POP MUSIC REVIEW : Smells Like Rock’s Future : In a benefit concert, Nirvana offers challenging new songs suggesting they may remain one of rock’s most influential ‘90s bands.

SAN FRANCISCO —  Nirvana, the most acclaimed and enigmatic arrival in ‘90s rock, had two messages to deliver as it stepped on stage here for its first U.S. concert in seven months.

The primary purpose of the benefit on Friday at the Cow Palace arena was to raise funds for rape victims in war-torn Bosnia-Herzegovina.

The second was to answer the myriad questions that have circulated over the past year concerning the band’s ability to survive, both emotionally and creatively, in view of the enormous expectations raised by 1991’s landmark “Nevermind” album.

By the end of the night, the Seattle trio had accomplished both goals in a triumphant performance that suggested the group may indeed possess the talent and will to remain one of rock’s most influential and inspiring forces in the ‘90s.

Nirvana’s social message was transmitted chiefly through bassist Chris Novoselic’s brief words of thanks and through information pamphlets distributed at the door.

Novoselic has relatives in Croatia and visited there in January to write an article for Spin magazine about the war and the need for health services for an estimated 30,000 rape victims.

Nirvana’s musical message was delivered in a galvanizing 90-minute set that showcased eight tunes from the group’s next album, which could be in stores by July.

There has been so much interest in Nirvana because “Nevermind,” the group’s major-label debut, helped change the face of modern rock by injecting the energy and independence of Seattle’s punk-spawned grunge scene into the nation’s musical mainstream. Estimated sales of the album: 4 million.

In such songs as “Smells Like Teen Spirit” and “Come as You Are,” lead singer Kurt Cobain expressed some of rock’s oldest themes--including the uncertainty and alienation of youth--in fresh and wondrous ways that made the music sound like the awakening voice of a new generation.

After “Nevermind,” record companies raced to sign more Seattle or grunge groups--creating a momentum that was intensified after another of those bands, Pearl Jam, also hit big.

But Nirvana, whose previous small-label album had sold only about 50,000 copies, was uneasy with the sudden mainstream attention.

Cobain, a shy, introspective person, seemed especially vulnerable to the hurricane of media assault and rock-world celebrity. His emotional fragility was compounded by health problems.

Doubts about the band’s future increased last year because of the infrequency of the group’s live shows and the absence of a second album.

Given this background, it’s easy to see why the atmosphere was tense Friday at the Cow Palace as an estimated 12,000 fans--some from as far away as Seattle and Los Angeles--waited to see just how viable a force Nirvana remains.

The answer came when Nirvana came out to conclude the concert, which also featured entertaining sets by the groups L7, the Disposable Heroes of Hiphoprisy and the Breeders.

Greeted by the fans’ supportive roar, Cobain waved appreciatively as he walked on stage with Novoselic and drummer David Grohl.

Strapping on his guitar, Cobain stood defiantly at the microphone and began singing “Rape Me,” the tenacious song that MTV refused to let Nirvana play at its video-music awards telecast last year.

Although the acoustics of the ancient arena made it hard to pick up all the words of that and other new songs, the tone of the music was clear and commanding.

Cobain, the group’s songwriter, has avoided two potential traps: emphasizing his punk roots in order to escape the mainstream attention, or expanding his pop-rock side in an effort to court that mainstream audience.

Instead, he continues to balance those sometimes conflicting elements, giving the music the kind of twin intimacy and aggression that has often fueled the most absorbing rock.

While there are traces of the “Nevermind” sound in some of the new songs, the material also reflects unmistakable advances.

Some of the new numbers, including the howling fury of “Scentless Apprentice,” are more intense than anything on the last album, while others exhibit greater emotional resonance. Among the latter: the enticing, ballad-leaning “All Apologies” and “Heart-Shaped Box.”

The band telegraphed its confidence in its new material and its own delight in being onstage again by returning after its scheduled hourlong set for a high-energy half-hour of bonus music.

To the delight of the fans, Cobain climaxed the set with a daredevil salute to his punk roots by leaping from one of the speakers onto the drum kit, crashing himself and Grohl to the stage.

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Backstage afterward, all three members of Nirvana confirmed their good spirits. The album, they said, was recorded in two weeks in Minneapolis and the group plans to tour as soon as it’s released.

A relaxed Cobain didn’t downplay the pressures on the band last year, but said the sessions themselves went remarkably well.

“I’ve never felt more relaxed in a recording session,” he said. “The next step is the mixing process. When I look back on ‘Nevermind’ I realize we really didn’t follow through on the mixing. It ended up too commercial and slick.”

Cobain, who found touring difficult in the past because of painful stomach problems, said medication in recent months has eased the condition, and that he is looking forward to more live shows.

The message Friday was that those shows should be memorable indeed. After a year of being surrounded by uncertainty and self-examination, Nirvana may be everything it appeared to be in “Nevermind”--and more.