
From pechmann@seis.utah.edu Fri Sep 11 08:27:47 1998
Date: Thu, 10 Sep 1998 17:55:26 -0600 (MDT)
From: "James C. Pechmann" <pechmann@seis.utah.edu>
To: earthw-list@nmt.edu
Cc: pechmann@uuss.seis.utah.edu
Subject: Suggested Picker Parameter Changes

To:  Earthworm System Users
Re:  Suggested Picker Parameter Changes

     If you are not satisfied with the performance of Rex Allen's
P-Picker algorithm on your network data, I invite you to take a look
at a recently-posted web document entitled "Suggested Picker Parameter
Changes," available at

     http://www.cnss.org/EWAB/ovr/picker_tune.html

This report describes and explains some provisional changes to the
standard parameter settings which we made at the University of Utah.
These changes were based on an analysis of the reasons for the
picker's failure to pick arrival times for some reasonably good
quality first arrivals recorded on our regional seismic network.  The
changes detailed in the web document appear to have increased the
number of usable picks routinely obtained by the picker for local
seismic events, not only on our own Earthworm system but also on
another Earthworm system where these changes have been implemented.

--Jim Pechmann

______________________________________________________________________

James C. Pechmann                    Tel:  (801) 581-3858
Research Associate Professor         FAX:  (801) 585-5585
University of Utah
Dept. of Geology & Geophysics        E-mail:  pechmann@seis.utah.edu
135 S 1460 E Rm 705
Salt Lake City, Utah 84112-0111
______________________________________________________________________
