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Hasada, Yoko*; Kumazawa, Mineo; Tsuruga, Kayoko*; Kunitomo, Takahiro; Kasahara, Junzo*
Handbook of Geophysical Exploration; Seismic Exploration, Vol.40, p.381 - 395, 2010/03
Nishida, Akemi; Suzuki, Yoshio; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*
Dai-58-Kai Riron Oyo Rikigaku Koenkai Koen Rombunshu (CD-ROM), 2 Pages, 2009/06
Reliable and strict evaluation is demanded to guarantee the safety of nuclear facilities against earthquake vibrations, in particular. Usually the necessary data have been acquired by determining the natural frequency and attenuation characteristics by utilizing microseisms as an excitation agent of the vibration. The presence of measurement errors and estimation bias has been inherent and problematic in this approach. Here we try to make a break through by introducing ACROSS technology, which have been providing very accurate and reliable data on subsurface, i.e., geologic targets. In this paper, we report the relevant strategy, general concept of this approach. The technical subjects on measurement system and also a potential method of analyzing data are reported in the subsequent two papers.
Nishida, Akemi; Suzuki, Yoshio; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*
Dai-58-Kai Riron Oyo Rikigaku Koenkai Koen Rombunshu (CD-ROM), 2 Pages, 2009/06
ACROSS (Accurately Controlled, Routinely Operated, Signal System) is such a precise metrology of frequency response characteristics that the accurately controlled sinusoidal waves (acoustic comb) is used as an input to the linear dynamic system, and induced vibration as an output is measured by the accelerometers synchronized accurately to input. This technology has been developed to be used on a routine basis for the subsurface structural analysis and state-monitoring of the geological targets. We discuss the theoretical background and the related subjects of applying this method to the artificial structures. Further we report the preliminary test experiments and results on the steel beam structure installed at TGC, JAEA.
Nishida, Akemi; Suzuki, Yoshio; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*
Dai-58-Kai Riron Oyo Rikigaku Koenkai Koen Rombunshu (CD-ROM), 2 Pages, 2009/06
The transfer function data in frequency domain acquired by ACROSS is analyzed by SOMPI method, which is based essentially on AR model as a discrete equivalent of linear dynamic system. The analysis is made in two steps, time domain analysis and space-wave number domain both in a consistent way as a linear dynamic system. We have derived an accurate set of vibration characteristics including attenuation and also the local characteristics such as wave propagation within the structural units and their interactions. Detection of small change in the structure is demonstrated by introduction of very precise measurement by ACROSS combined with the data analysis by SOMPI method.
Kumazawa, Mineo; Kunitomo, Takahiro; Nakajima, Takahiro; Tsuruga, Kayoko*; Hasada, Yoko*; Nagao, Hiromichi*; Matsumoto, Hiroshi*; Kasahara, Junzo*; Fujii, Naoyuki; Shigeta, Naotaka
JAEA-Research 2007-033, 155 Pages, 2007/03
JAEA-Research-2007-033.pdf:11.04MB
The developmental study made at Tono Geoscience Center under the Earthquake Frontier Research Project since 1996 is reported for a brand new technology system called ACROSS (Accurately Controlled, Routinely Operated, Signal System). Several examples of the field application are demonstrated by the test experiments at Tono Mine site. After the developmental works of 10 years, the ACROSS is brought to be a practical method applied to the remote monitoring of temporal variation of underground states at the Horonobe Underground Research Laboratory and also it is being applied to the expected focal region of the coming Tokai earthquake near Hamaoka in Shizuoka prefecture. Whereas ACROSS technology is not mature enough yet, it is shown to be a potential and versatile methodology applied even for the health monitoring of the construction such as building strongly coupled with the ground in addition to the underground study.
Nakajima, Takahiro; Nagao, Hiromichi*; Sayanagi, Keizo*; Noda, Yoichi*; Nagao, Toshiyasu*; Kumazawa, Mineo; Hasada, Yoko*
Tokai Daigaku Kaiyo Kenkyujo Kenkyu Hokoku, (28), p.21 - 28, 2007/03
Observation test was successfully made on the faint EM-ACROSS signals transmitted through the Earth's crust over the distance of 30 km. We transmitted a set of three sine waves around 1Hz from the grounded wire source with the dipole moment 4A 
150m. The signal level observed at the distance of 30 km was in the order of 0.01pT, which is 10
lower than the average level of environmental electromagnetic noise at the observation sites. The signal-to-noise ratio (S/N) of the observations becomes up to 5 by means of the optimized stacking of the raw observation data for the 40 days. signal-to-noise ratio (S/N) becomes larger. The result of this trial observation becomes a substantial experience for the monitoring of the area of earthquake generation or volcanoes in the future.
Hasada, Yoko; Kumazawa, Mineo; Tsuruga, Kayoko; Kunitomo, Takahiro; Kasahara, Junzo
Proceedings of 2nd International Workshop Active Geophysical Monitoring of the Earth Lithosphere (AMSEG 2005), p.35 - 37, 2005/09
The Sompi event analysis is a basic analysis method for ACROSS system, in which a set of time-localized events contained in the transfer function is extracted. Sompi is the Japanese word to mean existence or absence. We have established the fundamental algorithm and made revisions on the basis of Maximum Likelihood estimation (Hasada et al., 2004). To analyze numerous data acquired by continuous monitoring using ACROSS, automatic processing is necessary. We have attempted to improve the Sompi event analysis by using some additional techniques and examine the possibility of automatic travel time determination.
Tsuruga, Kayoko; Ogawa, Katsuro*; Nagao, Hiromichi; Hasada, Yoko; Fujii, Naoyuki*; Kasahara, Junzo; Kumazawa, Mineo
Chigaku Zasshi, 114(4), p.659 - 664, 2005/04
The 1st International Workshop on 'Active Monitoring in the Solid Earth Geophysics' was held in Mizunami city, Gifu, from June 30, 2004 to July 2. This paper discusses the significance of the active monitoring of the earth, and reports the summary of the workshop.
Tsuruga, Kayoko; Kunitomo, Takahiro; Hasada, Yoko; Kumazawa, Mineo; Shigeta, Naotaka; Kasahara, Junzo
IWAM04, 116 Pages, 2004/08
We are developing an active seismic monitoring methodology on the seismic ACROSS to detect any subtle change of geophysical properties in the Earth's crust. To demonstrate the availability of the seismic ACROSS, which uses coherent seismic waves actively, it may be the best to use several dense arrays routinely. In this study, we briefly review our seismic array observation system by the seismic ACROSS and their specifications, and report the latest results of array observation.
Tsuruga, Kayoko; Kunitomo, Takahiro; Hasada, Yoko; Kumazawa, Mineo; Shigeta, Naotaka; Kasahara, Junzo
2004 AGU Fall Meeting Program and Abstract, S31C-05, 0 Pages, 2004/00
We are developing an active monitoring methodology named ACROSS (Accurately Controlled Routinely Operated Signal System) to detect any subtle temporal change of physical properties in the Earth's interiors (Kumazawa et al., 2000). ACROSS is a comprehensive measurement system to determine continuously the transfer function of a linear system by means of the coherent signals. The combination of ACROSS transmission and array observation allow us to obtain the transfer function with high S/N (ratio of signal to noise) and S/B (ratio of signal to bias) in space and time. In this paper, we briefly review the specifications of our seismic array and report the latest results of the data analyses.
Kasahara, Junzo; Tsuruga, Kayoko; Hasada, Yoko; Yamaoka, Koshun; Kunitomo, Takahiro; Watanabe, Toshiki; Fujii, Naoyuki
2004 AGU Fall Meeting Program and Abstract, S31C-07, 0 Pages, 2004/00
Recently, a very strong reflected PP phase from the subducting plate boundary was found beneath the aseismic forearc slope of the Japan Trench. Similar strong PP reflection phase was observed near the plate boundary of the subducting Philippine Sea Plate and the Eurasian Plate, in the western part of Shizuoka Prefecture. These strong PP reflections are interpreted as reflections from the non-asperity region along the plate boundary caused by the presence of low-Vp material. Using continuous transmission of seismic waves from the ACROSS source located and /or the new ACROSS source under planning and the high sensitivity seismometers along the NS traverse line, we can delineate the temporal variation of seismic wave properties of the anomalously reflected PP phase along the boundary of subducting Philippine Sea Plate.
Hasada, Yoko; Kumazawa, Mineo; Tsuruga, Kayoko; Kunitomo, Takahiro
AGU 2004 Fall Meeting, 0 Pages, 2004/00
We have developed a method to extract "events" localized in time domain from a transfer function in frequency domain, which is a basic analysis method of ACROSS(Accurately Controlled Routinely Operated Signal System)and referred to as the Sompi event analysis. Though the validity of the Sompi event analysis is confirmed through various numerical tests especially for analysis of dispersive wave, there are some problems in practical application. Here we introduce a revised procedure by means of weighted least squares fitting, which is based on maximum likehood estimation.
Junzo, Kasahara; Tsuruga, Kayoko; Hasada, Yoko; ; Kumazawa, Mineo; Kunitomo, Takahiro
Gekkan Chikyu Gogai, (47), 141 Pages, 2004/00
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
Tsuruga, Kayoko; Kunitomo, Takahiro; Hasada, Yoko; Kumazawa, Mineo; Shigeta, Naotaka;
Gekkan Chikyu Gogai, (47), 95 Pages, 2004/00
There is a problem of vibration in a diagnosis system of helical evaporator tubes installed in a nuclear power station. Numerical simulations are implemented on the assumption that the vibration is caused by the Coulomb's friction. An analytical model is derived as a large scale nonlinear vibration system and a lot of computational cost would be required to carry out the simulations. The Transfer Influence Coefficient Method, which has high accuracy and efficiency in numerical computations, is applied and efficiently implements the simulations. The vibrations are qualitatively reproduced by the simulations. It enables us to make a pre-evaluation of several means to suppress the vibrations are qualitatively reproduced by the simulations. It enables us to make a pre-evaluation of several means to suppreess the vibration and the most effective devise is expected through the simulation.
Hasada, Yoko; Kumazawa, Mineo; Tsuruga, Kayoko; Kunitomo, Takahiro
Gekkan Chikyu Gogai, (47), p.61 - 68, 2004/00
A data set acquired by ACROSS is the transfer functions between transmitted signal and received one sampled within limited bandwidth. We have developed a method to extract event localized in time domain from frequency-domain transfer function and estimate the traveltimes, which is called the Sompi event analysis.
Nishida, Akemi; Suzuki, Yoshio; Hasegawa, Ken; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*
no journal, ,
Reliable and strict evaluation is demanded to guarantee the safety of nuclear facilities against earthquake vibrations, in particular. Usually the necessary data have been acquired by determining the natural frequency, the natural mode and attenuation characteristics by utilizing microseisms as an excitation agent of the vibration. The presence of measurement errors and estimation bias has been inherent and problematic in this approach. Here we try to make a break through by introducing ACROSS technology, which have been providing very accurate and reliable data on subsurface, i.e., geologic targets. In this presentation, we present the relevant strategy, general concept of this approach. The technical subjects on measurement system and also a potential method of analyzing data are presented, too. Some parts of this research result were obtained as the results of the JAEA director's fund for research and development in 2008.
Kunitomo, Takahiro; Nakajima, Takahiro; Hasada, Yoko*; Fujii, Naoyuki; Kumazawa, Mineo
no journal, ,
no abstracts in English
Kumazawa, Mineo; Ogawa, Katsuro*; Fujii, Naoyuki; Yamaoka, Koshun; Kunitomo, Takahiro; Nakajima, Takahiro; Tsuruga, Kayoko; Hasada, Yoko; Kasahara, Junzo; Shigeta, Naotaka; et al.
no journal, ,
no abstracts in English
