A note on differences in tsunami source parameters for submarine slides and earthquakes

The nature of tsunami sources is reviewed, including source duration, displacement amplitudes, and areas and volumes of selected past earthquakes, slumps and slides that have or may have generated a tsunami. This review shows that the velocity of spreading of submarine slides and slumps (1-100 m/s) can be comparable to the long wavelength tsunami Velocity c(T) = rootgh (30-140 m/s for water depth 100 < h < 2000 m). In contrast, typical velocities of spreading dislocations during most earthquakes are one order of magnitude larger (2-3 km/s). Other significant differences between earthquake and slide and slump sources are that the balance of the total uplifted material in the case of slides is essentially zero, while for earthquakes it can be considerable, and that the vertical displacements for slides and slumps, per unit area of their horizontal projection, can be orders of magnitude larger than during earthquakes. This can result in high concentrations of the total change in the potential energy of fluid, above the source, over much smaller areas than during earthquakes. (C) 2002 Elsevier Science Ltd. All rights reserved.