South American Tsunamis in Lyttelton Harbor, New Zealand

At 2347 UTC on April 1, 2014 (12:47 pm April 2, 2014 NZDT) an earthquake with a moment magnitude of 8.2 occurred offshore of Iquique in northern Chile. The temblor generated a tsunami that was observed locally and recorded on tide gauges and deep ocean tsunameters close to the source region. While real time modeling based on inverted tsunameter data and finite fault solutions of the earthquake rupture suggested that a damaging far-field tsunami was not expected (and later confirmed), this event nevertheless reminded us of the threat posed to New Zealand by tsunami generated along the west coast of South America and from the Peru/Chile border region in particular. In this paper we quantitatively assess the tsunami hazard at Lyttelton Harbor from South American tsunamis through a review of historical accounts, numerical modeling of past events and analysis of water level records. A sensitivity study for tsunamis generated along the length of the South American Subduction Zone is used to illustrate which section of the subduction zone would generate the strongest response at Lyttelton while deterministic scenario modeling of significant historical South American tsunamis (i.e. 1868, 1877 and 1960) provide a quantitative estimate of the expected effects from possible future great earthquakes along the coast of South America.