| Project/Area Number |
15340144
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | RIKEN (2004)
The University of Tokyo (2003) |
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Principal Investigator |
OTAKE Yuji RIKEN, Harima Institute, Senior Researcher, 新竹電子ビーム光学研究室, 先任研究員 (60282729)
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| Co-Investigator(Kenkyū-buntansha) |
ARAYA Akito University of Tokyo, Earthquake Research Institute, Associate Professor, 地震研究所, 助教授 (30272503)
IMANISHI Yuichi University of Tokyo, Ocean Research Institute, Research Associate, 海洋研究所, 助手 (30260516)
渡辺 好徳 東光サービス株式会社, FAシステム製造部, 研究員
WATANABE Yoshinori TOKO ESCO, Lid.FA system production division, Researcher
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥16,600,000 (Direct Cost: ¥16,600,000)
Fiscal Year 2004: ¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 2003: ¥9,300,000 (Direct Cost: ¥9,300,000)
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| Keywords | seismometer / magnetic levitation / permanent magnet / highly sensitive / wide band / vertical pendulum / nanometer technology / displacement detection / 高感度変位検出 / 長周期 / 磁気バネ |
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| Research Abstract |
The aim of this study is development of a highly-sensitive/wide-band seismometer utilized for a new stage on global seismology. The seismometer should measure acceleration under 10^<-9> m/s in a frequency from 0.003Hz to 100Hz. We show the results of our study below.
1.The DC power supply, having stability of less than 10^<-6> and noise of -130 dBV in a frequency over 1Hz, was developed.
2.Three practical seismometers using the rotational pendulum were built. The seismometer equips a float counter to a pendulum weight to correct the effect of an atmosphere pressure change at the weight, and a chamber to isolate an atmospheric pressure change.
3.The seismometer with the low noise DC power supply and without the chamber was able to measure as much as a noise level of 10^<-10>(m/s)/Sqrt(Hz) that is almost overcoming that of STS-II.
4.To consider observations in an under ground tunnel that has much humidity, the laser scale employing optical fiber cables for a laser input and outputs was developed. Because the active device like a laser diode is not suitable for such tunnel. The laser and photo diodes as thermal sources could be far placed (e.g.1km) from the scale by the fiber cables. The thermal effect from them, related to the low frequency noise of the seismometer, could be reduced.
5.The observation of the vertical component of earth back ground vibration noise using our developed seismometer was carried out at the SPring-8 site. The results of the observations showed the noise level of the seismometer was 10^<-7>(m/s)/Sqrt(Hz) in a low frequency side under 0.1Hz. This noise level was several times larger than that of CMG-3T seismometer and almost the same as CMG over 0.1Hz.
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