What happened
In the early hours of 27 February 2010, local time, the subduction zone off the Maule region ruptured, north of the 1960 earthquake area. The shaking damaged hundreds of thousands of homes, roads and bridges, including in Santiago and Concepción. The tsunami flooded coastal towns and the Juan Fernández Islands. About five hundred people died – relatively few for such a powerful earthquake, which is credited to Chile's building codes. GPS measurements showed that Concepción moved about three metres to the west.
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 (official20100227063411530_30) · Wikipedia (pl) · Wikipedia (en)