MADISON, Wis. -

A rare combination of troubles is driving up gas prices in the Great Lakes region.

GasBuddy.com petroleum analyst Patrick DeHaan said Friday that several Great Lakes states have seen prices surge about 40 cents per gallon in the last week.

That follows a pipeline rupture and shutdown in Wisconsin and equipment problems at refineries in Indiana and Illinois.

Illinois has experienced the biggest price jump, from a statewide average of $3.61 a week ago to $4.05 on Friday.

DeHaan said the combining of incidents is unusual and has created fears of a shortage that has spooked the gas market.

But he said it typically takes only a week or so to make refinery repairs, and prices should begin to drop during the next few weeks.