From: Barry Lotz barry_lotz@.............

Date: Wed, 9 Jul 2008 18:34:19 -0700 (PDT)

Steiner S-T Morrissey posted a discussion about this to psn on 13 nov 1999. I plotted a log-log sheet with "sensor count" on the y axis and distance from sensor on the x axis and drew magnitude lines (m =3.0,3.5,4.0, etc) . I then plotted individual points for each quake I recorded on this graph. I got pretty good correlation. Regards Barry John Lahrwrote: Steiner, You could use the equation for Ms magnitude to compute the expected surface wave amplitude at your location. The equation is given in this spread sheet: http://jclahr.com/science/psn/magnitude_files/ML_magnitude.xls under Sheet 2. This will just be an rough estimate of the amplitude you may see because the radiation pattern of the earthquake will also effect the amplitude. Cheers, John At 02:08 AM 7/8/2008, you wrote: >For my web page I automatically retreave current earthquake data from >USGS and NORSAR in order to make a table of earthquakes which my >instrument should be able to detect. I then calculate arrival times >for the P and S waves and add that to my plot as well. > >Quakes that satisfy the equation sqrt(10)^(m+2.5) > d, where m is the >magnitude and d is the distance in km, are currently in my list, and >that limit seems roughly to correspond to what I can detect. > >That is, I'm assuming that the strength of an earthquake drops by the >square of the distance. Is that a valid assumptation for earthquakes? > >-- >Steinar Midtskogen >http://voksenlia.net/met/seismometer/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) SteinerS-T Morrissey posted a discussion about this to psn on 13 nov 1999. I plotted a log-log sheet

with "sensor count" on the y axis and distance from sensor on the x axis and drew magnitude lines (m =3.0,3.5,4.0, etc) . I then plotted individual points for each quake I recorded on this graph. I got pretty good correlation.RegardsBarrywrote:John Lahr <johnjan@........>Steiner,

You could use the equation for Ms magnitude to compute the expected

surface wave amplitude at your location. The equation is given in this

spread sheet:

http://jclahr.com/science/psn/magnitude_files/ML_magnitude.xls

under Sheet 2.

This will just be an rough estimate of the amplitude you may see

because the radiation pattern of the earthquake will also effect the

amplitude.

Cheers,

John

At 02:08 AM 7/8/2008, you wrote:

>For my web page I automatically retreave current earthquake data from

>USGS and NORSAR in order to make a table of earthquakes which my

>instrument should be able to detect. I then calculate arrival times

>for the P and S waves and add that to my plot as well.

>

>Quakes that satisfy the equation sqrt(10)^(m+2.5) > d, where m is the

>magnitude and d is the distance in km, are currently in my list, and

>that limit seems roughly to correspond to what I can detect.

>

>That is, I'm assuming that the strength of an earthquake drops by the

>square of the distance. Is that a valid assumptation for earthquakes?

>

>--

>Steinar Midtskogen

>http://voksenlia.net/met/seismometer/

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