Frequently Asked Questions

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?

15) Transformation of seismic data to a phase-velocity-frequency image is based on the method described by

Park, C.B., R.D. Miller, and J. Xia, 1998, Imaging dispersion curves of surface waves on multi-channel record: [Exp. Abs.]: Soc. Explor. Geophys., p. 1377-1380.

16) The inversion data is based on the gradient iterative method described by

Xia, J., R.D. Miller, and C. B.Park, 1999, Estimation of near-surface shear-wave velocity by inversion of Rayleigh waves: Geophysics, v. 64, p. 691-700.

17) The following two articles will give you background information on higher modes.

[SurfSeis3] Xia, J., R.D. Miller, C.B. Park, and G. Tian, 2003, Inversion of high frequency surface waves with fundamental and higher modes: Journal of Applied Geophysics, v. 52, p. 45-47.

Luo, Y., J. Xia, J. Liu, Q. Liu, S. Xu, 2007, Joint inversion of high-frequency surface waves with fundamental and higher modes: Journal of Applied Geophysics, v. 62, p. 375-384.

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.

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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.

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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.

• [SurfSeis2] You can find step-by-step instructions in the v2.05 manual in the Manuals folder in your SurfSeis20 folder. See p. 7, Section 2.2 "Data Processing," which gives instructions for formatting (Step 1) and field setup (Step 2).
• [SurfSeis3] For SurfSeis 3 the interface has changed a little bit but the steps are the same. See p. 3 of the v3.05 manual in the Manuals folder in your SurfSeis30 folder.

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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).

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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).

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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.

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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.

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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 w^k is the weight of the kth data and tr(w) is the sum of the weights (= ).

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9) What formula is used to calculate the RMSE of VS, the RMSE Error and the VS error?

C = [G^TG +I]^-1G^T([GTG +I]^-1G^T)^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 v_s 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.

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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 one end of 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:
Assume the 48 geophones are located on stations 1001-1048 and a total of 13 seismic records were shot (acquired) with the source located at stations 999, 1001, … through 1023 for the records numbered from 101 to 113. SurfSeis can help you pull out (extract, cut) thirteen 24-channel records using the following steps.

1. Convert data from SEG2 to KGS format (say, line1.dat).
2. Apply geometry information (Field Setup) into the trace headers.
3. Click 'Display,' then 'Seismic' buttons, and open the converted kgs data file (say, line1.dat).
4. Find the "scissors" button located at the top right corner of the window displaying seismic data. (The "scissors" button is located on the row containing the pointing-hand buttons. If you do not see these buttons, click the 'Record…' label to activate/deactivate that row of buttons). Click the "scissors" button to display a 'Cut Records' window containing three tabs ('Record,' 'Trace,' and 'Time').
5. At the 'Record' tab select the end record at the 'End' drop box, or check the 'All Records' checkbox.
6. Click 'Save Output As' button to specify the output file name (the default in this example would be line1(CUT).dat.)
7. At the 'Trace' tab select the 'Begin' and 'End' trace numbers (e.g., 1 and 24). At both Increment boxes select 2 (this is because your source moved with 2 geophone intervals, i.e., 999, 1001, etc.)
8. Click the 'OK' button to extract (cut) the new set of records each containing now only 24 traces.
9. Open the new file (e.g., line1(CUT).dat) and go through the records using the pointing-hand buttons to make sure you have extracted the intended range of traces from each record.

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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.

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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.

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[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.

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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.

15) Transformation of seismic data to a phase-velocity-frequency image is based on the method described by

Park, C.B., R.D. Miller, and J. Xia, 1998, Imaging dispersion curves of surface waves on multi-channel record: [Exp. Abs.]: Soc. Explor. Geophys., p. 1377-1380.

16) The inversion data is based on the gradient iterative method described by

Xia, J., R.D. Miller, and C. B.Park, 1999, Estimation of near-surface shear-wave velocity by inversion of Rayleigh waves: Geophysics, v. 64, p. 691-700.

17) The following two articles will give you background information on higher modes.

[SurfSeis3] Xia, J., R.D. Miller, C.B. Park, and G. Tian, 2003, Inversion of high frequency surface waves with fundamental and higher modes: Journal of Applied Geophysics, v. 52, p. 45-47.

Luo, Y., J. Xia, J. Liu, Q. Liu, S. Xu, 2007, Joint inversion of high-frequency surface waves with fundamental and higher modes: Journal of Applied Geophysics, v. 62, p. 375-384.