M6.5 Earthquake Near Blenheim, NZ

john's picture

A magnitude M6.5 earthquake has just occurred (2:31 UTC) near Blenheim, NZ, a town on the northern end of South Island, just across the Cook Strait from Wellington. At a depth of only 9.9 km (6.2 miles), and only 22 km from Blenheim, there could be considerable damage, depending on the quality of construction. 

This earthquake occurred just 30 km to the southwest of the M6.5 earthquake that occurred in the Cook Strait on July 21.

That event did no major damage.

A quick analysis from the Hazard Viewer tool on this web site indicates a probability at the time of occurrence for M>6 events within 100 km of the Cook Strait was about 10% for the next year. 

Screenshots of the Viewer and a table of probabilities are attached. 

The probability rises rapidly to 66% over the next 3 years for M>6 in that circular region.

New Zealand has suffered the effects of several major earthquakes over the past 2 years. 

The M7.1 Canterbury earthquake of September 4, 2010, and the M6.3 Christchurch earthquake of February 22, 2011, did major damage to the city of Christchurch.

Estimates of the total insured damage from those events are as high as $30 Billion USD.  It may be decades before New Zealand fully recovers from these events [1].

Further calculations using the ground shaking tool indicate that shaking probably reached Mercalli Intensity VII in Blenheim, as large as 25%g for Peak Ground Acceleration.  Shaking of this magnitude can do considerable damage.

Early news reports indicate that the event was widely and strongly felt in urban areas including Wellington.


[1] http://en.wikipedia.org/wiki/2011_Christchurch_earthquake


DavidAlexander's picture

This is really sad news to hear that the earthquake is occured in near Blenheim. I have read the reviews about this tool in ninja essays which is effectively recognise the earthquake. I hope the goverment should help the people to provide exgracia.

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