Magnitudes of great shallow earthquakes from 1953 to 1977     

Katsuyuki Abe  Hiroo Kanamori 《Tectonophysics》1980,62(3-4)

The surface-wavemagnitudes M_s are determined for 30 great shallow earthquakes that occurred during the period from 1953 to 1977. The determination is based on the amplitude and period data from all available station bulletins, and the same procedure as that employed in Gutenberg and Richter's “Seismicity of the Earth” is used. During this period, the Chilean earthquake of 1960 has the largest M_s, 8.5. The surface-wave magnitudes listed in “Earthquake Data Reports” are found to be higher than M_s on the average. By using the same method as that used by Gutenberg, the broad-band body-wave magnitudes m_B are determined for great shallow shocks for the period from 1953 to 1974. m_B is based on the amplitudes of P, PP and S waves which are measured on broadband instruments at periods of about 4–20 s. The 1-s body-wave magnitudes listed in “Bulletin of International Seismological Center” and “Earthquake Data Reports” are found to be much smaller than m_B on the average. Through the examination of Gutenberg and Richter's original worksheets, the relation between m_B and M_sis revised to m_B = 0.65 M_s+ 2.5 which well satisfies the mg and M_sdata for M_sbetween 5.2 and  相似文献   

Structure and Evolution of the East Antarctic Lithosphere: Tectonic Implications for the Development and Dispersal of Gondwana   总被引：1，自引：0，他引：1  

Masaki Kanao  Masahiro Ishikawa  Mikiya Yamashita  Katsutada Kaminuma  Larry D. Brown   《Gondwana Research》2004,7(1):31

Lithospheric evolution of the Antarctic shield is one of the keystones for understanding continental growth during the Earth's evolution. Architecture of the East Antarctic craton is characterized by comparison with deep structures of the other Precambrian terrains. In this paper, we review the subsurface structure of the Lower Paleozoic metamorphic complex around the Lützow-Holm area (LHC), East Antarctica, where high-grade metamorphism occurred during the Pan-African orogenic event. LHC is considered to be one of the collision zones in the last stage of the formation of Gondwana. A geoscience program named ‘Structure and Evolution of the East Antarctic Lithosphere (SEAL)’ was carried out since 1996-1997 austral summer season as part of the Japanese Antarctic Research Expedition (JARE). Several geological and geophysical surveys were conducted including a deep seismic refraction/wide-angle reflection survey in the LHC. The main target of the SEAL seismic transect was to obtain lithospheric structure over several geological terrains from the western adjacent Achaean Napier Complex to the eastern Lower Paleozoic Yamato-Belgica Complex. The SEAL program is part of a larger deep seismic profile, LEGENDS (Lithospheric Evolution of Gondwana East iNterdisciplinary Deep Surveys) that will extend across the Pan-African belt in neighboring fragments of Gondwana.  相似文献   

Perspectives on Japanese ground water resources     

Fujinawa K 《Ground water》2002,40(4):332-333

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Temporal variation in primary magma compositions in the northeast Japan Arc     

Shigeru  Yamashita  Yoshiyljki  Tatsump Susumu  Nohda 《Island Arc》1996,5(3):276-288

Abstract A remarkable temporal variation in primary magma compositions has been found in the Northeast Japan arc. The trench-side magmas have become more enriched in FeO* and the backarc-side magmas have become more depleted in FeO* while retaining almost constant SiO, levels for the last ∼20 million years. In order to understand the origin of the temporal variation, FeO* and SiO, contents in partial melts are modeled for an adiabatically-rising mantle as a function of potential temperature and original composition of the mantle material. The result demonstrates that the primary magmas that are more depleted in FeO* were derived from the mantle materials either at lower potential temperatures or with compositions more depleted in basaltic components. A possible mechanism for the inferred primary magma variability is the change in depth intervals with time of magma production in a compositionally-layered mantle wedge; greater degrees of depletion at a greater depth is reconciled with a probable thermal regime in the mantle wedge.  相似文献   

Multiple scattering of SH waves in 2-D elastic media with distributed cracks     

Yoshio Murai  Jun Kawahara  Teruo Yamashita 《Geophysical Journal International》1995,122(3):925-937

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Finite element analysis of a meniscus mirror     

Y. Yamashita 《Astrophysics and Space Science》1989,160(1-2):145-147

Finite element analyses were carried out for a 7.5 m meniscus mirror of 20 cm thickness. Calculations were made for deformations of the mirror surface due to the gravity and the effect of a hole through which a lateral supporting mechanism would be installed. Vibrational eigenmodes were also calculated when the mirror is fixed by three axial and three lateral hard points.Paper presented at the symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.  相似文献   

Fault configuration produced by initial arc rifting in the Parece Vela Basin as deduced from seismic reflection data   总被引：1，自引：0，他引：1  

Mikiya  Yamashita  Tetsuro  Tsuru  Narumi  Takahashi  Kaoru  Takizawa  Yoshiyuki  Kaneda  Kantaro  Fujioka  Keita  Koda 《Island Arc》2007,16(3):338-347

Abstract   The Parece Vela Basin (PVB), which is a currently inactive back-arc basin of the Philippine Sea Plate, was formed by separation between the Izu-Ogasawara Arc (IOA) and the Kyushu-Palau Ridge (KPR). Elucidating the marks of the past back-arc opening and rifting is important for investigation of its crustal structure. To image its fault configurations and crustal deformation, pre-stack depth migration to multichannel seismic reflection was applied and data obtained by the Japan Agency for Marine-Earth Science and Technology and Metal Mining Agency of Japan and Japan National Oil Corporation (Japan Oil, Gas and Metals National Corporation). Salient results for the pre-stack depth-migrated sections are: (i) deep reflectors exist around the eastern margin of KPR and at the western margin of IOA down to 8 km depth; and (ii) normal fault zones distributed at the eastern margin of the KPR (Fault zone A) and the western margin of the IOA (Fault zone B) have a total displacement of greater than 500 m associated with synrift sediments. Additional normal faults (Fault zone C) exist 20 km east of the Fault zone B. They are covered with sediment, which indicates deposition of recent volcanic products in the IOA. According to those results: (i) the fault displacement of more than 500 m with respect to initial rifting was approximately asymmetric at 25 Ma based on PSDM profiles; and (ii) the faults had reactivated after 23 Ma, based on the age of deformed sediments obtained from past ocean drillings. The age of the base sediments corresponds to those of spreading and rotation after rifting in the PVB. Fault zone C is covered with thick and not deformed volcanogenic sediments from the IOA, which suggests that the fault is inactive.  相似文献   

Yellow fluorescence from baghdadite and synthetic Ca3(Zr,Ti)Si2O9     

Aierken Sidike  I. Kusachi  N. Yamashita 《Physics and Chemistry of Minerals》2006,32(10):665-669

Baghdadite from Fuka, Okayama Prefecture, Japan shows a bright yellow fluorescence under UV (Hg 253.7 nm) excitation. The photoluminescence (PL) spectrum at 300 K consists of one large band near 580 nm and two small UV bands at 318 and 397 nm. The optical excitation spectrum of the bright yellow fluorescence consists of two bands near 220 and 250 nm. The temperature dependence of the PL intensity exhibits linear thermal quenching. To reveal the origin of the bright yellow fluorescence from baghdadite, powder Ca₃(Zr,Ti)Si₂O₉ crystals are synthesized. Synthetic Ca₃(Zr,Ti)Si₂O₉ shows luminescence spectra similar to those of baghdadite, and the intensity of the yellow fluorescence is markedly increased by titanium addition. The origin of the bright yellow fluorescence from baghdadite is ascribed to the existence of titanium.  相似文献   

Phase disturbance of 100-kHz groundwaves by a circular island in the open sea     

Yamashita  M. Taguchi  K. 《Oceanic Engineering, IEEE Journal of》1981,6(1):26-31

The hyperbolic position fixing of ships by the Decca navigation system utilizes groundwave propagation. But the hyperbolic pattern will be disturbed by an isolated island. The instantaneous phase velocity and the bearing error are calculated from the equiphase lines near the island. It is found numerically and experimentally that the hyperbolic pattern is bent towards the island that is situated on the baseline between the master station and the slave one.  相似文献   

Symposium on Earthquake Prediction, Tokyo, 1976 December 13–15     

E. R. Lapwood  T. Usami  T. Yamashita 《Geophysical Journal International》1977,49(2):549-550

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