Brander bites his lip. "Well, that's the thing. The lower the activity near the end of a run, the longer the run seems to last."

She waits. She doesn't have to ask. Brander's far too proud of himself to not explain further.

"And if you assume that lower end-run activity reflects a smaller predicted quake, the cheese spends more time thinking about quakes with lower shoreline impact. Usually, though, it just stops when it hits the coast."

"There's a threshold," Lubin says.

"What?"

"Every time it predicts a coastal quake above a certain threshold, the model shuts down and starts over. Unacceptable losses. It spends more time thinking about the milder ones, but so far they've all resulted in unacceptable losses."

Brander nods, slowly. "I was wondering about that."

"Stop wondering." Lubin's voice is even more dead than usual. "That thing's only got one question on its mind."

"What question?" Clarke asks.

"Lubin, you're being paranoid," Brander snorts. "Just because it's a bit radioactive—"

"They lied to us. They took Judy. Even you're not naive enough —"

"What question?" Clarke asks again.

"But why?" Brander demands. "What would be the point?"

"Mike," Clarke says, softly and clearly, "shut up."

Brander blinks and falls silent. Clarke turns to Lubin. "What question?"

"It's watching the local plates. It's asking, what happens on N'AmPac if there's an earthquake here, right now?" Lubin parts his lips in an expression few would mistake for a smile. "So far it hasn't liked the answer. But sooner or later predicted impact's going to fall below some critical level."

"And then what?" Clarke says. As if I didn't know.

"Then it blows up," says a small voice.

Alice Nakata is talking again.

Ground Zero

Nobody speaks for a long time.

"That's insane," Lenie Clarke says at last.

Lubin shrugs.

"So you're saying it's some kind of a bomb?"

He nods.

"A bomb big enough to cause a major earthquake three, four hundred kilometers away?"

"No," Nakata says. "All of those faults it would have to cross, they would stop it. Firewalls."

"Unless," Lubin adds, "one of those faults is just about ready to slip on its own."

Cascadia. Nobody says it aloud. Nobody has to. One day, five hundred years ago, the Juan de Fuca Plate developed an attitude. It got tired of being endlessly ground under North America's heel. So it just stopped sliding, hung on by its fingernails and dared the rest of the world to shake it free. So far the rest of the world hasn't been able to. But the pressure's been building now for half a millennium. It's only a matter of time.

When Cascadia lets go, a lot of maps are going to end up in recyc.

Clarke looks at Lubin. "You're saying even a small bomb here could kick Cascadia loose. You're saying the big one, right?"

"That's what he's saying," Brander confirms. "So why, Ken old buddy? This some sort of Asian real estate scam? A terrorist attack on N'AmPac?"