Alpine fault quake, Geonet issue swarning

@Geonet:

M5.5 quake north-east of Milford Sound, 5 km deep at 3.24am. This quake was largely felt in the Queenstown and Wanaka areas, with over 600 felt reports submitted. Our duty seismologist can confirm that this quake looks to have occurred on the Alpine Fault

This fault system has the potential for larger events and we would like to make sure that you are prepared for a large earthquake at all times. Follow ‘s advice for preparing yourself, ‘s advice for preparing your home and for more

There were three quakes recorded this morning:

  • 5.5 – 3:24 am, 40 km north-east of Milford Sound
  • 3.9 – 3:33 am, 40 km north-east of Milford Sound
  • 3.9 – 3:35 am, 40 km north of Milford Sound

The depth of all three was 5 km – that’s shallow.

When I woke up to feel the first Christchurch earthquake (4 September 2010) my first thought after WTF was whether it was ‘the big one’ expected some time on the Alpine Fault.

I felt the next Christchurch quake (22 February) while at work, and a few aftershocks as well. Even from a distance they are quite disconcerting. Best to be prepared for them, as in many parts of New Zealand Earthquakes are inevitable.

Civil Defence: Preparing for an earthquake

Before an earthquake

During an earthquake

After an earthquake

New Zealand lies on the boundary of the Pacific and Australian tectonic plates. Most earthquakes occur at faults, which are breaks extending deep within the earth, caused by movements of these plates. There are thousands of earthquakes in New Zealand every year, but most of them are not felt because they are either small, or very deep within the earth. Each year there are about 150 – 200 quakes that are big enough to be felt. A large, damaging earthquake could occur at any time, and can be followed by aftershocks that continue for days or weeks.

GNS details on the Alpine Fault

The Alpine Fault, which runs for about 600km up the spine of the South Island, is one of the world’s major geological features. It’s the “on-land” boundary of the Pacific and Australian Plates.

This fault has ruptured four times in the past 900 years, each time producing an earthquake of about magnitude 8. Approximate rupture dates are 1717AD, 1620 AD, 1450 AD, and 1100 AD. Recent research (published in 2012) by GNS Science has extended our knowledge of the Alpine fault earthquake record back through the past 8000 years. Click here for more details of these findings.

 

 

Leave a comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: