Are Tsunamis Predictable?
By all rights, the 8.8-magnitude earthquake that struck
Chile in February 2010 should've
fifth most powerful since 1900. It originated in a subduction zone along the
Chile margin, a unique geological area where three tectonic plates are being
subsumed by the South American continent.
If that wasn't enough of an omen, a
9.5-magnitude quake in Chile 50 years earlier generated a tsunami that bent Hawaiian
parking meters like paperclips.
Yet, when the 2010 quake occurred, the resulting tsunami
arrived in Hawaii with a whimper. In fact, it barely warranted evacuation
warnings issued by the National Oceanic and Atmospheric Administration's (NOAA) Pacific
Tsunami Warning Center in Hawaii. Those warnings were based on a tsunami model that did not accurately predict the effects of Chilean tsunami.
The failure of that model — and the accuracy of another created by NOAA's Center for Tsunami
Research in Seattle, Washington — will prove invaluable at predicting future tsunamis. After all, each
prediction failure is an opportunity to figure out why the system failed in the
But the failure also underscores another question: Are
Researchers have become increasingly adept at predicting
what a tsunami will look like once it occurs, based
"We're still building models from
the 1960 Chilean earthquake," said Chris Goldfinger of Oregon State University.
"Twenty years from now, people will be sorting out the models for the 2010
quake. It's really a never-ending process."
Models that forecast the effects of tsunamis on Hawaii,
for example, must consider an underwater ridge that protects it from most
Forecast models depict the size and number of tsunami
waves, approximate arrival time, where the waves will make landfall, and how far
inland they will reach. They are compiled by tsunami researchers for faults
around the world; like an 8.8-magnitude quake along the Chile margin, for
example. When this quake occurred, researchers pulled up models based on this
very event; responders based their reactions on the predictions, which led to evacuation
Because of the factors involved in compiling an accurate depiction
of a tsunami and the relatively sluggish computing power currently available,
researchers compile models before they occur.
"It just takes too long to do them in real
time," Goldfinger said.
Time is an essential factor following a tsunami, and
quickly detecting tsunamis when they occur is as much a part of the field as
predicting the course and form they will take. Even a few extra minutes of warning can give
people in the tsunami's path time to reach higher ground, which unequivocally saves lives. The
Indian Ocean tsunami of 2004 struck land within 20 minutes and
killed around a quarter-million people because the area lacked an early warning
Since around 85 percent of tsunamis come from the Pacific
Ocean, American researchers have focused largely on the Pacific Northwest in
recent years. Geologists have predicted that the Cascadia subduction zone that
runs off the coast from Mendocino, Calif. to Vancouver, British Columbia may be due for
a massive quake. It's one of only two fault lines in the U.S. capable of
producing a major tsunami.
Since the mid-1990s, NOAA
are capable of sensing and recording tsunami activity and relay the information
back to land as an early warning system. As a tsunami is generated, these
tsunameter buoys can provide hours of additional time to reach safety.
The profile of a predictable tsunami is still being developed.
Most recently, researchers have begun to investigate how to detect faint
electrical currents created by tsunamis. As wave action drags ions through
saltwater and along the Earth's magnetic field, it generates an electrical
field that Manoj Nair of the University of Colorado has proposed may
be detected as an early warning system.
Tsunami researchers are taking this science
as far as they can, but they consistently run into a roadblock. Most tsunamis
are generated by earthquakes, and to predict one before it happens requires the
ability to predict a quake. Scientists have thus far been unable to make narrow
"We can't currently predict earthquakes over
timescales of days, weeks, months or even a few years," said University of
Washington seismologist Heidi Houston. "We have mostly moved to
forecasting earthquakes in a region over the next 30 to 50 years."
Still, the work tsunami researchers are compiling would
prove adequate in predicting tsunamis should earthquakes ever become
could predict an earthquake in sufficient detail, then scientists could do a
pretty good job predicting the resulting tsunami," Houston added.
Image: Indian Ocean tsunami, 2004 (NOAA); boat flung ashore in Indonesia by Indian Ocean tsunami (Chuck Simmins, Flickr)