Can earthquakes be predicted?

Shattered windows Christchurch Feb 2011

Earthquakes are not simple. They do not occur like clockwork in the same place and earthquakes are not evenly spread.

In the past scientists believed that a similar-sized earthquake happens on the same fault at regular intervals. However, there is a margin of uncertainty in recurrence intervals between ruptures on an active fault.

For example,

  • Intervals between ruptures on the South Island’s Alpine Fault range from 270 years to 500 years.
  • Between 1929 and 1934 New Zealand was hit by five major earthquakes of magnitude 7 or more. This is 10 times greater than the long-term average for earthquakes of magnitude 7.

It is possible to estimate where big earthquakes are likely in the next 50 to 100 years, based on geological investigations and the historical record of earthquakes. Also, once an earthquake has occurred, the number and size of aftershocks that follows will typically fall within a common pattern. Therefore estimates can be made of the probabilities of aftershock occurrence. Check out this video of Matt Gerstenberger explaining this process of earthquake aftershock forecasting based on statistical probabilities.

It is not yet possible to accurately predict the time and location of the next earthquake.

A number of physical changes have been observed before some earthquakes, but the problem is that so far, no particular change has been noted consistently.

The fact that many large earthquakes do have foreshocks indicates that something unusual is happening before these large events. With further research we may one day be able to make improved predictions of earthquakes.