## Tsunami Travel Time MapsNCEI, as the World Data Service for Geophysics (including Tsunamis), and the UNESCO-IOC International Tsunami Information Center, collaborate to provide tsunami travel time maps. Tsunami Source MapsEstimated travel times for historical tsunamis based on earthquake epicenters Coastal Locations MapsEstimated tsunami travel times from any point in the ocean to selected coastal locations Maps were generated using Tsunami Travel Times (TTT) software (see below) developed by Paul Wessel, Geoware. TTT software calculates first-arrival travel times on a grid for a tsunami generated at a given earthquake epicenter or coastal location. - Maps
**do not**provide information on the height or the strength of the wave,**only the arrival times** - There are several situations in which the estimated arrival times may not match observed arrival times of the tsunami waves, including but not limited to the following:
- Bathymetry is not accurate in the vicinity of the epicenter
- Epicenter is not well located, or its origin time is uncertain
- Epicenter is on land and a pseudo-epicenter off the coast must be selected
- Bathymetry is not accurate in the vicinity of the reporting station
- Nonlinear propagation effects may be important in shallow water
- Observed travel times do not represent the first wave but instead are later arrivals
## Tsunami Travel Time SoftwareThe technique to compute travel times is an application of Tsunamis are categorized as long waves, therefore, tsunami travel times can be computed with water depth as the only variable (Murty, T.S., Seismic Sea Waves Tsunamis, Bulletin 198) Long waves are where the distance between wave crests is much greater than the water depth through which the wave is traveling. Wave speed is computed from the square root of the quantity: water depth times the acceleration of gravity. So, tsunami travel times can be computed without any knowledge of the tsunami's height, wavelength, etc. |