Geol 455/655 - Lab 1, Run Synthetic Seismograms

The lab exercises in 455/655 will try to get you some experience in running a real, industrial-strength synthetic seismogram modeling code. That is our example problem this semester: modeling earthquake shaking in Nevada urban areas. Each lab exercise will give you experience with a part of what you will need to attack a real problem.

The first week, the objective is no more than to just run a modeling problem that is already set up, and describe the output.

Tasks:

  1. Get the Podcasts of our Las Vegas modeling effort from http://crack.seismo.unr.edu/sounds/sound-of-seismic.xml, or read about it on our Sound of Seismic pages.
  2. Get logon access to the Sun computers in LME 320- the instructors will take your information for the sysadmins to set this up for you.
  3. Read about guidelines, hints, and policies in using the Sun system.
  4. If you are using Windows, install PuTTY for SecureSHell (SSH) login access to our Sun workstations from any internet connection; and winscp (search for ``winscp 3.8.2'' at www.download.com) to make file transfers from your PCs to the Sun machines. (Don't worry about the legal warnings; your use of encryption in this class is legal in the US.) You will also want to find the Command Prompt application on your Start menu under Programs->Accessories.
  5. With a Windows machine you may also have to get a Java Software Free Download from java.com.
  6. Create your own folder for this lab exercise, both on your PC (I recommend putting the folder on your desktop), and on the Sun machines after logging in through SSH to blast.seismo.unr.edu with a command like ``mkdir labs''.
  7. Download all the files needed into this folder on your PC:
  8. Run the MA-CME interface on your own computer for the parameters of the test run in the MA/E3D input file test.in. On your PC, bring up a Command Prompt window and execute the following commands: ``cd desktop\labs\ma''; ``java CME''.
  9. In the 8 screens of the MA-CME interface, here are the parameters you need to set follow the test.in settings for this lab:
    1. Run Platform: preset run platform options to Nevada Seismological Lab Sun- blast
    2. Model Grid: dh=2; corner lat=37 lon=-117.75; X azimuth=135; extent length=300 width=200 depth=40; no attenuation
    3. Run Source: type=point P explosion; lat=36.6378 lon=-116.1710; depth=14; freq=0.09; moment=1e27 (what magnitude is this? how many megatons?)
    4. Rules Base: get the source file ``NTS-LV-Rules.java''
    5. Basin Data: basin file type=basin thickness data; get the basin file ``lv-langenheim-thick.asc''; interpolation radius=1; search=30
    6. Geotechnical Inputs: get geotech file ``lv-v30-wells.asc''; interpolation radius=0.5
    7. Model Time: dt=0.12; total modeled time=120
    8. Run Output: 3 types of output- A) type=image of max horiz ground velocity, depth=0 from surface, interval=1, base name=maxvel; B) type=movie, depth=0 from surface, interval=2, base name=snap; C) type=SAC synthetics, depth=0 from surface, station list is ``LSM 36.6378 -116.1710'' and ``UNLV 36.10871 -115.14157''
    9. Push the Save button to save your run parameters to a file named ``lab1.in''.
  10. Download this script lab1-run.sh and save it to your labs folder with the name ``run.sh''.
  11. Create a new folder within the labs folder called ``lab1''. Copy to this lab1 folder all the files needed to make this MA/E3D run: lab1.in; your downloaded run.sh script; lv-langenheim-thick.asc; lv-v30-wells.asc; all the contents of the ``ma'' folder, at least the ``.java'' files; and the NTS-LV-Rules.java file (delete the Rules.java file that got copied and then rename NTS-LV-Rules to ``Rules''- Windows may not show you the .java extension).
  12. Create a ZIP archive of the contents of your lab1 folder. In Windows, select all the files and select File->Send To->Compressed Folder. In Mac OS X, select the lab1 folder and File->Create Archive. Rename the ZIP file (folder) to ``lab1'' (Windows may not show you the .zip extension).
  13. Use scp to transfer the lab1.zip archive to your labs folder on the Sun blast.seismo.unr.edu . The direct Terminal command would be: ``cd labs; scp lab1.zip blast.seismo.unr.edu:labs/''.
  14. Use ssh to log into blast.seismo.unr.edu, and run the ``cd labs'' command, then ``unzip lab1.zip''.
  15. Run the model with a ``csh run.sh'' command.
  16. The run will take several minutes to complete. (If you want a runtime MA-CME output, you will have to add the ``visual movie=5 m=0 scale=1e4'' line to the ``.in'' file.)
  17. Try out the ``sac'' program on a Sun or Mac for plotting the data. Use the scripts linked below.
  18. Load the two easting horizontal-component seismograms into sac, plot the two on the same page, and convert and print the plot. Here are the commands to use in a Seismo Sun Terminal window (when you log in to a Sun, select the ``CDE'' environment if there is a choice, not ``Gnome''):
    1. setenv SACAUX /usr/local/sac/aux
    2. setenv SACGRAPHICS xwindows
    3. sac
    4. read LSM-sun.sac.000.x UNLV-sun.sac.001.x
    5. title " Lab 1: Compare X-Components at LSM and UNLV "
    6. ylabel "Velocity m/s"
    7. xlabel "seconds"
    8. p1
    9. At this point you should see a window with the two seismograms. You need to get a screen snapshot of this window, and either print it out or email the file to louie@seismo.unr.edu to turn it in. Here is how to print it when you are in the Sun CDE window environment:
      1. Point at the background of the screen and hold down the right mouse button. Select Applications->Snapshot from the pop-up menu.
      2. Drag the windows by their header bars to move the Snapshot and Image Viewer windows off the top of the SAC Graphics Window, so it is completely exposed.
      3. In the Snapshot tool select Snap Type ``Window'' and push the Snap button.
      4. Click the left mouse button on the SAC Graphics Window's header bar to get it's picture.
      5. The Image Viewer window will now contain the snapshot of the SAC Graphics Window. In the Image Viewer select ``File->Print...'' and adjust the image size to 90% and the Image Orientation to Landscape, and push the Print button.
      6. The print should emerge from the smaller printer in LME 320.
      7. In the Image Viewer you can also ``File->Save As...'' to save the snapshot as a TIFF file to send to Louie.
    10. quit (to quit SAC when you have your printout)
  19. Label the printed plot with a pencil, if necessary.
  20. Use the JRG Viewmat package to plot and view the movies contained in the ``snaps-x.flt'' and ``snaps-z.flt''output files.

What to turn in:

  1. The result: A properly and completely labeled plot of the 2 synthetic seismograms.
  2. The physics: An explanation of the differences between the seismograms, 1 paragraph.

Resources: