So does that mean the Korean Peninsula is no longer a geologically safe region from earthquakes going forward? That's scary.
Never has been: https://en.wikipedia.org/wiki/List_of_earthquakes_in_South_K...
There have always been earthquakes in Korea. They are just typically quite weak. Though the south region that is closer to Japan has experienced some intense ones, but nothing like the massive ones they have in Japan.
The entire Pacific region was full of volcanoes already. It's not a place you want to go if afraid of tectonic activity.