The tremor was felt strongly on the island and followed a 6.9 quake on Sunday (August 5) that killed at least 131 people and damaged thousands of houses.
Aid workers said that they were alarmed and ran out of their cars when they felt the aftershock hit the island. A witness said the latest tremor also sent people into the streets in a panic and caused buildings to collapse.
Spokesperson for the Disaster and Mitigation Agency (BNPB) Sutopo Purwo Nugroho classified this as an aftershock as the epicentre of the tremor happened in same segment as the previous quakes.
He also tweeted there was no potential for a tsunami.