Russian news agencies reported that local services were hit in the regional capital Irkutsk.
"Immediately after the tremors in Irkutsk, there were cuts in electricity, mobile connections and the internet, banks postponed work. Some houses lost roofs," reported RIA news agency from the city. "There were no victims," a spokesman for the local Emergencies Services Ministry told Reuters.
The official said the epicentre was around 30km northeast of the town of Baikalsk at 10.35am local time.
"There were no reports of serious destruction or casualties, thank God," the official said, adding that local buildings were designed to stand even stronger tremors.
He said that close to the shore of Lake Baikal, where a major pulp and paper plant is located, the tremor measured eight on the Richter scale.
Work at the plant, which environmentalists want closed, was suspended for an hour for safety checks, but had now resumed, said the spokesman.