Tsunami Travel Time

Get location of earthquake epicenter and time.

Get locations of buoys, and the sea surface height records for the period of the tsunami, for instance at http://www.ndbc.noaa.gov/dart.shtml

Get locations of tide gauges, and sea surface height records for the period of the tsunami, for instance at http://tidesonline.nos.noaa.gov/geographic.html  

Create a file with this information.  The easiest way it to use Excel, put in column headers LAT, LONG, NAME, enter the data, and save as a CSV file.

New DEM to open a map with bathymetry  (DEM) of the desired ocean basin. ETOPO is a good choice.

If your DEM has a poorly chosen extent for your tsunami (say because it breaks in the middle of the ocean basin you want) and you would like the entire route on a single map, there are several choices:

  1. Create a new DEM from the ETOPO5, centered on the area of interest:
  2. Quick vector map:

 Open Database  and open the CSV file with the locations of the buoys, tide gauges, and the epicenter.

On the "Calculate" menu of the map window, pick the "Rhumb lines" option.

Enter location of  epicenter and a buoy or tide gauge.  You can  type them in (START and END buttons), or cut and paste from the database (right click on record in the data, pick "copy coordinates to clipboard", and then select + buttons to add here).

Pick a point spacing or the number of points, and adjust the parameters until you are satisfied.  Point spacing will have equal distances between, except for the last point, while "Number of Points" will have constant spacing.

Select "Rhumb line"

 

The resulting database has the location of each point along the rhumb line, the elevation (-z is below sea level), and the length of that segment from the previous point.

Save it, using Report button on database table form, for import into Excel or Matlab to find the travel time for each segment, and the total time to get from the epicenter to the buoy. You can save either a CSV file, or a DBF (dBase) table.

You can also use the total distance and average depth for a potentially easier computation.


Last revision 3/24/2011