LAS VEGAS >>  The Mirage volcano on the Las Vegas Strip is erupting less frequently, but not for any geological reason.

The man-made volcano that has been spewing fire and water since the hotel’s 1989 opening, a first-of-its-kind attraction, will now offer two to three nightly shows as the Strip’s topography continues to evolve.

Before Monday, the volcano erupted every half-hour beginning at about dusk until midnight, wind permitting.

"With the variety of offerings on the Las Vegas Strip today, in contrast to 25 years ago, it made sense to us to reduce the number of shows in a way that wouldn’t diminish the visitor experience," according to a statement from MGM Resorts Inc., which owns The Mirage casino-hotel.

The company will monitor how much money the change saves, how much it will cut energy consumption and the reaction of visitors, company spokeswoman Mary Hynes said. There’s nothing in the works to change the frequency of the company’s Bellagio fountain show, she said.

The volcano is scheduled to erupt at 8 p.m. and 9 p.m. Sunday through Thursday. An additional 10 p.m. show will be offered Friday and Saturday.

The Strip evolved into something more akin to a theme park when casino mogul Steve Wynn debuted the volcano at The Mirage, which was followed by a fiery pirate ship battle in front of the Treasure Island and the now-iconic fountain show in front of the Bellagio.

Since then, the Strip has never stopped evolving, said David Schwartz, director of the University of Nevada, Las Vegas’ Center for Gaming Research.

"I think what gets people inside is shifting," Schwartz said of what drives a tourist to venture from the sidewalk into a casino. There are simply more entertainment options, he said.

Large-scale free entertainment outside of the area’s casinos has diminished in recent years, but street-facing restaurants and retail, where money can be made, have cropped up.

Treasure Island was sold in 2009, and the pirate battle disappeared nearly two years ago.

After becoming the owner of The Mirage, MGM spent $25 million in 2008 upgrading the volcano with more fire choreographed to a pounding drum-beat soundtrack. At the time, executives said the challenge continued to be getting the show’s numerous watchers to walk inside the casino to spend money.