A preliminary report on the Inangahua earthquake New Zealand , May 24, 1968

  • Earthquake and War Damage Commission

Abstract

"The Inangahua Earthquake of 5.24 a.m. on May 24, 1968 was the first New Zealand earthquake to reach magnitude 7 since that in Fiordland on May 24, 1960 ....
It became the sixteenth earthquake believed to have reached magnitude 7 or greater since 1848, since when all such earthquakes should have been observed ...."

"Faulting took place at two localities, near Inangahua Junction railway station and about three miles north of Rotokohu. In both places movements comprised horizontal, vertical and thrusting components.... Inangahua lies at the northern end of the 60-mile-long Grey-Inangahua Depression, a complex structural feature between predominately-granite ranges to the east and west ...."

"The maximum intensities reported are close to Inangahua, some 15 km south of the (instrumental) epicentre. Large landslides (one of them responsible for two deaths and another temporarily blocking the Buller River), serious damage to wooden structures including houses and bridges, bending of railway lines, breaking of underground pipes, slumping and cracking of roads, and ejection of ground water, establish an intensity of M.M.X ...."

"Because there were no major engineering works, (heavy commercial or industrial buildings) or multistorey buildings in the area, the main lessons for engineering seismology were indirect. The low casualties and relatively low damage may lead to severity of this earthquake being underated."

"From aerial reconnaissance late on the morning of the earthquake, it was clear
that severe damage to buildings had occurred at the township comprising Inangahua Camp and Inangahua Junction; and in farmland within a radius of five to eight miles."

"The 6.30 a.m. N.Z.B.C. radio news stating that mild earthquakes had been felt between Muriwai and Timaru, made us aware that no one knew of our plight. This prompted us to organise our community to spend an indefinite period in the shattered township."

"Immediately the emergency had been declared the safety of the people in the Inangahua area became our first consideration.... Of necessity the helicopters were required to fly and land in very difficult areas, flying late into the night,
landing under conditions that were hazardous because of the terrain, the continual fog and the encroaching darkness.... As soon as possible after the rescue and the providing of the necessary welfare, consideration was given to the restoration of roads, bridges, electric power and telephone lines, supply systems and other services.”

"A road block was established on the only accessible road into Inangahua and
official daily passes were issued by the police at civil defence headquarters
When the disaster area was finally opened to the public, police presence was essential, because sightseers attempted to wander across properties and through homes.”

"If one accepts the premise that people matter more than things, then public relations becomes of prime importance in any restoration work. Should a disaster, such as the one experienced on the west coast, this year of 1968, occur in an area of greater population density, then I think it would be necessary to have several men and women capable of dealing with people's questions, fears, and criticisms."

Published
1969-06-30
How to Cite
Earthquake and War Damage Commission. (1969). A preliminary report on the Inangahua earthquake New Zealand , May 24, 1968. Bulletin of the New Zealand Society for Earthquake Engineering, 2(2), 2-8. https://doi.org/10.5459/bnzsee.2.2.2-8
Section
Editorials