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Volume 28 (1972)
- Issue 6 Pages 229-
- Issue 5 Pages 181-
- Issue 4 Pages 131-
- Issue 3 Pages 103-
- Issue 2 Pages 39-
- Issue 1 Pages 1-
Volume 28, Issue 6
Displaying 1-5 of 5 articles from this issue
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Hideo WATANABE1972 Volume 28 Issue 6 Pages 229-241
Published: December 31, 1972
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSThe tide-gauge records of large tsunamis are classified into three types, A, B and C. The “A” type record is made up of one or a few large waves near the wave front. The “B” type record consists of one or a few wave groups. The “C” type is the combination of the “A” and “B” types. The data used are; the Kamchatka Tsunami of Nov. 4, 1952, the Aleutian Tsunami of March 9, 1957, the Chilean Tsunami of May 22, 1960 and the Alaska Tsunami of March 28, 1964.
The A type occurs mostly at isolated islands in the Pacific Ocean and occasionally at continental coasts. The B type is mostly distributed on the continental coast and along the island-arc. The distribution of the C type differs from tsunami to tsunami.
The relation between the delay time of the maximum wave and the the travel time of the wave front is as follows:
1). For the wave of the A type and the head wave of C type, the delay time (TD) is constant for all travel times.
2). For the first wave group of B and C types, the delay time (T1) is constant or slow decreases with travel time. For the second and third wave groups of B and C types, the definite decrease of delay times (T2 and T3) with travel time is observed.
The height (h) of the maximum wave of A and C types decreases generally with travel time. The maximum wave height along the path between Kamchatka and Chile, however, shows the increase. For all wave groups the wave, heights (H1, H2 and H3) of B and C typesincreases with travel time Some speculations on the causes of these features are also presented.View full abstractDownload PDF (1475K) -
Masayuki TOKUDA1972 Volume 28 Issue 6 Pages 242-253
Published: December 31, 1972
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSTaylor-Grortler vortices are longitudinal vortices resulting from a centrifugal instability. They are generated in the flow having a curved streamline with an increasing velocity in the direction of decreasing curvature.
It is shown that the air flow above wind waves and swells also satisfies locally the condition of the centrifugal instability. Numerical calculations indicate the possibility of generation of Taylor-GÖrtler vortices on the trough of sea waves. For example, when a wind of about 12.2m/s at 10-m level is blowing over sea waves of the wave length of 15m like the swell, the critical water wave height beyond which the vortices may be generated is about 0.5 m, and the critical wave length and the height of center of the generated vortices are about 24m and 3.7m, respectively. Further, about the relations between the generation of vortices and wind waves, it is shown that the condition of their generation is satisfied at the trough of waves for early stages of the wave generation.
In conclusion, it is expected that the Taylor-GÖrtler vortices change the wind profile along the sea surface, and also, play some part in the growth of wind waves, especially in the formation of their three dimensional structure.View full abstractDownload PDF (1930K) -
Evidence of an Approximate 3°C Increase in Mean Sea Surface Temperature Sometime Between 1941 and 1949F FAVORITE, D. R. MCLAIN1972 Volume 28 Issue 6 Pages 254-259
Published: December 31, 1972
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSAlthough February mean sea surface temperatures at Hachijojima indicate no long-term trends from 1926 to 1970, historical data from 1901 to 1967 (over 100, 000 observations) from ships-of-opportunity in the area south of Enshunada indicate an abrupt increase of approximately 3°C in both February and annual mean sea surface temperatures sometime between 1941 and 1949, possibly in 1942. This change is considered to be too large to be the result of differences that might have occurred in observational methods, and heat budget calculations indicate that surface cooling should have occurred. Cause for the increase is unexplained at this time.View full abstractDownload PDF (946K) -
Kinjiro KAJIURA1972 Volume 28 Issue 6 Pages 260-277
Published: December 31, 1972
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSThe radiation pattern of the tsunami generated by a broad crustal deformation on or near the continental shelf is examined analytically in the framework of a linear longwave approximation. Detailed discussion, however, is made only for a model of step-type bottom topography.
The proportion of the energy trapped on the shelf as edge wave modes relative to that radiated into deep water increases with the decrease of the long-shore dimension of the source. The nearer is the source to the coastline, the greater is the rate of total edge wave generation. However, the proportion of higher modes increases for the source near the shelf edge.
The proportion of the wave energy radiated in deep water, normal to the coastline, increases with the increase of the long-shore dimension of the source and/or the decrease of the depth difference between the shelf and deep water. Furthermore, this proportion increases with the increased distance of the source location from the coastline and approaches the value for the case without a shelf. For a source of the square shape, the directive difference of energy radiation in deep water is mainly caused by the refractive effect of the shelf edge. For larger long-shore dimension of the source, however, the geometric shape effect of the source is more important to cause the directive difference.View full abstractDownload PDF (2435K) -
Sigeru MOTODA1972 Volume 28 Issue 6 Pages 278-292
Published: December 31, 1972
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSDownload PDF (3051K)
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