16 Jul 2009

Southlanders can't believe quake has left them unscathed

9:22 pm on 16 July 2009

Southlanders can't believe it. They've just experienced New Zealand's biggest earthquake since the Napier quake of 1931, yet hardly any damage was done. And there's not one report of injury.

Invercargill residents report swinging lights, sloshing tankwater and bottles rattling in pubs, while Inspector Olaf Jensen says the police station got "a good shake". Goods were also knocked off shop shelves in Tuatapere.

Some power and phone lines went down, affecting a small number of houses in Invercargill and Te Anau, but they were soon fixed.

Otherwise, apart from a few landslips in Fiordland, nothing. Yet this was the world's strongest earthquake so far this year, triggering a tsunami alert (which came to nothing, or rather, to a wave 17cm high) and putting Australia and the Pacific on standby.

Like the Napier quake, which killed 250 people, and the Murchison quake of 1929, the one that shook Fiordland at 9.20pm on Wednesday measured 7.8 on the Richter scale. Its epicentre was 12km beneath Dusky Sound.

Within the next 24 hours seven major aftershocks were recorded, including a 5.6er 100km northwest of Tuatapere at 6.30pm Thursday. (A 6.1 quake was also recorded off the coast of Papua New Guinea at 10.44am Thursday.)

The Insurance Council said Thursday afternoon that claims relating to the quake had been minimal - which Civil Defence attributes to the building code and recent investment in infrastructure - but that Southland residents should still check their homes for any damage.

Meanwhile, the Department of Conservation has advised anyone planning a trip to Fiordland National Park to wait until safety checks have been carried out. DoC has been using a helicopter to check on trampers already in the park.

It's also keeping watch for possible landslips on Resolution Island, near the epicentre of the earthquake.

The Transport Agency and the Southland District Council have been assessing roads and bridges.

Why it didn't cause major damage

GNS Science seismologist Bill Fry says the quake, which was felt as far away as Taranaki, did not cause major damage, as the Napier one did in 1931, because the latter occurred in a densely populated area and in different terrain.

The biggest earthquake in recorded New Zealand history was an 8.2 one in Wairarapa in 1855. One person was killed by it.