The earthquake comes after a series of sizeable quakes around the country this week, including two moderate earthquakes near Milford Sound on Wednesday evening.
The first, a magnitude 5.5, struck about 40km northeast of Milford Sound at 6.13pm.
It was followed less than an hour later by a magnitude 5.6 quake about 35km northeast of Milford Sound.
Several smaller earthquakes were recorded in the same area afterwards.
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