When the USGS begins detecting a series of small earthquakes around the Los Angeles area, one geologist, Dr. Claire Winslow (Kerns) alerts her bosses to the possibility of a major earthquake that will flatten Los Angeles. But political concerns get in the way and her concerns are largely ignored, until more serious changes signal a major quake from a lesser-known fault line that runs directly under the city itself. When the horrific quake strikes, it will cause severe property damage as far south as San Diego, and as far north as 120 miles. It will cost billions to repair, and as many as 20,000 people may perish...

The montage showing emergency services getting ready includes Squad 51 and Engine 51 from "Emergency!" (1972) backing in the station.