WASHINGTON — The recent sharp drop in the global price of crude oil could mark the start of a massive sell-off that returns gasoline prices to lows not seen since the late 1990s — perhaps as low as $1.15 a gallon.

"All the hurricane flags are flying" in oil markets, said Philip Verleger, a noted energy consultant who was a lone voice several years ago in warning that oil prices would soar. Now, he says, they appear to be poised for a dramatic plunge.

Crude-oil prices have fallen about $14, or roughly 17 percent, from their July 14 peak of $78.40. After falling seven straight days, they rose slightly Wednesday in trading on the New York Mercantile Exchange, to $63.97, partly in reaction to a government report showing fuel inventories a bit lower than expected. But the overall price drop is expected to continue, and prices could fall much more in the weeks and months ahead.