Kara Capelli: Welcome to USGS CoreCast. I'm Kara Capelli and today, I'm here with Harley Benz, Scientist-in-Charge of the USGS National Earthquake Information Center. We're here to talk about the Magnitude 8.8 earthquake that struck Chile on February 27. Harley, why was there so much less damage in Chile than in Haiti when the earthquake there was about 500 times larger?
Harley Benz: Well, I think for a couple of reasons. I think the Chileans have a long history of large earthquakes across their 3,000-kilometer coastline. And so there's an awareness in Chile of the potential for large damaging earthquakes. Particularly following the 1985 earthquake which was near Valle Paraiso, I think the Chileans started investing heavily into modern building codes and modern infrastructure so that the country could withstand or be more resilient to these earthquakes.
And so, they minimized the loss of life because they were prepared to these large earthquakes. They built to a much higher standard and you see this in a smaller loss of life.
Kara Capelli: And thinking about the lessons in importance of preparation, where are the major earthquake hazards in the United States?
Harley Benz: The earthquakes hazards in the United States are primarily a western issue, although we have the well-known New Madrid earthquakes of 1811-1812. So we do have hazards in the Eastern US and Central US, but it's primarily in the Western US which is tectonically and seismically active.
Earthquake hazards are real in the US and interestingly, Chile has strong analogs to earthquake hazards in the Pacific Northwest and Alaska. So much of what we can learn from Chile, we can use to better understand the hazards in the Pacific Northwest and Alaska.
Kara Capelli: So if there were to be a major earthquake in one of these areas, does the United States have the systems and the building codes in place to mitigate the damage in these areas?
Harley Benz: Well, we would hope so. And I think with every earthquake that we have or we see damage, the engineering community learns a lot more about construction practices, and US is good about implementing and revising its building codes associated with earthquake hazards and risks.
And so each earthquake that we monitor and each earthquake that we look at in terms of the size of the earthquake and the damage, we learn. And that's why for the USGS looking and studying this recent Chilean earthquake is really important because we can learn something about what we have to do to put into practice in this country to make the community and the population more safe to hazards because we have very similar kinds of geologic structures under which will eventually have an earthquake.
Kara Capelli: So switching gears a little bit, Harley. I think a lot of people are probably wondering why so many earthquakes in such a short period of time? Are we seeing an increase for a reason? And has there been an increase in major earthquakes worldwide?
Harley Benz: Well, in any given year, we expect to have about 15 Magnitude 7.0 earthquakes per year and we have about one Magnitude 8.0 or larger per year. So given that perspective, we should expect about one Magnitude 7.0 earthquake worldwide, roughly once every month.
So the Haiti earthquake itself was not unexpected and where it happened. There's a long history in that part of the world of documented large earthquakes. Likewise in Chile, they have some 1500 documented large earthquakes over much of its 3,000-kilometer coastline.
So I think where these two earthquakes occurred and the size of these earthquakes was not unexpected. Are they related? Probably not. And did one trigger the other? We simply don't know but I expect that what we are just watching natural geological processes playing out off the coast of Chile and the northern portion of the Caribbean.
Kara Capelli: So what kind of follow-up research will the USGS be doing in Chile?
Harley Benz: Well, the kinds of research that the USGS is interested in following the Chilean earthquake is we'd like to understand the size of this earthquake, which direction did it come, the kinematics of the rupture, how long of the subduction zone ruptured, what was the distribution of slip along this entire rupture zone, look at the distribution of aftershocks. So trying to understand the physics of these very large earthquakes is fundamentally important to the USGS.
Likewise, understanding the damage that was produced from this is really important. What types of structures survived this and which ones didn't? And the distances from this very large earthquake and aftershocks, how far away do we see significant ground shaking and how well did the buildings respond.
So there's going to be lot of lessons learned from this earthquake in terms of engineering practices that we can adopt in the United States. And also, we just don't have a lot of these mega-earthquakes globally, so anything we can learn about the physics of these things becomes really important.
So we will be looking at this for a long time, both to understand the source of these earthquakes and also lessons learned from an engineering perspective.
Kara Capelli: Well, Harley, thank you so much for being here.
Harley Benz: You're welcome.
Kara Capelli: This CoreCast is a product of the US Geological Survey, Department of the Interior. Thanks for listening.