Running the numbers on quake risk

Although many people would like them to, scientists cannot predict earthquakes. They can, however, estimate the probability of one occurring using hazard modelling systems.

Paul Gorman from the Press quizzed GNS Science on the most up-to-date odds of another strong shake hitting quake-stricken Christchurch.

An excerpt (read in full here):

One in seven chance of 6.0

Canterbury has a one in seven or eight chance of a magnitude-6.0 to 6.4 earthquake in the next year, new figures show.

However, there is only a one in 50 chance of a magnitude-7.0 quake or higher, forecasts released yesterday show.

The Press had asked GNS Science to break down its latest quake forecasts for the next year.

That followed a briefing last Friday from GNS Science seismologist Kelvin Berryman which focused on the probability of two broad groups of quakes – those between magnitude 5.0 and 5.9, and between magnitude 6.0 and 7.9.

Those predictions were the first time the 7.9-magnitude figure had been used.

This week The Press received nearly two dozen telephone calls and emails expressing concern about the chance of such a huge quake and questioning if 7.9 was a mistake and should have been 6.9.

As a result, The Press requested a recalculation into narrower bands.

Those figures arrived yesterday after a long-winded process involving GNS Science, the Canterbury Earthquake Recovery Authority and Earthquake Recovery Minister Gerry Brownlee’s office…