A rapid earthquake information application for Apple iPhones should be released in early June, building on the popularity of the service.
GeoNet, a collaboration between the Earthquake Commission and Crown research institute GNS Science, has already launched an app for android phones featuring its faster quake information service called GeoNet Rapid.
Better instrumentation and a quicker reporting system means quakes can now be located and measured approximately as soon as the information is received, sometimes within tens of seconds.
More accurate details are then released as normal about 10 minutes after the quake, once they have been analysed.
GeoNet has been testing the new service on its website for the past three weeks and says the feedback has been generally positive.
Acting GeoNet project director Kevin Fenaughty said "minor tweaks" had been made to improve the service.
On average, about a quarter of visitors to the main website were clicking on the "rapid" test site too.
"That's a reasonably good number. We had one who said they preferred the 10 to 15-minute wait for the information," he said.
"I'm not sure why, but I think it's because they want to get the office sweepstake going first."
People seemed pleased with the rough accuracy of the rapid system and realised there was a trade-off between speed and precision, he said.
A small aftershock in Pegasus Bay at 10.40am yesterday was analysed within 30 seconds by the trial system as magnitude 3.4, eight kilometres deep and 20km east of Christchurch. The final analysis put it at magnitude 3.6, 8km deep and 10km northeast of the city.
GeoNet had begun using the new "summary magnitude" scale, which was a more reliable measurement for large and small quakes and more consistent with readings made overseas, he said.
There was generally about 0.2 of a magnitude difference between the new and old "local" or Richter magnitude. Some people would have noticed that what might have felt to them like a magnitude-4.0 quake was now registering, say, 3.8.
GeoNet staff were working with an outside agency to develop the iPhone app.