PSN-L Email List Message

Subject: Re: Representative stations?
From: Dan Bolser dan.bolser@.........
Date: Wed, 16 Mar 2011 08:56:47 +0000

On 16 March 2011 03:25, Christopher Chapman  wrote:
>   In seismology, is there a concept of a 'representative station', a
> station that collects very similar information to others? Or is the
> information from *every* station just as valuable (informative) as all
> the others?
> Are there lists of representative stations?
> Hi Dan,
>     There are strong motion, intermediate motion and weak motion sensors
> all used for different jobs. Check out The usual sensors
> detect from 50 or 30 Hz to periods of 120 seconds, exceptionally to 360
> or 1000 seconds. If you click on stations shown on a world map, say USGS
> or Iris, this calls up details of the seismometers being used at that
> station.

Thanks Chris, that's useful information. I was thinking that each
station would have similar equipment and be recording a similar
seismic 'signal'. Where can I get a table of the kind of data I can
get from each station?

> If I were the funding god, and I told you to axe all but 20, 50, 200,
> or 500 stations, which stations would you choose to keep and why?
>     You want to be able to see quite small quakes as well as
> the large ones and the signal decreases in amplitude as the
> distance increases. There are large areas in the oceans where you
> can't installqa seismometer. Cost is the other limitation. the
> instruments are expensive, they have high installation costs, they
> need to be powered and the signals need to be relayed and monitored.

Right. I was using the idea of 'funding god' to try to make my
question clear, i.e. which are the most important stations and which
ones are less important?

> My thinking is that 10 stations in one relatively small area must be
> collecting similar data, and you can (perhaps) represent *nearly* all
> 10 by picking just one of them (the most 'representative' one). Each
> 'new' station must add more information, but at some point, the amount
> of information gain from each additional station must plateau.
> Does any of that make any sense?
>     Not a whole lot.

Sorry for not being clear. What I was assuming is that two stations
within a short distance of each other collect broadly similar data.
(i.e. highly correlated (but time displaced) signals). Two stations on
opposite sides of the world collect broadly different (regional) data.

So if there were only three stations on earth, all collecting data in
the same way, two within 10 miles of each other (A and B) and one on
the other side of the world (C), and you had to de-commission one of
them, I'm guessing you'd pick A or B?

Does that make sense?

Thanks again for the info,

> Regards,
> Chris Chspman

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