Tutorial: Scenario ShakeMap Application

This tutorial demonstrates how to replicate Figure 1 as presented in:

Field, E. H, H. A. Seligson, N. Gupta, V. Gupta, T. H. Jordan, and K. Campbell (2005), Loss Estimates for a Puente Hills Blind-Thrust Earthquake in Los Angeles, California, Earthquake Spectra, 21, p. 329-338, DOI: 10.1193/1.1898332.

And also explains some additional features of the application.

Start by opening the required application:

...and follow the instructions below to reproduce various figures:

Figure 1A

  1. Under the "Intensity-Measure Relationship" tab, choose "PGA" from the "IMT" menu, and then choose "Abrahamson & Silva (1997)" from the "IMR" menu.
  2. Under the "Region and Site Params" tab, set the following as:

    "Min Longitude" = -119
    "Max Longitude" = -117
    "Min Latitude" = 33.5
    "Max Latitude" = 34.5
    "Grid Spacing" = 0.016667
    "Set Site Params" = "Use site data providers"
    "Default AS Site Type" = "Deep-Soil"

  3. Under the "Earthquake Rupture" tab set the following:

    "Select Method of Getting Eqk Rupture" = "Custom Eqk Rupture"
    "Rupture Type" = "Finite source rupture"
    "Magnitude" = 7.2
    "Rake (degrees)" = 90

    Now click "Set Fault Surface" & set the following

    "Grid Spacing (km)" = 1.0
    "Num. of Fault Trace Points" = 4

    Click "Fault Latitudes" and enter the following:

    Lat-1 (Degrees) = 33.9451
    Lat-2 (Degrees) = 33.9423
    Lat-3 (Degrees) = 33.9746
    Lat-4 (Degrees) = 34.0768

    and click "Update Latitudes" when done.

    Likewise for "Fault Longitudes":

    Lon-1 (Degrees) = -117.8679
    Lon-2 (Degrees) = -118.0315
    Lon-3 (Degrees) = -118.1253
    Lon-4 (Degrees) = -118.3194

    "Num. of Dips" = 1

    Click "Dips" and set it as 27 degrees

    Click "Depths" and set:

    "Depth-1 (km)" = 5.0
    "Depth-2 (km)" = 17.0

    "Finite Fault Type" = "Stirling"

    "Ave Dip Direction (degrees) " = leave this blank (so direction is perpendicular to ave strike)

    Now click "Make Simple Fault" at the bottom

    Finally, leave "Set Hypocenter Location" un-selected

  4. Click the "Exceedance Level/Probability" tab and set:

    "Map Type" = IML@Prob
    "Probability" = 0.5

    These settings will give us a map of the median intensity-measure level (IML).

  5. Click the "Map Attributes" tab and set the following:

    "Color Scheme" = "MaxSpectrum.cpt"
    "Color Scale Limits" = "Manually"
    "Color-Scale Min" = 0.0
    "Color-Scale Max" = 1.0
    "Topo Resolution (arc-sec)" = "18 sec California"
    "Highways in plot" = "None"
    "Coast" = "Draw & Fill"
    "Image Width (inches)" = 6.5
    "Plot Log" should NOT be selected
    "Generate Hazus Shape Files" should not be selected
    "Rupture-Surface Plotting" = "Draw Perimeter"

  6. Now click "Make Map" at the bottom of the application and you should see Figure 1A in a few seconds.

Figure 1B

(assumes completion of all prior steps)

  1. Click the "Earthquake Rupture" tab, change the Magnitude to 7.5.
  2. Click "Make Map" at the bottom, and in a few seconds you should see Figure 1B.

Figure 1C

(assumes completion of all prior steps)

  1. Change the Magnitude back to 7.2.
  2. Click the "Intensity-Measure Relationship" tab and change the IMR parameter to "Boore, Joyner,& Fumal (1997)".
  3. licking "Make Map" at the bottom you should see Figure 1C.

Figure 1D

(assumes completion of all prior steps)

  1. Click the "Earthquake Rupture" tab, change the Magnitude to 7.5.
  2. Click "Make Map" at the bottom, and you should see Figure 1D.

Figure 1E

(assumes completion of all prior steps)

  1. Click the "Intensity-Measure Relationship" tab and change the IMT parameter to "SA" and the "SA Period" parameter to 1.0. Also change the IMR parameter to "Abrahamson & Silva (1997)".
  2. Now click the "Map Attributes" tab and change the "Color-Scale Max" parameter to 2.11.
  3. Click "Make Map" and you should see Figure 1E.

NOTE - the PGV calculations in the paper assume that PGV is proportional to 1-sec SA according to the Newmark Hall (1982) relationship:

1-sec SA = 1.056 PGV (SI units)

Therefore, the SA plot just made is identical to the PGV plot in the paper.

Figure 1F

(assumes completion of all prior steps)

  1. Click the "Intensity-Measure Relationship" tab and change the IMR parameter to "Field (2000)".
  2. Click "Make Map" to produces the final image in the plot (Figure 1F).

Why do the Images Look Different?

  • The slight color differences are due to resolution & image-format differences between the figure for the paper and the images generated here.
  • The labeling and scale-format differences are due to post processing (touching up) done with Adobe Illustrator to make the figure for publication.
  • By the way, a PostScript version of the plots you made, as well as the GMT scripts and data files, are available for download; just scroll to the bottom of the window below each plot to see the download link. This allows you to edit the PostScript files.

What's the Difference Between the "Stirling" and "Frankel" Finite Fault Types?

The best way to see this is to compare the difference.

  • First, click on the "Map Attributes" tab and change the "Rupture-Surface Plotting" parameter to "Draw Discrete Points".
  • Now click the "Earthquake Rupture" tab, click "Set Fault Surface", set the "Grid Spacing" parameter to 2.0, and click the "Make Simple Fault" button at the bottom.
  • Clicking the "Make Map" should show you the map made previously but with a discretized version of the fault surface (rather than the outline of the fault being drawn).
  • This is the "Stirling" fault representation (where depth contours are parallel to the trace of the top of the fault).
  • Now click "Set Fault Surface" again, change the "Finite Fault Type" parameter to "Frankel's", and then click the "Make Simple Fault" button at the bottom.
  • Clicking the "Make Map" shows that Frankel's representation projects a rectangle down perpendicular to the local strike along the fault.

See also the glossary entries on Stirling and Frankel Fault Surfaces.

What is the Other Way of Selecting an Earthquake Rupture?

Besides creating a custom earthquake rupture (what we did above), you can also choose one from any available Earthquake Rupture Forecast (ERF). For example, one can compute a Scenario ShakeMap for one of the Puente Hills ruptures defined in the ERF used to make our National Hazard Maps.

  • Click the "Earthquake Rupture" tab, and under "Select method of getting Eqk Rupture" choose "Select EqkRupture from an ERF".
  • Under "Eqk Rup Forecast" choose "USGS/CGS 2002 Adj. Cal. ERF", and in the window that pops up click "Update Forecast" at the bottom.
  • Under "Source Index" choose source # 136 - their Puente Hills Characteristic source.
  • Each source can have multiple ruptures (i.e., difference magnitudes and/or rupture locations on the fault), so you need to give a Rupture Index as well (info on each is given below). Choose one and click "Make Map".
  • You might want to go back and select "Draw Perimeter" from the "Rupture-Surface Plotting" under the "Map Attributes" tab, otherwise you won't be able to see the shaking levels directly over the fault.

Generate HAZUS Shape Files

  • Choose "Generate Hazus Shape Files for Scenario" from the "Control Panels" menu, read the text, and click the button.