P. Heinrich et al., Numerical modelling of tsunami generation and propagation from submarine slumps: the 1998 Papua New Guinea event, GEOPHYS J I, 145(1), 2001, pp. 97-111
Deep and large submarine slumps may generate tsunamis as disastrous as tsun
amis of tectonic origin. Such a landslide is likely to be the origin of the
1998 July 17 tsunami of Papua New Guinea, the deadliest tsunami in the las
t 50 years. Water waves devastated a 20 km stretch of coastline, wiping out
three villages and killing more than 2200 people. A numerical model has be
en developed to study the efficiency of deep slumps in producing tsunamis a
nd has been applied to the Papua New Guinea event.
The landslide is treated as the flow of a homogeneous gravity-driven contin
uum governed by a rheological law. Water waves are generated by sea-bottom
displacements induced by the landslide. The shallow-water approximation is
adopted for both the landslide and the: associated water waves. The resulti
ng differential equations are solved by a finite difference method based on
shook-capturing. The shallow-water hypothesis is tested by comparison with
a model solving Navier-Stokes equations for a mixture of water and sedimen
ts. Sensitivity tests carried out for a 2-D Simplified geometry show that t
he water surface profile depends strongly on the constitutive law of the la
ndslide.
The 1998 event is simulated numerically by the shallow-water model, testing
different friction laws. The observed inundation height distribution is we
ll reproduced by the model for a volume of 4 km(3), with its top located at
a water depth of 550 m, and sliding with a Coulomb-type friction law over
a distance of 5 km.