Japan, France study GPS-based tsunami warning system

Researchers in Japan and France have begun joint
research using data from the recent tsunami catastrophe
in the Indian Ocean to study the prospect of using
global positioning system to track earthquakes and warn
of tsunamis.

"If the focus of the quake is near a GPS observation
point, we will be able to see the condition of the sea
surface from above and figure out details of the size
and speed of a tsunami right after it is developed,"
said Makoto Murakami, a research coordinator at Japan's
Geographical Survey Institute.

If successful, geologists will be able to record the
conditions of tsunamis immediately after an earthquake
is detected, track the movements of any consequent
tsunamis and issue precise warnings before the waves hit
shore.

When quakes and tsunamis jolt the earth and sea
surfaces, the atmosphere above them is in turn pushed up
and down. The vibration shakes electrons in the
ionosphere and results in a delay in electric waves
transmitted to observation stations from GPS satellites
some 20,000 kilometers above ground, Murakami said.

By analyzing data at the 1,200 GPS stations operated by
the institute in Japan, scientists will be able to track
the conditions of tsunamis within several hundred
kilometers from the coast, he said.

As there are a few tsunami observation equipment set up
at sea, scientists currently can only estimate the
movement and scale of tsunamis using data from
seismometers and tide gauges along coasts.

The Japanese institute, under the Ministry of Land,
Infrastructure and Transport, and the Paris Geophysical
Institute in France began basic research on the use of
GPS to track tsunamis after a June 2001 earthquake off
Peru.