Thread: SAC Macro Help to Kick Out EQs of certain epicentral distances

Dear Greg -

The header variable GCARC is the distance in degrees.

A strategy to process files is to write a macro (called, say, CHECK) to process ONE file, and then write another macro that invokes that macro for each file. E.g.

ls *.BHZ | awk ‘{print “MACRO CHECK”,$1}’ > /tmp/sac.in
cat << ‘EOF’ > CHECK
READ $1$
IF &1,GCARC LE 85
SC echo Keep $1$
ELSE
SC echo Ignore $1$
ENDIF
EOF

sac
SAC> macro /tmp/sac.in
…
…
…
SAC> quit

See chapter 5 of the SAC book for more examples and ideas about writing strategies.

On 17 Jan 2015, at 08:35, Greg Brenn <grbrenn<at>crimson.ua.edu> wrote:

Hello,

I was wondering if anyone could help me with writing a SAC macro that reads in multiple event files, and deletes any events that are beyond a certain epicentral distance away from the station.

I have events with epicentral distances from 30-90 degrees; however, I want to kick out any events with epicentral distances greater than 85 degrees.

Is there a way in SAC to kick out those events from 85-90 degrees that I don’t want?

I have checked the SAC header files, and the DIST functions are measured in km, and if I’m correct, that’s the value in the header that I want to look at.

Any ideas?

Thank you,

Greg
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George Helffrich
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