Korea’s most damaging may have been man-made. Two investigations both conclude that the quake was caused by injections of water deep underground, as part of a project to harness geothermal energy.

The findings also suggest that seismologists’ method for estimating how big an earthquake might be caused by pumping water underground is dangerously flawed.

Several dozen people were hurt and many buildings damaged in Pohang by the magnitude-5.5 quake in November last year . It was the second most powerful earthquake in South …