Mystery and Clarity From Amos, Morissette

Tori Amos and Alanis Morissette, two of this decade’s foremost rock divas, finished a joint excursion dubbed the “5 1/2 Weeks Tour” over the weekend at Irvine Meadows. Their separate sets, with no collaborative moments, might best be understood in terms of a song title by their peer, Sarah McLachlan: “Building a Mystery.”

Morissette tried hard on Saturday, the first show of a scheduled two-nighter, to build some mystery into her baldly declarative songs. Material from her album “Supposed Former Infatuation Junkie” frequently resorted to that instant aural signifier of mysteriousness, portent-laden Middle-Eastern stylings a la Led Zeppelin’s “Kashmir,” but some of it suffered from melodic blandness. Her 70-minute set flowered when she dropped any hint of mysteriousness and cast herself as the guileless, life-affirming young woman of the hits “Thank U,” “You Learn” and “Hand in My Pocket.”

Amos doesn’t have to build mysteries--she is one. This is one of the most enigmatic and sometimes simply baffling songwriters successful enough to line her walls with awards for platinum albums.

Playing an opening set that was slightly longer than Morissette’s, Amos oscillated like a subatomic particle whose exact nature can’t be pinned down. She was the yearning balladeer of “1000 Oceans,” a song from her new album, “To Venus and Back,” that’s lovely and simple and still and heartfelt enough for Emmylou Harris to sing. But she also was the singer whose stuff can be downright inscrutable, sealed off in her own coded world of symbols and visions. It didn’t help that at times Amos’ voice was obscured by the layered sound of her three-man band and her own grand piano and synthesizer.

But on balance, the mystery was alluring. Even the thornier, less pithy songs held interest as they swung between dense, storming band passages and ones in which Amos’ pure voice took flight in the soaring soprano art-song curlicues she got from Kate Bush.

Sometimes that stormy-then-dulcet pattern grew diffuse. But the set took on a sharp, brilliant focus with two songs Amos, who for years toured as a solo, acoustic act and still is most distinctive in that mode, played without her band. Her version of Nirvana’s “Smells Like Teen Spirit” (originally released in 1992, when the hit was fresh and Kurt Cobain was alive) deployed the rasp of a used-up female barfly along with a delicate whisper of isolation. Very scary. Then came the lovely “1000 Oceans,” which comes across as a fine, modern successor to the traditional folk ballad “The Water Is Wide.”

Perhaps, watching from the wings on this tour, Morissette has been able to absorb the best of Amos--the part in which meanings might be a little elusive, but one still gets the gist.