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671.
The Red Sea continental margin (RSCM) corresponds to a wide hinge zone between Red Sea and Arabian plate. This margin has been studied through geological and geophysical observations primarily in regard to the evolution of Red Sea rift. This margin is characterized by occurrence of thin sediments, significant onshore uplift, tectonic subsidence of the offshore sedimentary basin, active faulting and seismicity. Studies indicate that sedimentary sequences of the margin are deformed by faults and folds resulti... 相似文献
672.
The distribution of small fractures and water content of the Fourcade glacier on King George Island, Antarctica, was investigated in November 2006 and December 2007 by two ground-based (470-and 490-m-long profiles) and one helicopter-borne (470-m-long profile) ground-penetrating radar (GPR) surveys using 50-, 100-, and 500-MHz antennas. Radar images in the pre-migrated GPR sections are characterized by a smooth ice surface and irregular bed topography, numerous diffraction hyperbolas in the ice and at the g... 相似文献
673.
674.
Millimetre observations of three southern carbon stars, IRAS 07454-7112, IRAS 15082-4808 and IRAS 15194-5115 detected 14 molecular species and some of their isotopomers. The12C/13C ratio was found to vary between sources. 相似文献
675.
Eijiro Hiei 《中国天文和天体物理学报》2004,4(4):377-389
After surveying the spectra of 39 prominences observed by the Multichannel Infrared Solar Spectrograph at Purple Mountain Observatory and the 25 cm coronagraph at the Norikura Solar Observatory, we found that about 28% of them show small spatial scale (6"- 8") and short time scale (tens of seconds to a few minutes), unusual large broadening and large shift velocities in spectral lines including Hα, Hβ, Hε, Ca Ⅱ H, Ca Ⅱ K, Ca2Ⅱ 8542 A, He Ⅰ D3 and HeⅠ 10830 A. We present in detail two typical events observed respectively on 2002 May 27 and 1981 August 2. The full-width at half maximum of the widest profile of the 2001 prominence is 1.8 A for Ha and 2.9 A for He I 10830 A, while that of the 1981 prominence is 5.3 A for Hβ, 3.6 A for Ca Ⅱ K, 4.0 A for Ca Ⅱ H and 2.8 A for He Ⅰ D3. Such broadenings generally occur at a level of several-thousand kilometres above the chromosphere. Further, most of these prominences manifest a rotation of (0.4-1.35) ×10-2 rad s-1 pointing to the Sun and large line 相似文献
676.
Marcel - E. Denaeyer 《Bulletin of Volcanology》1963,25(1):201-215
Geological environment and origin of the palagonitised tuff volcanoes of the Kivu. Petrographical features (lapilli, palagonitisation, gangue). Their magmatic minerals and xenoliths. 相似文献
677.
The halfwidth method used for the determination of the electron density in flares is discussed from the point of view of possible errors which may enter the obtained results. The discussion includes an analysis of errors of measurement as well as errors of the method due to: (1) our incomplete knowledge of the electron damping, (2) the assumption of constant electron temperature, (3) the presence of residual self-absorption in high Balmer lines, and (4) possibly present non-thermal motions. It is shown that the factors (2) to (4) cannot induce any relative error in n
e higher than 30 % of the correct value, and the actual error usually is smaller. A comparison is made of the halfwidth-method application to active prominences and limb flares. 相似文献
678.
B. Hultqvist H. Borg L.-Ă. Holmgren H. Reme A. Bahnsen M. Jespersen G. Kremser 《Planetary and Space Science》1982,30(3):261-283
From an analysis of the local time distribution of the electron upper energy limit reached by the geostationary satellite GEOS-2 in cutting through the innermost part of the electron plasma sheet during fairly quiet conditions the following results have been obtained, among others. An electric field model given by , with the dusk singular point of the forbidden region boundary at 1500, instead of at 1800 M.L.T., is in quite good agreement with the observations. This means that effects due to the shielding by the hot plasma of the inner magnetosphere from the convection electric field are quite strong in situations of low disturbance level. The quiet-time convection electric field strength at 2100 M.L.T. in the geostationary orbit obtained from this analysis varies in the range 0.15–0.3 kV/Re. Six hours earlier or later in the satellite orbit the convection field is four times stronger. Also when the convection field varies, some information about its magnitude can be obtained from the keV electron measurements. 相似文献
679.
680.