A Tsunami

(Bill McGuire is director of the Benfield UCL Hazard Research Centrre in London. He has written or edited over 400 books, papers and articles on natural hazards, environmental change and geophysical events)

“The first thing you might see is the sea receding back to the horizon. Following that, you’ll see a breaking wave that gets bigger very, very rapidly. The thing is, it’s not a wave but a wall of water that carries on at the same level for tens or hundreds of kilometres.

The waves can come in for an hour or more and there’s no guarantee that the first is the biggest. So when one wave has passed, don’t think it’s all over and wander along the beach.  The waves slow as they reach the coastline and they increase in height, but they still hit the shore with speed of a car traveling in an urban area – and every cubic metre weighs a tonne.

If the earthquake that caused the tsunami happens nearby, you’re unlikely to receive a warning because the tsunami could get to the coast within 10 minutes or half an hour.

But if you feel strong ground shaking, then the minute it stops, head inland and uphill-preferably both. In many cases, you only need to be a few metres uphill or a kilometer inland and you’ll be safe. If it’s an extremely flat area and there’s nowhere to run, find the stoutest building around and get up as high as you can.

Afterwards, the rescue services will be slow to reach no matter you are. Disease will become a problem and you probably won’t be able to get uncontaminated water. In that case, move inland to find unaffected areas.”