The 1970 Tonghai earthquake occurred on 4 January with a moment magnitude of 7.1 and a maximum Mercalli intensity of X (Extreme). The strike-slip rupture originated on the Red River Fault, which had not experienced an earthquake above magnitude 7 since 1700, and affected Tonghai County, Yunnan province, China. At least 15,000 people were killed, making it one of the deadliest in its decade. The tremor caused between US$5 to $25 million in damage, felt over an area of . In Hanoi, North Vietnam, almost from the epicenter, victims left their homes as the rupture rumbled through the city.