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SurfSeis
Frequently Asked Questions |
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1) No variation along X-axis. When I run analysis (either auto or manual), all the 1D graphs work but I cannot generate a 2D profile. I get a message that says "Input file [filename].TXT has NO variation along X-axis. Data can not be displayed!" What is the problem? 2) Output file open failure I am attempting to format SEG2 files for SurfSeis running in Windows Vista. I see the message "OUTPUT FILE OPEN FAILURE!" when I attempt "Run Format." I also notice that although I specify Output file 1069kgs, the information just above "Output File Name" in Utils > Format states 1069kgs.DAT.DAT. Any ideas? 3) Invalid data format I'm having problems getting SurfSeis to read my input data. I get the error message "Invalid data format <nnnn.DAT>. Perhaps raw data in SEG-2 format?" 4) Setting vertical and horizontal scales on 2D profiles Does SurfSeis 3 have the ability for the user to set the vertical and horizontal scales on 2D profiles? 5) Changing assigned mode numbers In selecting higher modes, is it possible to pick dispersion curves and to change the number of the mode that has been assigned, in order to do tests with different mode numbers for a given dispersion curve? 6) Seeing only higher modes I suspect that I do not see the fundamental mode, only higher modes. Is this possible? 7) Defining only higher modes I cannot fit all modes together if I assume the slowest mode is the fundamental. I get a better fit if I assume my slowest mode is the first higher mode. Is it possible to define only higher modes with SurfSeis? 8) RMS error What are the formulas used to calculate RMS error in SurfSeis? 9) RMSE of VS, the RMSE Error and the VS error What formula is used to calculate the RMSE of VS, the RMSE Error and the VS error? 10) Emulate roll-along with a fixed spread How to use a fixed spread with SurfSeis software to emulate a roll-along data acquisition pattern (and avoid the "No variation along x-axis" error message). 11) New dongle with upgrade Do I get a new dongle when I upgrade my copy of SurfSeis 3? 12) Lost dongle My dongle is lost. How do I get a replacement? 13) Damaged dongle My dongle is damaged. What do I do? 14) License information for TsafeSerial not found I am getting a message "License information for TsafeSerial not found. You cannot use this control in design mode." SurfSeis ran fine yesterday. What happened?
18) What are the data input limits for SurfSeis? 19) How can I create a .grd file from a three-column text (.txt) file in SurfSeis? 20) Software known to conflict with the SurfSeis 3 dongle. 21) How do I use my own density, velocity, and/or Poisson's ratio values with SurfSeis? 22) During inversion for some dispersion curves the program closes but it doesn't give me an error. 25) How is the signal-to-noise ratio derived? 1) When I run analysis (either auto or manual), all the 1D graphs work but I cannot generate a 2D profile. I get a message that says "Input file [filename].TXT has NO variation along X-axis. Data can not be displayed!" What is the problem?
[SurfSeis3] The error "No variation along X-axis" means that all X locations are identical. This can happen as a result of using a fixed spread for all the shot records. When the spread is fixed, then the middle of the spread is always the same. This can be resolved by cutting shorter spreads for each record that changed location, with an identical offset range from each record, emulating roll-along acquisition. Then the middle of the spread of these shorter offset range records will be different. We describe this operation in detail at the following link: How to use a fixed spread with SurfSeis software to emulate a roll-along data acquisition pattern. 2) I am attempting to format SEG2 files for SurfSeis running in Windows Vista. I see the message "OUTPUT FILE OPEN FAILURE!" when I attempt "Run Format." I also notice that although I specify Output file 1069kgs, the information just above "Output File Name" in Utils > Format states 1069kgs.DAT.DAT. Any ideas? [SurfSeis3] Try a simple folder name, such as c:\TEST. Folder names that are too long sometimes cause problems. 3) I'm having problems getting SurfSeis to read my input data. [SurfSeis3] I get the error message "Invalid data format <nnnn.DAT>. Perhaps raw data in SEG-2 format?"
You need to convert the data to KGS format.
4) Does SurfSeis 3 have the ability for the user to set the vertical and horizontal scales on 2D profiles? [SurfSeis3] Yes, the outputs are text files that can be easily modified as needed (with Excel, for example). 5) In selecting higher modes, is it possible to pick dispersion curves and to change the number of the mode that has been assigned, in order to do tests with different mode numbers for a given dispersion curve? [SurfSeis3] Yes, you can edit the .DC file by clicking View, (Edit) Dispersion Curves on the menu, and delete/add points for every mode. You can also edit the .DC file as a text file and change the mode number digit (the last digit in each row). 6) I suspect that I do not see the fundamental mode, only higher modes. Is this possible? [SurfSeis3] Yes, we've seen this happen in some geological settings as well. 7) I cannot fit all modes together if I assume the slowest mode is the fundamental. I get a better fit if I assume my slowest mode is the first higher mode. Is it possible to define only higher modes with SurfSeis? [SurfSeis3] Yes, the inversion will run without a fundamental mode assigned. For optimal results you may still need more tests to tune up the maximum depth of the model. 8) What are the formulas used to calculate RMS error in SurfSeis? For the equal weight, the rms error at the ith iteration observed during inversion is calculated by the following
where O and T are the observed and calculated phase velocities. For the weighted case, the rms error is calculated by the following
where wk is the weight of the kth data and tr(w) is the sum of the weights (= 9) What formula is used to calculate the RMSE of VS, the RMSE Error and the VS error? C = [GTG +I]-1GT([GTG +I]-1GT)T, where G is an m × n matrix and stands for the Jacobian matrix of the inversion system (Xia et al., 1999) at the last iteration, I is the unit matrix, and the superscript T stands for the transpose operation. The root-mean-square (rms) error of each vs is determined by the corresponding diagonal element of matrix C. The formula only gives a rough measure of the rms errors because the damping factor could be varied in a large range at the last iteration. 10) How to use a fixed spread with SurfSeis software to emulate a roll-along data acquisition pattern (and avoid the "No variation along x-axis" error message). If you have estimated the necessary number of seismic spread channels (say, 24) and you have the ability to acquire data using a larger number of channels (say, 48), then you may find it more labor efficient to acquire MASW data using a fixed spread. Seismic records can be obtained by shooting from off one end of the spread (first shot outside the spread) and then continuing shooting into the spread (moving the source toward the middle of the spread). Then, from the data acquired in such a manner data, record traces can then be extracted (cut) to emulate a roll-along data acquisition pattern with a smaller spread (e.g., having 24 channels).
Example:
11) Do I get a new dongle when I upgrade my copy of SurfSeis 3? [SurfSeis3] No, the dongle you receive with your first purchase of SurfSeis 3 can be updated by you passing a C2V (customer-to-vendor) file to the SurfSeis Office at surfseis@kgs.ku.edu. She will generate a V2C (vendor-to-customer) file and return it to you via e-mail after payment (if appropriate) has been made. A new license (and therefore a new dongle) comes only with purchase of another copy of SurfSeis 3. Instructions for generating a C2V file and applying the returned V2C file are on p. 15-16 of the file" Manual3.05.pdf," which you will find in the C:\SurfSeis30\Manual folder. 12) My dongle is lost. How do I get a replacement? [SurfSeis3] You must purchase a new copy of SurfSeis 3 to get a new dongle--they are not available by themselves and there is no discount on replacement. Your SurfSeis 3 program cannot run without the dongle, so it is very important that you do not lose it. 13) My dongle is damaged. What do I do? [SurfSeis3] In general a damaged dongle means you need to purchase a new license. However, there is a chance your dongle can be recovered. If you ship us the dongle we will try to recover it. If we are able to do so, you will be responsible only for handling and return shipping charges. 14) I am getting a message "License information for TsafeSerial not found. You cannot use this control in design mode." SurfSeis ran fine yesterday. What happened? [SurfSeis2] It is likely that a copy of either WinSeis Turbo or WinSeis Lite was installed to this computer since the last time SurfSeis was successfully run. If both programs (SurfSeis 2 and WinSeis) are to be run on the same computer, WinSeis must be installed first, then SurfSeis. Please contact the SurfSeis Office at surfseis@kgs.ku.edu for instructions on how to proceed. Please explain what happened and the error message you are getting. Also please include your serial number.
18) What are the data input limits for SurfSeis? While there are no formal limitations, header-word numbers cannot exceed 32768 because of a header format limitation. This limitation affects the following parameters:
SurfSeis has been tested in-house with huge data sets and it worked fine. 19) How can I create a .grd file from a three-column text (.txt) file in SurfSeis? You can always make a .grd file from a .txt file by choosing from the menu "View," "2-D Vs Image," click the "Open" button, and from the "Files of type" select *.txt files to display. Chose a .txt file and the software will make a grid for you. You can change the interpolation algorithm by right-mouse-button clicking on the image, choosing "Options" and under the "Settings" tab there is an "Interpolation Algorithm" radio button. After making a new choice, click the "Update Image" button to make the new grid. The Kriging algorithm can be data demanding and in some cases may not work. If this is the case, then you can switch to Bilinear. In addition to the menu approach you can change it through the corresponding .INI file. SurfSeis remembers the used algorithm in the text file "INTPScheme.INI," which resides in the \INI subfolder of your SurfSeis install folder. There you can change "Kriging" to "Bililear," if needed, and then start the program, which will use the specified algorithm. 20) Software known to conflict with the SurfSeis 3 dongle.
System: Windows Vista 21) How do I use my own density, velocity, and/or Poisson's ratio values with SurfSeis? To use your own model, including different density, Vp, and/or PR ratios you need to select the "Fixed Vs model" radio button, which is located under the "Initial Vs Layer" tab of the "Inversion Controls" window (that is activated by clicking the "Controls" button"). 22) During inversion for some dispersion curves the program closes but it doesn't give me an error. Check your data points or the velocity model. One or more of your values is unrealistic or you may have random points on your dispersion curve that were not edited out. Once you correct this, your dispersion curves should complete processing normally. 23) The inversion algorithm generates systematically shallow reverse Vs at the very top of the section (e.g., around 3-5 m depth), even if the dispersion curve is monotonically decreasing and doesn't exhibit any velocity inversion for high frequencies. This can happen if you do not have enough high frequency data to support any layers below half of the shortest wavelength. 24) How can I reproduce the default interpolation which is used in SurfSeis to generate a 2D Vs map in Surfer? Very often Kriging with anisotropy ratio 2/1 to 4/1 can produce similar results. 25) How is the signal-to-noise ratio derived? Signal-to-noise ratio is defined as S/N where S is the root-mean-square amplitude for the whole trace, and N is the root-mean-square amplitude within the user-defined noise window. Or
where a[i] = seismic amplitude at sample i, Back to SurfSeis home Kansas Geological Survey Updated April 19, 2013 © 1998 by Kansas Geological Survey, The University of Kansas, all rights reserved ® Registered to Microsoft Corp., Redmond, WA (tm) Trade mark registered to Microsoft Corp. URL = http://www.kgs.ku.edu/software/surfseis/faq.html Comments or questions to mbro@kgs.ku.edu or SurfSeis@kgs.ku.edu |
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