Background
The tsunami that struck New Guinea on July 17, 1998 was the most devastating tsunami since the 1976 Moro Gulf, Philippines, tsunami and may surpass that event (Lockridge and Smith, 1984; Satake and Imamura, 1995). The high reported runups and the tremendous loss of life are of great concern to all, including the international scientific community. Scientists will closely examine this event in the coming months, in the ultimate hope of mitigating such disasters in the future.
New Guinea is a seismically active region, the site of an arc-continent collision, where tectonic plates are converging and sliding past each other. The tectonic boundaries and faulting in this region are very complex, as shown below.
The Earthquake
The recorded magnitude of the earthquake was
7.1, and the epicenter was located in northern New Guinea near the coast.
The fault mechanism from the National Earthquake Information Center (NEIC)
shown by the red-and-white ball indicates that the earthquake could have
occurred as uplift on a vertical fault or sliding on a horizontal fault.
The inset in the upper right corner of the figure shows the location of
the epicenter.
The Tsunami UPDATED 7/24/98
At present, too little is known about the July
17, 1998 earthquake and about the distribution of runup to formulate a
quantitative model of the tsunami. The reported runups are unusually large
for an earthquake of magnitude 7.1 (cf. Geist, 1998). Below, a descriptive
or qualitative simulation of the tsunami is computed by making several
assumptions about the source parameters of the earthquake. The model is
for descriptive purposes only--a quantitative model awaits more information
on the exact location of the earthquake and accurate measurements of runup.
Of equal importance, the grid size used in this simulation is quite large
and does not capture the nearshore behavior of the tsunami (cf. Titov and
Synolakis, 1997).
More information on this tsunami at Western Region Coastal and Marine Geology web site