• Date: 23 May 1960
• Source: Distant
• Cause: Earthquake in Chile

The M_W 9.5 Chilean earthquake that occurred on 23 May 1960, 7:11 pm (NZST) is the largest earthquake instrumentally recorded to date. Its main shock generated a tsunami that was not only destructive along the coast of Chile, but also caused numerous casualties and extensive property damage in Hawaii and Japan, and was noticeable along the shorelines throughout the Pacific Ocean area.

Observations of the tsunami were reported at more than 120 locations in New Zealand. The most affected locations occurred along the whole eastern seaboard from Cape Reinga to west of Bluff and to Stewart Island, but the tsunami was also observed at locations on the west coast of the North Island including Ahipara in Northland, and notably as far south as Whanganui and Paremata, but not at New Plymouth, Foxton, or Himatangi Beach.

On the western and north-western seaboard of the South Island, the tsunami was observed at Nelson, Motueka, as well as several West Coast towns. The tsunami was also experienced on the Chatham Islands, and Campbell Island, where water heights above sea level at the time were from 3m to over 5m at locations only a few kilometres apart in Perseverance Harbour.

The first arrivals on the east coast were at night, and in general, only noticed where the larger waves occurred or where smaller waves arrived on top of high tide. The first arrivals that were unmistakeable were within a short time of their predicted time.

The largest surges generally occurred within 12-15 hours after the first arrival, some within the first 2-4 hours. In the most affected areas, houses, roads, sheds, and paddocks were inundated; bridges, fences, and sheds damaged; and stock killed.