After the Pohang earthquake a few years ago, I started worrying about earthquake safety in my Korean apartment?

Korea is moderately seismic, less active than Japan but not earthquake-free, as the Pohang and Gyeongju quakes showed. Building safety has improved a lot: seismic design standards have been tightened over the years and now apply broadly to new and larger buildings, so most modern apartments are built to withstand moderate quakes, though older low-rise buildings and villas from before the standards are more of a concern. If you are worried, you can ask whether your building meets seismic design standards, and newer high-rise apartments are generally a safer bet. During an earthquake, the standard guidance is to drop, cover, and hold on: get under a sturdy table, protect your head, and stay away from windows and heavy furniture, then when the shaking stops, turn off the gas, open a door to secure an exit, and move outdoors to an open area away from buildings using the stairs, not the elevator. Do not rush outside while it is still shaking. Secure tall furniture to walls as a precaution, keep an emergency kit with water, a flashlight, and documents, enable emergency alerts on your phone, and check the Emergency Ready app, which has some English. Call 119 for emergencies.