Cook Strait aftershocks and forecast probabilities

Published: Mon Jun 2 2014 9:00 AM

The following probabilities were updated on a monthly basis until June 2014, after which time the probabilities had returned to pre-July 2013 levels.

As at June 2014, what were the probabilities of future significant earthquakes?

The table below summarises the expected probabilities (as of June 2014) of further earthquakes anywhere in the central New Zealand region shown on the accompanying map. This was an increase over and above what is normal seismicity for this part of New Zealand. The figures are based on the behaviour of aftershock sequences worldwide and the specific knowledge that scientists had of the Cook Strait sequence at that time. The figures are generated from computer models that are updated as the sequence continues. It shows that as time passes these probabilities become smaller, but any further significant earthquakes that do occur will cause these probabilities to change. The magnitude categories illustrate clearly how the probability falls away as magnitude increases.

Aftershock probabilities

Aftershock probabilities

Map showing the region for which earthquake probabilities have been calculated, indicated by the white box.

Map showing the region for which earthquake probabilities have been calculated, indicated by the white box.

After one year, how many were there?

Cook Strait Region Earthquakes

Cook Strait Region Earthquakes

Earthquakes of the Cook Strait sequence from 19th July up until 20th September. Cook Strait faults courtesy of NIWA.

Earthquakes of the Cook Strait sequence from 19th July up until 20th September. Cook Strait faults courtesy of NIWA.