Starfish

He waits for their reaction. Nobody says anything. Faintly, from outside, comes the sound of windchimes in mourning.

"Jesus. Look, any simulation is computationally most intensive whenever the number of possible outcomes is greatest. When a tremor crosses a fault it triggers ancillary waves perpendicular to the main direction of travel. Makes for very hairy calculations at those points, if you're trying to model the process."

Clarke stares at the screen. "Are you sure about this?"

"Christ, Len, I'm basing it on stray emissions from a blob of fucking nerve tissue. Of course I'm not sure. But I'll tell you this much: if you assume that this first jump represents the initial quake, and this last dropoff is the mainland, and you also assume a reasonably constant speed of propagation, these intermediate spikes fall almost exactly where Cobb, Beltz, and Cascadia would be. I don't think that's a coincidence."

Clarke frowns. "But doesn't that mean the model stops running as soon as it reaches N'AmPac? I would've thought that's when they'd be most interested."

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?"

"Wait a minute." Clarke holds up a hand. "They're not trying to cause an earthquake. They're trying to avoid one."

Lubin nods. "You set off a fusion charge on the rift, you trigger a quake. Period. How serious depends on conditions at detonation. This thing is just holding itself back until it causes as little damage as possible, back on shore."

Brander snorts. "Come on, Lubin, isn't this all kind of excessive? If they wanted to take us out, why not just come down here and shoot us?"

Lubin looks at him, empty-eyed. "I don't believe you're that stupid, Mike. Perhaps you're just in denial."

Brander rises out of his chair. "Listen, Ken —»

"It's not us," Clarke says. "It's not just us. Is it?"

Lubin shakes his head, not taking his eyes off Brander.

"They want to take out everything. The whole rift."

Lubin nods.

"Why?"

"I don't know," Lubin says. "Perhaps we could ask them."

Figures, Clarke muses. I just never get a break.

Brander sinks back into his chair. "What are you smiling at?"