Near-field modeling of the July 17, 1998 tsunami in Papua New Guinea

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 people. Numerical simulations show that seismic dislocation sources are not energetic enough to reproduce the observed tsunami along the coast. Tsunami generation by a submarine landslide has been simulated by a finite-difference model, assimilating the landslide to a flow of granular material. Long-wave approximation is adopted for both water waves and the slide. Numerical results show that observed inundation heights are well reproduced for a volume of 4 km³ located 20 km offshore, sliding downslope with a Coulomb-type friction.