To the northeast of the Idosawa Fault complex lies a separate normal fault trace , which was named the '' ' Yunodake Fault ' '' ( also '' ' Yunotake ' '' ) in 2011 . Distanced approx. 50 km ( 30 mi ) from the Fukushima Daiichi Nuclear Power Plant , the fault had been dormant for 120,000 &ndash; 130,000 before it ruptured during the magnitude 7.1 Mw Fukushima Hamadori earthquake on 11 April 2011 . Several geological surveys have since been conducted in its vicinity . Evidence of sedimentary rock layers deposited after the Late Pleistocene beneath the fault suggests that the Yunotake Fault had been in the active in the past
magnitude 7.1 Mw Fukushima Hamadori earthquake
April 2011 Fukushima earthquake
Idosawa Fault