The world's first earthquake early warning
system has begun operating in Japan. The government-developed system takes
advantage of the precious seconds between the first indication of a
powerful tremor and the arrival of the second, destructive terrestrial
shock. Some people have reservations about broadcasting such alerts.
If a large earthquake were to strike Japan today, some people would
receive advance notice.
This kind of public address alert, recorded at a Tokyo university, will
automatically be triggered at certain locations seconds before a big
tremor is felt. In other cases, such as trains, the alert will be
transmitted digitally, or by radio.
The secret to the system lies in the anatomy of an earthquake, which
actually generates two waves. The first is a smaller, primary wave that
travels at seven kilometers per second. The second wave, the one that can
cause damage, moves at a slower four kilometers per second.
The new system takes advantage of the gap between
the two waves to issue a warning that a quake is coming. Japan's
nationwide network of some 1,000 seismographs
, developed over several decades, is now linked to a
computerized system that can trigger the alert. It became operational this
Kenji Kuwashiro of the Keihin Kyuko Railway says its commuter train
network is already using the early warning system.
Kuwashiro says signals will be sent to all trains to allow engineers to
stop quickly, possibly before a potentially damaging seismic jolt hits the
While proponents of the system tout its ability to save lives at
constructions sites, aboard trains or in hospital operating theaters,
others fear the system might pose a new hazard. They worry that people
will panic if an alert is issued.
Makoto Saito, the senior
coordinator for the warning system at the Japan Meteorological Agency,
acknowledges this possibility.
Saito says national guidelines need to be drawn up and the public
educated about the system so it will save lives rather than endanger them.
In the meantime, out of caution, Japan's television and radio stations
are not yet planning to broadcast the alerts.
Japan is one of the
most vulnerable nations to earthquakes in the world. Some one-fifth of
all of the world's earthquakes of magnitude six or stronger
originate below or in close proximity to Japan.