I-MAG STS Corporation
Several readers in the Solomon Islands group, New Zealand, and Australia asked:
What do you think of the burst of major activity near the Loyalty Islands?
Specifically, could it lead to a major seismic event or even "just" dozens or
hundreds of earthquakes in a swarm like the recent events east
of Honshu Japan.
Generally, if all one has is forty to one hundred years of measurements (so
latitude, longitude and depth of the epicenter as well as Richter and date/time),
this is not enough information to predict major earthquakes, let alone get close on
time or location. Part of the problem is that a century is longer than most
seismologists live, but a blink in geological time. Most seismological data older
than forty years is fairly suspect in terms of accuracy. However, statistics has
methods for dealing with this challenge. We look at not only the history of where
and when events were, but also for areas where they were not. A prevailing theory
is that tension builds between plates as they move so that, absent an explanation
like being under a river delta, there should be a increasing chance of a major event
the longer a fault segment has been increasing tension. Haiti 2010 is often given as
an example of this. There are problems with determining if smaller earthquakes
are relieving tension, or are foreshocks leading to a larger event. Then there are
tuples - two or more earthquakes of comparable strength occur very close in space
and time. Our models compensate for tuples, but have no explanation why they
happen.
The hundreds of earthquakes between the eastern coast of Honshu and the
western edge of the Pacific Plate have no known precedent. Nor is it understood
why there was and is so much activity there as opposed to at plate edges.
New Zealand is in danger from tsunamis from at least three direction
(probably not from the west). There are two important considerations: the Coral Sea
and the southwestern Pacific are seismically VERY active - and so is
New Zealand iteself. AND New Zealand's economy depends on being able to export
dairy, meat, fruit and timber. The world economy and the individual companies could sustain a lack of
New Zealand produce for months. The over 4.5 million people of Zealand,
with an estimated GDP of $190 billion (purchasing power parity) could not.
As things stand now, New Zealand exports about $37 billion per year and
imports almost $40 billion. The reserves of $20 billion in gold and foreign exchange
are offset by $90 billion in external debt and would be wiped out in a
year.