Geologists like Chuck Bailey, chair of the geology department at the College of William & Mary, are pointing to an apparent connection between increasing water weight on the surface of the Earth and seismic activity.
He joined Morning Edition Host Phil Liles to talk about that connection, and how the planet could see a rise in earthquakes over the years.
This interview has been lightly edited for length and clarity.
Phil Liles: Professor Bailey, according to new studies on climate change, and how it affects earthquakes, the connection seemed to be caused by the weight of water on the Earth's surface. Can you explain that?
Chuck Bailey: I can. As our planet's climate is changing, what we're doing is we're effectively melting water, we're taking it out of the ice caps in places like Antarctica and Greenland, and we're distributing it more broadly in the ocean, and the ocean is getting hotter.
So it's expanding, it's covering more of the Earth's surface than it had before. What that means is that extra water in the ocean basins is putting more of a load on parts of the earth that really haven't had load for a certain amount of time. It's kind of this minor effect, but it is actually happening over a lot of the oceans.
Where do our fault lines begin in Virginia? And where do they end?
Where do they begin and end? I can tell you that Virginia has got faults from one end of the state to the other. Most of them are inactive faults — that is, their faults that last slipped or had an earthquake tens if not hundreds of millions of years ago. But some of those fault zones are effectively zones of weakness: The rocks are ground up, they're pretty weak.
In the modern world, there are sometimes enough stresses that are sufficient that you actually get slipped along some of these ancient faults. And we would say that they've been reactivated.
The USGS survey suggests that atmospheric pressure caused by major storms — like hurricanes — have shown to occasionally trigger what is known as slow earthquakes. Your thoughts on that?
Another way to think about this is that when we say earthquake, we have a pretty clear picture in our mind; that would be a fault that ruptures, and immediately we have seismic waves sort of shaking, which can go from subtle to violent, which radiate out in all directions from the epicenter.
It turns out there are slow earthquakes and those slow earthquakes occur when effectively a fault zone is slipping and sliding, but it's doing that at a much more luxurious pace. That typically happens because you have enough water in these fault zones, that the pressures are such that the particles are able to slip and slide, if you will.
Those sort of slow earthquakes are things that are kind of an active recent research frontier trying to figure out exactly when and how they move. And some of them may well, especially ones that are sort of in the shallow surface, respond to changes in atmospheric pressure. I wouldn't say that's the primary driver of those, but it's possible.
What can we expect in the coming years?
I think that the simple answer to your question, Phil, is we're gonna have more climate change, and we're gonna have more earthquakes. Whether they're directly related or not is kind of a big question. We're going to continue to have earthquakes, because the processes that are driving our planet — the plate tectonic processes — are kind of always there at work.
And in certain circumstances, the stresses will build up. Faults in Virginia in places like New York or New Jersey will likely be reactivated by some of these stresses. A few weeks ago, we had a moderate-sized earthquake west of New York City that caught a lot of people's attention.
That was an ancient fault, but it was reactivated by modern stresses.
Professor Bailey as always, a wonderful, wonderful interview. Thank you for taking the time to speak with me today.
