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Volume 11 (1965)
- Issue 3-4 Pages 87-
- Issue 2 Pages 41-
- Issue 1 Pages 1-
Volume 11, Issue 3-4
Displaying 1-7 of 7 articles from this issue
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Seiji NARUSE, Kumizi IIDA1965 Volume 11 Issue 3-4 Pages 87-97
Published: March 30, 1966
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe vertical movements of land suarface in Nobi Plain are investigated by using the data of continuous observation at several stations. The crustal movements are estimated by comparison between the present observed data and the results of precise levellings. It is found that, in general, the rate of movements is not large in the most parts of the Plain with a tendency to increase from north to south region or from east to west region, and that the subsidence in the area around the coast of Ise Bay is mainly explained by the contraction of alluvium. The crustal movement is going on in a sense that the area around Ichinomiya is rising and that the coastal region of Ise Bay is sinking. The rate of upheaval at Ichinomiya amounts to about 13 mm/year and the largest rate of sinking is about 13 mm/year near Yokkaichi.View full abstractDownload PDF (1066K) -
Shigetaka IIJIMA, Seichi OKAZAKI1965 Volume 11 Issue 3-4 Pages 98-106
Published: March 30, 1966
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESS -
Takeshi DAMBARA1965 Volume 11 Issue 3-4 Pages 107-113
Published: March 30, 1966
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSNear the mareographic station at Aburatsubo in the Miura Peninsula, Kanagawa Pref., the observation with the water-tube tiltmeter has been made by the Earthquake Research Institute of the University of Tokyo. Two tiltmeters are set in approximately west-east and north-south direction. In this peninsula the first order leveling surveys were repeated many times by G. S. I. in order to secure the leveling datum in Tokyo by connecting it with the mean sea level at Aburatsubo. Using this leveling data, the inclination of the ground near Aburatsubo can also be calculated. First the direction of the axis and the angle of the maximum inclination are derived by using the tiltmeter's record, where W-E and N-S tiltmeters are assumed to be set in the direction of the angle ψ from the east and ψ' from the north respectively (Section 2). Next, necessary equations of computing the components in the directions of two tiltmeters from the direction of the axis and the angle of the maximum inclination which are read from the equal vertical movement lines drawn by using the repeated leveling surveys (Fig. 3). The observed inclinations in two components (θ in W-E and θ' in N-S) with tiltmeters are shown in Table I. The calculated inclinations from the result of the leveling survey in the same directions as mentioned above are shown in Table II. Then the secular change in inclination, 40 and 40' in two ways are calculated and they are compared in Fig. 4. They are not in good coincidence. As the interval of bench marks in the first order leveling by G.S.I is about 2 km, the region of over 2 or 3 km is necessary in order to obtain reliable equal vertical movement lines. On the contrary, the inclination with the tiltmeter at a very point only corresponds to that in very small area. The reason of unsatisfactory coincidence mentioned above is seemed to be due to such opposite condition of two methods of observation.View full abstractDownload PDF (696K) -
I. On the G. S. I, type Standard MagnetometerIetsune TSUBOKAWA, Minoru TAZIMA, Naomi FUJITA1965 Volume 11 Issue 3-4 Pages 114-126
Published: March 30, 1966
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSIn order to secure consistent accuracy for the magnetic survey, the Geographical Survey Institute decided to construct a new standard magnetometer in 1956. Since the G. S. I. field magnetometer after the priciple proposed by one of the writers already has shown sufficient absolute accuracy in the measurement of direction of the geomagnetic vector, the writers aimed to develop an absolute standard instrument measuring only the horizontal intensity.
The principle of the instrument, the G. S. I. Standard Magnetometer, is illustrated in Fig. 1. It consists of two coaxial and concentric coils, the primary standard and the auxiliary, which are placed horizontally on a theodolite and almost in the geomagnetic meridian and, in the center of these coils, a rotating coil-detector whose rotating axis is vertical to the horizon. The primary standard is wound on a precisely completed bobbin of Telex glass and its constant is computed from the coil dimensions measured precisely. It cancels most part of the horizontal intensity (about 99%) by passing through it the constant electric current regulated with the electrical standards.
The auxiliary coil cancels the residual field completely by adjusting the current through it and nullifying the output of the rotating detector. The intensity of the current is measured with a rugged potentiometer, the precision of which is about few parts of 104. The effects of erroneous settings of the axes of the coils and the theodolite are made negligible by taking the average of the observed values corresponding to two positions of the theodolite differing by 180°in azimuth from each other, and by adding the level correction deduced from the readings of a level attached to the theodolite and parallel to the axes of the Helmholtz-Gaugain coils.
The reliability of the absolute value of this magnetometer depends mainly on the absolute value of the coil constant of the primary standard and those of the electrical standards. Examining carefully all error sources, it is concluded that the G. S. I, Standard Magnetometer secures the absolute accuracy of 1 × 10-5 in measuring the horizontal intensity of the geomagnetic field.View full abstractDownload PDF (4618K) -
II. On the Construction of Standard Coil of the G. S, I. typeStandard MagnetometerNaomi FUJITA, Ietsune TSUBOKAWA1965 Volume 11 Issue 3-4 Pages 127-138
Published: March 30, 1966
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSAs reported in the preceeding chapter, the absolute accuracy of the G. S. I. Standard Magnetometer depends mainly on the coil-constant of the primary standard coil and the values of the electrical standards (standard cells and standard resistances). Of these, the coil is specific to the standard magnetometer. This chapter therefore deals with the methods of producing precisely completed coil bobbin and copper wires of uniform diameter and cross section and the process of constructing the Helmholtz-Gaugain standard coil. This paper also reports the methods of fine measurements of coil dimensions (radius, distance, pitch and number of turns of the two windings of the coil) in the accuracies of better than 0.5X10-5 in order to secure the composite accuracy of 1X10-5 in the coil-constant.View full abstractDownload PDF (5737K) -
III. On the Measurement of Gyromagnetic Ratio, γp using the G. S. I. type Standard MagnetometerIetsune TSUBOKAWA, Naomi FUJITA1965 Volume 11 Issue 3-4 Pages 139-142
Published: March 30, 1966
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSDuring the period of developing the G. S. I. Standard magnetometer, proton precession magnetometers have come into practical use. Since the precessional frequency of the proton is proportional to the ambient magnetic field, it is quite important to determine the reliable value of the proportional coefficient, known as the gyromagnetic ratio 1. . In 1960, the XII th General Meeting of IUGG at Helsinki adopted γp = 2.67513×104/Γ. sec as the provisional international value. This is based on the value measured in a considerably strong magnetic field (about 12Γ). After completion of the standard magnetometer, we made comparison measurements with the proton precession magnetometer which is developed also in our institute and measures the horizontal intensity of the geomagnetic field. The result is, adopting the international value, HS-HP = 0.0γ ±0.4γ where Hs and HP are the values measured with the G. S. I. Standard Magnetometer and the G. S. I. H. Proton Magnetometer respectively. This may show that the value of γp is still constant in a weak field such as the geomagnetic field.View full abstractDownload PDF (412K) -
Ietsune TSUBOKAWA, Minoru TAZIMA, Naomi FUJITA, Takao SETO1965 Volume 11 Issue 3-4 Pages 143-154
Published: March 30, 1966
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSIn principle, the nuclear magnetometer is sensitive only to the total intensity of the geomagnetic field. However, it becomes also possible to measure the component or the direction of the field by adding adequate artificial field. This paper reports the general principle of measuring H, Z and D with proton precession magnetometers. Effects of erroneous set-tings of a theodolite and the coil which generates artificial uniform field are eliminated by the suitable combination of observational positions of the instrument. Several types of instruments which have been and now being developed in Geographical Survey Institute are also introduced.View full abstractDownload PDF (6845K)
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