In the early morning of 24 May 1968, the northern South Island was rocked by a magnitude 7.1 earthquake centred near Īnangahua Junction, a small community 40 kilometres east of Westport. At 5.24 a.m. people there were woken by shaking violent enough to throw them out of bed. Many hastily escaped from their homes, amidst falling chimneys and roof tiles.
At Whitecliffs a limestone bluff collapsed onto a farmhouse and pushed it downhill, killing one woman instantly and fatally injuring another. Shortly after the earthquake, one man died near Greymouth when his car hit a section of road that had subsided at a bridge approach. Three men were killed later when a helicopter crashed.
Effects in Īnangahua
At daylight, a relief centre was set up in the Ministry of Works yards in Īnangahua. People gathering there were dismayed to hear radio news broadcasts at 6.30 a.m. mention only mild earthquakes – the rest of New Zealand seemed unaware of Īnangahua’s plight. All roads out of the area were blocked and there was no telephone, or electricity to send radio messages. Several hours later, however, a driver contacted Gisborne on his truck radio. By late morning commercial and air force helicopters were coming into the area to survey damage.
The earth explodes
Ruth Inwood, an Īnangahua dairy farmer, recalls the moment the quake struck:
‘I thought it was the end of the world … The noise was horrendous. …Our fridge was flipped on its side, a heavy three-seater sofa was thrown across the lounge, ceilings were ripped open, windows exploded out of their frames, cupboards were completely emptied, and broken ornaments and crockery littered the floor. … It was like an explosion underneath us. The house was shunted up in the air and then it shook violently. A lot of houses were knocked clean off their piles.’ 1
The impact elsewhere
Other West Coast towns were heavily shaken: more than two-thirds of the chimneys in Greymouth, Westport and Reefton were damaged. Reefton residents realised that help would be needed in isolated areas. Four people, including a constable and a doctor carrying a pack of medical supplies, walked to Īnangahua Junction. There the doctor treated most patients outdoors because aftershocks were still jolting the area.
The Īnangahua tremors triggered numerous landslides in the surrounding mountains. A huge landslide dammed the Buller River above Īnangahua Junction. The rising water backed up for 7 kilometres, raising the river 30 metres above its normal level. If the landslide dam had burst, the river would have flooded not only Īnangahua but also Westport. Everyone in its path had to be evacuated.
Twelve hours after the quake, one group of about 50 people started walking from Īnangahua Junction towards Reefton. Army and commercial helicopters began flying people to Rotokohu, where they could board buses to Reefton, while air force helicopter crews checked all outlying farmhouses. In all, 235 people were airlifted out. The earth-filled river eventually overflowed the landslide debris, but eroded it downward gradually without causing serious flooding.
The earthquake ruined many years of costly work improving and sealing the highways in the Īnangahua and Buller Gorge areas. Over a 50-kilometre stretch, the road through Buller Gorge was blocked in more than 50 places, either buried under slips or with gaps where the road itself had fallen into the gorge. The earthquake had damaged or destroyed 50 bridges. It also derailed two goods trains, and over 100 kilometres of damaged railway track had to be re-laid.