South Korea shut down two of its reactors after two magnitude 5 earthquakes hit the country. I was very surprised to read that South Korean reactors are only designed to sustain a 6.5 or 7.0 earthquake. These are not very large earthquakes as compared to the ones that seem to regularly jolt Japan.
The article cites an anti-nuclear activist, Park Jong-kwon, who pointed out that reactors designed to withstand a magnitude 7.0 earthquake can be "knocked down" by a combination of smaller quakes (e.g., 4.5 and 5.8).
South Korea has 25 reactors!
Building nuclear power plants in geologically active areas was insane:
Jane Chung South Korea's biggest earthquake triggers nuclear safety concern. Reuters, http://www.reuters.com/article/us-southkorea-nuclear-quake-idUSKCN11J0R2
Korea's Meteorological Agency said the two earthquakes, of magnitude of 5.1 and 5.8, occurred near the city of Gyeongju. They could be felt in the capital Seoul, over 300 km (186 miles) to the northwest....
Nonetheless, Korea Hydro & Nuclear Power Co shut down four nuclear reactors at the Wolsong complex in Gyeongju as a precaution. South Korea's reactors are designed to withstand a magnitude 6.5 or 7.0 earthquake, according to the Nuclear Safety and Security Commission.