Well, I understand that the phase pics that Winquake sets will not 
always be dead on accurate.  My main concern was that Winquake "doesn't 
quite agree with itself".  That is, the lines that can be turned on with 
the Phases button do not exactly match the positions of the phase 
picking arrows that can be turned on with the P/S button, and the time 
differences indicated by the two sets of markers are not quite the 
same.  I have assumed that the distance estimate that Winquake generates 
is based on the position of the arrows, and that if I want to attempt to 
identify the P/S onsets manually, it is the arrows I should be using, 
rather than the phase lines that are controlled by the Phases button.  
It's all pretty academic anyway, since you really have to expand to a 
very short time interval to even notice the discrepancy.

Larry


On 9/20/2010 7:46 PM, Thomas Dick wrote:
> Larry, sitting over here near the New Madrid and Mt Carmel faults I 
> have notice that here too. I learned to use the Regional table and 
> then NOT put too much faith on arrival times. I think I had a multiple 
> comment thread several years ago in which this was discussed in 
> detail. I even uploaded my Winquake file and Univ of Southern Indiana 
> files through Vase as comparision. I even used satellite time. I was 
> told these tables were averages, not written in stone, and variations 
> are to be expected over shorter distances.
>
> Larry Conklin wrote:
>>  I recorded a couple of small events the other day, a 2.9 followed 
>> shortly by a 2.7, at a distance of around 200 miles.  I noticed that 
>> when I turn on the P and S phase marker lines in Winquake, they don't 
>> line up with the P and S phase markers (ie. the veritical arrows).  
>> The amount of discrepancy depends on which table I select, and isn't 
>> all that great unless I really zoom in tight.
>>
>> So, two questions.  Why the difference?  And which should I use to 
>> estimate the distance to the event, the arrows or the phase lines?  
>> (Not that it really makes much difference, since I usually have a lot 
>> of uncertainty where the phase onsets are anyway.)
>>
>> Larry Conklin
>> Liverpool, NY
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