Seismic research shows at least two more fault lines have been discovered in South Canterbury, but none offshore.
GNS Science has identified South Canterbury and the Mackenzie basin now have about nine fault lines, up from seven in 2002.
The findings were revealed by GNS Science yesterday, which has just wrapped up a major project, alongside National Institute of Water and Atmospheric Research (Niwa), to revise the New Zealand National Seismic Hazard Model (NSHM).
The research has also pinpointed 200 fault lines throughout the country that could cause catastrophic tsunamis if a significant earthquake struck.
However, the fault lines found in South Canterbury did not carry that risk, NIWA principal scientist Philip Barnes said.
The new faults identified in South Canterbury have appeared in the Timaru high country, Mackenzie District and Waimate hills.
Dr Barnes said there did not appear to be any new fault lines out to sea, along the east coast, south of Banks Peninsula since 2002.
There are two coastal faults south of Timaru.
Another four have been identified out to sea at the bottom of the South Island and a cluster of about 20 at the lower end of the west coast, some of which were identified in 2002.
Dr Barnes said New Zealand had to prepare for marine quakes in many locations. "There are many earthquake faults on the seafloor around our coasts and the next major earthquake could be centred offshore."
Niwa research shows a large fault found offshore near Canterbury had the potential to cause a significant tsunami.
The large fault was found in the bedrock under Pegasus Bay shortly after the February quake in Christchurch when GNS Science and Niwa conducted a survey of 800 square kilometres.
Newly identified faults have now been added to the NSHM, raising the total number of known fault lines by about 200 - to nearly 530.
- The Timaru Herald