1931 Hawke’s Bay Earthquake
On 3 February 1931, one of the three largest historical earthquakes ever recorded in New Zealand struck Hawke's Bay. The magnitude M7.8 earthquake was produced by rupture on a northeast-trending buried fault, probably the Napier-Hawke Bay Fault. The focus (initiation point) of the earthquake was about 20 km north and a little east of Napier and some 30km deep (this initiation point differs from some earlier reports and has been determined following further research by GNS Science). There was only a minor surface rupture along a 15 km stretch of the fault, but the blind faulting produced an uplifted area of 1500 km2 with a maximum of 2.7 m of uplift. In Hastings, about 1 m of ground subsidence occurred. The Ahuriri Lagoon was raised 1-2 m and partially drained. Near Napier the coastline was raised and some boats moored in the harbour were left sitting on harbour floor. A tsunami was also experienced along parts of the Hawke Bay coast.
Some land came up and some went down in 1931. Blue shows areas that dropped and red areas of uplift (Map courtesy of GNS Science)
The ‘Hawke’s Bay earthquake’ was the most devastating in New Zealand history. 256 people lost their lives, either from collapsing buildings or in the widespread fires that followed the earthquake. Many buildings at that time were constructed of unreinforced masonry or had poorly supported concrete facades that collapsed in the shaking. The fires that destroyed downtown Napier were left to burn as the water supply in town failed. All the bridges into town collapsed and the main roads into Hawke’s Bay suffered severe damage.
Following the first earthquake the region shook with hundreds of aftershocks. Although earthquakes were difficult to measure in those days, there were appropriately 150 aftershocks in the 12 hours post earthquake, and 525 in the 14 days post earthquake, including a powerful magnitude M7.3 earthquake 10 days later. It is also thought the magnitude M6.9 earthquake near Wairoa on 15 September 1932 may have been caused by the fault that ruptured in the 1931 earthquake. The shaking from the 1932 earthquake damaged buildings in Gisborne and Wairoa and caused the collapse of the Wairoa River bridge.
HAWKE’S BAY EARTHQUAKE STORIES & PICTURES
People who lived through the earthquake had some dramatic stories to tell and some are told below.
1931 Earthquake Survivor Stories
The following quotes are from 'The Shock of '31' By Geoff Conly, AH & AW Reed Ltd
Mr P.W Barlow, chief surveyor with the Napier branch of the Lands and Survey Department, had just completed drafts of letters to be typed when the room began to shake. He pushed his large swivel chair out from his desk, lay on the floor, put his legs under the desk and his head under the chair. He felt the culmination of the earthquake as a violent shake, 'similar to the shaking a fox terrier given when killing a rat' he said. Then came the big crash. Bricks were raining into the room and the dust was so thick he could not see his hand 25 centimetres away from his face.
Wilson Wright was 5 years old and never thought the sound of school bells would be replaced by the sound of an earthquake. At home, music from a gramophone echoed through his parents' house - his mother was busy with the household chores. 'The room shook, the chimney fell, and she ran outside as the second shock came,' said Mr Wright. His father, manager of the freezing works at Pakipaki, escaped injury but found himself in an unlucky position when the quake struck. 'He stepped out on to the veranda roof over the railway siding, just as it collapsed. He described it was like coming down in a lift, except he was chased by falling bricks. Afterwards he had the grim task of organising search parties to collect the dead bodies.'
Mavis Rowe was 16 when the earthquake struck and she was working at a Shamrock Street home. 'It was a hazy, muggy sort of day. Two of us must have been up the front of the house … and there was just this awful noise. For a minute you'd think a truck had run into the house,' she said. 'It was so noisy with the house creaking and groaning and the chimneys coming down. You couldn't in your wildest dream imagine what those quakes were like. There was stuff falling all the time. I grabbed Auntie'. They found they couldn't get out of the back of the house, so they hurried back down the long hall toward the front door. But the quake had jammed the door shut. 'I was all prepared to get a shoe and break a window in the bedroom and push Auntie out. But another big jolt started and the door flew open. I pushed her down the hall and she never flew down those steps so fast in all her life!' Outside, a wooden fence was swaying down and touching a lemon tree before swaying back up again. 'I thought, the ground will open up and swallow us, but there's nothing we can do about it' she says. Across the road, a woman was calling 'my crystal, all my crystal'. Mavis said 'I thought: what does she want crystal for? It's the end of the world, she won't need that'.
This new home in Eskdale was destroyed in the 1931 earthquake (Photo courtesy of Ruth Kay)
The 1931 earthquake prompted a number of changes in New Zealand’s approach to earthquake hazard management. New construction regulations were developed so that structures would be built to minimise damage from earthquake shaking. Although construction regulations were not implemented until 1942, the government began to develop a system of earthquake insurance and compensation (which we know of today as the Earthquake Commission (EQC)), and civil defence strategies were enacted to ensure that public safety and relief would be taken care of in future earthquakes.