著者
浅川 賢一 田幸 敏治
出版者
公益社団法人 応用物理学会
雑誌
応用物理 (ISSN:03698009)
巻号頁・発行日
vol.49, no.12, pp.1185-1191, 1980-12-10 (Released:2009-02-09)
参考文献数
15

The microvibration of the ground was measured by the 50 meter vacuum interferometer which was installed in the underground tunnel in the Nagatsuta Campus of the Tokyo Institute of Technology. There are often anomalous vibrations caused by cars passing on a near road for example. We propose a new method to detect and distinguish such anomalous vibrations. The signal which represents the vibration of the ground is put into a prediction error filter which is made from the normal part of the stignal. If there are any anomalous vibrations, its output, namely prediction error, becomes greater, and we can easily recognize its existence. This method is very sensitive and its characteristics is clerrly revealed by investigating the power spectrum and the frequency histograms of the signal.
著者
浅川 賢一 田幸 敏治 平田 照二
出版者
公益社団法人 応用物理学会
雑誌
応用物理 (ISSN:03698009)
巻号頁・発行日
vol.48, no.6, pp.519-525, 1979-06-10 (Released:2009-02-09)
参考文献数
11
被引用文献数
1

A 50 meter modified Michelson interferometer has been installed in an underground tunnel in the Nagatsuta campus of Tokyo Institute of Technology. It is enclosed by vacuum pipes and illuminated by a frequency stabilized 633 nm He-Ne laser. The displacement of the interference fringes is converted to voltage with an accuracy of about 1×10-10. From the spectral analysis of the fluctuations of the interference fringes, it is found that the power spectral densityof the microtremor at the quiet time has peakes at 1 cycle/day and its har-monics, also at 0.3, 0.6, and 3 Hz, and that the values at around 10 Hzincrease when cars pass by on the road near the tunnel.