PORTLAND – Corrosion was the apparent cause of this month’s collapse of a 540-foot communications tower in the city’s East Deering neighborhood, according to preliminary inspections.

The inspections indicate that the metal in the anchoring system on Portland Radio Group’s 17-year-old steel tower had corroded in marshy soil and its guy wires became insecure. The company is still waiting for an official report on the cause from the tower’s insurance company.

No one was injured when the tower fell on Dec. 11, but it pulled down power lines, crushed two vehicles and knocked WMGX and WYNZ off the air temporarily. The incident pointed up the lack of local, state or federal government oversight of tower maintenance.

Portland Radio Group said Monday that it has hired Electronics Research Inc. of Chandler, Ind., to design and install a 528-foot replacement tower and excavation could start within two months.

Portland Radio Group officials said the new tower would take into account its location on the coast of Maine, where wind, tidal water and ice take their toll.

“It will be a state-of-the-art structure,” said Barry Hobbins, a Saco lawyer retained by Portland Radio Group. “Because of what occurred, we want to make sure everyone feels confident with the design of the new tower.”

The new tower will be held in place by three sets of double guy wires. It also will be designed to collapse on itself if it fails, as most modern towers are designed to do. And all metal located below ground level would be coated with epoxy and sunk in concrete, said Ernest Jones, vice president of engineering for the structural division of Electronics Research Inc.

The cost of the project has not been determined.