[IP] Re: Japan's earthquake warning system

[David Farber <dave@farber.net>]

Begin forwarded message:

From: Hasan Diwan <hasan.diwan@gmail.com>
Date: March 26, 2007 7:37:53 PM EDT
To: dave@farber.net
Subject: Re: [IP] Japan's earthquake warning system

On 26/03/07, David Farber <dave@farber.net> wrote:
The system detects a quake's initial P wave, which is the first jolt you
feel, before the more severe S wave reaches you.  (Both start out at the
epicenter essentially simultaneously, but P waves travel faster; about
5km/s in rock, while S waves are about 60% of that.)
P-waves are longitudinal and can travel through all types of  
material. S-waves are transverse and travel through matter that  
supports shear stress (read solids).
--
Cheers,
Hasan Diwan <hasan.diwan@gmail.com>

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