"Only the target area in Peschanaya Bay. We must cross the lake to the other three sites, which are on the eastern sh.o.r.e."

The old fishing boat motored past the docks of Listvyanka, pa.s.sing a hydrofoil ferry slicing into port on its return from a transport run to Port Baikal on the opposite sh.o.r.e of the Angara River. The sleek enclosed pa.s.senger ferry looked out of place beside the small fleet of aged wooden fishing boats that filled Listvyanka's waters. Escaping the small harbor, the fishing boat turned north, hugging the craggy western sh.o.r.e of the cold lake. Deep, rich forests of taiga marched down to the sh.o.r.eline in a carpet of green, interspersed with rolling meadows of thick gra.s.s. The rich colors of the landscape against the crystal blue lake made it difficult for Theresa to picture the stark bitterness of the region in the dead of winter, when a layer of ice four feet thick covered the lake. A shiver at the thought made her glad she was visiting when the days were longest.

It was of little matter to Theresa, though. The petroleum engineer's true love was traveling and she would have gladly visited the lake in January just for the experience. Bright and a.n.a.lytical, she had chosen her career less for the intellectual challenge than for the opportunity to travel to remote places around the globe. Extended stints in Indonesia, Venezuela, and the Baltic were broken up by the occasional two-week a.s.signment like this one, where she was sent to survey an offbeat prospective oil field. Working in a man's field proved to be no setback, as her vivacious personality and humorous outlook on life easily broke down barriers with men who weren't already attracted to her athletic build, dark hair, and walnut eyes.

Forty miles north of Listvyanka, a shallow bay called Peschanaya cut into the western sh.o.r.eline, protecting a narrow sandy beach. As the captain nosed the boat's prow into the bay, Tatiana turned to Theresa and proclaimed, "We will start here."

With the engine thrown into neutral and the boat drifting, Roy and Wofford lowered the side-scan sonar towfish over the stern as Theresa mounted a GPS antenna onto the side rail and plugged it into the sonar's computer. Tatiana glanced at a fathometer mounted in the wheelhouse and shouted, "Depth, thirty meters."

"Not too deep, that's good," Theresa said as the boat moved forward again, towing the sensor a hundred feet behind. A digitally enhanced image of the lake bed scrolled by on a color monitor that captured the processed sound waves emitted from the towfish.

"We can acquire meaningful results as long as the depth stays under fifty meters," Wofford said. "Anything deeper and we'll need more cable and a bigger boat."

"And more caviar," Roy added with a hungry look.

Slowly the fishing boat swept back and forth across the bay, its hardened captain spinning the ship's wheel lightly in his hands as the four visitors on the stern hunched over the sonar monitor. Unusual geological formations were noted and their positions marked, as the experienced oil surveyors looked for lake bed features that might indicate a hydrocarbon seep. Further studies, using core sampling or geochemical a.n.a.lysis of water samples, would still need to be undertaken to verify a seep, but the side-scan sonar would allow the surveyors to zero in on future geological points to examine.

As they reached the northern edge of the bay, Theresa stood and stretched as the captain swung the boat around and aligned it for the last survey lane. Toward the center of the lake, she noticed a large dirty-gray ship sailing north. It appeared to be some sort of research vessel, with an old-style helicopter wedged on the stern deck. The rotors on the helicopter were sweeping in an arc, as if preparing to take off. Scanning above the bridge, she noted oddly that the ship's mast appeared to be flying both a Russian and an American flag. Likely a joint scientific study, she mused. Reading up on Lake Baikal, she was surprised to learn of the West's scientific interest in the picturesque lake and its unique flora and fauna. Geophysicists, microbiologists, and environmental scientists migrated from around the world to study the lake and its pure waters.

"Back on line," Roy's voice shouted across the deck. Twenty minutes later, they reached the southern edge of the bay, completing their multilane sweep. Theresa determined that there were three lake bed structures seen with the sonar that would warrant further examination.

"That wraps it up for the opening act of today's program," Wofford said. "Where to next?"

"We will cross the lake to a position here," Tatiana said, tapping the map with a slender finger. "Thirty-five kilometers southeast of our current position."

"Might as well leave the sonar in the water. I don't think this boat can go much faster than our survey speed anyway, and we'll get a look at the water depths as we cross over," Theresa said.

"No problem," Wofford said, taking a seat on the deck and stretching his legs up onto the side railing. As he casually watched the sonar monitor, a quizzical expression suddenly appeared on his face. "That's odd," he muttered.

Roy leaned over and studied the monitor. The shadowy image of the lake bottom had abruptly gone haywire, replaced by a barrage of spiked lines running back and forth across the monitor.

"Towfish bouncing off the bottom?" he asked.

"No," Wofford replied, checking the depth. "She's riding forty meters above the lake floor."

The interference continued for several more seconds, then, as abruptly as it started, it suddenly ceased. The contours of the lake bottom again rolled down the screen in clear imagery.

"Maybe one of those giant sturgeon tried to take a bite out of our towfish," Wofford joked, relieved that the equipment was working properly again. But his words were followed by a low, deep rumble that echoed across the water.

Far longer and lower pitched than a clap of thunder, the sound had an odd m.u.f.fled quality to it. For nearly half a minute, the strange murmur echoed across the lake. All eyes on the boat scanned north in the direction of the noise, but no visible source was evident.

"Some sort of construction?" Theresa asked, searching for an answer.

"Maybe," Roy replied. "It's a long ways off, though."

Glancing at the sonar monitor, he noticed a brief spate of noise that minimally disrupted the image before a clean contour of the lake bed reappeared.

"Whatever it is," Wofford grimaced, "I just wish it would stop messing with our equipment."

-2-

TEN MILES TO THE NORTH, Rudi Gunn walked onto the bridge wing of the gray-hulled Russian research vessel Vereshchagin and looked up at the azure sky overhead. Removing a thick pair of horn-rimmed gla.s.ses, he carefully cleaned the lenses and then peered upward again. Shaking his head, he walked back onto the bridge and muttered, "Sounds like thunder, but there's hardly a cloud in the sky."

A hearty laugh erupted at his words, flowing from a portly man with black hair and matching beard. Dr. Alexander Sarghov resembled a circus bear, his large frame softened by a jovial demeanor and warm ebony eyes that twinkled with life. The geophysicist from the Russian Academy of Sciences Limnological Inst.i.tute enjoyed a good laugh, especially if it was at the expense of his newfound American friends.

"You Westerners are very amusing," he chuckled in a heavily accented voice.

"Alexander, you'll have to excuse Rudi," answered a warm, deep voice from the opposite side of the bridge. "He's never lived in an earthquake zone."

The green opaline eyes of Dirk Pitt sparkled with mirth as he helped heckle his deputy. The head of the National Underwater and Marine Agency stood up from a bank of video monitors and stretched his six-foot-three frame, his palms sc.r.a.ping against the deckhead. Though more than two decades of undersea adventures had exacted a toll on his rugged body, he still had a lean and fit form. Just a few more wrinkles around the eyes and a growing tussle of gray at the temples indicated a wavering battle with age.

"An earthquake?" Gunn speculated. The brainy deputy director of NUMA, an Annapolis graduate and former Navy commander, stared out the bridge in wonder.

"I've only been in one or two, but those were felt and not heard."

"Puny ones just rattled the dishes, but larger quakes can sound like a string of locomotives running by," Pitt said.

"There is a great deal of tectonic activity under Lake Baikal," Sarghov added. "Earthquakes occur frequently in this region."

"Personally, I can do without them," Gunn said sheepishly, retaining his seat by the monitor bank. "I hope they don't disrupt our data collection of the lake's currents."

The Vereshchagin was engaged in a joint Russian-American scientific survey of Lake Baikal's uncharted current flows. Not one to stay confined in NUMA's Washington headquarters, Pitt was leading a small team from the government research agency in collaboration with local scientists from the Limnological Inst.i.tute at Irkutsk. The Russians provided the ship and crew, while the Americans provided high-tech son.o.buoys and monitoring equipment which would be used to paint a three-dimensional image of the lake and its currents. The great depth of Lake Baikal was known to create unique water-circulation patterns that often behaved unpredictably. Tales of swirling vortexes and fishing boats getting pulled underwater by their nets were common stories among the local lakeside communities.

Starting at the northern tip of the lake, the scientific team had deployed dozens of tiny sensors, packaged in orange colored pods that were ballasted to drift at varying depths. Constantly measuring temperature, pressure, and position, the pods relayed the data instantaneously to a series of large underwater transponders that were positioned in fixed locations. Computers...o...b..ard the Vereshchagin processed the data from the transponders, displaying the results in 3-D graphic images. Gunn glanced at a bank of the monitors in front of his seat, then focused on one in particular, which depicted the midsection of the lake. The image resembled a pack of orange marbles floating in a bowl of blue ice cream. Nearly in unison, a vertical string of the orange b.a.l.l.s suddenly jumped rapidly toward the top edge of the screen.

"Whoa! Either one of our transponders is going tilt or there's a significant disturbance at the bottom of the lake," he blurted.

Pitt and Sarghov turned and studied the monitor, watching as a flood of orange dots raced toward the surface.

"The current is uplifting, at a dramatic rate," Sarghov said with a raised brow. "I find it difficult to believe the earthquake was severe enough to produce that kind of effect."

"Perhaps not the earthquake itself," Pitt said, "but a resulting side effect. A submarine landslide set off by a minor quake might create that sort of uplift."

A hundred and thirty miles north of the Vereshchagin and two thousand feet beneath the surface, Pitt was exactly right. The rumblings that first echoed across the lake were the shock waves from a strong earthquake, measuring 6.7 on the Richter scale. Though seismologists would later determine that the quake's epicenter was near the lake's northern sh.o.r.e, it created a devastating effect midway down the western flank, near Olkhon Island. A large, dry, barren landma.s.s, Olkhon sat near the center of the lake. Directly off the island's eastern sh.o.r.eline, the lake floor dropped like an elevator down a steep slope that ran to the deepest part of the lake.

Seismic studies had revealed dozens of fault lines running beneath the lake floor, including a cut at Olkhon Island. Had an underwater geologist examined the fault line before and after the quake, he would have measured a movement of less than three millimeters. Yet those three millimeters was sufficient enough to create what the scientists call a "fault rupture with vertical displacement," or an underwater landslide.

The unseen effects of the quake sheared off a mountain-sized hunk of alluvial sediments nearly twenty meters thick. The runaway chunk of loose sediments slid down a subterranean ravine like an avalanche, acc.u.mulating ma.s.s and building momentum as it went. The mountain of rock, silt, and mud fell a half mile, obliterating underwater hills and outcroppings in its path before colliding with the lake bottom at a depth of fifteen hundred meters.

In seconds, a million cubic meters of sediment was dumped on the lake floor in a dirty cloud of silt. The m.u.f.fled rumble of the ma.s.sive landslide quickly fell away, but the violent energy produced by the slide was just unleashed. The moving sediment displaced a ma.s.sive wall of water, driving it first to the bottom ahead of the landslide and then squeezing it up toward the surface. The effect was like a cupped hand pushing under the surface of a bathtub. The force from millions of gallons of displaced water had to be redirected somewhere.

The submarine landslide had fallen in a southerly direction off Olkhon Island and that was the direction that the mounting swell of water began to move. To the north of the slide, the lake would remain relatively undisturbed, but to the south a rolling wave of destructive force was released. At sea, the moving force of water would be labeled a tsunami, but in the confines of a freshwater lake it was called a seiche wave.

An upsurge of water punched the surface in a ten-foot-high rolling wave that drove south along the lake's lower corridor. As the wave pushed into shallower depths, the upswell squeezed higher, increasing the size and speed of the surface wave. To those in its path, it would be a liquid wall of death.