watching as a flood of orange dots raced toward the surface.
âThe current is uplifting, at a dramatic rate,â Sarghov said with a raised brow. âI find it difficult to believe the earthquake was severe enough to produce that kind of effect.â
âPerhaps not the earthquake itself,â Pitt said, âbut a resulting side effect. A submarine landslide set off by a minor quake might create that sort of uplift.â
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 quakeâs epicenter was near the lakeâs northern shore, it created a devastating effect midway down the western flank, near Olkhon Island. A large, dry, barren landmass, Olkhon sat near the center of the lake. Directly off the islandâs eastern shoreline, 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 âfault rupture with vertical displacement,â 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, accumulating mass 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 muffled rumble of the massive landslide quickly fell away, but the violent energy produced by the slide was just unleashed. The moving sediment displaced a massive 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 lakeâs 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.
On the bridge of the Vereshchagin, Pitt and Gunn tracked the development of the killer wave with growing alarm. An enlarged three-dimensional map of the lake south of Olkhon Island showed a swirl of orange dots jumping in rapid succession across an expanding line.
âDial up the surface pods only, Rudi. Letâs find out exactly whatâs going on up top,â Pitt requested.
Gunn typed a short command into the computer and a two-dimensional image suddenly appeared on the monitor, showing an array of surface pods bobbing over a five-mile stretch of the lake. All eyes on the bridge focused on the screen as one orange pod after another visibly jumped in a slow line of progression from north to