Dimensionen darstellen. Dabei sind die Materialparameter skalare Funktionen der Invarianten des Spannungszustandes.
RésuméFluage et dilatation des roches, contraintes figées dans le massif et relatiens de comportement On présente une analyse micro-rhéologique des caractéristiques de déformation des roches, basée sur la structure multiminérale et polycristalline des roches ignées ou métamorphiques et de quelques roches sédimentaires. La structure polygranulaire des roches du type des grès est aussi envisagée. On prend en compte l'histoire de la formation des roches et de la tectonique.Des résultats d'essais de fluage en torsion sur des grès d'Echang sont données et analysés. On présente une nouvelle méthode d'essais où l'échantillon est soumis à un chargement par échelon et où la déformation est mesurée en fonction du temps. De cette façon, le fluage en fonction des contraintes et du temps peut être obtenu très facilement à partir d'essais sur un seul échantillon.On présente une hypothèse sur l'origine et la fonction des contraintes figées dans le massif et le relachement de l'énergie de déformation est étudié au moyen de résultats d'essais typiques. L'importance pratique de ces noyaux de contraintes est discutée et l'on montre que le fluage et les contraintes figées sont des facteurs fondamentaux du comportement des roches qui doivent être étudiés avec soin dans la pratique.A partir de résultats expérimentaux et au moyen de raisonnements physiques, on établit les relations de comportement et la généralisation à trois dimensions de l'équation expérimentale de Griggs =a +b logt +ct où les paramètres du matériau sont des fonctions scalaires des invariants des contraintes.
With 8 Figures 相似文献
229.
Information about seasonal crop water consumption is useful to develop the appropriate irrigation scheme. Measurements of energy balance components using the Bowen ratio method were made for a complete growing season at a vineyard in the arid region of northwest China. Vine in the experiment was furrow‐irrigated using a trellis system. The measured evapotranspiration was compared with estimates using the soil water balance method. It is shown that the Bowen ratio method provided accurate estimates of evapotranspiration from the vineyard and this requires that the Bowen ratio system is appropriately installed. The energy balance components showed typical diurnal pattern with peaks that occurred around the midday, except for the ground heat flux which delayed its peak by 2–3 h. The sensible heat flux was greater than the latent heat flux and followed the net radiation closely. The ratio of the latent heat flux to net radiation was low in the early growing season and increased over time. Under the limited irrigation experienced in the vineyard, the latent heat flux was controlled by available soil moisture and the total evapotranspiration in the growing season was 253 mm. The seasonal progression of the crop coefficient is similar to that reported in the literature, with the maximum occurring during the month of September. The crop coefficient can be estimated as a non‐linear function of day of year (DOY) and used to estimate evapotranspiration from vineyards in the region. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
230.
The effects of frictional forces acting on the sidewalls of buried box culverts are presented as determined with finite element method (FEM) and detailed soil modelling. The possibility of reducing earth pressure on deeply buried concrete box culverts by the imperfect trench installation (ITI) method has been contemplated during the last several decades. There have been limited research results published primarily regarding the qualitative aspect of load reduction in ITIs. It was found during the course of this study that significant frictional forces develop along the sidewalls of box culverts and adjacent sidefills in ITIs. Current American Association of State Highway and Transportation Officials provisions do not consider these frictional forces, but they cannot be neglected in ITIs, as their effect is dominant. An optimum geometry for the soft zone in ITIs is presented to maximize earth load reductions. The soil–structure interaction at the box culvert–soil interface was found to have a significant effect on total earth pressure acting on the bottom slab. Predictor equations for earth load reduction rates were formulated for ITIs incorporating the optimum soft zone geometry based on the FEM. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献