Invoked comment.
I think it was an aftershock of The 7.6 on the 10th in the same area.
South American, Antarctic, and Scotia plates meet in the Drake Passage. There are parallel running fault zones.
Most active is The Shackleton Fracture Zone, which I've just looked up is the southern transform boundary of the Scotia plate. Which is actually a "transpressional fault zone" (Boundary + Strike slip + Compression).
The quakes here are usually on faults resulting from The South American Plate and The Antarctic Plate squeezing and fracturing the Scotia Plate.
Depending on which fault zone, its likely a strike-slip fault. There is some subduction in the southwest boundary and Eastern boundary, but it's an extremely complex system of faulting, micro plates, and continental plates move at varying speeds.
It would take too long to explain.
It happened in a VERY active area for quakes between 6 and 8 Magnitide though.
And when they happen they are mildly felt or damaging to any human population.
I think there was Tsunami warning, some coastal evacuation for The main shock 7.6, but otherwise Chileans called it Viernes. It was felt in the MMI II to MMI III range in the closest major city of Punta Arenas. Most wouldn't have felt it.
Chile mocks most peoples earthquakes. They get an 8.5+ megathrust every 80 years or so. And a 7.0 or greater every 22 months. And this one doesnt even count as Chile.