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Volume 6, Issue 2
Displaying 1-7 of 7 articles from this issue
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Toshi ASADA1953 Volume 6 Issue 2 Pages 69-73
Published: October 25, 1953
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSThe frequency distribution of the max. amplitude, α, and the max, acceleration, α, at a station is expressed by N(α)da=ka-mda and N(α)dα=k′α-m′dα, respectively. A relation, m′=(m-1/q+1), holds between m and m′, q being defined by the formula α=coast. αq. The predominant period of earthquake motions T can be calculated according to the above mentioned relation, as we have α=(2π/T)2α, or T=const α1-q/2. The observed values at Hongo, Tokyo are as follows,
m=1.74, m′=2.12, q=0.66, and T=const. α0.17.View full abstractDownload PDF (402K) -
Yasuo SHIMAZU1953 Volume 6 Issue 2 Pages 74-83
Published: October 25, 1953
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSIn case of finite elastic strain, we must distinguish the following two view points. (L) Whether the initial unstrained position is used as the independent variables in terms of which the strain is described, or (E) the final strained position is used. It is shown in §2 that four sorts of strain definitions are possible. Two of them are (L) and the other two are (E). In §3 and §5, two sorts of definitions of stress are shown. They are (L) and (E) respectively. Admitting these definitions, eight sorts of expressions for the stress-strain. relations are obtained. These eight expressions are equivalent, and we may adopt any of them in accordance with circumstance. The transformation theorem between these expressions is also given.View full abstractDownload PDF (724K) -
The Research Group for Explosion Seismology1953 Volume 6 Issue 2 Pages 84-90
Published: October 25, 1953
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSThe third explosion seismic observation, which succeeded to the last two observations of Oct. 25, 1950 and Dec. 27, 1951 were carried out July 25, 1952 in North-Eastern Japan. In this experiment 5.5 tons of carlit were exploded at Isibuti adjacent to the site of the preceding two explosions for engineering purposes. In this case the amount of explosives was not sufficient that the accuracies of the arrival times observed at distant stations of the first motion were poorer than in the cases of the last two explosions. The arrival time of every phase is shown in Table 2 and the travel-time curves are shown in Fig. 2. The travel times at the observation stations in the southern direction lies on three different straight lines which are given by the following equations,
t′3=12h 05m+(-0.06±0.06)sec.+(0.1673±0.0003)see.Δv′3=5.98±0.01km/sec.
t′4=12h 05m+(3.7±0.3)sec.+(0.139±0.002)sec.Δv′4=7.17±0.07km/sec.
t′5=12h 05m+(1.9±0.3)sec.+(0.279±0.001)sec.v′5=3.58±0.002km/sec.
(Δ being measured in kilometers.)
On the other hand, in the western direction, the equations are obtained as follows,
t3″=12h 05m+(0.00±0.05)sec.+(0.172±0.001)sec.Δv&3Prime;=5.81±0.03km/sec.
t5″=12h 05m+(1.03±0.4)sec.+(0.287±0.009)sec.Δv″5=3.5±0.2km/sec.
The velocity of seismic waves “v3” in the western direction is smaller than “v3′” of the southern direction. In the case of the second explosion-seismic observation the velocity “v” of the same layer in the eastern direction was larger than “v3′” of the southern direction. If we assume the structure shown in Fig. 3, the explanation to this will be that the lower layer, of which velocity is 5.9km/sec, is overlaid by the soft layer of 2.56km/sec having the interface that dips 38' to the vest.View full abstractDownload PDF (687K) -
Ziro KAWASE1953 Volume 6 Issue 2 Pages 91-100
Published: October 25, 1953
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSObservations by seismograph-galvanometer couples are carried out at many observatories. But it may be considered that seismic wave form will be deformed by the process of changing the motion of pendulum into electric current, especially when electric amplifier is equipped with.
To obtain undeformed seismographic recording with high magnification, the author has adopted the multiplier phototube (Mazda MS-6S), which was used as a direct amplifier. The light sensitive plate is struck by light beams changing proportional to the displacements of pendulum. This phototube is connected directly to power tube 6V6 which feeds electric current proportional to the displacement of pendulum to the recorder.
Experimental observation was put in practice by a seismograph, period 2 seconds, damping ratio about 30. But the long period seismograph could not be uséd because of the predominance of daily ground inclination at our observatory.View full abstractDownload PDF (4289K) -
Nozomu DEN1953 Volume 6 Issue 2 Pages 101-108
Published: October 25, 1953
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSA very low frequency amplifier is required to study the various nature of the explosion-seismic waves and the weak seismic waves. For this purpose, the author designed the several types of amplifiers with high gain in the range of 1 to 30 c. p. s. These are as follows:
MG-II type (Fig. 1), MG-IV type (Fig. 3),
MG-VI type (Fig. 4), MG-VIII type (Fig. 6).
A type of the voltage stabilizer is designed also. (Fig. 8. 9).View full abstractDownload PDF (739K) -
Shinichi YAMAGUCHI1953 Volume 6 Issue 2 Pages 109-110
Published: October 25, 1953
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDownload PDF (213K) -
Kyozi TAZIME1953 Volume 6 Issue 2 Pages 111-112
Published: October 25, 1953
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDownload PDF (233K)
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