老挝国家地震监测台网布局与组网

老挝国家地震监测台网(LEMN)是“一带一路”倡议下中国推进援外地震台网建设的又一重要工程,为了及时总结台网建设经验,从该台网的布局、组网、设备配备、台网链接方式等方面进行详细阐述,为我国未来省域地震监测台网和新时代援外台网的建设积累详实的参考资料。     

老挝国家地震监测台网布局与组网

老挝国家地震监测台网（LEMN）是“一带一路”倡议下中国推进援外地震台网建设的又一重要工程,为了及时总结台网建设经验,从该台网的布局、组网、设备配备、台网链接方式等方面进行详细阐述,为我国未来省域地震监测台网和新时代援外台网的建设积累详实的参考资料。     

宿迁数字测震台网建设效益分析

宿迁市数字测震台网是宿迁市防震减灾"十三五"规划的重点项目,介绍了宿迁数字测震台网的建设内容、台网布局,分析了宿迁测震台网监测能力,以及台网建成后,在宿迁市防震减灾、地震预报研究和保障社会稳定方面发挥的重要作用等。     

中国地震台网观测系统特性分析与资料应用研究

正2000年以来我国地震观测系统得到了迅速的发展,目前已建成了由国家数字地震台网、区域数字地震台网、火山数字地震台网和流动数字地震台网组成的新一代中国数字地震台网。中国地震台网中心每天汇集的数据量达到40GB,可以说,我国地震台网产出的观测数据积累到了一定程度,如此海量的地震波形数据为地震监测与研究提供了丰富的原始资料,     

西藏地震监测台网的建设与发展

回顾西藏自治区地震监测台网发展历程,介绍西藏测震台网、地球物理台网和GNSS台网的建设与发展现状,并对西藏地区测震台网、地球物理台网和GNSS台网的未来发展提出建议,建议进一步优化各类台网布局,提升西藏地区地震监测能力和地球物理参数获取能力,为防震减灾工作和地球科学研究提供高质量观测数据。     

陕西测震台网技术系统

通过测震台网网络技术平台,分析其系统构成及虚拟台网、3G无线传输、远程网络监控等技术在陕西测震台网的应用.该平台的建成,提高了测震台网运行质量及流动测震台网的快速响应能力,实现省、市测震台网观测数据的实时共享,对进一步提升地震部门地震响应能力、完善监测体系,具有重要意义.     

广西数字测震台网建设成果及效益分析

介绍了"十五"广西数字测震台网建设的基本情况,分析了台站布局、观测动态范围和台基环境地噪声水平对台网地震监测能力的影响。实现与邻省台网和地方社会台网的联网与数据共享后,台网监测能力得到进一步提高。以广西数字测震台网投入运行前后记录到的地震情况,阐述了广西数字测震台网技术成果及所取得的社会经济效益。     

对全国地震基本台网的展望与工作设想

随着科学技术的发展与地震监测工作的需要,继全国地震基本台网之后,在我国及各地区又相继建立了一批区域测震台网、流动测震台网、大震速报台网、763长周期台网等。近年来,随着数字技术和计算机技术的飞速发展,又出现了数字地震台网。数字测震观测技术与系统的出现无疑在测震技术与测震观测上是一次巨大的变革与进步,对各类测震台网的     

江西数字测震台网建设效益分析

介绍“十五”江西数字测震台网建设的基本情况,分析台站布局、观测动态范围和台基环境地噪声水平对台网地震监测能力的影响,阐述江西数字测震台网技术成果及所取得的社会经济效益.实现与邻省台网的联网与数据共享后,台网监测能力得到提高.     

区域测震台网监测效能评估方法研究及应用

如何通过评价区域测震台网方式,改善与提高我国区域测震台网监测效能,是当前我们面临的一个新的课题。本文提出的一个省级区域测震台网监测效能评价体系基本思路是,通过建立台网监测效能评价子系统,引入动态统计,指标分析,目标评价,公众评判的综合分析与关联评价方法,探讨我国省级测震台网系统性能与台网运行,维护能力及资料产出、数据服务之间的相互关联。以安徽区域测震台网为例,检验区域台网监测效能评价体系的可行性与实效性。     

Episodic tectonic plate reorganizations driven by mantle convection

Periods of relatively uniform plate motion were interrupted several times throughout the Cenozoic and Mesozoic by rapid plate reorganization events [R. Hey, Geol. Soc. Am. Bull. 88 (1977) 1404-1420; P.A. Rona, E.S. Richardson, Earth Planet. Sci. Lett. 40 (1978) 1-11; D.C. Engebretson, A. Cox, R.G. Gordon, Geol. Soc. Am. Spec. Pap. 206 (1985); R.G. Gordon, D.M. Jurdy, J. Geophys. Res. 91 (1986) 12389-12406; D.A. Clague, G.B. Dalrymple, US Geol. Surv. Prof. Pap. 1350 (1987) 5-54; J.M. Stock, P. Molnar, Nature 325 (1987) 495-499; C. Lithgow-Bertelloni, M.A. Richards, Geophys. Res. Lett. 22 (1995) 1317-1320; M.A. Richards, C. Lithgow-Bertelloni, Earth Planet. Sci. Lett. 137 (1996) 19-27; C. Lithgow-Bertelloni, M.A. Richards, Rev. Geophys. 36 (1998) 27-78]. It has been proposed that changes in plate boundary forces are responsible for these events [M.A. Richards, C. Lithgow-Bertelloni, Earth Planet. Sci. Lett. 137 (1996) 19-27; C. Lithgow-Bertelloni, M.A. Richards, Rev. Geophys. 36 (1998) 27-78]. We present an alternative hypothesis: convection-driven plate motions are intrinsically unstable due to a buoyant instability that develops as a result of the influence of plates on an internally heated mantle. This instability, which has not been described before, is responsible for episodic reorganizations of plate motion. Numerical mantle convection experiments demonstrate that high-Rayleigh number convection with internal heating and surface plates is sufficient to induce plate reorganization events, changes in plate boundary forces, or plate geometry, are not required.     

BOOK REVIEW

Book review in this article
Handbuch der Physik/Encyclopedia of Physics, Ed.: S. Flügge
The Aurora. By S.-I. Akasofu, S. Chapman and A. B. Meinel.
Time-Variations of Cosmic Rays. By S. E. Forbush.
Magnetic Properties of Rocks and Minerals. By T. Nagata.     

Comment on “A note on the free-surface effect on the topographicaily induced vorticity field in a homogeneous flow” by lee-or merkine

Abstract

MASS LOSS AND EVOLUTION OF O-TYPE STARS. I.A.U. Symposium No. 83. Edited by P. S. Conti and C. W. H. de Loore. Reidel, Dordrecht. (ISBN 90-277-0989-0 pbk) 1979. Price U.S. $31.50.

A MATHEMATICAL INTRODUCTION TO FLUID MECHANICS by A. J. Chorin &; J. E. Marsden, 205 pages, paperback, Springer Verlag. (ISBN 0-387-90406-9 and ISBN 3-540-90406-9) 1979. Price: DM 29—US $16.00.     

Curvelet阈值迭代法地震随机噪声压制(英文)

本文将近些年发展起来的多尺度分析技术——Curvelet变换与求解优化反演问题的阈值迭代法相结合,研究了基于Curvelet变换的阈值迭代法在地震数据随机噪声衰减中的应用。充分利用了Curvelet变换对地震数据表示的稀疏性,提出将地震数据随机噪声压制问题转化为基于Curvelet稀疏变换的L1范数最优化问题,并采用前人提出的阈值迭代法求解。通过与常规的中值滤波、FX反褶积和小波阈值法去噪方法对比,理论合成数据和实际数据试算表明,Curvelet阈值迭代法去噪法具有优势,该法不仅能够获得较高的信噪比,而且对有效信号的损失较小。为充分利甩Curvelet的多尺度、多方向特性,提出了在Curvelet阈值迭代法去噪结果的基础上再进行方向控制,进一步提高了数据信噪比。     

Global seismicity of 2003: centroid–moment-tensor solutions for 1087 earthquakes

Centroid–moment-tensor (CMT) solutions are presented for 1087 earthquakes that occurred during 2003. The solutions are obtained using the method of Dziewonski et al. [Dziewonski, A.M., Chou, T.-A., Woodward, J.H., 1981. Determination of earthquake source parameters from waveform data for studies of global and regional seismicity. J. Geophys. Res. 86, 2825–2852] and applying corrections for aspherical Earth structure as represented by the whole-mantle shear-velocity model SH8/U4L8 of Dziewonski and Woodward [Dziewonski, A.M., Woodward, R.L., 1992. Acoustic imaging at the planetary scale. In: Emert, H., Harjes, H.-P. (Eds.), Acoustical Imaging, vol. 19. Plenum Press, New York, pp. 785–797]. The model of inelastic attenuation of Durek and Ekström [Durek, J.J., Ekström, G., 1996. A radial model of inelasticity consistent with long-period surface wave attenuation. Bull. Seism. Soc. Am. 86, 144–158] is used to predict the decay of the waveforms. The focal mechanisms of the largest, or otherwise significant, earthquakes of 2003 are reviewed.     

Cainozoic history of southern New Zealand: An accord between geological observations and plate-tectonic predictions

Sea-floor spreading data from the Southwest Pacific have recently been used to predict the Cainozoic geological history along the Indo-Australian/Pacific plate boundary. Geologic and sedimentologic data pertaining to this plate boundary where it crosses southern New Zealand, as the Alpine Fault, are summarised and discussed. It is concluded that there is a close accord between the plate-tectonic predictions and South Island Cainozoic geological history. In particular, (1) no Cainozoic plate boundary traversed the New Zealand region prior to 38 m.y. B.P. (late Eocene); (2) transcurrent movement on the Alpine Fault took place largely between ca. 30 m.y. B.P. (middle Oligocene) and ca. 10 m.y. B.P. (late Miocene); and (3) the period 10 m.y. B.P. to present corresponds to a phase of oblique compression, continental collision, and mountain building along the Alpine Fault sector of the plate boundary. There is a close correlation between the sites and histories of Cainozoic sedimentation and this tectonic timetable.     

Ra or Ra/Ba dating of Holocene volcanic rocks: application to Mt. Etna and Merapi volcanoes

This paper shows how ²²⁶Ra–²³⁰Th disequilibria can be used to date Holocene volcanic rocks from some well selected volcanoes. A systematic study of these disequilibria on historical or well-dated volcanic samples is indeed first required to test the applicability of this method. Two examples are described here to illustrate its potential. In the case of Mt. Etna, the good correlation observed between (²²⁶Ra)₀ activities at the time of eruption and Th contents in lava flows from the last two millennia [M. Condomines, J.C. Tanguy, V. Michaud, Magma dynamics at Mt. Etna: constraints from U–Th–Ra–Pb radioactive disequilibria and Sr isotopes in historical lavas, Earth Planet. Sci. Lett. 132 (1995) 25–41] is used to infer the ages of several newly analysed lava flows. The calculated ages are in good agreement with those deduced from the archaeomagnetic curve describing the variation of the geomagnetic field direction in southern Italy [J.C. Tanguy, I. Bucur, J.F.C. Thompson, Geomagnetic secular variation in Sicily and revised ages of historic lavas from Mt. Etna, Nature 318 (1985) 453–455, J.C. Tanguy, M. Le Goff, V. Chillemi, A. Paiotti, C. Principe, S. La Delfa, G. Patane, Variation séculaire de la direction du champ géomagnétique enregistrée par les laves de l'Etna et du Vésuve pendant les deux derniers millénaires, C. R. Acad. Sci. Paris 329 (1999) 557–564, J.C. Tanguy, M. Le Goff, C. Principe, S. Arrighi, V. Chillemi, A. Paiotti, S. La Delfa, G. Patane, Archaeomagnetic dating of Mediterranean volcanics of the last 2100 years: validity and limits. Earth Planet. Sci. Lett. 211 (2003) 111–124]. We also present a whole set of new U-series data on historical, recent, and older samples from Merapi (Indonesia), and show that the (²²⁶Ra)/Ba ratio has probably maintained a quasi-steady state value during at least the past four millennia, and can be used to infer the (²²⁶Ra)₀/Ba ratio of old volcanics at the time of eruption, and thus their ages. Comparison with ¹⁴C ages available on three samples [R. Gertisser, J. Keller, Temporal variations in magma composition at Merapi volcano (Central Java, Indonesia): magmatic cycles during the past 2000 years of explosive activity, J. Volcanol. Geotherm. Res. 123 (2003) 1–23] shows an excellent agreement. These dating methods, based on the post-eruptive decrease of ²²⁶Ra excesses can be confidently used to date young rocks on both volcanoes, an important step to infer their recent eruptive history and magmatic evolution. It also opens the possibility to extend the geomagnetic field variation curve back into the past few millennia. The promising results obtained in this work should encourage new systematic U-series studies to test the applicability of such methods to other permanently active volcanoes showing ²²⁶Ra excesses.     

Torsional vibration of an orthotropic Cylindrical Shell

Summary This paper is concerned with the determination of torsional vibration of an orthotropic Cylindrical Shell assuming the elastic constants to be proportional to thenth power of the distance from the axis of the shell. The solution is obtained in terms of Bessel functions.c/o Dr. A. K. Dutta, P. 7. A H. B. Town, Block A, P. O. Sodepur, Dt. 24-Paraganas, West Bengal, India.     

BOOK REVIEWS

Book review in this article
F. S. G rant and G. F. W est , Interpretation Theory in Applied Geophysics, McGraw-Hill Comp., New York, 1965, 583 pp., price $ 17.50.
A rchaeo -P hysica . Technische und naturwissenschaftliche Beiträge zur Feldarchäologie. Mit Beitragen von E. Le Borgne, I. Scollar, J. D. Mudie, J. Görier, H.-J. Appel, G. Strunk-Lichtenberg, Böhlau Verlag, Köln, Graz, 1965, 202 pp., 124 fig.
H. T akeuchi , Theory of the Earth's Interior, Blaisdell Publishing Company, Waltham (Mass.), Toronto, London, 1966, 131 pp.
G. D. G arland , The Earth's Shape and Gravity, The Commonwealth and International Library, Geophysics Division, Pergamon Press, Oxford, London, Edinburgh, New York, Paris, Frankfurt, 1965, 183 pp., price: 17s 6d.     

Impact of salt stress on the features and activities of root system for three desert halophyte species in their seedling stage

Linkage between belowground and aboveground sections of ecological system is mainly depending on root system. But root system is the parts of plant that people less understand. The absorption function of root system is closely related to their morphology and activity. Moreover root system can interact with the environmental stress under the adverse situation, and adjust its system to take adaptation responses in morphology and physiology to strengthen its survival chance. This research is focused on three desert halophyte species of H. ammodendron (C.A.Mey.) Bge., S. physophora Pall., and S. nitraria Pall. under solution culture, to study the differences of their root system morphology and activity in the seedling stage under varying salt concentration conditions. The study results show that: A certain salt concentration can promote development of these three halophytes; but rather high salt concentration will restrain their growth, in particular inhibit the root system development. Under the same salt concentration condition, S. nitraria Pall. grows fast and accumulates the largest amount of biomass. Under relatively low salt concentration, the length of axial root and the total length of root system of these three halophyte species are all increased; and compared to the checking samples, S. physophora Pall. occupies the top place of root system growth, but the high salt concentration will restrain the increase of total root length; among them, the impact intensity on S. physophora Pall. is lighter than to H. ammodendron (C.A.Mey.) Bge. and S. nitraria Pall. is lighter; the salinity does not bring distinct influence on the average diameter of root system of these three plant species, but trends to reducing the size; under the solution culture conditions, the middle and lower parts of the axial root of H. ammodendron (C.A.Mey.) Bge. and S. physophora Pall. are rather equally distributed, but the central zone of S. nitraria Pall. root system is more significantly increased than the upper and lower zones; salt concentration does not bring significant impact on the root system spatial distribution of each species. The root activity of the three plants is increased along with the increase of the salt concentration. When the salt concentration is low, the root activity is not significantly increased; but when the salt concentration is high, the root activity is increased significantly. The experimental results show that the saline tolerance capacity of H. ammodendron (C.A.Mey.) Bge. is lower than the other two species, and the capacity of S. physophora Pall. ranks the top place.