GWEN IFILL: Our lead story. A powerful earthquake in the mountains of central Italy killed more than 150 people today, flattening entire towns. The 6.3 magnitude quake was centered near L’Aquila, northeast of Rome.
Italian officials said as many as 100,000 people in the region may have been left homeless.
We have a report from Robert Moore of Independent Television News.
ROBERT MOORE: In a tragedy that has in every sense shaken this ancient town to its core, these are the rare moments to treasure. This man was pulled from the rubble by rescuers. His relief, his reaction to the knowledge he had cheated death was overwhelming.
For the exhausted crews who had worked for three hours here, it was a glimmer of hope, that there might be more stories that could unfold.
And a few hours later, we watched similar scenes of a four-story apartment block that had collapsed. Local people and firefighters at times using their bare hands. So great was the need for care as masonry was removed. At least three people were trapped but miraculously alive under the shattered concrete.
One woman, Francesca, was found with just a broken shoulder. She was taken to an ambulance amid chaotic scenes. A photo of Francesca, recovered from the ruins, shows one of the luckiest people alive.
It’s 12 hours since the earthquake struck and hours since Francesca was rescued from this very building. And still there’s hope for more survivors, but as always it is a battle against the odds and against the clock.
So we waited for the rescue of another woman called Claudia, but suddenly the faces around us told the story. Relatives crying. Rescue workers using a bed sheet to cover the scene. This young 22-year-old another victim of an earthquake that had shattered this town in the darkest hour of the night.
Dozens of people have been saved thanks to an epic rescue effort that began within minutes.
L’Aquila has faced tremors and earthquakes over the centuries. But how can a family truly prepare for a moment like this?
Fifteen thousand buildings are damaged, including the city’s hospitals. It forced paramedics and hospital staff to work outside, to improvise emergency care as best they could.
And all around them are signs of the forces at work when an earthquake strikes, not just the images of destruction best viewed from the air, but look at this gaping hole in the ground, swallowing one car, leaving another on the edge.
Local residents uniformly speak of a terrible noise, of a 30-second tremor, and then the race for their lives out of buildings and on to the streets.
The death toll is proving very difficult to calculate, for┬ábeyond this historic city are outlying villages where the destruction is still being assessed. The redeeming feature we witnessed here is the scale of the rescue effort and the determination of the emergency teams to keep looking for survivors.
L'Aquila directly above fault
GWEN IFILL: For more about what may have led to today's seismic upheaval, we're joined by David Applegate, senior science advisor for earthquake and geologic hazards at the U.S. Geological Survey.
Welcome, Mr. Applegate.
DAVID APPLEGATE, U.S. Geological Survey: Thank you.
GWEN IFILL: So let's compare to what we've seen in recent years. How big an earthquake, how major an earthquake, how unexpected an earthquake was this?
DAVID APPLEGATE: Well, in terms of -- for example, the China earthquake that struck in May of this past year, this is a considerably smaller earthquake. It ruptured a much shorter piece of the Earth's crust.
Unfortunately, for the city of L'Aquila, it was basically directly under it. And that is the key, is it's the location of the earthquake relative to the population.
In terms of it being unexpected, Italy is very geologically active. Of course, it's a land of volcanoes. It's a land of earthquakes. There was an earthquake not terribly far away, about 90 kilometers away, close to Assisi, in 1997 that did irreparable damage to the basilica in that famous town.
Importance of building codes
GWEN IFILL: Is it the mountainous region that we're in here where this happened that contributes to it in some way?
DAVID APPLEGATE: Actually, the mountains are there because of the plate collision process. The Earth's tectonic plates, in this case the plate of Africa, colliding up against the European plate, that kind of a collision zone is where we get most of the tectonic activity, most of the earthquakes.
Italy is one of the most geologically complex locations. Not only do you have these two giant plates coming, but you also have parts that are trying to squeeze out to either side. And that's why you have this big backbone that's essentially running straight down the axis.
GWEN IFILL: Which are the mountains.
DAVID APPLEGATE: Which are the mountains. So the mountains are there because, you know, the earthquakes and the mountains are directly linked.
GWEN IFILL: So is it possible that seismic activity happens there all the time and people just don't notice it or they don't take full appreciation of the warnings?
DAVID APPLEGATE: Well, certainly, small earthquakes are happening quite frequently. And these larger earthquakes -- this is the challenge that earthquakes happening not on this sort of human timescale.
We tend to focus on the most immediate problems, but this is the emphasis, you know, preparedness. And, of course, as we've seen, the importance of having building codes so that you have buildings that can withstand the kind of shaking that can be expected and, indeed, in this situation is expected.
GWEN IFILL: A building code in an area where the buildings are hundreds of years old.
DAVID APPLEGATE: Absolutely. One of the things that was disturbing was to see damage to some of the more recent structures in addition to, for example, I saw accounts of a dormitory and several other structures where the codes could have been in place. With the older structures, then the emphasis is on retrofitting. And a big challenge there is cost.
Computer imaging helps responders
GWEN IFILL: What can you tell us -- I mean, now we have access to computer imagery and being able to look at great distances at small places. What can you tell us, based on that, on the extent of the damage here beyond just this town we're all focused on right now?
DAVID APPLEGATE: Well, what we try to do in the wake of any damaging earthquake is as fast as possible to give as much information to the people who are trying to respond to it.
So we look at -- we'd actually make a model of what is the shaking intensity that can be expected and overlay that against population. In this case, the town of L'Aquila was, you know, 68,000 people exposed to severe shaking.
So within a few minutes of the earthquake, that information can be provided to the aid agencies, to the response agencies, whereas otherwise, you know, this was in the middle of the night. Communications may be out. It may be a, you know, certain amount of town before people know that this is a humanitarian disaster.
And that's what -- we're trying to use the best technology we can with our global network of seismometers and other capabilities to get the information quickly so that aid can be brought in as fast as possible.
Shallow quakes are more destructive
GWEN IFILL: Is there a single -- we're used to in our country hearing reports about what happens along the San Andreas Fault. And we learned a lot about what was happening in China last year. Is there a single risk factor that you could point at in a place like Italy that you could say, "Well, they were living right on the fault; this was going to happen sooner or later"?
DAVID APPLEGATE: One of the big challenges is that there -- especially in a geologically complex place like Italy, there are an awful lot of faults. This particular fault that it appears to have taken place on was a known structure, but some of the biggest earthquakes that we've had, for example, the one under Los Angeles in 1994, it's what we call a blind thrust. The fault doesn't even come to the surface. But, of course, the shaking does come up to the surface.
So what we look at is, what's the probability over longer time periods of an earthquake, of shaking, strong shaking, happening? And that's what we turn into seismic hazard maps, and that's what, in turn, can underpin good building codes.
GWEN IFILL: And the terminology is that a shallow earthquake is a bad earthquake?
DAVID APPLEGATE: That's right, because all of the energy is going to be concentrated right up towards the surface. The deeper the earthquake is -- you could have a very large magnitude earthquake, but if it's far from the surface, well, all of that energy is going to be dissipated before it reaches the surface.
This one was shallow. It was only a few miles deep. And, unfortunately, it was very close to these populated areas.
GWEN IFILL: David Applegate of the U.S. Geological Service, thank you so much.
DAVID APPLEGATE: Thank you.