A 5.2 magnitude earthquake has struck tonight 25km northwest of Milford Sound.
The quake was 3km deep and moderate shaking has been felt close to the epicentre.
People who felt the quake have taken to social media, describing it as a "decent jolt, and another saying windows shook in her house.
One person on Twitter posted: "Whoaaaaaaa, that's about the strongest I've ever felt in ZQN (though am up in Glenorcy in the mountains currently). Everybody in town ok?"
The quake was felt widely across the lower South Island, including across Central Otago and as far as Dunedin.
Geonet now says the quake was a moderate 5.3 with 1587 "felt reports" from as far north as Auckland.