"The Big One: The Great Los Angeles Earthquake" is almost two movies in one.

The two-part, four-hour production (Sunday and Monday at 8 p.m., Ch. 2) is half soap-opera, half disaster film. And the second half is considerably better than the first.Set in the near future, the miniseries centers on Claire Winslow (Joanna Kerns of "Growing Pains), a seismologist who has developed a method of predicting earthquakes. She sees The Big One coming, but her family, friends and the government bureaucracy don't want to listen.

"Most people don't deny the fact that there's going to be a large earthquake, it has been said so many times," said Steve Bryant, a real-life seismologist with the U.S. Geological Survey and an adviser on the miniseries. "Generally, they put it in the back of their minds. They say, `Well, it won't happen to me today.' That's where the denial comes in."

The first two hours are rather fragmented, with several related and unrelated plot lines weaving around each other. There's even a rather silly political assassination subplot thrown into the mix.

But when the Big One hits early in Part 2, the entire tone changes. The devastation of an 8.0 directly under the city of Los Angeles, followed by a 7.2 aftershock, is dramatically and movingly portrayed.

Buildings, roads and bridges crumble. Power fails, telephones go dead, gas mains break and fires break out. Thousands - perhaps tens of thousands - are killed, and hundreds of thousands are injured.

And Los Angeles is cut off from the rest of the world. While the city burns and people die, outside help is not available.

Surprisingly, the emotional impact of "The Big One" is intense. It's almost reminiscent of the nuclear-war telemovie "The Day After" a few years ago.

The producers spent a lot of money on the special effects, and they're excellent. For the most part, they're feature-film quality.

Dan Lauria ("The Wonder Years"), who stars as Clair's husband, found himself caught at Los Angeles International Airport when the quake hit.

"Well, I'll tell you, no matter how lightweight that wall is, if I drop it on you it doesn't take much acting to look scared," he said.

Perhaps the most frightening thing about "The Big One" is the trailer on the screen just before the credits. It says that 39 states will experience major earthquakes at some point in the future, and lists several cities expected to suffer major jolts.

One of those is Salt Lake City - with a 7.0 predicted.