On the Water Level Fluctuations with Long Periods Off the Coast of Toyama Wan

Abstract

It is known that there are periodic water level fluctuations off the coast of Toyama Wan. Investigation on the periodic water level fluctuations was carried out to prevent wave disasters by wave observations and wave generating experiment. Water levels were observed at three points of Toyama New Port, Iwasehama and Iida Wan. The water level fluctuations with the periods of about 10 minutes or more were investigated using the water level data observed at the three points and wave generating experiment data.
The results of this investigation are:
(1)The water level fluctuations with the periods from about 10 minutes to about 1 hour are proper oscillations driven by water level fluctuations due to moving low atmospheric pressure or earthquake, in horizontal shallow water off the coast.
(2)Proper oscillation with the period of about 36 minutes between the Toyama coast and the southern coast of apex of Noto peninsula, causes a beat phenomenon with the same period as the proper oscillation period to swells which invade Toyama Wan from north.
(3)There is greater tsunami risk on the coast of Iida Wan as compared with the Toyama coast.