Large quake off the coast of Christchurch

A magnitude 5.7 earthquake has occurred at 1:13pm New Zealand time, 2 km east of Christchurch  approximately 8 km deep. So far we have received 3108 felt reports from Hawke's Bay to Invercargill. The highest level of impact from our felt reports so far has been MMI 8 in central and Christchurch. This is also shown in the coloured Shake Map to the right - which models shaking intensity in Modified Mercalli Intensity.

This quake is too small to have caused a tsunami.

Liquefaction

The highest recorded peak ground acceleration (PGA) from this quake was 0.4g (PGA is a good measure of the intensity of the shaking). For contrast, the highest recorded PGA from the February 2011 M6.3 quake was 2.2g, and in December 2011 M5.9 quake was 0.8g. Liquefaction in Christchurch often occurs when PGA is above 0.1g and we've had many stations in northern, central, and eastern Christchurch recorded PGAs above this level. This matches the reports that have been coming in of liquefaction is spots around the city.

 

Aftershocks

The last time Christchurch experienced a quake above magnitude 5 was nearly 4 years ago, with the magnitude 5.2 quake 20km east of Christchurch.

There have been aftershocks generated from this earthquake. At the time of writing (10:30am 15/2/16) there have been 105 aftershocks, the largest is a magnitude 4.2 quake, 10 km east of Christchurch.

Aftershock probabilities for the Canterbury region in the next year:

Please see the Canterbury Aftershocks page for the updated aftershock table.

 

 

 

 

What are our scientists up to?

  • InSAR (images from satellites) will be collected on Tuesday which was part of routine surveying of the region. GNS Scientist, Ian Hamling will be comparing these radar images to ones taken before the quake to look for signs of deformation caused by the earthquake.
  • GPS surveys were completed last week as part of an annual detailed campaign looking at deformation in the Central South Island. These campaigns are a collaborative effort between LINZ, University of Otago and GNS Science. Due to the earthquake, several sites near Christchurch are currently being resurveyed. This data may provide additional constraints on the deformation caused by earthquake.
  • GNS Science, in collaboration with Christchurch City Council, is organising surveys of cliff collapse and rock falls in the Port Hills this week following Sunday’s earthquake. These regions have been frequently surveyed since the Christchurch earthquake sequence began. Data will be collected by helicopter, remote controlled drones and groups of scientists and technicians on the ground.
  • GNS Science is also collaborating with EQC and Tonkin & Taylor to determine the extent and severity of liquefaction. GNS Scientist, Pilar Villamor, has been investigating historical liquefaction events to better understand why some regions, such as those along the Christchurch coast, are more susceptible to liquefaction.

As information from this work comes in, we'll let you know!

 

 

Last updated: 1:00pm, Monday 15th February 2016

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