SAC Help

A forum for SAC users to exchange ideas and ask questions about SAC usage, installation, portability, etc.

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sac-help@lists.ds.iris.edu
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Active Message Threads for October 2022

Prasad Kasulanati
2022-10-28 12:28:28 - 2022-10-31 15:49:21
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
Monumoy Ghosh
2022-10-21 17:34:51 - 2022-10-21 22:04:43
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
Joana Carvalho
2022-10-19 16:11:46 - 2022-10-20 10:53:02
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
George Randall
2022-10-17 11:32:12 - 2022-10-19 09:56:22
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]
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George Randall
2022-10-18 09:00:56 - 2022-10-18 21:23:00
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]
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Robert Herrmann
2022-10-18 16:29:52
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
Robert Herrmann
2022-10-18 16:25:09
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
No replies
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