Tsunami studied by Newcastle professor will help to warn

Apr 2 2009 by Tony Henderson, The Journal

HOW waves behave has occupied mathematician Robin Johnson for 40 years. So when the most extreme version of wave power, a tsunami, devastated coastal areas of Thailand, Indonesia and Sri Lanka on Boxing Day in 2004, it prompted a fresh study by the Newcastle University professor of applied mathematics.

Working with colleague Prof Adrian Constantin, Prof Johnson has now produced a mathematical formula which helps understand how seaquakes result in tsunami waves.

The formula will feed into work which seeks to improve future ability to predict how destructive a tsunami will be.

Prof Johnson said that the disturbance of the sea bed by a quake could lift water up or down, creating tsunami waves.

He said: “What you get on the coastline depends on the shape of waves that are produced initially.

“What we found was that the number and height of the tsunami waves hitting the shoreline depends on the shape of the initial surface wave in deep water.

“The difficulty is that to understand in detail how a tsunami wave moves and behaves you need to know how it started in the deep ocean and we can never know that in any particular case.

“However, it is possible to monitor seismic activity and then to give sufficient warning to vulnerable coastal regions that a tsunami is on its way.

“Automatic sensors have been in the Pacific Ocean for a number of years and sensors have now been placed in the Indian Ocean.”

The research shows that the number of peaks and troughs in the initial disturbance out at sea will dictate the number of wave fronts that will steepen and eventually produce tsunami waves.

Prof Johnson studied aeronautics for his first degree and then studied for a PhD in wave propagation, or how waves and water in motion behaves.

Better understanding in this area helps in the design of vessels, oil rigs and sea defences.