Francesco Peduto, president of the Italian National Council of Geologists, said it was "absurd" that people could die in "such a low magnitude earthquake".
In a statement, Peduto also argued that such a low magnitude earthquake would not normally cause buildings to collapse.
At least two people were killed when a 4.0 magnitude earthquake hit the southern island of Ischia at around 9pm on Monday night. Firefighters worked through Tuesday to pull survivors from rubble, including a seven-month-old baby and his two siblings.
According to Peduto, the impact of the quake in tourist hotspot Ischia could have been reduced if more time and resources had been invested into prevention.
"What leaves one truly dumbfounded is the lack of preventive measures," he said.
The geologist also argued that the government has been slow in its recovery efforts after last year's series of deadly earthquakes in central Italy.
"There has been a lot of talk, but 12 months later hardly anything has been done," said Peduto.
Egidio Grasso, president of the Order of Geologists in Campania, the affected region, suggested the collapse of buildings on Ischia could have been attributed "to crumbling and illegally constructed buildings that were built without any verification of seismic threats".
According to a 2017 report on Italy's coastal regions by environmental research organization Legambiente, Ischia is one of the worst areas in Campania for illegal construction.
Campania ranks as the top region in Italy for illegal construction, according to Legambiente's Mare Monstrum report.
According to the report, "it is mostly 'old illegal' constructions that deface the coastline, ones that have survived for decades...second houses on the seashore that enjoy the special attention of politicians, both national and local, always careful to prevent the bulldozers from arriving."