11,000 aftershocks since Christchurch quake

More than 11,200 aftershocks have been recorded by GNS Science since the first Canterbury earthquake, two years ago today.

The magnitude-7.1 earthquake struck 11km beneath Darfield at 4.35am on September 4, 2010.

The tremor caused widespread damage across the Canterbury region but no fatalities.

Since then, thousands of quakes have rattled the region, the most damaging a magnitude-6.3 on February 22 last year, which claimed 185 lives.

In the past two years there have been 54 aftershocks between magnitude 5 and 5.9, and three between magnitude 6 and 6.9.

The size and frequency of the quakes has slowly decreased; The last tremor over magnitude 5 struck on May 25 - a 5.2-magnitude jolt off the coast, 10km east of Belfast, at a depth of 11km.

GNS Science forecast that in the year to August 2013, there is a 74 per cent probability of a magnitude 5-5.4 earthquake striking, a 32 per cent probability of a magnitude 5.5-5.9 quake, a 10 per cent chance of a 6-6.4 quake, a 3 per cent chance of a 6.5-5.9 quake and a 1 per cent chance of a 7-7.9 quake.


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