Ichiro Takahashi
Chiba University
Publications 28
#1Ichiro TakahashiH-Index: 11
#2Kazutaka FukushimaH-Index: 24
Last.Hajime IizukaH-Index: 2
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#1Michel André (UPC: Polytechnic University of Catalonia)H-Index: 41
#2Ryoichi Iwase (JAMSTEC: Japan Agency for Marine-Earth Science and Technology)H-Index: 10
Last.Antonio M. Sanchez (UPC: Polytechnic University of Catalonia)H-Index: 3
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A system for the real-time and fully automated detection, classification and localisation of acoustic sources in the marine environment has been developed at the Laboratory of Applied Bioacoustics (LAB) of the Technical University of Catalonia (UPC). The system features modules for the detection, the classification and localisation of short tonal sounds and impulsive sounds and the quantification of the level and the spectral characteristics of the background noise. The system has been successfu...
2 CitationsSource
#1Ryoichi Iwase (JAMSTEC: Japan Agency for Marine-Earth Science and Technology)H-Index: 10
#2Ichiro TakahashiH-Index: 11
Last.Kenichi KatoH-Index: 1
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Through the waveform analysis of click sounds that have been observed with a bottom installed single hydrophone of the multidisciplinary cabled observatory on deep seafloor off Hatsushima Island in Sagami Bay, some features of sperm whales, such as diving depth, speed and body length were studied. In addition, echo intensity variations of Acoustic Doppler Current Profiler (ADCP) were observed that indicate diving whales roughly consistent with the result of waveform analysis on hydrophone data. ...
1 CitationsSource
#1Katsumi HattoriH-Index: 27
#2Hisashi IshikawaH-Index: 1
Last.Chie YoshinoH-Index: 11
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#1Takafumi KasayaH-Index: 14
#2Kyohiko MitsuzawaH-Index: 13
Last.Toshiyasu NagaoH-Index: 16
view all 11 authors...
Sagami Bay is an active tectonic area in Japan. In 1993, a real-time deep sea floor observatory was deployed at 1,175 m depth about 7 km off Hatsushima Island, Sagami Bay to monitor seismic activities and other geophysical phenomena. Video cameras monitored biological activities associated with tectonic activities. The observation system was renovated completely in 2000. An ocean bottom electromagnetic meter (OBEM), an ocean bottom differential pressure gauge (DPG) system, and an ocean bottom gr...
16 CitationsSource
#1Ichiro Takahashi (Chiba University)H-Index: 11
#2Katsumi Hattori (Chiba University)H-Index: 27
Last.Nobuhiro Isezaki (Chiba University)H-Index: 11
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Geoelectrical and geomagnetic fluctuations are considered the end product of several geophysical phenomena. In particular these signals measured in seismically active areas can be attributed to stress and strain changes associated with earthquakes. The complexity of this problem has suggested the development of advanced sophysticated methods to investigate the heterogeneous nature of these fluctuations. In this paper, we analyzed the time dynamics of short-term variability of geoelectrical poten...
6 CitationsSource
#1Hisashi Ishikawa (Chiba University)H-Index: 1
#2Katsumi Hattori (Chiba University)H-Index: 27
Last.Nobuhiro Isezaki (Chiba University)H-Index: 11
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The variations of geoelectrical potential differences in Hakuba area, Nagano Prefecture, Japan have been investigated. The noises originated from the DC-driven trains were found to contaminate the natural geoelectrical potential data. The most intense influence of trains occurred when the train was running nearby measuring dipoles. The gradient of the potential was deflected towards the railways and/or the position of the train, exhibiting a certain correlation between the power supply data at s...
2 CitationsSource
4 CitationsSource
#1Hiroaki Toh (University of Toyama)H-Index: 6
#2Kiyoshibaba (UTokyo: University of Tokyo)H-Index: 23
Last.Ichiro Takahashi (Chiba University)H-Index: 11
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[1] Four ocean bottom electromagnetometers provided seafloor geoelectromagnetic data for more than nine months in order to reveal mantle dynamics beneath the eastern margin of Japan Sea, where several large and hazardous earthquakes have repeatedly occurred so far. High-quality magnetotelluric (MT) data from the seafloor array, together with those of four additional land sites in northeast Japan, were analyzed and carefully corrected for topographic/bathymetric effects to extract two-dimensional...
22 CitationsSource