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USGS Explains
Live Seismo vs Quake Database

From: Lisa Wald 
Sent: Tuesday, July 01, 2003 8:50 AM
Subject: Re: Siesmo Info


Without having seen the seismograms that you were looking at, I can only guess 
that perhaps the signals that you thought were earthquakes were really some 
other type of "noise" such as a local source (trucks, train, animal, etc) or 
from communication disturbances (static). A seismic signal has to be recorded 
on a certain minimum number of seismic stations to be declared a possible 
earthquake by the automatic system. If it is declared a possible earthquake, 
then it is further evaluated to make sure it is not regional noise, or a quarry 
blast, sonic boom, or some other type of source. If it is really an earthquake, 
it is then located and recorded in the archive. 

Hope this helps.

Lisa Wald
USGS Earthquake Hazards Program
Golden, CO

On 6/16/03 9:12 PM, Angel wrote:

> How come the quakes that are registering on the live siesmograph page like
> Florida are not on the list?