Can someone who knows something about geology comment: is it normal for semi-large earthquakes to be correlated like this? When we went to Google News, the first thing we found were other earthquakes in Colorado and off Indonesia.
It is near 0% likely that the Colorado earthquake and Virginia earthquake are related as VA and CO are on different faults. It's not 0% because, quite frankly, it's hard to model the earth.
This wikipedia article on plate tectonics explains how the Earth crust is composed of different sections all sliding past/under each other. http://en.wikipedia.org/wiki/Plate_tectonics Since the earthquakes occur at the friction points between the plates, this should help explain why Japan and California has a lot, and Virginia and Colorado not so much.
One of the major problems humans have with earthquakes is the assumption that we should/can predict them. As such, whenever there are earthquakes close in time to one another, the first assumption is that the first earthquake caused the second. Aftershocks are such an example where this assumption holds because the primary earthquake causes secondary earthquakes. However, in the general case, this assumption does not hold.
The gravity of this situation is clear in Italy where seismologists are on trial for manslaughter for not predicting the L’Aquila earthquake: http://www.nature.com/news/2011/110526/full/news.2011.325.ht...
The open letter in support of these seismologists is here (I'm #4580): http://www.mi.ingv.it/open_letter/