Earthquake Research Institute
Centre de recherche public Contact |
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1-1-1, Yayoi, Bunkyo-ku, Tokyo
113-0032 Tokyo
Japon
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Description
(Extrait du site web) |
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Spurred by the Great Kanto Earthquake of 1923, the Earthquake Research Institute was established in 1925 as a research institute within The University of Tokyo. The institute,s mission, unchanged since its foundation, is to contribute to the reduction of natural disasters by developing a path to a greater understanding of earthquakes, volcanoes and other phenomena through cutting-edge research and observation of the Earth. To this end, the institute invests great effort in developing ever more accurate observational tools capable of withstanding extreme environments, and actively pursuing cooperative relationships with other institutions working in the field, both marine and terrestrial, observing earthquakes and tectonic movements and examining the structure of the earth. Theoretical and experimental models based on observational data and laboratory experiments, and computer simulations based on such models, are essential for the prediction of phenomena such as earthquakes and volcanoes. The institute also carries out research that is directly relevant to reducing the impact of disasters, such as elaborating the tectonic structures that give rise to strong tremors, and experiments on the response of man-made structures to earthquakes. In 2005 the Office of International Earthquake and Volcano Research Promotion was established, opening another perspective on international research cooperation.
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Profil scientifique partiel |
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Domaines étudiés partiels
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Domaines scientifiques
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Quelques documents de Earthquake Research Institute
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The MU-RAY project: Summary of the round-table discussions
Auteurs :
François Beauducel, A. Bross, S. Buontempo, G. De Lellis, Y. D´eclais, L. D’auria, G. Festa, P. Gasparini, K. Hoshina, J Marteau, G. Miele, S. Pastor, O. Pisanti, H. Taira, M. Tanaka, T. Uchida, M. Vassallo, I. Yokoyama et A. Zollo
Masquer le résumé
The MU-RAY project has the challenging aim of performing muon radiography of the summit cone of Mt.
Vesuvius. The muon telescopes developed for this purpose will be available for the radiography of other
volcanoes, in particular Stromboli. The scientific goals, the strategy for their implementation and the baseline
detector design are discussed in detail. A tentative time schedule for the project is drawn.
Introduction : History of the Catalogue.
Auteurs :
John Milne
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A Catalogue of 8331 Earthquakes reconded in Japan between 1885 and 1892, by John Milne, F.R.S., F.G.S.
Source :
University of Tokyo
Global Surface Wave Tomography Using Seismic Hum
Auteurs :
Hitoshi Kawakatsu, Jean-Paul Montagner, Jean-Paul Montagner et Kiwamu Nishida
Pas de résumé disponible
Source :
INIST
Whole mantle SH velocity model constrained by waveform inversion based on three-dimensional Born kernels
Auteurs :
Nozomu Takeuchi
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A whole mantle SH velocity model is obtained by using a unique data set and techniques. Body and surface waveforms including major and multi-orbit phases are used as a data set and are inverted by using 3-D Born kernels. The resultant model, SH18CE, reveals the different natures of the two major upwelling systems: the strong low velocity anomalies beneath Africa extend for more than 1000 km from the core-mantle boundary (CMB), whereas those beneath the Pacific are restricted to 300-400 km from the CMB. The results also show the variable natures of stagnant slabs on the 670 discontinuity around Japan: the depths of the strongest high velocity anomalies within the stagnant slabs are different region by region, which is consistent with the detailed delay time tomography model in this area.
Source :
University of Tokyo
地震波形の時間周波数解析ツールの開発 : 首都圏地震観測網 (MeSO-net)構築におけるノイズ調査への適用
Auteurs :
幸治 宮川 et 慎一 酒井
Masquer le résumé
We developed a spectrogram analysis tool working on Matlab to check on a seismic waveform data easily. This tool can display waveforms, power spectrum densities (PSD), and PSD spectrograms of ground motion recorded in WIN format. It can be used to evaluate a temporal variation of ground motion, and compare waveforms and spectrums for data from dierent channels. In this paper, we outline this tool and show its application to MeSO-net (Metropolitan Seismic Observation network) data recorded at Yayoi station (YYIM).//From the analysis of whole day waveform, it is found that the noise level from 6 AM to 6 PM is more than ten times larger than that in the midnight because of a higher human activity, and the noise caused by train is recorded from 5 AM to 0:30 AM, which are trains’operation hours. //We then compare ground noise levels between YYIM, YYI0 and ASO. YYIM station is located in Tokyo University and its sensor is installed about 20m beneath the ground. The sensor at YYI0 is installed at the surface just beside the YYIM borehole. ASO is a permanent seismic station operated by Tokyo University, and one of the quietest sites in Kanto plain. From the analysis using this tool, YYIM (20m deep) is 10 to 20dB quiet than YYI0 in the range more than 5 Hz, and ASO is more than 20dB quiet than YYIM in the range lower than 20Hz.
Source :
University of Tokyo
Characteristics and source modeling of broadband seismic signals associated with the hydrothermal system at Satsuma-Iwojima Volcano, Japan
Auteurs :
Takao Ohminato
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The broadband seismic data observed at Satsuma-Iwojima volcanic island in southwestern Japan show a wide variety of interesting features. One of them is the periodic and frequency-dependent amplitude modulation of volcanic tremors. Another interesting feature is the occurrence of very long period (VLP) seismic pulses synchronized with the tremor amplitude modulation. Both the tremor amplitude modulation and the VLP pulses have fairly regular intervals of 46-50 min, suggesting a spatially fixed, non-destructive repetitive source. We performed waveform inversions to reveal the source mechanism of the VLP pulses, assuming a point source embedded in a medium that realistically represented the topography of the island. Numerical tests showed that the Green's functions used in the inversion were significantly affected by the topography. The observed VLP pulses were well explained by the rapid expansion of an inclined crack 100 m beneath the floor of the summit crater, which had a seismic moment of 3 × 10^10 Nm. Both the characteristic amplitude modulation and the VLP pulses are explained systematically by a model consisting of a water-filled crack and a network of gas paths. The water-filled crack was heated above the boiling temperature of the water in it. A sudden break of the unstable superheated state caused sudden vaporization and a pressure increase, which was observed as the VLP pulse. The network of gas paths consisted of swollen portions and constricted portions, which worked as tremor generators when vapor from the water-filled crack passed through.
Source :
University of Tokyo
On crystallization at the inner core boundary
Auteurs :
Jl Le Mouel, Jp Poirier et Hisayoshi Shimizu
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It is widely believed that a mushy layer develops at the ICB while the outer core material freezes onto the inner core. This view is obtained in reference to metallurgical or analog experiments on solidification carried out in the laboratory where morphological instability almost always follows constitutional supercooling. However, morphological instability is not an automatic consequence of supercooling: supercooling and stable solid-liquid interface may coexist under certain conditions such as might perhaps occur at the ICB. If these conditions are realized, there could be both solidification on the ICB and crystallization of small solid particles in the supercooled layer (slurry layer). We made a linear stability analysis of a unidirectionally advancing solid-liquid interface under the ICB conditions. Several values of liquidus slope against concentration of light material (mc) are used for the stability analysis. It was confirmed that supercooling and interstability may coexist if |mc| is low although this value of |mc| is believed to be too small as the liquidus slope at the ICB. The estimated amount of supercooling in the layer is of order 0.1K, and this provides an estimate of the size and population of solid particles in the slurry layer. However, even though the value of |mc| is small, to sustain such slurry layer at the ICB is unlikely due to (i) the difficulty of continuous supply of enough number of nuclei into the layer and (ii) the Rayleigh-Taylor instability by the compositional buoyancy. It is most probable that mushy layer exists at the ICB.
Source :
University of Tokyo
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