Satellites help Japan after disaster strikes

On 11 March, thousands of people were killed and entire towns were wiped off the map when a massive earthquake and tsunami hit Japan. Sadly, there is no way to predict such disasters. However, space technology is able to play an important role in the rescue and relief effort.

The quake measured 9.0 on the Richter scale and was one of the largest ever recorded. It was caused when two huge slabs of Earth’s crust suddenly moved along a deep trench in the Pacific Ocean. The violent motion of the ocean floor shifted Japan about 4 m towards North America. The sea bed was also pushed upwards, triggering huge waves which smashed into the coast.

Under an international agreement, images of the disaster area soon began to arrive from many satellites. These include Germany’s TerraSAR-X and RapidEye, France’s SPOT-5, ESA’s Envisat, and others from the USA. The images are provided free of charge to local authorities and aid workers. Radar images are especially valuable, since they show the surface in all weathers, day or night.

By comparing before-and-after images from space, the extent of the widespread damage can be made as fast as possible. Search and rescue teams on the ground quickly discover how the landscape has changed and where their help is most needed.

Over the coming weeks and months, access to the latest satellite data will continue to be an important part of the crisis response, helping with future rebuilding and recovery. Satellite data will also help improve our understanding of these geological threats. One day, they may even help to give advance warning of future megaquakes.