For those trying to learn more about the recent Chilean earthquake, All My Faults Are Stress Related has a clear explanation of the magnitude vs. the intensity of earthquakes, comparing the two recent large earthquakes featured in the media in Chile and Haiti.
Please read Professor Hannula’s account, not mine: I am not a geologist, as she is. I am just trying to point interested readers to what seems a clear, simple source of information by someone with the appropriate expertise. That disclaimer in place, my reading of her words are that, briefly put, magnitude relates the amount of energy released in the event whereas intensity relates the effect at the Earth’s surface expressed in a subjective way to convey the impact felt. She reports that the US Geological Survey’s estimated maximum intensity ratings (at the time of posting) of the two earthquakes are VIII (Chile) and IX (Haiti); the higher on the scale, the more impact felt.
All My Faults Are Stress Related was previously hosted at scienceblogs.com, but seems to have reverted to a stand-alone blog. It has one of the best blog titles I know of: great word play in that title.