Damage and intensities in the magnitude 7.8 1931 Hawke's Bay, New Zealand, earthquake

Abstract

This paper is the result of a study of the shallow Mw = 7.8 Hawke's Bay earthquake which occurred in the North Island of New Zealand, 2 February 1931 (UT), and which was the final spur to the production of the first earthquake loadings code in New Zealand issued in 1935. This earthquake was a direct hit on two provincial towns (Napier and Hastings) and was the most damaging in New Zealand's history, causing the most casualties, major fires, and much damage to the built and natural environments. It gives the first overall description of the damage (to the buildings and lifelines) in this major event in modem earthquake engineering terms, and presents the first intensity map for the event determined directly in the Modified Mercalli (MM) scale. The zone which experienced the highest intensity (MM10) was confined to a modest area of onshore land (about 300 km2) above the centre of the rupture surface.