Japan has developed a very sophisticated Early Earthquake Warning (EEW) system that is linked to the nation's broadcasters as well as to wireless telephones, stand alone devices and the internet.
Here is an instructional video about Japan's EEW system produced by the Japanese Meteorological Agency:
Demonstrations of the Japanese Early Earthquake Warning (EEW) system:
This is an aircheck from NHK from an unknown date of a magnitude 6.0 earthquake that reached a intensity of 6-upper (on the Shindo scale from 0 to 7) in Shizuoka Prefecture southwest of Tokyo:
An over the air system that replicates the Japanese EEW system is in use in Chile. Here is an example of an activation of their system. Notice the many similarities to the broadcast from Japan:
EEW at REC
REC Networks' J1 Radio
uses data from Japan's EEW system to deliver warning messages over the air and our website. For more information, visit http://en.j1fm.com/earthquake