[time-nuts] USGS: GPS for seismic work

Rex rexa at sonic.net
Sun May 20 02:55:39 UTC 2012


I was at the USGS open house for a couple hours. My first time to go.

Was also my first time to see a commercial choke ring GPS antenna up 
close. Was interesting to see the antenna shifted a few inches and 
causing a step function on the internet screen where they where 
monitoring it along with a few permanent logging station antennas that 
were (fortunately) stable while we were watching.

Also enjoyed seeing a hand held XRF Spectrometer (Xray Fluorescence) for 
identifying the material in random samples. And good to chat with the 
guy who carried it around Afghanistan for the last few years helping 
(the Afghanies?) learn what neat stuff their country contains. He also 
had an entertaining story about shopping for silver items -- "90% 
silver, sir." He pulls the XRF out of his pack and scans to find more 
like 20% silver.

Quite a few interesting discussions with several people around the 
place. Also bought a nice large wall map of California with nice relief 
view of the mountains for $9.

Well worth the drive from San Jose.



On 5/19/2012 6:09 PM, Hal Murray wrote:
> It wasn't hard to find the right people at the Open House.
>
> GPS is interesting for big quakes.
>
> Most seismometers measure acceleration.  It's a double integration to get
> displacement which is what they are used to working with.  Big quakes last
> longer which leads normal seismometers to get into troubles with drift.  GPS
> doesn't have any drift problems.  The cross over is somewhere in the mag 7-8
> range.
>
> Japan has a large earthquake warning system.  On the big tsunami of last
> year, they weren't looking for long enough.  They estimated 7.9.  In
> hindsight, they probably could have gotten better data sooner by using GPS.
>
> This news story says that they can see the disturbance in the ionosphere.
>    http://www.cbc.ca/news/technology/story/2012/04/23/f-tsunami-research.html
>
>




More information about the time-nuts mailing list