Damage and intensities in the magnitude 7.8 1929 Murchison, New Zealand, earthquake

Abstract

This paper is the result of a study of the Ms = 7.8 Murchison earthquake which occurred in the South Island of New Zealand, on 16(UT) June 1929, a few years prior to the introduction of the first earthquake loadings code in New Zealand. It gives the first description of the damage to buildings in this event in modern earthquake engineering terms, and presents the first Modified Mercalli (MM) intensity map for the event determined from the original felt information. Some definitions of `well-built' pre-code buildings are proposed: these should help in dealing with safety and conservation issues raised when considering the future of such `earthquake risk' buildings. No evidence was found for MM10 intensities, although ground shaking of this strength probably occurred in the unpopulated mountainous countryside close to the fault rupture. Recommendations for improving the criteria for determining MM intensity are made in respect of (1) pre-code buildings and (2) seismically-induced landslides.