Book Description

The important wave parameters to be considered for tsunami model studies are wave height and period, and wave-front orientation. The first two of these parameters can be determined by marigraphic measurements or by visual observations; however, wave-front orientation has never been accurately observed at the problem site (Crescent City, Calif.). A digital computer program was written to plot wave rays from three recent epicentral locations to Crescent City to obtain approximate tsunami-front orientations. The refraction diagrams were checked by comparing the computed and actual arrival times of the wave fronts. The actual arrival times were obtained from recording tide stations at Crescent City and Hilo, Hawaii. Initial wave-front orientations near the earthquake epicenter were either assumed or taken from the literature, A tentative frequency relation was derived and a risk-duration relation was prepared from the frequency relation. The selected values of the test-wave dimensions (height and period) and orientation determine, to a considerable extent, the model configuration necessary to ensure results sufficiently accurate for purposes of the model study. Since experience in the design and operation of long-period wave models is scant, it was deemed necessary to conduct preliminary tests utilizing a pneumatic wave generator in a two- dimensional flume. The results of these tests were compared with theoretical predictions from an idealized mathematical model and on the basis of these tests, a preliminary model design was proposed.