The Rising Sea (NUMA Files 15)

Paul shook his head. “If there was a new range growing up down there, I’d expect to see ridges and folding in the outer sedimentary layers. And we’d certainly detect a mild upslope.”

Gamay studied the readout for any sign of what Paul was describing, but she saw nothing to suggest a change in elevation. “Let’s let it play out before we go back to the drawing board.”

“Not much else we can do,” Paul said.

Gamay sat back, reaching for her cup of tea with one hand and tapping the keyboard with the other. Lazily, she cycled through a host of other readings: virtual topography, water temperatures and salinity levels. The computer organized the information into a series of displays and graphs, but the data made no sense.

“Something’s wrong with the instruments,” she said, putting the teacup down.

“Why do you say that?”

“According to the temperature profile, it’s getting warmer as the Remora goes deeper.”

Paul glanced over her shoulder. “Have you passed through a thermocline?”

“No,” she said. “No sudden change, just a slow, steady increase, approximately one degree for every seventy feet. That indicates a continuous mixing instead of boundary layer.”

“What about the salinity?” Paul asked.

Gamay tapped the key to bring up another sensor reading. “Even more screwed up than the temperature profile. According to this, the salinity is decreasing as we descend.”

“That can’t be right. Can you run a diagnostic on the sensor probes?”

Gamay didn’t know enough about the ROV to diagnose a problem with the sensors, let alone fix it remotely. “Maybe if Joe was here,” she said. “All I got was a rudimentary lesson on driving the thing.”

“Bring it back up,” Paul suggested. “Not all the way, just a hundred feet or so.”

“What good will that do?”

“If the sensors are failing, the temperature will continue to rise,” he said. “But if they’re working properly and we are actually dealing with an inverted temperature profile, the water should grow colder again.”

“Sneaky,” she said. “I like it.”

Gamay changed the dive angle and put the ROV into an ascent. “Temperature dropping, salinity rising. The sensors are working correctly. Now what?”

“Resume course,” Paul said.

Satisfied but confused, Gamay adjusted the dive profile once more and sent the Remora back toward the deep. She had it level off at a depth of five hundred feet so they could map a wide section of the bottom before investigating up close.

“Still flat,” Gamay noted.

“Amazing,” he said. “I’ve gotten shirts back from the dry cleaner that aren’t that smooth.”

“So, no mountain range,” Gamay said, “but temperature and salinity data that defy logic. Any thoughts?”

“Not at the moment,” Paul said. He glanced at the chart. “You’re nearing the epicenter of Kenzo’s earthquakes. Change course to the west.”

She made the adjustments and the readout changed. “We’re picking up something new.”

“Ridges and hills?” he said hopefully.

“Sorry, Charlie, it’s a depression. It looks like a subsurface canyon.”

The information on the chart suggested a flat plain. But as the Remora’s sonar bounced off the seafloor, a deep V-shaped gash was revealed. The point of the V was aimed like an arrow at Shanghai. “Let’s take a look at that chasm.”

Gamay was already changing course and directing the sub into the gap.

“Temperature continuing to rise,” she said. “Salinity continues to drop.”