On Wed, 14 Jul 1999, angel rodriguez wrote:
> I Have been working on several new ideas to make my station more useful
> to Nome and was going to install a network of several senors 30 km
> apart to be able
> to lace small local events with just my station.  I was going to have
>  Over the weekend
> some mention that an array might be better not only for local event
> but that I could also locate regional events quite well and that the
> array was much smaller maybe even within a 1 km radius.  Can any one
> shed some light on this idea, can it be done with the kind of stuff we
> use? I have several Marks L4C's I was planning to use. Is there
> anything published that I can get my hands on.  Any URL's?

   Arrays have a lot of power, even if the instruments are not broadband.
They are usually constructed to study the lithosphere and upper mantle
directly below the array, but more uses have been employed as people tinker
with the data.  There is a ton of literature on this stuff, because everyone
from the oil industry to huge multi-million dollar scientific projects uses
them.  To get a good array going for locating local events you should have at
least three of them in a triangular arrangement.  Being precisely geometrical
with the arrangement is not necessary, because the analysis can handle any
general location.  With five sensors, making a large "X" shape with a sensor
located in the middle is a good arrangment.  If, on the other hand, you want
to study a specific line in the Earth then you just line them up along it.
   You will need separate recording stations each timed using something
accessible to each (eg. GPS).  The most widely used devices for arrays are
part of the PASSCAL array (Passive Array for the Seismic Study of the
Continental Lithosphere or something like that) which are owned and
distributed by the IRIS consortium, of which just about every major university
is a member (www.iris.edu).  They have a nice compact system of broadband
sensors, programmable digital recorders, and power supplies like solar panels.
They probably have tons of stuff on installing and operating these types of
arrays.

> My other question is does anyone one know of the Chinese
> company that make broad band sensors and how to get hold of them.

No...never heard of them.

John Hernlund
E-mail: hernlund@.......
WWW: http://www.public.asu.edu/~hernlund/

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