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.
"I consider myself innocent before God and men," said another convicted defendant, Bernardo De Bernardinis, a former official of the national Civil Protection agency.
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," and cited the devastation wrought in the southern United States in 2005 when levees failed to protect the city of New Orleans during Hurricane Katrina.
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."
The world's largest multi-disciplinary science society, the American Association for the Advancement of Science, condemned the charges, verdict and sentencing as a complete misunderstanding about the science behind earthquake probabilities.
There are swarms of seismic activity regularly in Italy and most do not end up causing dangerous earthquakes, said AAAS geologist Brooks Hanson, deputy editor of the organization's Science magazine. He said that if seismologists had to warn of a quake with every swarm there would be too many false alarms and panic.
"With earthquakes we just don't know," Hanson said Monday. "We just don't know how a swarm will proceed."
Comments on Twitter about the verdict abounded with references to Galileo, the Italian scientist who was tried as a heretic in 1633 for his contention that the Earth revolved around the sun and not vice versa as Catholic church teaching then held. In 1992, then-Pope John Paul II declared that the church had erred in its ruling against the astronomer.
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.