An unexploded World War II bomb detonated at Miyazaki Airport in southwest Japan, damaging a runway and canceling over 80 flights, though no one was injured.

The explosion created a 23-foot-wide crater, and bomb disposal experts confirmed it was a 500-pound American bomb likely dropped during the war.

The airport, built in 1943 by the Imperial Japanese Navy, has seen unexploded ordnance before. The cause of the bomb’s sudden explosion after over 70 years is unknown, USA Today has reported.

The airport is set to reopen on Thursday, and unexploded bombs remain a common discovery in Japan.

Written by B.C. Begley