No. 2 +0,/,**, Technical Research Report, Earthquake Research Institute, University of Tokyo, No. 2, pp.+0,/,,**,. XY * * ** *** **** ***** Development of a Tiltmeter with a XY Magnetic Detector (Part +) Toyotaro TAKEDA*, Hidefumi WATANABE*, Etsuro KOYAMA**, Yasuhiro HIRATA***, Shigeru WATANABE**** and Masaomi ONISHI***** Abstract We have developed a simple borehole-type tiltmeter. The first generation (CA--01,) was completed in September +332. Its sensitivity was low and its specification was not enough for precise observation of the ground motion, and we are improving it since February,***. During the process, we carried out several observations to check their specifications and to compare with a water-tube tiltmeter that was already put to practical use in many observations. As a result, we have recently completed the new model CA--3+1(fourth-generation). The measurement sensitivity of this tiltmeter using a XY magnetic detector is higher than +* 2 radian, and zero point drift is less than +* 2 radian/day. These values are enough to meet the practical requirement for measuring the crust deformation accompanied with volcanic activity. In this paper, we report the outline of the developing process of the tiltmeters. Key words : Tiltmeter, XY Magnetic Detector, High Sensitivity, Magnetometer, Borehole +332 CA--01,,***,.,**, 3,,**, +*,+ * ** *** **** ***** * Volcano Research Center, ** Asama Volcano Observatory, Volcano Research Center, *** Earthquake Observation Center, **** Fujigawa Observatory, Earthquake Observation Center, Earthquake Research Institure, University of Tokyo ***** Macome Corporation. XY XY 16
XY 17 XY., + XY CA--3+1 f+3mm L +**mm, mm f2*mm m, XY + +33- +332 + CA--3+1 -
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20,* / +, +- +*, + +.* CA--01, +** mrad CA--11. +* mrad mrad,/ m CA--11. *.+ mrad day CA--01,, + mrad CA--01, + + m rad + m rad CA--2/. - CA--2/.,*** ++,+,**+ 3,* -** - - N -/ E, N // W, m rad N -/ E, N // W + mrad CA--2/.A N // W - m rad - Yanagisawa, +32* 3* XY - CA--2/.A,*** ++,+,**+ 3,* CA--2/.B CA--2/.C CA--2/.A CA--2/.B,*** ++,+,**+ + +1 CA--2/.C,**+ + +1 3,*
XY 21 CA--2/.B + +2 CA--2/.C + +3, mrad B C - *., mrad CA--2/.C N // W - a b c d. CA--3+1.. CA--3+1 - -,**+ ++,.,/ +** nt +, -. WTT Corrected data Raw data Magnetometer Raw data Magnetometer. - N -/ E - N // W Kakioka nt Magnetometer Corrected data Raw data Corrected data CA--3+1 Magnetometer nt rad CA--3+1 +rad.**nt CA--3+1 WTT N // W - - WTT +, +- Seiche Yanagisawa, +32* WTT /** WTT CA--3+1 CA--3+1 +* nt FUJ + m rad / FUJ CA--3+1,**,.,/,1 -. E-W. N-S Corrected data. Raw data Magnetometer Magne-
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XY 23 / CA--3+1 FUJ,**,.,/-,2 E-W N-S
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XY 25, CA--11. - CA--2/. + CA--01,. CA--3+1 CA--3+1 - CA--2/. : +33-3- +33- C+, *,. +332 3- +332 +*/. +313,/, +*+ +-.. Yanagisawa, M., Observations of Seiche-Related Tilt in the Aburatsubo Observatory, +32*, Bull. Earthq. Res. Inst., //, --+ -./.