[EAS] WEA used in NYC bombings

[John Willkie]

>From my limited knowledge, virtually all earthquake waves are supersonic, some >14,000 mph.  The idea as I understand it is to use supersonic electronics that report the first shock to points that won't feel the shock at remote locations until some time (seconds) later.  From experience, the waves tend to diminish over distance, depending on geology.  The Easter Quake(s) of a few years back (epicenter 100 miles distant) were deep, and the epicenter was basically on sand and alluvial fill; residents there mostly reported smooth waves.  To me, in San Diego, on more solid ground, we felt sharp shocks, but with less up-and-down than in Calexico.

I think it's an open question as to whether such short-term notifications will help much, absent "the big one," which could come any hour, day, week, month, year, decade or century. 

Anyone who has ever been at a vantage point when even a moderate earthquake hits tends to remember "terra firma" undulating like a rip current as the earthen waves go through.

Any earthquake beneath the ocean within 100 miles of land that causes a large tsunami won't give people along the coast enough warning to even kiss one's a** goodbye.  Fire Island might be remote, but look at Coronado, CA on Google Earth.  Note the two routes in/out: a bridge (2-3 lanes out) and a 12-mile route over a glorified sandbar to the South.  <24 feet above mean sea level.

John
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From: Robertm <bcstlists at icloud.com>

This was discussed a few weeks ago on one of these EAS lists.

A simple explanation of the earthquake warning system is that there is a supersonic shock wave that precedes the actual shock wave. This means that the earthquake has commenced. The time between these supersonic waves and the Main shock can be seconds. The problem with public warning is the latency in the various warning systems would not always get the warning through in time.

Interestingly enough our ancestors had an early warning system. Over the time they observed that dogs went crazy just before a quake. Basically they were responding to the same supersonic pre-tremors that EEW is exploiting. So if you want EEW with low latency, stay close to your dog.