Tsunami Travel Time Approximation

Eric Grosfils, Pomona College


Students are asked to calculate approximate tsunami travel times across the Pacific basin. The assignment builds off of a lab introducing students to Spatial Analyst, and challenges them to think carefully about raster preparation and the extraction of data from a raster using shapefile features.


Type and level of course
Used in an Introductory GIS course topically focused for geology undergraduates.

Geoscience background assumed in this assignment
basic familiarity with a bathymetry map; knowing basic wave propagation concepts helps, but a goal of the assignment is to promote independent investigation into tsunami wave propagation and assess differences between the product a student produces and a comparable "expert" prediction.

GIS/remote sensing skills/background assumed in this assignment
Loading and manipulating a raster using the raster Calculator; basic Spatial Analyst skills (e.g., calculating a Distance product); Zonal Statistics and statistics tools in Spatial Analyst

Software required for this assignment/activity:
ArcGIS with Spatial Analyst extension

Time required for students to complete the assignment:
1-3 hrs (longer if reprojected ETOPO1 raster isn't provided to student, but instead needs to get generated by them)


GIS/remote sensing techniques students learn in this assignment
Using the raster calculator as an efficient means of performing basic calculations. Extracting data from a raster using zonal statistics and a shapefile. Determining the shortest distance between two points.

Other content/concepts goals for this activity
Builds on students' understanding of the reasons for using specific projection types, specifically tapping into why a given projection is or isn't appropriate to use when addressing a given problem.

Higher order thinking skills goals for this activity
Students must conceptualize how best to prepare a dataset for analysis. The travel times determined using GIS alone will be flawed, and part of the exercise is to assess reasons why this might be the case through comparison with an animation showing the results from a more complex simulation.

Description of the activity/assignment

To prepare for this assignment students work through a lab that introduces them to the basic use of Spatial Analyst. Students are asked to expand upon this introduction by solving a tsunami travel time problem that benefits from careful, intelligent use of the Raster Calculator and Zonal Statistics tools. The result is different than that produced by other methods, and students draw on their previous background and complementary research to assess why this is the case.

Determining whether students have met the goals

I evaluate a map product that allows me to assess the sophistication and accuracy of their raster processing concepts. I assess a written description of the steps used to generate their map product and assessment. I assess the sophistication and accuracy of their analysis concerning possible sources of error/difficulty with the final outcome.
More information about assessment tools and techniques.

URLs and References

Impact tsunami animation: http://es.ucsc.edu/~ward/2004MN4(a).mov

For more information about 2004MN4, couched in terms of an advocacy argument for mitigating NEA hazards, can be found at http://www.spaceref.com/news/viewnews.html?id=1024

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