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Joint Australian Tsunami Warning Centre

Glossary of Terms

Bathymetry:

The measurement of the depth of the ocean floor from the water surface and is the oceanic equivalent of topography.

Inundation:

The horizontal extent of flooding from the sea.

Moment Magnitude (Mw):

A measure of the energy release by an earthquake. There are a number of different scales for measuring the magnitude. The Moment Magnitude is based on the size and characteristics of the fault rupture, and can be determined from long-period seismic waves.

Run-up:

The maximum height of the water onshore observed above a reference sea level. Run-up is usually measured at the horizontal inundation limit.

Seismic:

Of or having to do with earthquakes.

Subduction zone:

An area on the Earth where two tectonic plates meet and move towards one another, with one sliding underneath the other and moving down into the earth at rates typically measured in centimetres per year.

Wave amplitude:

This is quoted as half the wave height. It should be recognised that tsunami waves are typically not symmetrical.

Wave height:

The vertical distance between the trough and the crest of a wave.

Wavelength:

The mean horizontal distance between successive crests or troughs of a wave pattern.

Wave period:

The time taken for a one wavelength to pass a given point.