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Abstract

This paper describes the concept and a brief history of EEW, which is almost equal to the development of the UrEDAS, Urgent Earth- quake Detection and Alarm System. UrEDAS is the first practical P-wave early warning system. And the explanations of early warning systems and the actual example of disaster prevention by this system are also described. Finally I would like to discuss on the role of national or public organization about the earthquake disaster prevention, especially in Japan. The concluding remarks as follows: 1) Network alarm is effective for middle distance area, but risky because of the data interruption caused by the network error, 2) On-site alarm by FREQL or AcCo is useful for anywhere, even in epicentral area, 3) Early Earthquake Information distributed by JMA is full of error and useless for damage area because of too late warning, and 4) the nation-wide-organization must be issued the detailed earthquake information as soon as soon as the earthquake terminated, and issuing alarm is not a role of these organizations.