A magnitude-6.1 earthquake has rattled north-eastern Japan but no tsunami warning has been issued.
There have been no immediate reports of casualties or damage to property.
The seismic centre of the quake that jolted the region at 6:23am (local time) on Thursday was off Fukushima prefecture, the Japan Meteorological Agency said.
On Monday, a magnitude-7.4 quake rocked the same region, generating tsunami waves of up to 1.4 metres.
A tsunami warning prompted thousands of residents to evacuate their homes.
In March 2011, a magnitude-9 quake and resulting tsunami struck the same region, claiming the lives of 18,500 people and causing Japan's worst atomic accident at the Fukushima Daiichi Nuclear Power Station.
Earthquake-prone Japan sits at the convergence of four tectonic plates. The country is also home to 110 active volcanoes.
