Supported by
Why the Italy Quake Was So Severe
Dan Bilefsky and
The combination of a shallow fault and old, unreinforced masonry buildings led to widespread devastation in the earthquake that struck central Italy early Wednesday.
The magnitude-6.2 quake killed at least 241 people and left hundreds more injured. Many people were trapped in the rubble of collapsed buildings.
Like other villages and towns in the mountainous area, Amatrice, where the mayor lamented that “half the town no longer exists,” has stone churches and other buildings that were constructed centuries ago, when little if anything was known about earthquakes. Unless they have been reinforced in recent years, such structures are easily damaged or destroyed by shaking.
“Even 100 years ago, they didn’t know how to build structures to withstand earthquakes,” said David A. Rothery, professor of planetary geosciences at the Open University in Milton Keynes, England.
The earthquake was less powerful than many recent deadly quakes. The magnitude-7.8 earthquake that struck Nepal in April 2015, for instance, killing 8,000 people, released roughly 250 times more energy.
transcript
Powerful Earthquake Strikes Central Italy
A 6.2-magnitude earthquake nearly 100 miles northeast of Rome has left hundreds dead and many more injured. The mayor of one town, Amatrice, said at least half of his town was destroyed.
(SOUNDBITE) (Italian) UNIDENTIFIED ITALIAN OFFICIAL REASSURING PERSON UNDER RUBBLE, SAYING: (BEGINS IN PROGRESS) “Are you able to breathe a bit?” PERSON UNDER RUBBLE: “Only a bit.” “A bit ok. The important thing is to stay calm. Police officers are now on their way. We will try to remove this (indicating rubble). We are waiting for them in order not to hurt you, OK?” PERSON UNDER RUBBLE: “I understand, but I need to go to the bathroom (toilet).” “I know it isn’t pleasant to say this, but if you need to urinate, go ahead.”
But the Italian quake was very shallow: According to the United States Geological Survey, it occurred about six miles below the surface. “Shallow earthquakes cause more destruction than deep earthquakes because the shallowness of the source makes the ground-shaking at the surface worse,” Professor Rothery said.
Video from Amatrice and other towns near the quake center showed heaps of masonry rubble from buildings that had been shaken apart.
Earthquakes are set off by the movement of the earth’s crust, which is divided into large sections called tectonic plates. The Apennine Mountains, where the quake occurred on Wednesday, are in an area where one plate, the African, is moving under another, the Eurasian.
Because of the complex interaction between the plates, the basin of the Tyrrhenian Sea, off Italy’s west coast, is spreading. It is this spreading, and the tension it creates in the Apennines, that led to the quake.
The area of Wednesday’s temblor experienced significant earthquakes in the past, including one with a magnitude of 6.3 near the town of L’Aquila in 2009 that killed at least 295 people, injured more than 1,000 and left 55,000 homeless.
The two quakes had much in common in terms of genesis and depth,” said Massimo Cocco, a geologist with the National Institute of Geophysics and Volcanology in Rome.
After the 2009 quake, seven members of a national commission on risk prevention were arrested on charges of failing to adequately warn L’Aquila about the earthquake risk. They were found guilty of manslaughter in 2012 and sentenced to six years in prison, but they were cleared in 2014 by an appeals court.
Mr. Cocco said that Italy had anti-seismic construction laws for new buildings, but that little has been done to reinforce existing buildings.
“Resilience is just too low compared to the frequency and the high impact of natural phenomena,” he said.
Gaia Pianigiani contributed reporting.
Get news and analysis from Europe and around the world delivered to your inbox every day with the Today’s Headlines: European Morning newsletter. Sign up here.
Advertisement