A magnitude 7.0 earthquake struck Northern Tibet on October 22. Chinese authorities say at least 16 people died and 76 were hurt. The latest casualty as for October 24 is at 16.
The quake hit at 10:33 p.m. local time in a sparsely populated, high-altitude area of Nagqu, about 400 km from Lhasa. That was 8:18 p.m. in Nepal. The US Geological Survey (USGS) places the epicentre about 191 km east-northeast of Nagqu, at a depth of 18 km.
Damage and relocation
Chinese official media reported that at least 339 homes and 20 livestock sheds collapsed. More than 12,000 residents were relocated to safer areas, according to Chinese state media. Authorities have warned that houses with cracked or leaning walls could fall in further shaking.
Rockfalls closed a section of National Highway 317 to ordinary traffic. Emergency and support vehicles were let through while crews cleared the debris. Communications were disrupted in some areas, and local railway authorities halted trains passing through the region as an emergency measure.
Rescue in hard conditions
Rescuers are working at high altitude in cold weather, with intermittent snow. Authorities have delivered prefabricated housing units, tents, folding beds, flashlights and winter clothing. Thousands of personnel have been sent to help with rescue and damage checks.
China’s Earthquake Networks Centre recorded 413 aftershocks by October 23. The USGS has also logged several. Aftershocks are smaller quakes that follow a large one as the crust adjusts. They can go on for days or longer and can bring down buildings already weakened by the main shock.
Why the region shakes
The Tibetan Plateau sits where the Indian Plate is pushing north into the Eurasian plate. That collision raised the Himalayas and the plateau, and it keeps building stress along faults. When the stress releases suddenly, the ground shakes.
The USGS classed this event as normal faulting within the plateau. China's centre reported a depth of about 10 km, against the USGS figure of 18 km. The difference is cause of the use of different instruments and methods by the agencies.
The USGS noted that the thinly populated area around the epicentre limits how many people were exposed to the strongest shaking. The collapsed homes and the deaths show the local effects were still serious.
A second quake on October 24
A magnitude 5.3 earthquake was recorded in the wider Nagqu region on October 24.
