What happened
On the afternoon of 12 May 2008, local time, the Longmenshan fault at the boundary of the Tibetan Plateau and the Sichuan Basin slipped along about 250 kilometres. Mountain towns such as Beichuan and Yingxiu were almost entirely destroyed, and landslides blocked rivers, creating dangerous quake lakes. About 69,000 people died and more than ten thousand were listed as missing. The collapse of many schools sparked a debate in China about construction quality.
How to read these data
Magnitude measures the energy released at the focus: each step is about 32 times more energy, so an M 9 earthquake releases about a thousand times more energy than an M 7. Its effects, however, also depend on focal depth, distance to cities, ground conditions and building quality – a shallow M 7 beneath a city can be deadlier than a deep M 8 under the ocean.
Data: USGS ComCat (usp000g650) · Wikipedia (pl) · Wikipedia (en)