Earth Planets Space, Vol. 60 (No. 2), pp. 155-160, 2008LETTER
Yih-Min Wu1 and Hiroo Kanamori2
1Department of Geosciences, National Taiwan University, Taipei, Taiwan
2Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
(Received June 22, 2007; Revised August 25, 2007; Accepted September 11, 2007; Online published February 19, 2008)
In view of the remarkable success of the Japan Meteorological Agency earthquake early warning system (developed jointly with the National Research Institute for Earth Science and Disaster Prevention) during the 2007 Noto Hanto earthquake, we explore the use of an on-site early warning method with the hope of eventually enhancing the existing system for more robust and faster warning. We determined two early warning parameters τc and Pd using the K-NET and KiK-net data for the 2007 Noto Hanto earthquake as well as 20 large earthquakes in Japan. An extended method suggests a possibility of using the initial displacement amplitude data for faster warning. For the two nearby sites at the epicentral distances of 7 and 19 km of the 2007 Noto Hanto earthquake, an early warning can be ideally issued at 2.27 and 5.46 s, respectively, before the peak ground motion velocity occurs at the site.
Key words: Earthquake early warning, magnitude, seismic hazard mitigation, P -waves.