There was a massive (Richter 8) Earthquake in Peru overnight. I recently wrote a Google Maps mashup that illustrates the relative power of earthquakes on a Google Map as they happen, the one leaves you in no doubt as to how powerful it was:
http://cuff.radioactiveyak.com/2007/08/peru-gets-hammered.html

Earthquake Mashup:
http://earthquake.googlemashups.com

I really don't understand your legend.

Sorry, I'll try to make it more clear. In the mean-time:

The three different ring colours represent today (red), yesterday (yellow), last two months (grey).

The smaller, 'dark' central circle for a quake is the damage radius – while the concentric circle with the light shading is the radius to which people would have 'felt' the earthquake.

oh ok. At first sight it seems to mean that the bigger the circle is, the older the earthquake is. [I hope this sentence is understandable]

Ahh, yes I see what you mean. I'll have to think of a way of making that clearer :)