The US Geological Survey said it recorded a 6.9 tremor of the Sumatra.
The epicentre was located at Pematangsiantar, about 126 kilometres southeast of the island’s capital Medan. The quake stuck at a depth of 183 kilometres.
There was no tsunami threat and no initial reports of damage or casualties there, according to BMKG.
It comes 12 hours after an earthquake of magnitude 7.7 and dozens of aftershocks struck off eastern Indonesia, killing at least 40 people and injuring 40 others.
Suharyanto, the head of Indonesia’s national disaster mitigation agency, said earlier that people were trapped in several buildings.
“These will be the initial targets of the disaster response teams,” said Suharyanto, who, like many Indonesians, uses one name.
Two helicopters and a plane were being readied to assist in rescue operations. (AFP)
