A magnitude 4.0 earthquake was detected by seismic measuring systems near Oliver, B.C., on Saturday morning, with people near the town feeling "sustained shaking" for up to 25 seconds.

Oliver is located in the south of the Okanagan Valley. The quake was centred 21 kilometres east of the town.

People from Grand Forks, B.C., and Washington State — up to 150 kilometres way — felt the shudder.

Earthquakes Canada initially reported the preliminary magnitude at 4.3, but has since reassessed the quake.

The USGS rates the magnitude at 4.2, saying it was triggered five kilometres underground.