Date: Mon, 29 Jul 2002 10:46:11 -0600 From: "Jonathan M. Hanson" <jhanson@..............> Subject: Re: WinSDR update
Larry -
I just got off the phone with Lew Katz (Utah Geophysical). It would
appear that the simplest way to estimate direction to the quake is by
simply plotting particle motion. For example, specify a time window that
contains the P wave. Then plot the EW component on the X axis and the NS
component on the Y axis. This will give a crude estimate of direction to
(or from) the quake. Looking at the first motions would eliminate the
reduncy in solution. If velocity sensors are used, I presume that one
would want to integrate the data before plotting. Also, it probably
would be useful to apply this method to either filtered or unfiltered
data just to have a bit more control. An identical approach could be
used for other phases but, depending on the particle motion with respect
to the line-of-site to the quake, interpretation would be different.
Also, one could include the Z coordinate but this might be difficult to
interpret unless you put up a 3D box frame on the screen with slider
bars so that you could rotate the box (with particle tracks plotted
inside the box) in 3D. There are much more sophisticated methods (see
for example the Users Manual for PITSA by Scherbaum and Johnson, IASPEI
Software Library Vol 5, p. 119) but the simple method outlined here
would be easy to implement.
I can delve into this further if you need additional references, etc.
Regards, Jon
Larry Cochrane wrote:
>Hi Jonathan,
>
>Thanks for the update. On the WinQuake wish list is the ability to plot the
>direction based on three components. The problem is I don't know how to do
>this so I need to do some research before I can add this feature.
>
>Regards,
>Larry Cochrane
>Redwood City, PSN
>
>----- Original Message -----
>From: "Jonathan M. Hanson" <jhanson@..............>
>To: <winsdr@..............>
>Sent: Sunday, July 28, 2002 8:07 AM
>Subject: WinSDR update
>
>
>>Hi Larry -
>>
>>Thanks for the WinSDR update. I have not contacted you since I got my
>>system going so here is a brief update.
>>
>>A friend of mine (Lew Katz, Pres. Utah Geophysical) has lent me several
>>geophones to play around with. The most intriguing is an Electro-Tech
>>EV-17H that he dug out of one of his storage units. I have not been
>>able to find any information on this unit but it seems to have a
>>somewhat lower frequency response than the Mark Products geophone I
>>purchased from you. I have attached a couple of jpegs showing recorded
>>quakes about 60 miles (Huntsville, UT) and a couple of hundred miles
>>(Yucca Mtn, NV) as recorded by this unit on June 2 of this year. The
>>picture labeled june14_02 shows both quakes..the first is the Huntsville
>>quake and the second is the Yucca Mtn quake. The picture labeled
>>june15_02C shows the Huntsville quake. I would appreciate any
>>information you might have on the EV-17H. I did a web search and the
>>only hit I got on Electro-Tech was one geophone on the SEG "virtual
>>museum" site. I suspect my unit was built in the 40's or 50's but this
>>is pure speculation. I have not yet had the time to build a long-period
>>sensor but hope to do so shortly.
>>
>>Do you have any short or long term plans of adding some sort of
>>polarization filter module to WinQuake? This might allow those users
>>that are recording 3 components to get an estimate not only of the
>>distance to the quake but also direction. There is a rather large amount
>>of mining activity in Utah and surrounding states. A directional filter
>>would help me sort out the mining-associated activity from other activity.
>>
>>Best regards,
>>
>>Jonathan Hanson
>>
>
>
>
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