Modest earthquakes may trigger large submarine landslides, responsible for
disastrous tsunami waves, as demonstrated by the Papua New Guinea event of
July 17, 1998. The relatively small earthquake was followed by unexpectedly
high waves, up to 15 m wiping out 3 villages and killing more than 2200 pe
ople. Numerical simulations show that seismic dislocation sources are not e
nergetic enough to reproduce the observed tsunami along the coast. Tsunami
generation by a submarine landslide has been simulated by a finite-differen
ce model, assimilating the landslide to a flow of granular material. Long-w
ave approximation is adopted for both water waves and the slide. Numerical
results show that observed inundation heights are well reproduced for a vol
ume of 4 km(3) located 20 km offshore, sliding downslope with a Coulomb-typ
e friction.