Inangahua Earthquake 1978

Earthquakes: Inangahua

FROM Canterbury Library Website

When: 24 May, 1968

Where: Inangahua Junction, West Coast

Summary

Inangahua was devastated by an earthquake in 1968 which left 70 percent of the dwellings in the town uninhabitable.

What happened

• Inangahua Junction is at the point where the Inangahua River meets the Buller River, 30 kilometres north of Reefton and 45 kilometres south-west of Westport.
• After the gold rush years of the mid 19th century, the population of Inangahua dropped until there were only about 300 inhabitants at the time of the 1968 earthquake.
• At 5:24 am on Friday 24 May, 1968, an earthquake measuring 7.1 on the Richter scale struck the West Coast.
• Throughout the country people were still recovering from the shock of the Wahine sinking on 10 April earlier that year.
• The Inangahua earthquake caused damage up and down the West Coast, but Inangahua Junction suffered the most and was quickly declared a disaster area.
• If the earthquake had been centred in an area where there was a higher population, there would probably have been a greater loss of life. As it was, three people died.
• Two women were killed when a landslide struck a house, one dying of her injuries later in hospital.
• Around the Inangahua area landslides and other upheavals blocked the roads, buckled the railway lines, and cut off the town. Communication with the outside world was not possible until two and a half hours after the earthquake. In the meantime the local inhabitants had to be ready to spend the night in the stricken town in case help could not reach them.
• For a while the Buller River was dammed by a massive landslip about 6 kilometres upstream from Inangahua, and threatened to flood the town.
• Unlike the Murchison earthquake of almost 40 years before, helicopters could be used to take people out of the disaster area. By 9.30 pm on the day of the earthquake almost 200 people had been lifted out and then bussed to Reefton.

How many died: 3 (3 also killed in a rescue helicopter accident at the time).

Other events and outcomes

• The earthquake damage was made worse by more and more aftershocks. 15 earthquakes measuring more than 5 on the Richter scale were recorded over the next four weeks.
• Heavy rain fell the next day and made it more difficult to clear the roads blocked by landslides. Houses suffered more damage as the rain came in through the holes in the roofs.
• Roadblocks were set up outside Inangahua Junction to control who went into the disaster area. Police were on patrol to keep out sightseers and looters of the empty houses.
• Food and other supplies were sent from other parts of New Zealand, and the Inangahua Earthquake Disaster Relief Fund was set up to help the refugees.
• The railway line was reopened three weeks later and people returned to their homes in Inangahua within the month. The roads took longer to clear.

Richter scale

An earthquake is measured by its size, known as its magnitude. A Californian seismologist (earthquake researcher), Charles Richter, developed his scale as a way of comparing one earthquake with another. The Richter scale calculates the size of an earthquake by the amount of movement of the ground at the epicentre, using the height of the biggest shockwave and the time between the waves. These measurements are taken by a seismograph. However the actual force of an earthquake can also be affected by the depth of the earthquake.
Another way of measuring an earthquake is the Modified Mercalli scale, which measures the intensity of the earthquake, or the actual effect on people, buildings and the ground itself.