Abstract
Often, tsunamis have been treated as a static problem. First studies
demonstrated that for earthquake rupture velocities in the span of 1.5
km/s to 3 km/s, the kinematic and static part of the tsunami can be
treated separately. The deformation generated by an earthquake is copied
into the sea surface and then the tsunami is propagated. However, very
slow earthquake rupture velocities in the span of 0.1 to 1 km/s have not
been included into tsunami modeling. Here, we calculate tsunami
efficiency, based on Kajiura’s definition, for different models. We
demonstrate that rupture velocity cannot be neglected for very slow
events, i.e, rupture velocities slower than 0.5 km/s. We calculate a
relation between Magnitude, Rupture Velocity and Tsunami Amplitude to
the Efficiency of very slow tsunamigenic earthquakes. Megathrust
earthquakes (Mw >8.5 ) with very slow rupture velocity
amplify energy from 10 to 60 times larger than moderate to large
earthquakes.