An earthquake in Fiordland measuring 7.8 on the Richter scale rattled the South Island and sparked a 90-minute tsunami alert last night.

Though the quake appears to have caused little damage, an alert from the Pacific Tsunami Warning Centre in Hawaii was issued for southern New Zealand soon after it struck at 9.22pm, 100 kilometres north-west of Tuatapere in Southland.

The earthquake was estimated to be approximately 12 kilometres deep, and was followed by two sizeable aftershocks, the first of a 6.1 magnitude 20 minutes later, and the second measuring 5.9 just before 2am.

Though both quakes were far from any towns, phones went down in east Invercargill power was out in Otatara, and a water main was broken in Winton, north of Invercargill.

The quake was felt strongly in Dunedin, Invercargill and Timaru, and Christchurch residents have reported feeling it as a long, rolling motion. People as far north as Wellington are said to have felt the earthquake to a lesser extent.

At 7.8 on the Richter scale, last night’s quake in Fiordland was among the second largest earthquakes records in New Zealand since European colonisation. The only one to top it was the 8.2 magnitude quake in Wairarapa on January 23, 1855.

One of New Zealand’s most famous earthquakes, also measuring 7.8, was in Napier in 1931, and caused the largest loss of life and most extensive damage of any recorded New Zealand quake.

News of last night’s earthquake was quickly picked up by world media, with reports appearing within the hour on BBC, CNN and Sky News websites.

For more information on New Zealand earthquakes check out the seismology category on NZS.com.

Significant events can have an impact on people everywhere in New Zealand…

The earthquake that shook Gisborne yesterday measured 6.6 on the Richter Scale and was felt in the lower North Island and upper South Island. The quake was centred fifty kilometres offshore and forty kilometres deep.

Fallen chimneys, weakened foundations and damaged buildings resulted from the quake last night, frightening residents and sending many running for cover. An elderly woman died shortly after the quake and eleven people were reportedly injured. Many buildings remain closed today, as their safety is assessed.

The wide-reaching effects of such an event can even be seen on our very own site…

Today’s top sites on NZS.com show users are keen to find Gisborne websites and information on earthquakes and seismic activity in New Zealand. These sites all made it to our top ten sites today:

• Gisborne radio
• Current New Zealand earthquake information
• Gisborne Herald newspaper online

Find the latest New Zealand news updates and information on the Gisborne earthquake online.

The earth moved for South Islanders in the early hours of this morning.
An earthquake measuring 6.7 on the Richter scale shook Southland. While there were no reports of injury or damage, the quake was felt strongly across the South Island. GNS Science duty seismologist Mark Chadwick said the quake, which struck at 1.29am, was centred 60km from Milford Sound at a depth of 24km. A 4.6 magnitude aftershock followed at 2.50am and a second aftershock was felt at 6:34am. There was no risk of a tsunami, although further aftershocks are likely over the next couple of days.

As Carl’s earlier post mentioned, Geonet provides up-to-date information on New Zealand quakes – here they keep us clued up on the most recent earthquakes, including today’s shake-up and aftershocks. They operate a nationwide network of seismic stations that transmit their data to the GeoNet Data Management Centre (DMC) where it’s analysed by automated processes. The information is released to the public if the Duty Officer confirms that the earthquake is real and significant.

They’re clever with their seismic reporting after the event, but will they be able to predict a big quake?
As Wikipedia, the great equalizer, tells us: “the reliability and reproducibility of prediction techniques have not been established.” So it’s unlikely that we’ll be warned before a big one strikes, although seismologists can calculate the probability that a quake will occur in a particular location. And when the earth experiences a flurry of seismic activity, there’s no need to panic; a ’swarm’ of earthquakes doesn’t necessarily indicate a high-magnitude quake is on the way. You may be comforted or frightened by this fact, but GeoNet records around 15,000 earthquakes in and around New Zealand each year, only 250 of which are big enough to be felt.

Read more about NZ earthquakes, but don’t get too shook up about it!

There’s no escaping earthquakes in New Zealand. Even the Chatham Islands is susceptible to them. Small earthquakes happen every day in New Zealand, but most are not felt. Larger earthquakes (above about Magnitude 3.0) are recorded by GeoNet and usually make it onto their website within a few minutes, showing the time, location, depth and magnitude. This lets you know whether it was a small earthquake close by, or a whopper a long way away. You can even help them with their research by telling them if you felt it or not.