Wave radar may help tsunami predictions

A two-year empirical research program is planned to begin in April in Japan to develop a next-generation tsunami prediction system by calculating the estimated height of a tsunami when they reach the coast from data obtained through ocean wave radars installed along the coast.

The project will be undertaken in Wakayama Prefecture by Kansai University, the Land, Infrastructure, Transport and Tourism Ministry, the Internal Affairs and Communications Ministry and others.

Based on lessons learned from the tsunami caused by the Great East Japan Earthquake, the research is aimed at providing more accurate tsunami predictions within five minutes of the occurrence of an earthquake so residents would be able to evacuate quickly.

In preparation for the possible simultaneous occurrence of the Tokai, Tonankai and Nankai earthquakes, the research is aimed at seeing the system in practical use in four to five years.

An ocean wave observation radar system sends radio waves toward the ocean’s surface and analyses the radio waves reflected off ocean waves, calculating the speed and size of the ocean waves.

This radar system is typically used to monitor tidal currents. In the case of the March 11, 2011 earthquake, it was discovered that an ocean wave radar system installed by the land ministry in Wakayama Prefecture detected the tsunami about 30 kilometres (19 miles) off the coast. Professor Tomoyuki Takahashi of Kansai University noted this discovery.

Under the planned project, the radar system will be installed at two locations along the coast of the prefecture to monitor the ocean up to about 60 kilometres (37 miles) off the coast around the clock.

The research will be conducted by collecting data on ocean waves during typhoons and after small or mid-size earthquakes.

The data will be then analysed by computer after taking into consideration the topographical features of the coast and seabed, thereby enhancing precision in predicting tsunami heights when they reach the coast. Research will also be conducted to establish a system under which predictions will be sent to the Meteorological Agency before being transmitted to all municipalities and citizens so they can promptly prepare for evacuation.

The Yomiuri Shimbun