Four top Italian disaster experts quit their posts Tuesday, saying the manslaughter convictions of former colleagues for failing to adequately warn of a deadly 2009 earthquake means they can't effectively perform their duties.

A court in the quake-devastated town of L'Aquila convicted seven former members of Italy's so-called "Great Risks Commission" and sentenced each of them to six years in prison, prompting predictions that experts would be discouraged from working in Italy for fear of similar risks of prosecution.

Commission President Luciano Maiani and two other members resigned, along with a top official for earthquake and volcano risk in the national Department of Civil Protection. Maiani said Monday's court ruling made it impossible to work in a "calm and efficient" way.

Prosecutors alleged the defendants — who included some of Italy's most internationally respected quake experts — didn't properly inform town residents of the risk of a big quake following weeks of small tremors. But scientists have ridiculed the case, saying earthquakes cannot be accurately predicted. The convictions are expected to be appealed.

With the verdict, "we understood why the Great Risks Commission has that name," a front-page commentary began in Corriere della Sera, a Milan daily. "The great risks are those to its members, as one deduces from the verdict."

Senate President Renato Schifani has called the convictions and prison terms "strange, embarrassing."

Many scientists and commentators have noted that the court case failed to address a major cause of fatalities in disasters like quakes and mudslides: erecting homes, schools, hospitals and other public buildings on quake-prone terrain without the proper construction techniques or materials to make the structures more resilient.

After the April 2009 quake, which left 308 people dead, many experts said that the 6.3-magnitude temblor wouldn't have caused such extensive damage if buildings been constructed or retrofitted to meet modern quake zone construction standards.

In Washington, the American Geophysical Union described the verdict and prison sentences as "troubling," and expressed concern that they could "ultimately be harmful to international efforts to understand natural disasters and mitigate associated risk."

"While the facts of the L'Aquila case are complex, the unfettered exchange of data and information, as well as the freedom and encouragement to participate in open discussions and to communicate results, are essential to the success of any type of scientific research," the union, a professional and scientific organization with members from over 146 countries, said in a statement Tuesday.