Reuters: Japan launches earthquake early warning system
Japan launched an early warning system for earthquakes on Tuesday which would give emergency personnel and train operators a head start -- albeit several seconds -- before the actual tremors strike. Trains could be stopped and workers at construction sites can take cover using the advance information, said the Meteorological Agency, which is in charge of the system. The system would send alerts once it detects primary waves, or the first waves of an earthquake that do not cause major rattling, but travel faster than secondary waves that are responsible for shaking. The warning could precede the shaking by about 10-20 seconds and would also include the expected intensity of the tremor, but the grace period would be much shorter and in some cases none, if the focus of the tremor is close by, an agency official said...more...
Other news reports say that these early warnings will not be broadcast on TV for fear of spreading panic. There are plans to do so at a later date when broadcasters have agreed on appropriate guidelines.
