🚀 go-pugleaf

In article <CARASSO.94Jan24112935@Quaestor.Inference.COM> carasso@Inference.COM (dr. carasso) writes:
>An Earthquake travels --what-- about 900 MPH?  The speed of sound in

Strong shaking arrives at the S wave velocity - about 4 km/s, or about
9000 mph.  You're off by a factor of ten.

>dirt.  Northdrige the quake center is 15 miles away where a lot of

It was also 10 miles down.  If we approximate the wavefront as spherical,
the first motion arrives 15 miles away only shortly after it arrives at
the epicenter.  Also, the qauke needs a few seconds to rupture completely,
and an alarm mechanism would need time to get the location of the
quake and its magnitude and send the info off.  Tall order, and it would
proabbly take up to 15 seconds even for the best possible system.

>damage happened.  If there was a sensor and an alarm you would know 60
>seconds before the earthquake hit.  Even 15 seconds, enoough time to
>wake up and get under a table could save 100's of lives, in a strong
>quake.  

Right concept, wrong location.  I have been arguing for earlywarning systems
for years.  Tom Heaton has argued long before I did.  No one's listening.

There is now way location 15 miles from Northridge could have been
forewarned.

>Why is this not being done!  Why is there not Earthquake monitors

Partly because the immediate vicinity, were damage is greatest, gets no
warning.  Partly because it is expensive to implement.  Partly because
there is trouble with false alarms and missed qaukes.  Partly lawyers.


-- 
Richard Stead
Center for Seismic Studies
Arlington, VA
stead@seismo.css.gov