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New Zealand Disasters

Earthquakes: Wellington

When: 23 January 1855

6Where: Wellington

Summary:

In 1855 a magnitude 8.2 earthquake the most powerful ever recorded in New Zealand rocked the southern part of the North Island. Caused by movement along a fault in Palliser Bay, it altered the landscape of the Wellington region and affected its subsequent urban development.

What happened

  • Wellington settlers had experienced their first major earthquake on 16 October 1848, during a strong gale and heavy rain. It was followed by several aftershocks, causing severe damage in Wellington. 3 people died when a wall collapsed onto them. The strength of the earthquake was measured at 7.1 on the Richter scale, and was centred in the Wairau Valley, in Marlborough.
  • Six years later on 23 January 1855, Wellington was struck by a second major earthquake at 9:11 pm, which measured at 8 on the Richter scale. This was the largest recorded earthquake to have hit New Zealand.
  • At the time Wellington had a population of approximately 6000 people. The damage was extensive with timber houses as well as brick buildings collapsing. Approximately four-fifths of the chimneys in Wellington fell down.
  • Brick houses destroyed in the 1848 quake had been replaced by timber houses, but there were still some brick buildings which suffered damage in 1855. One was a two-storey hotel which collapsed, killing the owner. This was the only death in Wellington from the earthquake.
  • The Government Offices, which housed the Wellington Provincial Government, were completely demolished.
  • In the harbour, the water washed in and out in huge waves every twenty minutes by up to several metres, flooding some of the houses on the beach front.
  • In the Wairarapa three Māori died when a house collapsed on them.
  • The centre of the earthquake was in the south-west Wairarapa along the Wairarapa Fault, about 25 kilometres from Wellington, and was felt as far away as Canterbury.

How many died: 4 (1 in Wellington, 3 in the Wairarapa)

Other events and outcomes

  • One effect of the earthquake was the raising of the Wellington coastline, causing a noticeable difference in the level of up to 1.5 metres.
  • Large landslips had swept down the sides of the Rimutaka Ranges, and there were gaping fissures in the Wairarapa Plain, some up to 5 metres deep.
  • Parts of Wellington were later reclaimed when swamps partly dried out by the effects of the quake were fully drained and built on.
  • Another result of the newly-raised land in Wellington was that the shipping basin planned for the city was abandoned and the land used for a cricket ground instead - the Basin Reserve.
  • It was realised that the wooden buildings built after the 1848 earthquake had stood up to the shaking better than other constructions. When Wellington was rebuilt the main commercial buildings in the city were built of brick because of the fire risk of a wooden building, but most of the homes were rebuilt in timber.

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.

Sources

Disaster Fiction