Southern quakes a concern

A GNS seismologist is ‘‘quite concerned’’ by the increased number of earthquakes in the south during the last fortnight, but there is no need to fear monger, he says.

There have been 10 quakes in the vicinity of Milford Sound and Te Anau in the past 15 days, according to the GeoNet website.

Seismologist Dr Bill Fry said the quakes had been small compared to a massive 7.8 magnitude quake in Fiordland in 2009.

‘‘There’s concern [but] there’s no need to fear monger,’’ he said.

Earthquakes could not be predicted because of the ‘‘chaotic system’’.

‘‘We are between the Pacific and Australian plates and they are converging quite fast and this has to be accommodated through earthquakes, and that’s why we have them across the country.’’

‘‘We do know when you have earthquakes there’s an increased chance of another bigger earthquake, but the chance is still very small.’’

The 7.8 quake in Fiordland in 2009, which was 12km deep, was felt in Fiordland, Queenstown, Gore and Invercargill, with power briefly cut in some areas and supermarkets reporting stock falling off shelves.

The United States Geological Survey website put the quake’s epicentre underneath Resolution island in Dusky Sound.

Fry said the small quakes in recent weeks were a reminder that people should be prepared in the event a big one did strike.

‘‘It’s a great reminder for people to have earthquake kits and discuss their plans with family, friends and neighbours. If there’s a silver lining, that’s it.’’

Emergency Management Southland manager Angus McKay, speaking at a Southland Civil Defence emergency management group meeting in February, updated city leaders on preparations to deal with a predicted Alpine Fault rupture, which is forecast to be 30 times bigger than the Kaikoura earthquake.

Given the Alpine Fault has historically ruptured three times every thousand years, and the most recent one was in 1717, scientists believe there is a 30 to 50 per cent chance the rupture will happen within the next 50 years, McKay said.

The EQC website says essential services to a home may be disrupted when natural disaster strikes, and the electricity and water supplies may be cut off and roads damaged.

Supplies at the ready, and in an easy-to-find location, should include warm clothes, blankets, food and drinking water for at least three days, torch, batterypowered radio, first-aid kit and gas cooker.

Recent earthquakes in the south:

A magnitude 4.2 quake at a depth of 5km 30km north of Milford Sound on September 22 at 7.02am.

A magnitude 4.3 quake at a depth of 5km, 45km north of Milford Sound on September 21 at 7.47am.

A magnitude 2.7 quake at a depth of 5km, within 5km of Milford Sound on September 14 at 6.23pm.

A magnitude 3.9 quake at a depth of 2km, 30km north-west of Milford Sound on September 14 at 5.23pm.

A magnitude 3.4 quake at a depth of 11km, 10km north-east of Milford Sound on September 13 at 11.39pm.

A magnitude 3.9 quake at a depth of 26km, 70km west of Te Anau on September 11 at 8.56pm.

A magnitude 3.6 quake at a depth of 5km, 30km north-west of Milford Sound on September 9 at 3.32am.

A magnitude 4.6 quake at a depth of 5km, 60km north-west of Milford Sound on September 9 at 1.09am.

A magnitude 4 quake at a depth of 34km, 40km north-west of Te Anau on September 8 at 9.44am.

A magnitude 4.3 quake at a depth of 96km, 15km north-west of Te Anau on September 7 at 7.23pm.

Source: GeoNet.