The upheaval wrought by the 22 February earthquake in Christchurch, NZ, is illustrated in new radar imagery.

The Magnitude 6.3 tremor killed more than 160 people and shattered a city already reeling from a previous seismic event in September.

Data from the Japanese Alos spacecraft has been used to map the way the ground deformed during the most recent quake.

It shows clearly that the focus of the tremor was right under the city's south-eastern suburbs. The type of image displayed on this page is known as a synthetic aperture radar interferogram.

It is made by combining a sequence of radar images acquired by an orbiting satellite "before" and "after" a quake. The technique allows very precise measurements to be made of any ground motion that takes place between the image acquisitions. The coloured bands, or fringes, represent movement towards or away from the spacecraft. In this interferogram, the peak ground motion is almost 50cm of motion towards the satellite. [ BBC NEWS ]