From grant.mott at gmail.com Mon Mar 2 12:54:59 2009 From: grant.mott at gmail.com (Grant Mott) Date: Mon, 2 Mar 2009 13:54:59 -0700 Subject: [SAC-HELP] Is there a quick way to search for a displacement response? Message-ID: <8b5bc2250903021254w70670542u4ebbb505b92e452e@mail.gmail.com> I am trying to find a time history of displacements. Typically, I have found that sac files are acceleration time histories. It appears (based on the header - dependent variable) that there may be displacement data available. Does anyone know of any time vs. displacement data? Is there a quick way to narrow my data search to only displacement data? Thanks! Grant -------------- next part -------------- An HTML attachment was scrubbed... URL: From agallego75 at gmail.com Thu Mar 5 07:24:42 2009 From: agallego75 at gmail.com (Alejandro Gallego) Date: Thu, 5 Mar 2009 10:24:42 -0500 Subject: [SAC-HELP] sac error Message-ID: <22b092c10903050724p75e5c61cl74fdf237dc40a3a0@mail.gmail.com> Hi could you please tell me what means this error and how can I fix it. ERROR 0: Resulting error from shift exceeded tolerance (1e-6): 0.00025 Please report bug to: sac-help at iris.washington.edu this occur when I am usgin plotpk, picking phases Thanks Alejandro From huang.zhch at gmail.com Mon Mar 9 04:35:21 2009 From: huang.zhch at gmail.com (Zhouchuan Huang) Date: Mon, 9 Mar 2009 19:35:21 +0800 Subject: [SAC-HELP] help-"merge" Message-ID: Hello, I have problem using "merge". I would like to read file names from another file and make it as variables. But it seems that the "merge" command needs a full name. e.g. I can read a file this way:* r 1997.123.*.sac*, it works well. but when I use merge: *merge 1997.123*.sac*, it returns the error: *Error 108: file does not exist*. So could you help me? Thank you very much! -- Zhouchuan Huang School of Earth Sciences and Engineering Nanjing University 22 Hankou Road Nanjing 210093 P.R.CHINA. Tel:+86 13675137130 -------------- next part -------------- An HTML attachment was scrubbed... URL: From george at gly.bris.ac.uk Mon Mar 9 05:55:41 2009 From: george at gly.bris.ac.uk (George Helffrich) Date: Mon, 9 Mar 2009 12:55:41 +0000 Subject: [SAC-HELP] help-"merge" In-Reply-To: References: Message-ID: Dear Zhouchuan Huang - This is probably not what you want to do. If you look at the merge command documentation, merge works as a binary operator: it merges one file in memory with a file in a list. Thus, if you have file.z file_a.z file_b.z file_c.z in your directory and then READ file.z; MERGE file_*.z this would be an error: only one file is in memory, and three files are in your list. Rather, you'd want READ file; MERGE file_a.z; MERGE file_b.z; MERGE file_c.z But if you really have three files in memory, then MERGE file_*.z should work. If not, it is a bug, but you can work around it by doing something like, cat << EOF > domerge sc echo $1$ | awk '{printf "setbb flist \"@%s\"\n",@$0}' > /tmp/tmp.macro m /tmp/tmp.macro sc rm /tmp/tmp.macro merge %flist% unsetbb flist EOF macro domerge 1997.123*.sac On 9 Mar 2009, at 11:35, Zhouchuan Huang wrote: > Hello, > ? > I have problem using "merge". > I would like to read file names from another file and make it as > variables. But it seems that the "merge" command needs a full name. > e.g. I can read a file this way: r 1997.123.*.sac, it works well. > ????? but when I use merge: merge 1997.123*.sac, it returns the error: > Error 108: file does not exist. > ? > So could you help me? Thank you very much! > > -- > Zhouchuan Huang > School of Earth Sciences and Engineering > Nanjing University > 22 Hankou Road > Nanjing 210093 > P.R.CHINA. > Tel:+86 13675137130 > > > > > _______________________________________________ > sac-help mailing list > sac-help at iris.washington.edu > http://www.iris.washington.edu/mailman/listinfo/sac-help > George Helffrich george at geology.bristol.ac.uk -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: text/enriched Size: 1806 bytes Desc: not available URL: From char at lanl.gov Wed Mar 11 14:29:54 2009 From: char at lanl.gov (Charlotte A. Rowe) Date: Wed, 11 Mar 2009 15:29:54 -0600 (MDT) Subject: [SAC-HELP] linux SAC problem Message-ID: <53211.128.165.0.81.1236806994.squirrel@webmail.lanl.gov> Hi, I'm new to the SAC help list so maybe this has been addressed elsewhere. I have obtained the latest Linux version and have carefully gone through all the setup instructions on my machine. Unfortunately I don't have administrative access to my own (institutional-owned) laptop so have had to put the SAC files into alternate directories and adjust the paths and environmental variables accordingly. When I invoke sac, all I get is a Floating Point Exception. I have put this same version of SAC onto my own, personal computer at home, and had no problems at all. The differences between the two are that I can be root on the home machine so can put the files in their 'normal' place, and also the two machines are running different flavors of Linux: The home machine is running Ubuntu. This machine that won't run SAC is Red Hat 2.6.9-5ELsmp Can anyone offer an insight as to what the problem might be? I'm not even trying to read files or open a plotting window at this point, I just type "sac" and get a floating exception. Thanks! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Dr. Charlotte A. Rowe EES-17 M.S. D408 Los Alamos National Laboratory Los Alamos, NM 87545 U.S.A. char at lanl.gov Ph: (505) 665-6404 FAX: (505) 667-8487 Associate Editor, BSSA *****correspondence***** ------ "Never eat more than you can lift" - Miss Piggy From pppmali at 126.com Thu Mar 12 02:25:40 2009 From: pppmali at 126.com (pppmali) Date: Thu, 12 Mar 2009 17:25:40 +0800 (CST) Subject: [SAC-HELP] SAC_macro Message-ID: <28196341.897861236849940413.JavaMail.coremail@bj126app59.126.com> Dear Sir I have three questions about macros in the SAC: (1)In the example, particle motion plots are produced for five different two second time windows on the same data file: READ ABC SETBB TIME1 0 DO TIME2 FROM 2 TO 10 BY 2 XLIM %TIME1 $TIME2 TITLE 'Particle Motion from %TIME1 to $TIME2$' PLOTPM SETBB TIME1 $TIME2 ENDDO (Why is a dollar sign needed after TIME2 in the TITLE command?) (2)In the example, we need to calculate the tangent of an angle that has already been stored in the blackboard in degrees: u: GETBB ANGLE s: ANGLE = 45.0 u: SETBB VALUE (TAN (DIVIDE (MULTIPLY (PI) %ANGLE%) 180.)) s: ==> SETBB VALUE 1.00000 We can rework the above example into a more natural form by intermixing regular (prefix) and embedded arithmetic functions: u: SETBB VALUE (TAN ((PI) * %ANGLE / 180. )) s: ==> SETBB VALUE 1.00000 (Why is the percent sign needed after ANGLE in the first example and is not needed in the second example?) (3)The next example uses the SUBSTRING function to extract the month of the event and store it into a blackboard variable. {u:} FUNCGEN SEISMOGRAM {u:} SETBB MONTH (SUBSTRING 1 3 '&1,KZDATE&') {s:} ==> SETBB MONTH MAR (Why are the quotes needed around the header variable KZDATE?) I am eager to hear from you! Thanks! Sincerely Yours Ma Li -------------- next part -------------- An HTML attachment was scrubbed... URL: From iit.amarjeet at gmail.com Mon Mar 16 04:14:07 2009 From: iit.amarjeet at gmail.com (amarjeet kumar) Date: Mon, 16 Mar 2009 07:14:07 -0400 Subject: [SAC-HELP] Datagen is not working Message-ID: <6a9280120903160414ibb380bbm7195bb7650367809@mail.gmail.com> Myself Amarjeet Kumar, a 3rd year student of the Department of Exploration Geophysics at IIT Kharagpur, India.I am very new user of SAC software, I have got one project based on SAC software.I requested for SAC software on IRIS..And I installed it on my laptop. I have ubuntu installed in my laptop. Whenever I am trying to execute DATAGEN commands, I am getting this message:- ERROR 131: sac/datagen directory not found. contact llnl for this data(peterg at llnl.gov ). What do i do now?Please help with respect, Amarjeet Kumar 3rd year Integrated MSc student IIT Kharagpur, WB-721302 INDIA -------------- next part -------------- An HTML attachment was scrubbed... URL: From savage at uri.edu Mon Mar 16 06:03:09 2009 From: savage at uri.edu (Brian Savage) Date: Mon, 16 Mar 2009 09:03:09 -0400 Subject: [SAC-HELP] Datagen is not working In-Reply-To: <6a9280120903160414ibb380bbm7195bb7650367809@mail.gmail.com> References: <6a9280120903160414ibb380bbm7195bb7650367809@mail.gmail.com> Message-ID: <903DA1CB-89CE-4F0E-B2F1-FD49BCA37E34@uri.edu> Dear Amarjeet Kumar The datagen command at some time in the past required data from LLNL. This data was and is not distributed with SAC. If you need seismic data you can use the "funcgen seismogram" command. It will generate a seismogram for you without any extra data. I will guess you will have a difficult time getting the data from LLNL as they do not support SAC now. The distribution is being handled by IRIS. If you really need to data within datagen, I am sure we can find an old distribution somewhere which contains the data associated with this command. Brian Savage On Mar 16, 2009, at 7:14 AM , amarjeet kumar wrote: > Myself Amarjeet Kumar, a 3rd year student of the Department of > Exploration > Geophysics at IIT Kharagpur, India.I am very new user of SAC > software, I have got one project based on SAC software.I requested > for SAC > > > software on IRIS..And I installed it on my laptop. I have ubuntu > installed > in my laptop. > > Whenever I am trying to execute DATAGEN commands, I am getting this > message:- > > ERROR 131: sac/datagen directory not found. contact llnl for this > > > data(peterg at llnl.gov). > > > What do i do now?Please help > > with respect, > > Amarjeet Kumar > 3rd year Integrated MSc student > > > IIT Kharagpur, WB-721302 > INDIA > _______________________________________________ > sac-help mailing list > sac-help at iris.washington.edu > http://www.iris.washington.edu/mailman/listinfo/sac-help -------------- next part -------------- An HTML attachment was scrubbed... URL: From Ms at geo.ku.dk Sun Mar 22 12:07:13 2009 From: Ms at geo.ku.dk (Mohammad Youssof Ahmed Soliman) Date: Sun, 22 Mar 2009 20:07:13 +0100 Subject: [SAC-HELP] BAZ macro Message-ID: <49C69A71.73B6.00CD.0@geo.ku.dk> Hi all, Actually I tried many times to produce a polt for (BAZ vs Time )for the Receiver functions that I got but I could not. Could you help me to do that I am not using sac2000(to use Prof. Herman Package) but I am using sac(101.1)on linux 64bit machine. Thanks a lot with my best regards, Mohammad Youssof Mohammad Youssof PhD Candidate Geophysics Group University of Copenhagen ?ster Voldgade 10 1350 K?benhavn K Location: 03.1.381 Phone: +45 353-22460 -------------- next part -------------- An HTML attachment was scrubbed... URL: From griscom at suitable.com Fri Mar 27 18:44:59 2009 From: griscom at suitable.com (Daniel Griscom) Date: Fri, 27 Mar 2009 21:44:59 -0400 Subject: [SAC-HELP] SAC/SACA file format verification Message-ID: Dear Sirs/Madams, I'm the author of a free IRIS-supported Macintosh program called SeisMac, which uses Mac laptops' built in accelerometers to convert the laptops into (not very accurate) seismographs. You can find more about it at . I'm finishing off an update which will let you export selected data as a binary SAC or ascii SACA file. I think I've got it right (Global Earthquake Explorer successfully reads the SAC files), but I'd love to have further confirmation. Would any of you be able to review example files and tell me if I've made any format errors? Or, point me to other tools which will read/validate SAC/SACA files? I've uploaded the same set of data in three ways: - Comma-separated values (all three axis): - Binary SAC file (Z axis only): - Ascii SACA file (Z axis only): (If you have a Mac laptop and would like to play with exporting data yourself, the latest binary is at ) Thanks, Dan -- Daniel T. Griscom griscom at suitable.com Suitable Systems http://www.suitable.com/ 1 Centre Street, Suite 204 (781) 665-0053 Wakefield, MA 01880-2400 From chad at iris.washington.edu Fri Mar 27 21:36:24 2009 From: chad at iris.washington.edu (Chad Trabant) Date: Fri, 27 Mar 2009 21:36:24 -0700 Subject: [SAC-HELP] SAC/SACA file format verification In-Reply-To: References: Message-ID: Hi Dan, Very cool stuff. The binary file seems to work fine in sac (the reference application), the PQL waveform viewer and my sac2mseed converter. The ASCII/ALPHA file has a small problem. The recognized NULL value is "-12345.00", as you can see from the snippet below from SeisMacData.SACA the null value seems to have "61" in place of "00" which causes minor havoc with the interpretation. Chad -- top of SeisMacData.SACA -- 0.020000 -12345.61 -12345.61 -12345.61 -12345.61 0.000000 21.34106 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 -12345.61 On Mar 27, 2009, at 6:44 PM, Daniel Griscom wrote: > Dear Sirs/Madams, > > I'm the author of a free IRIS-supported Macintosh program called > SeisMac, which uses Mac laptops' built in accelerometers to convert > the laptops into (not very accurate) seismographs. You can find more > about it at . > > I'm finishing off an update which will let you export selected data > as a binary SAC or ascii SACA file. I think I've got it right > (Global Earthquake Explorer successfully reads the SAC files), but > I'd love to have further confirmation. Would any of you be able to > review example files and tell me if I've made any format errors? Or, > point me to other tools which will read/validate SAC/SACA files? > > > I've uploaded the same set of data in three ways: > > - Comma-separated values (all three axis): > > > - Binary SAC file (Z axis only): > > > - Ascii SACA file (Z axis only): > > > (If you have a Mac laptop and would like to play with exporting data > yourself, the latest binary is at >) > > > Thanks, > Dan > > -- > Daniel T. Griscom griscom at suitable.com > Suitable Systems http://www.suitable.com/ > 1 Centre Street, Suite 204 (781) 665-0053 > Wakefield, MA 01880-2400 > _______________________________________________ > sac-help mailing list > sac-help at iris.washington.edu > http://www.iris.washington.edu/mailman/listinfo/sac-help > From george at gly.bris.ac.uk Sat Mar 28 03:39:09 2009 From: george at gly.bris.ac.uk (George Helffrich) Date: Sat, 28 Mar 2009 10:39:09 +0000 Subject: [SAC-HELP] SAC/SACA file format verification In-Reply-To: References: Message-ID: Dear Dan - This will be a very useful SeisMac feature. There are two minor problems with the specimens that you provided: 1) Undefined character values in the binary file should be padded with blanks, not trailing zero characters, to their field lengths (8 or 16 characters, as appropriate); 2) Undefined values should numerically be -12345.00 in the alphanumeric file. Something else you might think about are: 3) I think that you can safely set IDEP to IACC (integer number 8) to signify that the dependent variable is acceleration. 4) The component naming fields KCMPNM for the traces don't follow FDSN standards. (See Appendix A of the SEED manual). My reading of the manual suggests that, for the sample rate shown, the channels should be named with three-letter codes BNx, where x is the orientation letter. N (middle character) is the code for an accelerometer. ZNE aren't useful because orientation can't be guaranteed. XYZ are probably OK for consistent usage with your program documentation, though they aren't FDSN-endorsed. FDSN would prescribe them to be 123 (orthogonal but orientation not guaranteed). On 28 Mar 2009, at 01:44, Daniel Griscom wrote: > Dear Sirs/Madams, > > I'm the author of a free IRIS-supported Macintosh program called > SeisMac, which uses Mac laptops' built in accelerometers to convert > the laptops into (not very accurate) seismographs. You can find more > about it at . > > I'm finishing off an update which will let you export selected data as > a binary SAC or ascii SACA file. I think I've got it right (Global > Earthquake Explorer successfully reads the SAC files), but I'd love to > have further confirmation. Would any of you be able to review example > files and tell me if I've made any format errors? Or, point me to > other tools which will read/validate SAC/SACA files? > > > I've uploaded the same set of data in three ways: > > - Comma-separated values (all three axis): > > > - Binary SAC file (Z axis only): > > > - Ascii SACA file (Z axis only): > > > (If you have a Mac laptop and would like to play with exporting data > yourself, the latest binary is at > ) > > > Thanks, > Dan > > -- > Daniel T. Griscom griscom at suitable.com > Suitable Systems http://www.suitable.com/ > 1 Centre Street, Suite 204 (781) 665-0053 > Wakefield, MA 01880-2400 > _______________________________________________ > sac-help mailing list > sac-help at iris.washington.edu > http://www.iris.washington.edu/mailman/listinfo/sac-help > George Helffrich george at geology.bristol.ac.uk From griscom at suitable.com Sat Mar 28 05:28:03 2009 From: griscom at suitable.com (Daniel Griscom) Date: Sat, 28 Mar 2009 08:28:03 -0400 Subject: [SAC-HELP] SAC/SACA file format verification In-Reply-To: References: Message-ID: Dear Chad and George, Many thanks: this is exactly the help I was looking for. In detail: At 9:36 PM -0700 3/27/09, Chad Trabant wrote: >The ASCII/ALPHA file has a small problem. The recognized NULL value >is "-12345.00", as you can see from the snippet below from >SeisMacData.SACA the null value seems to have "61" in place of "00" >which causes minor havoc with the interpretation. Hello, Chad. Ooops, missed that. I fixed a rounding issue and broke something else. I'll try again. At 10:39 AM +0000 3/28/09, George Helffrich wrote: > 1) Undefined character values in the binary file should be >padded with blanks, not trailing zero characters, to their field >lengths (8 or 16 characters, as appropriate); Are you sure? The SACA example I have uses trailing nulls (which surprised me). > 2) Undefined values should numerically be -12345.00 in the >alphanumeric file. I'll fix this. > 3) I think that you can safely set IDEP to IACC (integer >number 8) to signify that the dependent variable is acceleration. The values in the data section are in m/s/s, not nm/s/s; would you still suggest IACC ("Acceleration in nm/sec/sec")? > 4) The component naming fields KCMPNM for the traces don't >follow FDSN standards. (See Appendix A of the SEED manual). My >reading of the manual suggests that, for the sample rate shown, the >channels should be named with three-letter codes BNx, where x is the >orientation letter. N (middle character) is the code for an >accelerometer. ZNE aren't useful because orientation can't be >guaranteed. XYZ are probably OK for consistent usage with your >program documentation, though they aren't FDSN-endorsed. FDSN would >prescribe them to be 123 (orthogonal but orientation not guaranteed). Ah, hadn't seen that reference. Excellent. Letter by letter: 1: The band code letter. My sample rates can be from 20Hz to 500Hz (user selected). Should I change based on the sample rate? If so then I'd switch between S, E or D, assuming that for accelerometers "corner period" means the native resonance of the detector, which in this case is extremely high. 2: Instrument code: pretty clearly "N". 3: Orientation code. I want the vertical samples to be marked vertical, but don't want to imply specific directions for the two horizontal vectors. I'm using "1", "2" and "Z" right now; should I switch to "X", "Y" and "Z"? Or perhaps even "2", "3" and "Z" (with vertical being the primary component of interest)? Thanks again, Dan P.S. For all you Mac-owning seismologists, I'd also be interested in any feedback you may have about the data export process. Right now you choose the axis and name and then save, which means to save all three axes you have to enter three different names. I'm considering going to saving a folder instead of a file, with the folder containing three axis files. Thoughts? -- Daniel T. Griscom griscom at suitable.com Suitable Systems http://www.suitable.com/ 1 Centre Street, Suite 204 (781) 665-0053 Wakefield, MA 01880-2400 From george at gly.bris.ac.uk Sat Mar 28 06:30:33 2009 From: george at gly.bris.ac.uk (George Helffrich) Date: Sat, 28 Mar 2009 13:30:33 +0000 Subject: [SAC-HELP] SAC/SACA file format verification In-Reply-To: References: Message-ID: <677c20aca416997afe540f32669ea963@gly.bris.ac.uk> Dear Dan - Some responses to your queries: On 28 Mar 2009, at 12:28, Daniel Griscom wrote: ... > At 10:39 AM +0000 3/28/09, George Helffrich wrote: >> 1) Undefined character values in the binary file should be padded >> with blanks, not trailing zero characters, to their field lengths (8 >> or 16 characters, as appropriate); > > Are you sure? The SACA example I have uses trailing nulls (which > surprised me). Positive. The binary format is defined by Fortran behavior. Character fields are blank-filled; trailing nulls have no significance in Fortran. > ... > >> 3) I think that you can safely set IDEP to IACC (integer number 8) >> to signify that the dependent variable is acceleration. > > The values in the data section are in m/s/s, not nm/s/s; would you > still suggest IACC ("Acceleration in nm/sec/sec")? I'm not particularly bothered by the units discrepancy, but you could fix it either by 1) multiplying samples by 10**9; 2) setting SCALE to be 10**-9 with unchanged samples; 3) go back to setting IDEP to IUNKN (but you *do* know, after all). > >> 4) The component naming fields KCMPNM for the traces don't follow >> FDSN standards. (See Appendix A of the SEED manual). My reading of >> the manual suggests that, for the sample rate shown, the channels >> should be named with three-letter codes BNx, where x is the >> orientation letter. N (middle character) is the code for an >> accelerometer. ZNE aren't useful because orientation can't be >> guaranteed. XYZ are probably OK for consistent usage with your >> program documentation, though they aren't FDSN-endorsed. FDSN would >> prescribe them to be 123 (orthogonal but orientation not guaranteed). > > Ah, hadn't seen that reference. Excellent. Letter by letter: > > 1: The band code letter. My sample rates can be from 20Hz to 500Hz > (user selected). Should I change based on the sample rate? If so then > I'd switch between S, E or D, assuming that for accelerometers "corner > period" means the native resonance of the detector, which in this case > is extremely high. > > 2: Instrument code: pretty clearly "N". > > 3: Orientation code. I want the vertical samples to be marked > vertical, but don't want to imply specific directions for the two > horizontal vectors. I'm using "1", "2" and "Z" right now; should I > switch to "X", "Y" and "Z"? Or perhaps even "2", "3" and "Z" (with > vertical being the primary component of interest)? Hmmm. The first character choice depends on the idea of a seismometer's corner period, where its response to velocity turns flat. Accelerometers aren't built to be flat to velocity anywhere. Their response is broad band, however, because they are flat to acceleration from DC to a very high frequency. In that spirit, I'd use either B or H as appropriate to the sample rate. My vote for the last character is XYZ, since you'll never be FDSN-compliant if you want to use Z (but a laptop on my lap isn't guaranteed to have Z up, either). At least there will be a clear link between the trace names and the computer-fixed coordinate system. > ... > P.S. For all you Mac-owning seismologists, I'd also be interested in > any feedback you may have about the data export process. Right now you > choose the axis and name and then save, which means to save all three > axes you have to enter three different names. I'm considering going to > saving a folder instead of a file, with the folder containing three > axis files. Thoughts? Only this: Folders don't seem to have any benefit other than reducing file name typing. In the save dialog just provide a choice of a file prefix and whether to save X, Y, Z, or all components. Then generate the suffixes like the component names. Trying to encode too much information in a file name leads to quite cumbersome names like what rdseed writes! George Helffrich george at geology.bristol.ac.uk From mohamed.salah at ist.utl.pt Mon Mar 30 11:03:27 2009 From: mohamed.salah at ist.utl.pt (Mohamed Kamaleldin Abdel Galeil Salah) Date: Mon, 30 Mar 2009 19:03:27 +0100 Subject: [SAC-HELP] Poles and Zeros Message-ID: <20090330190327.aeismdjgo40w84cg@mail1.ist.utl.pt> Dear SAC users I am working on data from a list of seismic stations which have different types of sensors: CMG-40, CMG-3T-120s, CMG-3ESP, STS-1, and STS-2. I need to remove the instrument response from SAC files. I could get information on Poles and Zeros data. However, I could not find enough information about the normalizing factor and hence, how to calculate the CONSTANT value. If any one has information about the CONSTANT of these sensor types, I will appreciate it! Regards! From griscom at suitable.com Mon Mar 30 17:13:58 2009 From: griscom at suitable.com (Daniel Griscom) Date: Mon, 30 Mar 2009 20:13:58 -0400 Subject: [SAC-HELP] SAC/SACA file format verification Message-ID: [Trying to send this a third time... Dan] At 1:30 PM +0000 3/28/09, George Helffrich wrote: >On 28 Mar 2009, at 12:28, Daniel Griscom wrote: >>At 10:39 AM +0000 3/28/09, George Helffrich wrote: >>> 1) Undefined character values in the binary file should be >>>padded with blanks, not trailing zero characters, to their field >>>lengths (8 or 16 characters, as appropriate); >> >>Are you sure? The SACA example I have uses trailing nulls (which >>surprised me). > >Positive. The binary format is defined by Fortran behavior. >Character fields are blank-filled; trailing nulls have no >significance in Fortran. Righto. >>> 3) I think that you can safely set IDEP to IACC (integer >>>number 8) to signify that the dependent variable is acceleration. >> >>The values in the data section are in m/s/s, not nm/s/s; would you >>still suggest IACC ("Acceleration in nm/sec/sec")? > >I'm not particularly bothered by the units discrepancy, but you >could fix it either by 1) multiplying samples by 10**9; I've been wondering about limitations in the field width for SACA files, which are specified as "G15.7". The example I have represents a float in 15 characters: six characters holding spaces, one character holding a space or minus sign, and nine characters with digits and a decimal point, e.g. > 1.000000 -12345.00 -12345.00 -12345.00 -12345.00 > 0.000000 1043.000 -12345.00 -12345.00 -12345.00 > -12345.00 -12345.00 -12345.00 -12345.00 -12345.00 What if I need more than nine digits to represent something; can I start expanding into those left six spaces? >2) setting SCALE to be 10**-9 with unchanged samples; ditto? >3) go back to setting IDEP to IUNKN (but you *do* know, after all). Maybe I DO know, but just don't wanna tell... >Hmmm. The first character choice depends on the idea of a >seismometer's corner period, where its response to velocity turns >flat. Accelerometers aren't built to be flat to velocity anywhere. >Their response is broad band, however, because they are flat to >acceleration from DC to a very high frequency. In that spirit, I'd >use either B or H as appropriate to the sample rate. Well, you can argue it either way, but I'm fine with B/H. >My vote for the last character is XYZ, since you'll never be >FDSN-compliant if you want to use Z (but a laptop on my lap isn't >guaranteed to have Z up, either). At least there will be a clear >link between the trace names and the computer-fixed coordinate >system. Makes sense to me. >>... >>P.S. For all you Mac-owning seismologists, I'd also be interested >>in any feedback you may have about the data export process. Right >>now you choose the axis and name and then save, which means to save >>all three axes you have to enter three different names. I'm >>considering going to saving a folder instead of a file, with the >>folder containing three axis files. Thoughts? > >Only this: Folders don't seem to have any benefit other than >reducing file name typing. In the save dialog just provide a choice >of a file prefix and whether to save X, Y, Z, or all components. >Then generate the suffixes like the component names. The problem with this is that saving multiple files with one "Save As" dialog means I have to handle file name collisions, as the built-in code assumes you're saving with the name as typed by the user. That's the big benefit of using the folder; it's a single item, so the "Save As" dialog handles all the special cases correctly, but I still end up with three files (I'm thinking with the name typed by the user, plus ".X.SAC"/".Y.SAC"/".Z.SAC"). >Trying to encode too much information in a file name leads to quite >cumbersome names like what rdseed writes! Yeah, they're ugly, but here we'd only be adding another six characters. Not too bad. Thanks again, Dan -- Daniel T. Griscom griscom at suitable.com Suitable Systems http://www.suitable.com/ 1 Centre Street, Suite 204 (781) 665-0053 Wakefield, MA 01880-2400 From crotwell at seis.sc.edu Tue Mar 31 14:18:28 2009 From: crotwell at seis.sc.edu (Philip Crotwell) Date: Tue, 31 Mar 2009 17:18:28 -0400 Subject: [SAC-HELP] SAC/SACA file format verification In-Reply-To: References: Message-ID: <1e63606c0903311418x1c6d522dia121e37bc8305b39@mail.gmail.com> Hi Just tried your example sac file with GEE, our education data viewer, yet another test passed. GEE is here if you are interested. http://www.seis.sc.edu/GEE Only additional thing I noticed was the kinst, kstnm and knetwk headers which were MyInstru, MyStatna and MyNetwor. They should probably either be somewhat meaningful or set to the null value. KINST is "Generic name of recording instrument. " and so you could put something in there to identify either the mac's accelerometer or maybe SeisMac itself? KNETWK is the network, but since you are not part of a network, probably should be undef or maybe XX which is seed for "not a network". KSTANM might be something you could pull from the Mac's name or allow users to configure this? thanks, Philip From aagalos at geol.uoa.gr Tue Mar 31 15:57:46 2009 From: aagalos at geol.uoa.gr (Apostolos Agalos) Date: Wed, 1 Apr 2009 01:57:46 +0300 (EEST) Subject: [SAC-HELP] constant for poles and zeros In-Reply-To: References: Message-ID: Dear Mohamed Kamaleldin Abdel Galeil Salah if you know the pole-zeros then you have to multiply the constant of the digitizer with the constant of the recording instrument and possibly with 2pi. -- Agalos Apostolos Phd student of Seismology - University of Athens ###Personal Info### Greek:http://dggsl.geol.uoa.gr/cv/gr_agalos.html English:http://dggsl.geol.uoa.gr/cv/en_agalos.html > > Message: 5 > Date: Mon, 30 Mar 2009 19:03:27 +0100 > From: Mohamed Kamaleldin Abdel Galeil Salah > Subject: [SAC-HELP] Poles and Zeros > To: sac-help at iris.washington.edu > Message-ID: <20090330190327.aeismdjgo40w84cg at mail1.ist.utl.pt> > Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; > format="flowed" > > Dear SAC users > > I am working on data from a list of seismic stations which have > different types of sensors: CMG-40, CMG-3T-120s, CMG-3ESP, STS-1, and > STS-2. I need to remove the instrument response from SAC files. I > could get information on Poles and Zeros data. However, I could not > find enough information about the normalizing factor and hence, how to > calculate the CONSTANT value. > If any one has information about the CONSTANT of these sensor types, I > will appreciate it! > > Regards!