Earthquake disaster may be reduced if the information on the arrival and the intensity of principal motion of a large earthquake is issued before its arrival. The Japan Meteorological Agency (JMA) has a plan to issue this kind of information, called the Nowcast earthquake information, in the near future. JMA has developed a data processing system for this purpose in cooperation with the Railway Technical Research Institute. This paper describes an outline of this project and presents new methods to estimate the hypocenter and magnitude in a short time after the detection of P waves, which are called the B- method, territory method and grid search method. This paper also presents a prototype system of the application of this information to an early earthquake alarm system for railways.

Copyright (c) 2003 Railway Technical Research Institute