WELLINGTON, Aug. 26 (Xinhua) -- New Zealand scientists have discovered there is no connection between major fault lines in the North and South islands through central Cook Strait -- meaning that an earthquake fault rupture may be contained to one island ifit occurred.
The findings are part of research released on Tuesday by the National Institute of Water & Atmospheric Research (NIWA) which provides vital new information to help assess the potential hazardof earthquakes in New Zealand.
It was the first time scientists have been able to comprehensively map the active offshore faults in the Wellington and Cook Strait region - New Zealand's most active seismic risk area.
NIWA has mapped about 20 active faults in the Wellington and Cook Strait region capable of generating earthquakes of magnitude 7 or greater, but none of them connect from the North Island to the South Island. Some of the faults are the offshore extensions of large faults on land, whereas others are entirely submarine.
The two-year study of the seafloor, supported by NIWA's deepwater research vessel Tangaroa, together with new and archivedseismic profiles from other sources, gives the first clear picture of all active faults in the offshore region.
The work is part of the project "It's Our Fault", jointly funded by the Earthquake Commission, Wellington City Council and ACC, which involves a comprehensive review of the likelihood, size, location and likely impact of large earthquakes in the Wellington region.
These new findings by NIWA will assist the project, which includes studies by GNS Science and Victoria University of the major faults on land and modeling of the potential impacts of future earthquakes.
NIWA's Ocean Geology Principal Scientist, Dr Philip Barnes said the new findings are a breakthrough for earthquake research in New Zealand.
For the first time NIWA scientists have also been able to use high resolution images of the sedimentary layers below the seabed to assess the prehistoric earthquake activity of some of the faults - dating back as far as 18,000 years ago.
GNS Science Geologist, and Project Leader for the "It's Our Fault project", Russ Van Dissen said, "knowing that there is no connection between the North and South island major fault lines will have a critical impact on the accuracy of modeling to assess earthquake risk."
