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Volume 16, Issue 4
Displaying 1-8 of 8 articles from this issue
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Microseisms of ScandinaviaTetsuo SANTÔ1963 Volume 16 Issue 4 Pages 165-180
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSOrigin of microseisms is re-examined by using the data of I. G. Y. at Kiruna and Uppsala, Sweden.
Microseisms observed at these Scandinavian stations revealed the following clear connection with the travelling courses of cyclones over the Ocean.
1. A cyclone which takes such distant course as far as more than 1000km from Norwegian coast increases, without any exception, the periods but does not the amplitudes of microseisms.
2. A cyclone which moves along the course approximately from 500km to 1000km far off the Norwegian coast increases both the amplitudes and periods of Scandinavian microseisms.
3. Due to a small cyclone which moves near Scandinavian coast, microseisms are increased in their amplitudes only.
Swells generated by a cylone gradually lose their amplitudes and gain their periods during the travelling over the Ocean. Therefore, the observed facts given above tell that the amplitudes and periods of microseisms are both completely controled by those of swells at some coast near the stations on the land.
This suggestion was confirmed by comparative studies between the estimated arrival times of swells due to each distant cyclone at some coasts near the station and the beginning of long period microseisms observed.
The following three facts were also observed.
4. A double or a tripple cyclone over the Ocean has no effect upon microseisms.
5. Microseismic wave hardly propagate over the Ocean.
6. Propagation of microseismic waves is disturbed by topographical irregularity of the continent.View full abstractDownload PDF (1610K) -
Tatsuhiko WADA, Tamotsu FURUZAWA, Hiroyasu ONO1963 Volume 16 Issue 4 Pages 181-187
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSThe Abuyama seismograms of the great Chilean Earthquake of May 22, 1960 were studied. Long-period Rayleigh waves R3 and R4 were read, digitized, and Fourier-analyzed. The directivity function, defined by Ben-Menahem, was computed from amplitude ratio R3/R4. A fault of 1200km, with an azimuth of W 80°S, and a rupture velocity of 3.5km/sec gave the best fit to the result obtained by Press and others.View full abstractDownload PDF (504K) -
Mitsuo KEIMATSU1963 Volume 16 Issue 4 Pages 188-196
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSWe have lots of records concerning the earthquakes in Nanching from A. D 225 up to the present, and among them the ones in Ming period are numerous and accurate in particular. For Nanching had been the capital from the beginning of Ming Dynasty to 1421, and since then, the capital being moved to Peiching, it had turned into vice-capital to the end of the Dynasty. Besides the earthquake was thought of as one of the most important heaven-sent warnings to the government of the emperor, so that the earthquake occurring just where the emperor resided had been thought much of especially. In making the chronological table of the earthquakes in Nanching in Ming period, I came across the fact that the small earthquakes had been frequently happening there from 1425 to 1430. The frequency is remarkable not only in the chronological table in this paper, but also throughout the whole history of the earthquakes in Nanching. These many frequent earthquakes seem to have certain resemblances; first, the intensity of the shock was slight, estimated 1-2 by Japanese seismic intensity scale, second, the felt area was limited to Nanching and its neighborhood, third, the magnitude is estimated very small, but whether they were shallow-focused ones, I cannot tell. To lay hold of the small earthquakes occurring in succession at short intervals so plainly as this is really a very rare occasion throughout the whole history of the earthquakes in China. See the chronological table on my paper in the next number.View full abstractDownload PDF (1076K) -
Sadao MIYAMOTO1963 Volume 16 Issue 4 Pages 197-203
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSThe distinctive feature of this astatic magnetometer is that it is set vertically on a galvanized iron sheet, as shown in Figures 1 and 2, and has no damper.
This magnetometer is located at Hakone, which is very near to the epicenters indicated in Figure 3. The epicentral distance is about 3 kilometers.
The sudden change of magnetic field causes the oscillation of needle as shown in Figures 5 and 6.
The relation between these phenomena and volcanic earthquakes is shown in Figure 4.
The period covered by the record is from February 18, 1960 to May 5, 1960. During this period, there was no magnetic storm and no earthquake, nor thunder, when the abnormal oscillation of this magnetmeter occurred
Therefore, it is concluded the cause of the oscillation of the magnetometer is the sudden change of the magnetic field several days before a volcanic earthquake. According to the writer's experiment, the period of oscillation during the magnetic change is 1/10 to 1 second.View full abstractDownload PDF (516K) -
Sadao MIYAMOTO1963 Volume 16 Issue 4 Pages 204-207
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSA systematic observation of the special astatic magnetometer in five stations will be practiced on September in 1963.
Fig. 1 shows the distribution of the observatories.
When a large earthquake within 200km from a observatory, many abnormal records might be expected before an earthquake.
But the cause has been unknown though the writer has been observed and studied for several years.
Relation between the abnormal magnetic phenomena and an earthquake will be made clear in the feature.View full abstractDownload PDF (361K) -
Isao TORIUMI1963 Volume 16 Issue 4 Pages 208-214
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSBy experience of trial manufacturing of the prototype of random shaking table, 2nd enlarged one was accomplished. Several tests of model in large size (max. length 2m, breadth 1.5m and height 2.7m) mounted on this table was executed. These tests complement the imperfection of analysis by computer and supply some data to the original design of structure making clear concretely the behaviors of structures at the time of earthquake.View full abstractDownload PDF (3933K) -
Tetsuo SANTÔ1963 Volume 16 Issue 4 Pages 215-217
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDownload PDF (464K) -
Mineo KUMAZAWA1963 Volume 16 Issue 4 Pages 217-219
Published: December 25, 1963
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDownload PDF (373K)
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