Using GPS to Detect Imminent Tsunamis
- Tuesday, 01 December 2009
Reliable tsunami warnings could be generated within minutes of causative earthquakes.A promising method of detecting imminent tsunamis and estimating their destructive potential involves the use of Global Positioning System (GPS) data in addition to seismic data. Application of the method is expected to increase the reliability of global tsunami-warning systems, making it possible to save lives while reducing the incidence of false alarms. Tsunamis kill people every year. The 2004 Indian Ocean tsunami killed about 230,000 people. The magnitude of an earthquake is not always a reliable indication of the destructive potential of a tsunami. The 2004 Indian Ocean quake generated a huge tsunami, while the 2005 Nias (Indonesia) quake did not, even though both were initially estimated to be of the similar magnitude. Between 2005 and 2007, five false tsunami alarms were issued worldwide. Such alarms result in negative societal and economic effects.
GPS stations can detect ground
motions of earthquakes in real time, as
frequently as every few seconds. In the
present method, the epicenter of an
earthquake is located by use of data
from seismometers, then data from
coastal GPS stations near the epicenter
are used to infer sea-floor displacements
that precede a tsunami. The displacement
data are used in conjunction with
local topographical data and an
advanced theory to quantify the destructive
potential of a tsunami on a new
“tsunami scale,” based on the GPSderived
tsunami energy, much like the
Richter Scale used for earthquakes. An
important element of the derivation of
the advanced theory was recognition
that horizontal sea-floor motions contribute
much more to generation of
tsunamis than previously believed. The
method produces a reliable estimate of
the destructive potential of a tsunami
within minutes — typically, well before
the tsunami reaches coastal areas.
The viability of the method was
demonstrated in computational tests in
which the method yielded accurate representations
of three historical tsunamis
for which well-documented groundmotion
measurements were available.
Development of a global tsunami-warning
system utilizing an expanded network
of coastal GPS stations was under
consideration at the time of reporting
the information for this article.
This work was done by Y. Tony Song of
Caltech for NASA’s Jet Propulsion Laboratory.
The software used in this innovation is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-45940.