Saturday, March 17, 2012

Tsunamis & Seafloor Topography

Seafloor features affect how tsunami waves build in intensity as they approach a coastline. Scientists have hypothesized that seafloor mountains and chasms also affects the strength and height of the moving ocean wave fronts.

NASA JPL scientists and researchers from the Ohio State University used satellite altimeter data that had recorded sea levels changes to within an accuracy of a few centimeters following the 2011 Tōhoku earthquake to confirm this hypothesis.

Jason-2 Satellite
Data from Jason-1, Jason-2, and Envisat satellites that passed over the wave fronts caused by the the 2011 Tōhoku earthquake confirmed that islands, ocean floor chasms, and submerged mountains play a role in deflecting or amplifying tsunami waves even at distances of thousands of miles from the source of the disturbance.

Sea level changes from the satellite data following the Tōhoku tsunami were verified with results from GPS sensors and buoy data recorded by NOAA's DART program.

(1)Wave peaks are shown in reddish-brown.
(2)Seafloor depressions are depicted in bluish-green.
(3)Mid-ocean ridges, peaks, and islands are depicted as grayscale outlines.

The simulation above, created from the 2011 satellite data, shows refraction, bending, and merging of waves as they propagate thousands of miles.

Source: The Seafloor Focuses and Merges Tsunami Waves published March 12, 2012 by NASA Earth Observatory.