A Dunedin man is concerned Otago residents are not aware of a
fault off the coast which could have an impact as great as
the Alpine Fault in an earthquake.
However, GNS Science says the fault is known but is
After the recent earthquakes in Christchurch and north
through to Wellington, Middlemarch man Phil Ford started to
think about the anomaly he saw in maps of the sea floor off
the east coast of the South Island.
He is a University of Otago PhD student, and although it was
not the topic of his research, he looked closer at the
sea-floor maps, coming to the conclusion there was a fault
running along the edge of the continental shelf off the east
coast people should be aware of.
''If this is active, it is much more important to the east
coast of the South Island.''
He was not aware it had been mapped as the Waipounamu fault.
Its close proximity to the east coast - about 30km from Otago
Peninsula - meant there was a real tsunami risk, he believed.
''People should be aware.''
While it might not be considered active by GNS, he believed
its distinct edge, which had not been ''muted'' by
sedimentation over time, meant there was a possibility it
could be active but more research was needed to determine
Christchurch's experience showed inactive or unknown faults
could cause major damage, he said.
He had written a paper that was yet to be peer-reviewed or
published to highlight the risk and hoped others would
investigate the fault.
''More work and a better scientific understanding is now
crucial. Further evaluation of the fault should put it more
reliably into a broad understanding of seismic hazards facing
the various communities of the eastern South Island.''
GNS Science communications manager John Callan said the
fault, or belt of faults, was first proposed in the 1970s and
the evidence was based mainly on the shape of the sea floor.
''The fault, or faults, are not regarded as active and are
not thought to have not ruptured or produced earthquakes for
about 100,000 years.''
A GNS scientist produced a map in mid-2000 naming it the
It was not one of the 550 onshore and offshore faults in the
New Zealand Active Faults Database, he said.
Otago Regional Council environmental engineering and natural
hazards director Gavin Palmer said the council's 2005
commissioned report on seismic hazards did not include risks
posed by off-shore faults.
However, this year the council would be updating that report
and collating all available information on seismic hazards
That information would be assessed to see if more research
needed to be done or response made to a hazard.
Suitable information would be incorporated into the council's
natural hazards database, which was available to the public
Niwa declined to comment on Mr Ford's paper until it had been
peer-reviewed in a scientific journal.