1. Make Your Own Map
a. Open the view with that contains your area of interest (for example, for a state in the US, open the United States view).
b. Select from the Map menu, Make Your Own Map.
c. Click OK.
d. With the mouse, click and hold (drag) from the upper left hand corner of the area of interest to the lower right hand corner.
e. Click Yes; map appears on screen.
f. To get a better topographic background (shaded relief map) or to add topography if the screen (background) is blank, you can select an elevation file (etopo5 or topo30) if these files have been added to the TOPO folder within the SEISVOLE folder (see SeisVolE Teaching Module 1, “Downloading and Installing SeisVolE”), otherwise, go to g.
1) Select Shaded Terrain, Digital Elevation Models from the Map menu.
2) A dialog box will appear; in the upper left hand corner click on:
World 5-minute DEM (ETOPO5), if the area is outside the US, or,
USA 30-second DEM (TOPO30), if the area is in the conterminous US and you have added the topo30 elevation file.
3) In the lower left hand corner of the dialog box, be sure that the boxes to the right of ETOPO5 and TOPO30 look like the following:
g. Click OK.
h. Select Redraw from the Map menu (move the mouse quickly away from the map area after selecting Redraw to avoid generating a blank area behind the mouse position as the new map is drawn).
i. Adjust buttons at bottom of screen (magnitude cutoff, selecting earthquakes or volcanoes, etc.) if necessary.
j. Adjust menu items at top of screen (set dates, magnitude/depth scale, etc.) if necessary.
k. Add title and city locations (select Annotations from the Map menu) if desired.
l. Click Repeat to start earthquake sequence.
m. To save the view, select Save View As from File menu.
n. To save the image (for printing or exporting to another document), select Make Bitmap from Options menu. Save the Bitmap file in the SEISVOLE folder or other location. This file can be imported into an MS Word document or an image processing program such as Adobe Photo Deluxe.
2. Adding Shaded Relief Topographic Maps
a. Add the files etopo5 and topo30 to the TOPO folder within the SEISVOLE folder (for information on downloading the topographic data files, see SeisVolE Teaching Module 1, “Downloading and Installing SeisVolE”).
b. To use these elevation files to add shaded relief topographic maps to the background of the make your own map displays, see the Make Your Own Map instructions.
3. Creating Frequency-Magnitude Plots
a. Select a standard view or make your own map.
b. Set Dates (in the Control menu), for example, for 41 years of data, set dates to Jan. 1, 1960 to Dec. 31, 2000.
c. Select earthquakes or eruptions (buttons at bottom of screen).
d. Set magnitude cutoff (for earthquakes or eruptions); start with a small magnitude cutoff, for eruptions, begin with 1; for earthquakes, begin with 3 for California, 4 for the conterminous US, and 5 for the rest of the world.
e. Run the view (click on Repeat if needed), write down the total number of events within the area (for magnitudes greater than or equal to the cutoff magnitude) from the counter to the right of the map display.
f. Increment the magnitude cutoff and repeat (begin at e.).
g. Make a data table and a graph of the data (see examples below; see Excel instructions).
Frequency-Magnitude data for Kuriles and Kamchatka view,
Magnitude Number of events
(in 41 Years)
*IDEAS: Use 0.5 magnitude interval; suggest 1 yr/sec speed step interval; use step to look at individual events; good idea to plot by hand first, then use excel; suggest linear scale then use logarithmic scale in graph.
n Suggest that students, in groups of four, each make a plot of a different region and compare the resulting plots.
n Ask students, “How can this information be used to help forecast future events?” “How is this information useful for hazard assessment?”
Graph of Frequency-Magnitude data:
4. Making a Cross-Section
a. Select a view or make your own map.
b. Run the map (view earthquakes and/or eruptions through time); note the depth extent of the hypocenters; set Magnitude/Depth Scale in the Earthquakes menu (for subduction zones, normally, set the maximum depth to 500 or 750 km).
c. Select the Set Up Cross-Section View from the Control menu.
d. Click on the map; a red profile will appear on the map and a rectangular area with data boxes and buttons will appear near the bottom of the screen.
e. Adjust Azimuth, profile Length, and profile Width (hypocenters within the white rectangular area will be projected onto the profile); use the arrows to adjust the azimuth, when you stop clicking on the arrows, the red profile will rotate on the map to the new orientation; highlight the Length and Width values and type in new values; click Redraw to view the profile; adjust azimuth, length and width until satisfied; click on the red profile, hold down the left mouse button and drag the profile into the desired position; click OK; see example below:
Profile (red line) and area (white rectangle) of epicenters to be projected onto the profile for a cross-section view. Profile azimuth, profile length and profile width values are given in the data boxes at bottom left. The area/view is the Kuriles and Kamchatka standard view. Earthquake depths are color-coded according to the depth scale in the upper right.
f. In the Control menu, click on MapView/3D/Cross-Section and then on Cross-Section View.
g. Run the map (view earthquakes and/or eruptions through time); an example is shown below:
Cross-section view showing hypocenters corresponding to the epicenters shown in the white rectangle in the view shown above. Hypocenters are color-coded according to the depth scale in the upper right. The vertical scale is depth in km. The horizontal scale is distance along the profile in km. The profile is oriented from NW (on the left) to SE (on the right).
h. To save the view select Save View As from the File menu.
i. To save the image to print or export to another document, select Make Bitmap from the Options menu. Save the Bitmap file in the SEISVOLE folder or other location. This file can be imported into an MS Word document or an image processing program such as Adobe Photo Deluxe.
5. Importing Earthquake Data from the USGS PDE Catalog
a. One can obtain earthquake hypocenter data for specific regions and for smaller magnitude ranges than are already included in the catalog in SeisVolE (to update the SeisVolE catalog, to add events that have occurred since you installed your version of SeisVolE, from the Internet, simply use the Options menu and select Update Hypocenters via the Internet; you must be connected to the Internet at the time that you request the update). Small magnitude data for specific regions or time periods are useful to better define and study the seismicity and tectonics of specific areas or to investigate specific main shock events or aftershock sequences. The data can be downloaded from the USGS earthquake search location on the Internet, converted to the SeisVolE hypocenter data format (.hy4) and displayed using SeisVolE. To obtain the additional data (be cautious in requesting data as the request could involve very large numbers of events), go to http://www.earthquake.gov (a USGS Internet site), select Latest Worldwide Earthquakes and then Earthquake Search.
b. Select the Rectangular Search option and the Compressed File Format. Enter the latitude and longitude range of interest (from a regional map in SeisVolE, it is easy to find the latitude and longitude of a rectangular area that surrounds and event or area of interest (note that south latitudes and west longitudes are negative numbers) by using selecting Coordinates from the Options menu; this tool displays the latitude and longitude of the cursor on the screen), and the magnitude range of interest and select Submit Search.
c. The requested data will appear on your screen. Select (with the mouse, as shown above) and Copy (from the Edit menu of your browser) the data (without the header information). Open MS Word and Paste the data into a new document. Select all of the data and convert the text to Courier Font, font size 8. From the File menu, select Page Setup and convert the document to Landscape format (these changes will allow each event to be represented by one line of text on your screen making it easier to view the data and the file).
d. Place your cursor (blinking line) at the top left of the text file (before the first space on the first line). From the Edit menu, select the Find option and enter the characters: “ PDE”, that is, enter a space and then PDE into the rectangular area provided. Click on Replace and enter the characters PDE into the Replace With rectangle. Click on Replace All. This find and replace sequence removes the blank space that exists at the beginning of each line in the PDE files.
e. Save the resulting list as a text only file with a file extension .dat by selecting Save As from the File menu and changing the format with the Save as Type window (and arrow) at the bottom of the dialog box. Save the file in the SEISVOLE folder. For example, the following list is part of a file of earthquake data from Turkey (aftershocks of the August 17, 1999 M7.8 earthquake) that we downloaded from the USGS search and that we named TurkAft.dat.
PDE 1999 0817000139.13 40.748 29.864 17 G 1.276.3997.8Z617.70MEGS 6.70MDISK 366381.C.FG....F......
PDE 1999 0817001517.72* 40.648 30.751 10 G 1.454.912 366025................
PDE 1999 0817001626.15 40.741 29.970 10 G 1.305.038 366059................
PDE 1999 0817002105.49* 40.653 30.435 10 G 1.024.615 366027................
PDE 1999 0817003154.15* 39.762 30.310 10 G 1.393.9 8 366012................
PDE 1999 0817003448.12* 40.722 29.947 10 G 1.364.1 8 366024................
PDE 1999 0817004421.43 40.654 30.646 10 G 1.144.428 366057................
f. Open a DOS Prompt (you may have a shortcut on your desktop, or go to the Start menu, lower left hand corner of the screen; go to Programs and then select the DOS Prompt with the cursor). A window will appear that probably includes the line C:WINDOWS> with the cursor to the right of the >. Type CD.. (to get to C:) and then CD seisvole to access the SEISVOLE folder. Type eqselect turkaft.dat turkaft.hy4 and hit return (enter; replace the turkaft in the statement with the file name that you’ve chosen). If everything has worked, the SeisVolE DOS program eqselect (see help file for more information) will display some summary information about the data that have been converted to the .hy4 format. Type exit to exit the DOS window. A view of the DOS window with the commands described above (before the enter on the eqselect command) is shown below.
g. You are now ready to display the new data in a Make Your Own Map view in SeisVolE. For example for the Turkey aftershock data, we opened the SeisVolE Europe view and selected Make Your Own Map from the Map menu, and then selected a small area of Turkey that contained the 1999 main shock event. The map appears (with a shaded relief background that is of low resolution because we’ve chosen a small area and only the etopo5 elevation file is available) and events from the world.hy4 file are plotted. To properly display the aftershock data, we selected the TurkAft.hy4 file using the Earthquake File command from the Earthquake menu, adjusted the dates to 1999-2000 (Set Dates from the Control menu), adjusted the magnitude cutoff to 2 with the tool at the bottom of the screen, added a scale (Annotations/Scale from the Map menu), and adjusted the magnitude scale to display a minimum magnitude of 2 (Magnitude Depth Scale from the Earthquakes menu). Then selecting Repeat, the image with the aftershock locations shown below was produced (one could also adjust the earthquake depth scale to better define the depths of the aftershocks by color-coding). Notice that the aftershock sequence defines a segment of the fault that slipped during the August 17, 1999 main shock event.
Ó Copyright 2001. L. Braile and S. Braile. Permission granted for reproduction for non-commercial purposes.