Advances in science will soon allow earthquakes to be located and measured in under a minute by national quake agency GeoNet.
The collaboration between the Earthquake Commission and GNS Science is about to launch major changes to the way it handles quake data.
As well as setting up a new "GeoNet Rapid" system, it is introducing a quake-magnitude scale which it says gives measurements more consistent with those made by overseas seismological institutions such as the United States Geological Survey.
GeoNet Rapid is scheduled to begin testing on a trial website on March 6, with the revised magnitude scale likely to start at the same time.
GeoNet project director Ken Gledhill said the present Richter or "local magnitude" scale roughly overestimated by 0.2 to 0.3 of a magnitude the actual size of quakes of magnitude 6 or higher.
"[However], it is not that simple and depends on things like depth and the actual mechanism of the quake. The idea is to get consistency from earthquake to earthquake and not have the big differences with the USGS, although there will always be differences."
GeoNet's calculations put the September 4, 2010, quake at magnitude 7.1 and the February 22 event at magnitude-6.3, while the USGS said the same quakes were of magnitude 7.0 and 6.1 respectively.
Gledhill said there was also confusion in the public's mind over different figures because there were "more different magnitude scales than I have fingers".
The Richter scale was unreliable for quakes above about magnitude 6, while the more complicated and comprehensive "moment" magnitude, which was based on the actual quake source dimensions and properties, could not be calculated for quakes below about magnitude 4, he said.
"The magnitudes of earthquakes cause much confusion, with different organisations publishing different values for the same earthquake. And often more data results in the magnitude being revised up or down."
To clear up the confusion, GeoNet would begin using "summary magnitude", based partially on moment magnitude, which combined the best of both scales, Gledhill said.
"Some methods have proven to be better for smaller events and others for bigger events. The summary magnitude weights the methods accordingly."
During the past year GeoNet had also been working on a faster reporting system, though still using the existing seismograph network, and was almost ready to unveil it for public testing.
"Improving our earthquake location system has been planned for a long time.
"Prior to the Christchurch earthquakes, EQC had already encouraged us to add the goal of faster earthquake locations to the work plan."
However, the huge workload for GeoNet since the September 2010 quake had put a hold on that.
GeoNet Rapid, developed in conjunction with German and Swiss scientists and engineers, could recognise earthquake locations as fast as it received and processed the data, Gledhill said.
Initial locations could be found in tens of seconds but in big quakes, or those off the coast, it could take two or three minutes, the time it took for seismic energy to travel the length of the country.
The system would, at first, be a "trade off" between speed and accuracy, and would require fine-tuning during the testing phase.
GeoNet would welcome comments once the trial was under way, he said.
An Android application was also being tested and plans were underway for an iPhone app.
Original article:
http://www.stuff.co.nz/science/6426316/GeoNet-to-get-rapid-updates
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March 02, 2012, 01:57:11 PM