Big Three Plot Strategy for November Ratings Sweeps : Television: NBC flexes its muscles; ABC stays faithful to its series; CBS has a paper-thin lineup.

A Los Angeles earthquake. Teen sex on “The Cosby Show.” Stephen King’s nightmare miniseries, “It.” And Laura Palmer’s killer, revealed at last.

Welcome to TV’s November ratings sweeps.

It begins Thursday. And rarely will viewers have a better chance to understand the Big Three networks--their strengths and weaknesses.

A classic education in TV strategy, the match-up offers a textbook example of powerful NBC at work--from the four-hour miniseries “The Big One: The Great Los Angeles Earthquake” to shrewdly conceived special episodes of regular programming, from “Cheers” to “The Cosby Show” to “Quantum Leap.”

At the opposite pole is ABC, which will offer “It,” King’s four-hour fright show--but, with an extraordinary degree of confidence, is sticking almost exclusively with its regular series as it stalks NBC for the top position.

And then there is suddenly deflated CBS, in mourning over the huge sums it lost because of its brief World Series, and badly exposed by a paper-thin November lineup that depends heavily on such widely seen motion pictures as “Fatal Attraction” and “Moonstruck.”

Some viewers may get a kick out of watching CBS Entertainment President Jeff Sagansky help out one of his sitcoms when he appears Nov. 8 in “Doctor, Doctor.” But that’s strictly for Hollywood. They won’t care in Peoria.

Barring a surprise, CBS could well be finished for the season by the end of the sweeps. Among its publicized highlights, for instance, are the season premiere of “Dallas” on Friday--with daytime soap star Susan Lucci appearing--and Burt Reynolds shaving his mustache on his “Evening Shade” sitcom the same night. Things can’t get much more desperate.

From the opening moment of the monthlong Nielsen ratings sweeps, NBC is aiming to simply blow away the competition. Thursday, as it happens, is NBC’s strongest night, and it will lead off the sweeps with a special one-hour “Cosby Show” about teen sex, demurely entitled “Just Thinking About It.”

In the episode, a young woman who is a cousin of obstetrician Cliff Huxtable, the Cosby character, turns to him for a prescription for birth-control pills when she is under pressure to prove her affection for her boyfriend.

With this hour, NBC clearly hopes to take immediate and overpowering control of the sweeps and demolish such competition as Fox TV’s “The Simpsons.”

It is notable that NBC’s “The Big One” and ABC’s “It” are both relatively brief miniseries, and that such past, long-form ventures as “Lonesome Dove” and “War and Remembrance” are simply too expensive for today’s soft national economy.

All three networks are under terrific pressure from the new TV competition. And the advertising slump that has affected virtually all media has made them tighten their belts even more.

CBS was really devastated by Cincinnati’s four-game blowout of Oakland in the World Series. Analysts figure that the hard-pressed network, which may have lost $100 million on baseball this year, could have sharply reduced that deficit with the income from the remaining three contests.

Under the circumstances, Reynolds’ mustache doesn’t seem too significant a cure.

CBS does, however, have a Nov. 12 special, “The Honeymooners Anniversary Special,” with Art Carney and Audrey Meadows reminiscing about the great series that starred the late Jackie Gleason. And the network clearly hopes it will emulate the extraordinary ratings success of last season’s special about “I Love Lucy.”

Unfortunately, the “Honeymooners” special has been scheduled against the final hour of NBC’s “The Big One,” which will be seen Nov. 11 and 12.

ABC’s strategy of just driving ahead with its week-in, week-out series will be interrupted significantly only a few times. “It,” which concerns seven old friends who reunite in their hometown to confront an evil force they thought they had destroyed 30 years earlier, will be broadcast Nov. 18 and 20. The notable cast includes Harry Anderson, John Ritter, Tim Curry, Richard Masur, Annette O’Toole and Tim Reid.

On Nov. 10, meanwhile, ABC’s “Twin Peaks” promises yet again--if anyone still cares--that the solution of Laura Palmer’s murder is upon us. “The identify of Laura Palmer’s killer is finally revealed,” says a network announcement.

But if “Twin Peaks” doesn’t really deliver the goods this time, it could well alienate many of its fans--even those who long ago stopped really being concerned with the solution and simply enjoy the exotic atmosphere of the series.

ABC also has one other intriguing special during the sweeps--”Call Me Anna,” a Nov. 11 production starring Patty Duke in a dramatization of her autobiography.

But almost as intriguing as ABC’s sweeps philosophy is its shrewd cash-register thinking as a corporation. One of the reasons it is sticking faithfully with its series, with few changes expected before year’s end, is that any move of a show enables an advertiser to pull out.

Thus, for instance, if “China Beach,” now sold out on Saturdays despite low ratings, switched places with “Cop Rock,” which is seen on Wednesdays, it could cause ABC to suffer a multimillion-dollar loss.

Patience has turned out to be a virtue for ABC as second-year series such as “Doogie Howser, M.D.,” “Life Goes On” and “The Young Riders” have gotten stronger.

Who would have thought, for instance, that “Life Goes On,” a drama involving a young man with Down’s syndrome, would beat out a high-spirited NBC musical about teen-agers, “Hull High,” which was bumped from the schedule this week?

Still, NBC is where most of TV’s muscular moves will be noticeable during the sweeps, which help set ad prices for local stations. Though struggling in recent years as a creative force, NBC is an often-irresistible company simply because of its sense of showmanship under Brandon Tartikoff, an astonishingly buoyant, Barnum-like impresario.

Consider some of the special events NBC has created out of its regular series during the sweeps. The 200th episode of “Cheers,” TV’s highest-rated series, will be commemorated with an hour show Nov. 8. And then the 200th episode will be broadcast Nov. 15--which is getting a lot of mileage out of one program.

Meanwhile, Scott Bakula, the time-traveling, character-changing hero of “Quantum Leap,” will be transformed into a 1958 female beauty pageant contestant in next Friday’s show. And then he will be thrust into the Watts riots on Nov. 9.

“The Big One” is described as “what could happen when a seismologist has reason to believe a cataclysmic earthquake will hit Los Angeles in a few days’ time.” The cast includes Joanna Kerns and Ed Begley Jr.

On Nov. 5, NBC offers “On Thin Ice: The Tai Babilonia Story,” about the champion skater. On Nov. 19, the network presents Mary Tyler Moore and Tony Curtis in “Thanksgiving Day,” a black comedy about how a quirky family copes after the father drops dead at the holiday dinner.

Then there’s NBC’s promotable 100th episode of “Matlock” Nov. 6. And NBC gets the most out of Robert Stack on Nov. 7 when he follows his hit show “Unsolved Mysteries” with a guest shot immediately afterward on “The Fanelli Boys.”

Fast ball. Curve. Slider.

It’s the sweeps.