PSN-L Email List Message

Subject: RE: Help me LEARN
From: "Stephen Hammond" shammon1@.............
Date: Fri, 26 Feb 2010 09:48:06 -0800

Hi Jerry, There is no such thing as a dumb question and it is OK to make
mistakes. This list has always supported learning and that was one of the
main purposes we developed the original BBS and Larry creating the first

I have a question. It may sound basic but it's just a thought. You don't
record many local events I take it. Which table are you using to calc the
P&S waves in Winquake? Open Winquake click on table and select the radial
button "regional" in the lower right of the popup. As for the amount of data
to cut. Check the PSN Redwood City website (Larry's) and look at the event
files. Locate 100223.200336.ate That should give you an idea of the amount
of data to save for a local event. The rule of thumb is you want to provide
enough data so the background noise level can be established before the
event occurred. On the backend of the event you don't want to chop off any
seismic waves. For a local event start to end of the event is about 1.5 min.
Winquake default is to trap 3 min. Poor ratings: The ratings are based on
the data at the sites used for analysis. Your data may also be poor or it
could be good. It depends on your location in relation to the epicenter and
the direction of the energy and the instruments orientation N/S -- E/W -- Z
in relationship to the event. I live near the San Andreas fault zone and
there are times when the data is poor for many local on smaller events. Many
times the assessment rating is an arbitrary judgment scale based on the
assessment of the seismologist that reviewed the event file. UPLOAD DATA: I
took a look at the PSN event files for this event and I only see two event
files from JP3 and HZ3 in Texas. Have you posted any data to the event

Regards, Steve Hammond
PSN San Jose, Aptos, CA 


-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of Thomas Dick
Sent: Friday, February 26, 2010 7:54 AM
To: psn-l@..............
Subject: Re: Help me LEARN

GPayton wrote:
> After reading many posts on the PSN Net, it is obvious that I know 
> very little as compared to MANY of you out there.   I am often 
> embarrassed to ask a question and turn to the books to try to resolve 
> my question(s).  Even at that, many time I fall short.
> So!  Question:
>     1)    Today's trace of the 3.1 event in Oklahoma  displays 
> in WinQuake that both the *Pb* & *Sb* were seconds *_BEFORE_* the *P* 
> & *S* times.  To me, that seems like I get a bouncing ball BEFORE I 
> actually drop it!  What did I do wrong?  Is this a matter of the 
> "tables" being off?  Or, am I wrong in assuming it is incorrect?
>     2)    Another "pause" that I have when using WinQuake of any event 
> is HOW LONG to plot it.  Obviously, a local event would be short, a 
> regional would be a little longer and a teleseismic may be over an 
> hour.  But, I was wondering IF there was a rule-of-thumb time that you 
> experienced people use?
> Thanks & Best regards,
> Jerry
According to the St. Louis network
> _
, this quake was not a good one ... they rated it as poor. I have 
followed their analysis faithfully and such a rate makes for some poor 
readings of the incoming times of wave types.

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