In the aftermath of today's earthquake we've looked at funny tweets and seismic videos, earthquake-related eats, checked in on our local nuclear plant and gotten some tips on how to survive another one. But for a little more information on what exactly occurred today, we turned to Larry Brown, a Cornell University professor of geology in the Department of Earth and Atmospheric Sciences and the director of the Institute for the Study of the Continents.

Hi Larry, thanks for talking with us. Can you tell me a little bit about what we just experienced? Yes, it's one of those rare but very significant earthquakes that occur in the eastern United States. It is distinct primarily because it is quite large for this area. I think it may be the largest one to have occurred in the Virginia area [Ed. just about]. The fact that it occurred near Washington, D.C. sort of gets some people's attention. And the fact that it did not occur in California makes it one of those mysterious earthquakes that don't occur according to the simple tenets of plate tectonics, so it's quite an interesting event.

Should we expect aftershocks? Probably. Most earthquakes do have some sort of aftershocks after them. They could be as large as typically up to one magnitude unit smaller than the main event, which is a factor of 10, so that's quite a bit smaller. There could be some aftershocks of some size, many of them will be too small to notice.

Are aftershocks ever larger than the initial shocks? In that case the aftershock would be called the earthquake and the earlier shock would be called a pre-shock. So the big earthquake gets top billing. It's a bit of semantics here. So by definition aftershock is smaller than the earlier shock, but there are pre-shocks. We're still trying to understand the mechanics of earthquakes to understand what the linkages are between these two, so it's a little bit more than semantics. It is important to know what triggers what. There can be smaller earthquakes that trigger larger earthquakes, and to that extent, whether you call it a fore-shock and the main shock, or the main shock and a bigger aftershock, is a bit of a semantic question. What's important is, why are they linked.

Do you think there is any evidence that there is a relation between the earthquake in Colorado yesterday and the one today here? Very unlikely. There is certainly a lot of interest in remote trigger of earthquakes. Generally they relate to really big earthquakes and areas that are very tectonically active. One could conceive of some fairly unlikely series of events in which an earthquake could trigger, but it would be extremely unlikely.

Sorry for my ignorance, I know nothing about earthquakes having lived in New York my whole life... And that's why this one's interesting!

It really is. Can you tell us anything about dizziness, and why some people feel queasy after? Yeah, I think you're being shaken around, you're losing your sense of stability. The psychological impacts of earthquakes are fairly well documented. It's very unnerving to find yourself no longer on stable ground, especially if you are on an upper floor building, because the building's response will be a function of the structure of the building. It tends to be a fact that higher floors move further than lower floors, and frankly you get motion sickness. I think a lot of it's psychological. You're walking and suddenly the ground you expect to be stable is no longer stable. It can be very disconcerting.