Quantifying tsunami risk at the Pisco, Peru LNG terminal project

C.E. Synolakis, E.A. Okal, J.C. Borrero

We examine and quantify the tsunami risk near Pisco, Peru, where a major Liquefied Natural Gas facility is in project at Playa Loberia. We re-assess the historical record of tsunami damage along the coast of Central and Southern Peru, from 9 deg. S (Chimbote) to 19 deg. S (Arica), building seismic models of the events involved, and conducting numerical simulations of the run-up at Pisco that such models predict. We then evaluate possible return periods for the main seismic events under consideration, from a combination of historical datasets and plate tectonics arguments. We classify tsunami hazard according to the amplitude of their run-up on the coast: decimetric tsunamis (0.1 to 1 m) do not carry a specific hazard over and beyond that presented by storm waves. Metric tsunamis (a few meters) can inflict severe damage to coastal and harbor communities, and result in inundation distances of up to 1 or 2 km. Finally, dekametric tsunamis (10 m and above) are catastrophic events leading to the total destruction. We estimate that a scenario of metric run-up, which could substantially damage port facilities and lead to a number of fatalities, may have a repeat time at Pisco of about 60 years. A catastrophic tsunami of dekametric amplitude, capable of totally destroying harbor infrastructures, may have a repeat time of about 110 years. This result is also consistent with the "back-of-the-envelope" observation that the city was destroyed four times over the past 400 years. The last such tsunami took place 134 years ago.