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Active Message Threads for October 2022
Prasad Kasulanati
Greetings to all!
I have two queries.
1. Picking the regional seismic phases:
Are there any possibilities of marking the regional seismic phases using auto pick?
2. Velocity model in SSSTRAVELTIME:
How to define the velocity model for computing the travel time apart from the pre-defined global velocity models (iasp91 and ak135)?
Regards
Prasad Kasulanati
Ph D Scholar
Geo Sciences and Technology Division
CSIR-Nort East Institute of Science and Technology
Jorhat - 785 006
Replies
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Re: Define the Velocity model for stacking - George Helffrich - 2022-10-31 15:49:21
Monumoy Ghosh
I use this script below.
sac <<!
echo on
r ${rootname}T ${rootname}R ${rootname}Z
qdp off
rtr
rmean
taper
bp co $bp1 $bp2 p 2
ppk
ch a ${timeaa} ka a
wh
ch f ${timeff} kf f
wh
w pol_T${lowp}_${higp}_${root}.${cha}T pol_T${lowp}_${higp}_${root}.${cha}R
pol_T${lowp}_${higp}_${root}.${cha}Z
r pol_T${lowp}_${higp}_${root}.${cha}?
fileid on type name
ppk
q
!
But the pol_* files doesn't show the band pass filtered signal
Replies
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Re: bandpass command problem in 102.0 - George Helffrich - 2022-10-21 16:51:40
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Re: bandpass command problem in 102.0 - Onur Tan - 2022-10-21 22:04:43
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Joana Carvalho
Hello SAC users
I am trying to normalize some sac files. I know how to normalize to 1 using the max amplitude but I want to both max and min amplitude and thus normalize my negative amplitude to -1 and the positive to 1.
Is it possible to do it in SAC?
I let you a file to use as example.
Thanks in advance, and I am sorry if this is not the proper way to ask for help.
Joana Carvalho
Replies
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Re: Normalization in -1 1 range - Geo . - 2022-10-20 10:53:02
George Randall
Hello Sac Users
I received an email from a fellow retired seismologist who has used SAC
for decades and is a user of macros and Blackboard Variables. He encountered
an apparent issue with large numbers not working. I have experimented and
I think SETBB/GETBB don't seem to work for numbers >= 2^31
SAC> setbb ts1 3.14159
SAC> getbb ts1
ts1 = 3.14159
SAC> setbb ts2 2.0E+09
SAC> getbb ts2
ts2 = 2000000000
SAC> setbb ts3 2.2E+09
SAC> getbb ts3
ts3 = -2147483648
trying 2^31 -1 and 2^31
…
[more]
Replies
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Re: Blackboard Variable confusion - Brian Savage - 2022-10-17 12:22:16
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Re: Blackboard Variable confusion - George Helffrich - 2022-10-17 17:45:05
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Re: Blackboard Variable confusion - Onur Tan - 2022-10-19 09:56:22
Brian and George,
I want to thank both of you for your timely and thoughtful replies!
The suggested workarounds are great idea, and I have forwarded
them to my fellow retiree as I doubt he reads the sac-help list and
I have pointed him at the list.
I am delighted to know that after 38 years of using SAC, that you are
both devoting your time and effort to maintaining and improving SAC
and helping so many users with your insight into SAC issues with the
sac-help list.
I hope the seismic resear…
[more]
Replies
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Re: Blackboard Variable confusion - Hrvoje Tkalčić - 2022-10-18 21:23:00
Robert Herrmann
Sorry about the previous Email
I am now reading
http://ds.iris.edu/files/sac-manual/manual/tutorial.html#floating-point-precision-in-sac
No replies
I understand the need for extended precision in the timing variables B, E,
... T9
However why was DELTA included? Is that ever a real problem?
Also EVLO EVLA STLO and STLA are double precision. Is the computation of
GCARC DIST AZ and BAZ now done internally in double precision, and if so,
why are are they still single precision in the header.
Bob Herrmann
Saint Louis University
