I first noticed the nonstandard use of the preposition of following alerted in this item on a site about uncompassionate government policies:
After the city council was alerted of the free lunches, it ruled that she would have to acquire a variance to give away food next summer – or pay a fine of $600 a day.
When I did a web search of the phrase “alerted of,” I found hundreds, mostly in headlines:
Todd County Sheriff’s Officials Alerted Of Phone Scam
Oil Company Was Alerted of Michigan Spill
PAC was alerted of chit fund scam in August last year
Parents alerted of whooping cough in Elmbrook School Dist.
The verb alert and its past participle form alerted are usually followed by the preposition to:
Police alerted to shooter in car
Newfane Community Alerted to Home Invasion
Parents alerted to improper internet use
The adjective alert is also followed by to:
Parents must be alert to child predators.
Be alert to any change in behavior.
The idiom “on the alert” is followed by for:
The troops were on the alert for land mines.
The book collector was on the alert for the missing Dickens first edition.
Alert entered English in the 16th century from French alerte, “watchful, vigilant.” The word originated in Middle French as a phrase used by the military: à l’herte, “on the lookout, on the watch.”
Alert is used as a noun to mean “a call or military signal to prepare for an attack; a warning of potential danger; an announcement to look out for.” Some examples of this use are: tornado alert, red alert, Amber alert.
As a verb, alert is transitive: The shopkeeper alerted police to the presence of the wanted man.
The nonstandard use of “alerted of” instead of “alerted to” may be the result of confusing alert with warn. People are warned of danger, but alerted to danger.