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arc second - a mapping and navigational term describing a unit of distance on a curved surface as a fraction of an angle, measured in degrees, minutes and seconds of arc. In these maps, 30 arc seconds represents about 1km distance.

bathymetry - measurement and mapping of ocean depths, distinguished from sea floor topography, which deals with the nature of the sea floor.

epicenter - the location of an earthquake, measured in latitude and longitude.

GIS - geographical information system, usually referring to computer based map creation and reading systems

run-down - the returning effect of water from a tsunami that has washed ashore. Much like a rip in surf waves.

run-up - the maximum height on land that water from a tsunami reaches as it washes inland. Not to be confused with the wave height.

tsunami earthquake - an relatively small earthquake that produces an unusually large tsunami

tsunamigenic earthquake - an earthquake that produces a tsunami