Firefighters search collapsed buildings for victims of the western China earthquake on April 14, 2010, in Qinghai Province's Yushu County (map of China).
Striking at 7:49 a.m., local time, the earthquake had a magnitude of 7.1, according to the state-run China Earthquake Networks Administration. As of midday, eastern time, at least 400 earthquake victims are believed dead and an additional 10,000 injured, according to Chinese state media.
The strong earthquake today was one of six magnitude 5 or higher quakes to strike along the Longmenshan fault system in Qinghai within three hours, the U.S. Geological Survey reported—the strongest such showing since 1976.
The same fault system spawned a magnitude 7.8 earthquake in May 2008, but in neighboring Sichuan Province. (See pictures of the 2008 China earthquake aftermath.) Sichuan is much more populous than Qinghai and, partly as a result, saw earthquake fatalities approaching 90,000. (See "China Earthquake Delivered Seismic One-Two Punch" .)
Both major earthquakes were symptoms of India's ongoing, slow-motion collision with Asia, which gave rise to the Himalaya. In Qinghai, the two tectonic plates slide against each other, while in Sichuan, the Indian plate dives beneath its vast Asian counterpart (more on plate tectonics).