LAS VEGAS – Real volcanos may take millennia to form, but in Las Vegas they take just 20 years to look dated.

That’s what The Mirage hotel-casino figured when it initiated a $25 million facelift of its iconic erupting volcano on the Las Vegas Strip.

The faux rock fountain first erupted in 1989 and its bursting spray of water lighted red to look like lava is among the city’s classic sights for strolling pedestrians. The volcano was among the flashiest early casino “features,” a free element of spectacle added to deliver whimsy, wow factor and gamblers.

Still, the casino concluded, it could be so much more.

And so it will be.

The volcano is getting 120 new fireball-throwing devices that will be choreographed to erupt in sync with a rumbling drum score co-composed by former Grateful Dead drummer Mickey Hart and piped into the desert air through a high-tech sound system, according to company officials who will officially announce renovation details Wednesday. The project won’t be completed until later this year.

Some of the fireball devices will spout gas flames 12 feet in the air, while others ooze fiery “lava” down the volcano’s crevices. The flames will appear to burst close to passers-by – but not too close.

“It looks dangerous, but in reality it’s not. We just want people to stand back on their heels,” said Jim Doyle, the director of new technologies at the Sun Valley, Calif.-based design firm WET.

WET is perhaps best known as the firm behind the Bellagio hotel’s fountains, and Doyle acknowledges the dancing water jets just down the Strip were an inspiration for the volcano’s new look.

He spent two years developing a fire-shooting device that could sleep in the volcano’s surrounding lagoon during the day and emerge at night for hourly shows. The miniature robots can be choreographed, but in the foreseeable future the fireballs will dance to Hart’s score, he said.

Along with longtime creative partner Zakir Hussain, the legendary jam band percussionist said he brought in dozens of instruments to reinterpret the sound and the vibration of “the earth belching.”

“It’s our version of a birthing of a volcano, which is filled with a lot of different kinds of emotional content, anticipation and anxiety. It’s filled with magic and power,” Hart said. “You might even be able to feel the lava coming down on top of you.”

This bigger, better volcano is the last piece of the 20-year-old resort’s recent overhaul. Owner MGM Mirage Inc. has spent $110 million upgrading rooms and suites at The Mirage, as well as adding a new nightclub, restaurants and the Cirque du Soleil’s Beatles-themed “Love.”

Mirage President Scott Sibella said he wished the property’s signature feature was a little closer to the new indoor attractions. Since the volcano first erupted, casinos have learned to put such features inside to bring people closer to their casinos.

Sibella said The Mirage may someday add a bridge connecting the street-level volcano to the casino entrance.

“It does draw thousands of people for every eruption,” he said, “but the challenge is getting them inside the property.”