"It's a sad day for science," said seismologist Susan Hough, of the U.S. Geological Survey in Pasadena, Calif. "It's unsettling." That fellow seismic experts in Italy were singled out in the case "hits you in the gut," Hough said.
In Italy, convictions are not definitive until after at least one level of appeals, so it is unlikely any of the defendants would face jail immediately.
Other Italian public officials and experts have been put on trial for earthquake-triggered damage, such as the case in southern Italy stemming from the collapse of a school in a 2002 quake in which 27 children and a teacher were killed. But that case centered on allegations of shoddy construction in quake-prone areas.
State TV noted that this was the first time prosecutors had brought a case based on the failure to predict an earthquake.
Among those convicted Monday were some of Italy's most well-known and internationally respected seismologists and geological experts, including Enzo Boschi, former head of the National Institute of Geophysics and Volcanology.
"I am dejected, desperate," Boschi said after the verdict. "I thought I would have been acquitted. I still don't understand what I was convicted of."
The trial began in September 2011 in this Apennine town, whose devastated historic center is still largely deserted.
The defendants were accused in the indictment of giving "inexact, incomplete and contradictory information" about whether small tremors felt by L'Aquila residents in the weeks and months before the April 6, 2009, quake should have constituted grounds for a quake warning.
The 6.3-magnitude temblor killed 308 people in and around the medieval town and forced survivors to live in tent camps for months.
Many much smaller earth tremors had rattled the area in the months before the quake, causing frightened people to wonder if they should evacuate.
Prosecutors had sought convictions and four-year sentences during the trial. They argued in court that the L'Aquila disaster was tantamount to "monumental negligence."
Relatives of some who perished in the 2009 quake said justice has been done. Ilaria Carosi, sister of one of the victims, told Italian state TV that public officials must be held responsible "for taking their job lightly."
Defense lawyer Filippo Dinacci predicted that the L'Aquila court's verdict would have a chilling effect on officials tasked with protecting Italians in natural disasters. Public officials would be afraid to "do anything," Dinacci told reporters.