Vince/ SLAM/ SLAMWorkflow.html

SLAM workflow in Cronin's lab


The purpose of this web page is to outline the work process involved in performing the Seismo-Lineament Analysis Method in Vince Cronin's lab at Baylor. All original components of the SLAM process (including, in particular, the computer codes) are Vince Cronin's intellectual and personal property, and are copyright (2014) by Vincent S. Cronin. Their use for scientific and educational purposes is permitted and encouraged.

This web page is a work in progress.

Acquire earthquake data

Hypocenter location: latitude, longitude, depth

USGS latest EQs
USGS catalog
ISC catalog
SCEC catalog
NCEDC catalog
Felix Waldhauser's DD catalog for N. California

Focal mechanism (orientation of nodal planes)
You might want to refer to the focal mechanism primer at

USGS latest EQs
USGS catalog
ISC catalog
SCEC catalog
NCEDC catalog
NCEDC catalog

Acquire and prepare DEM data

I suggest that the minimum map area be specified by computing the horizontal distance from the epicenter to the surface trace of the more gently inclined nodal plane. Using a ballpark number for the average elevation of the epicentral area in meters (you can get this from Google Earth) added to the absolute value of the hypocenter depth in meters, the horizontal distance to the trace (in meters) will be equal to (elevation + |depth|) / tan(nodal plane dip angle). Divide that number by 1000 and you have the horizontal distance in kilometers, and divide that number by 111°/km and you have the angular distance from the epicenter to the mean ground-surface trace of the nodal plane. That will be the minimum radius from the epicenter that you will want your map to include. So, for example, if that distance was 0.1°, I would want a DEM file from the epicenter's latitude - 0.15° to the epicenter's latitude + 0.15°, and the same for the longitude. (Yes, we know the longitude angle will be different anywhere but the equator, but this is an initial ballpark number.)

Chris Breed of Baylor's Center for Spatial Research has made a couple of videos that describe (most of) the process of acquiring a DEM from the US National Map Seamless Server, manipulating it in ArcGIS, and ending-up with a suitable ASCII DEM for use in the Slam code.

  1. Acquire DEM data in an ArcGRID format
  2. Convert the DEM data to an ASCII file with standard 6-line header (refer to Chris Breed's video)
  3. Thin and crop DEM data for use in SLAM code. The resulting file size needs to be compatible with the computer that will be used to run the SLAM procedure.

Use SLAM code to define seismo-lineaments

  1. Modify SLAM code as appropriate for the data or problem
    A current version of the SLAM code is available via
  2. Run SLAM code and generate graphic output
  3. Create final graphic products using a graphics app like Canvas, Illustrator, etc.

The rest of the SLAM process

  1. Geomorphic analysis of seismo-lineaments
  2. Analysis of known faults relative to geomorphic lineaments within/adjacent to seismo-lineaments. Start with the Quaternary Fault and Fold Database of the United States, at
  3. Consideration of overlapping seismo-lineaments (possibly two events on the same structure)
  4. Consideration of hypocenters of other possibly-related earthquakes (3-D planar regression of hypocenters with associated statistics)
  5. Develop hypotheses for the location of seismogenic faults
  6. Design of field study to test hypotheses
  7. Analysis of field data and synthesis with earthquake data
  8. Interpret the results in a manner that is mindful of the competing interests to identify possible seismogenic faults while not extending beyond a reasonable interpretation of the data.

An example set of codes and data from Tori Worrell's MS thesis

Some References

Ashburn, Jeremy, 2015, Investigation of a lineament that might mark the ground-surface trace of the Dog Valley fault, Truckee area, northern California: B.S. thesis, Baylor University, accessible via

Bayliss, Brian, 2007, Test of a method for recognizing unmapped seismogenic faults: M.S. thesis, Baylor University, accessible via

Cronin, V.S., 2014, Seismo-Lineament Analysis Method (SLAM), using earthquake focal mechanisms to help recognize seismogenic faults, in Grutzner, C., Choi, J-H., Edwards, P., and Kim, Y-.S., [editors], Proceeding of the 5th International INQUA Meeting on Paleoseismology, Active Tectonics and Archeoseismology, 21-27 September 2014, p. 28-31, ISBN 9791195344109 93450; available online via
A PDF file of Vince Cronin's presentation at the INQUA PATA meeting in Busan, South Korea, is accessible via, and provides a visual introduction to SLAM.

Cronin, V.S., Millard, M., Seidman, L, and Bayliss, B., 2008, The Seismo-Lineament Analysis Method (SLAM) -- A Reconnaissance Tool to Help Find Seismogenic Faults: Environmental and Engineering Geology, v. 14, no. 3, p. 199-219. Available via GeoScience World at

Dickinson, Jordan, 2015, A seismo-lineament study of magnitude 3.3-5.3 earthquakes near Trinidad, Colorado: B.S. thesis, Baylor University, accessible via

Lancaster, Daniel, 2011, Correlation of earthquakes with seismogenic faults along the Northern Arizona Seismic Belt, southwestern margin of the Colorado Plateau: M.S. thesis, Baylor University, accessible via

Lindsay, Ryan, 2012, Seismo-lineament analysis of selected earthquakes in the Tahoe-Truckee area, California and Nevada: M.S. thesis, Baylor University, accessible via

Millard, Mark, 2007, Linking onshore and offshore data to find seismogenic faults along the Eastern Malibu coastline: M.S. thesis, Baylor University, accessible via

Rasaka, Brandon, 2016, Correlation of selected earthquakes with seismogenic faults, central Oklahoma: M.S. thesis, Baylor University, accessible via

Reed, Tyler, 2014, Spatial correlation of earthquakes with two known and two suspected seismogenic faults, north Tahoe-Truckee area, California: M.S. thesis, Baylor University, accessible via

Seidman, Lauren, 2007, Seismo-lineament analysis of the Malibu Beach quadrangle, Southern California: M.S. thesis, Baylor University, accessible via

If you have any questions or comments about this site or its contents, drop an email to the humble webmaster.

All of the original content of this website is © 2014 by Vincent S. Cronin