2010 Chili Tsunami Hydraulic data observed at Choshi offshore and their application to Anti-tsunami design of Offshore Structure

Abstract

Water surface profile and velocity distribution of 2010 Chilean earthquake tsunami was observed by using the Ultrasonic-type wave gage and ADCP placed on the sea bottom 11m deep and 3 km offshore of Choshi city, Chiba prefecture, Japan. The following findings were made. 1) Measured data can be linearly separated into tidal and tsunami component and wave component by adapting numerical filter with the threshold period of 60seconds. 2) Existence of tsunami does not have large effects on the wind waves and swells component distribution. 3) Observed tsunami current velocity profile was affected by the tsunami deformation due to the sea bottom topography. 4) The tsunami current velocity vertical distribution follows power low with 1/n=1/5 to 1/7. Based on these findings tsunami wave force acting on the small diameter ocean structure was proposed.