Beijing: A strong earthquake measuring 6.9 on the Richter scale jolted the Nyingchi city and surrounding areas in Tibet, close to the border with Arunachal Pradesh, in the early hours today. No casualties were reported immediately but the quake caused power failure and damage to properties and roads in several villages of the region. The epicentre of the quake was detected at a depth of 10 km in Nyingchi, the state-run Xinhua news agency reported. 

Four minor aftershocks measuring between 5 and 3.1 on the Richter scale were reported from the city's rural areas. Basang Cering, party chief in Zhaxigang village of Lunang Township, told Xinhua that he could not stand still inside his house when the quake struck. Six houses in his village were damaged in the jolt. Sources with local electricity supply said the power grids of both the Tibetan province and Nyingchi are operating normally, though an emergency response mechanism has been launched. 

The China Seismological Bureau observed that the highest seismic intensity of the quake affected an area of 500 square metres, which is sparsely populated. The tremors triggered falling rocks, blocking a highway linking Nyingchi's city proper with Tangmai, one of the quake-hit townships. 

Armed police transport troops are clearing the road. The Fire Department of the Ministry of Public Security said firefighters from Nyingchi are ready in Tangmai Township. Another team of rescuers will take a helicopter to Gyalha village at the epicentre, after the road to the village was blocked by rocks. The Ministry of Transport has also dispatched staff to investigate the safety condition of bridges in the affected area. 

The Tibet subsidiaries of Chinese telecom providers China Mobile and China Tower said that their networks are operating normally. But the Tibet branch of China Telecom reported the disruption of an optical cable for broadband service in Pome and Zayul counties.