The epicenter of the quake, initially reported as a magnitude 6.1, was in a national park area in northern Zambia close to Lake Tanganyika.
The quake, which struck at 02:32 am, could be felt across the lake in Tanzania and to the north in the neighbouring Democratic Republic of Congo, the USGS said.
It was very shallow, at a depth of only 10km, which would have magnified its effect, but a magnitude 5.7 quake is considered moderate.
Much of the impact was however felt in the Zambian town of Kapula in the western region, which lies near the borders of Tanzania and the Democratic Republic of Congo.
There are no reports of casualties although eyewitnesses say the quake has caused panic among residents of south western Tanzania.
In September last year, a powerful earthquake hit north western Tanzania, killing 16 people and causing massive destruction on infrastructure in the region.