This week's Terraform is something special: It's a hybrid format, what we've taken to calling "reported science fiction"—a deeply researched, exhaustively detailed story about what will happen when the so-called "Really Big One" (a 9.0 magnitude earthquake) hits Portland, as scientists expect it will in coming decades. (Hint: Read the footnotes!) But I'll let writer and archivist Adam Rothstein explain his creation, "After the Big One," below. Trust me, this one, an epic, 5-part feat of speculation—and the most immersive fact-based fiction you'll probably ever read—is worth diving in deep. -Brian Merchant, Terraform editor

There is a 22 percent chance that by the time you finish reading this sentence, there will have been an earthquake somewhere on earth. This is a probability that is hard to grasp—it seems both obvious and diffuse. The world is a big place, and most earthquakes are relatively small.