Quick Dips

A Shaky Capital

A spate of small earthquakes in the Wellington region lately has residents nervous and scientists excited. The tremors could indicate that a large earthquake may be on the way, but it's hard to make predictions.

Earthquakes are not uncommon in Wellington. In 1848 the fledgling city was rocked by a large shock centred in Marlborough. Five years later it was hit again, this time from the Wairarapa. From 1929 to 1942 there was a string of earthquakes but things have been fairly quiet since then, says Professor Jim Ansell of Victoria University's Research School of Earth Sciences.

"We don't really understand how big earthquakes link together, " he says. Ansell's research team is using satellite-based measurements to plot the slow movements of the plates that clash under the region. They hope to be able to estimate the frictional forces and stresses involved. This data may enable them to develop a model that can predict accurately where and when an earthquake will occur.

Collaboration with the Wellington Regional Council has led to preparation of a hazard map. This outlines which areas are at most risk from land movement and suggests appropriate building codes. Ansell compares it to a forest fire danger sign.

"People still go through the forest [when the sign ranks fire danger as high], " he observes. "It just means you take slightly different precautions because the risk levels are different."