New Zealand tsunamis 1840–1982

Abstract

An extensive search of newspaper reports, archival material, and the literature has revealed that many more tsunamis have affected the New Zealand coast than hitherto realised. 32 tsunami events are listed, including their probability of occurrence, the maximum runup height, as well as the epicentre and Richter magnitude for those events associated with earthquakes. Most coastal regions of New Zealand are reported as experiencing tsunamis. Generally these events have been associated with earthquakes, although the tsunami source mechanisms have also been attributed to large rotational slumps, submarine slumping along the Chatham Rise, and submarine mud volcanism associated with diapiric intrusions on the continental shelf off Poverty Bay. Tsunami waves and seiching accompanying the Krakatoa eruption of 1883 appear to have been induced by pressure coupling between the atmosphere and oceans.

Most tsunamis have affected the east coast. This largely reflects both exposure to pan-Pacific origins and the presence of a tsunamigenic seismic zone off the east coast of the North Island. Nine tsunamis from distant sources are identified, and it appears that those generated from South America produce higher waves in New Zealand. However, the highest waves experienced have been derived from locally generated tsunamis.

Damage arising from tsunamis is greater than previous authors have credited and includes damage to shipping, wharves, bridges, and coastal dwellings.

Keywords:

• tsunamis
• New Zealand
• distribution
• earthquakes
• geologic hazards