Christchurch Cathedral remains in ruins after it was badly damaged during the February 22, 2011 earthquake in Christchurch..
A "damaging" aftershock has shaken Christchurch, the southern New Zealand city devastated by a shallow 6.3-magnitude quake in February 2011.
The aftershock was measured as having a magnitude of 5.2 and struck at a depth of 6.2 miles, 12 miles east of Christchurch, the Fairfax press reported, citing Geonet Rapid, which monitors geological hazards in New Zealand.
It was felt strongly across Christchurch, with one Twitter user posting that it lasted for more than 10 seconds and caused the building they were in to rock back and forth.
Last year's quake in Christchurch, which killed 185 people, lasted 37 seconds and struck at a depth of about 3 miles.
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The city was rocked again by a series of large earthquakes last December, two days before Christmas, that injured 60 people, The Sydney Morning Herald wrote.
An initial 5.8-magnitude quake was followed by a series of aftershocks, including a magnitude 6 and two more magnitude 5 or above.
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Meanwhile, Agence France-Presse reported that researchers have discovered New Zealand is even more unstable than previously thought, recording deep tremors lasting up to 30 minutes — much longer than ordinary earthquakes — along its biggest fault line.
The so-called "creeping earthquakes" are being detected along a section of the Alpine Fault, which runs the length of the South Island, according to a study led by Victoria University geophysics professor Tim Stern.
The quakes are occurring 12 to 27 miles beneath the Earth's crust. However, it's not yet known what the seismic activity means for the future risk of a sizeable earthquake.