His mobile rang four times, then switched to voicemail.

Fate had ruled otherwise. In that case, she'd just wait.

She wiped the dripping hair from her eyes and went inside, hoping that, if nothing else, the coffee machine was ready for action.

Tsunami

The sea was full of monsters. Since the beginning of human history it had been a place for symbols, myths and primal fears. The six-headed Scylla had preyed on Odysseus's companions. Angered by Cassiopeia's boastfulness, Poseidon had created Cetus, a sea monster, and cast sea snakes at Laocoon when he foretold the fall of Troy. Sirens were lethal to sailors unless they stopped their cars with wax. Mermaids, aquatic dinosaurs and giant squid haunted the imagination. Vampyroteutis infernalis was the antithesis of every human value. Even the horned creature of the Bible had risen from the sea. And then, to top it all, science, whose first allegiance was to scepticism, had taken to preaching the message of truth that lay at the heart of the legends. The coelacanth was alive. The giant squid existed. For thousands of years people had feared the creatures of the deep, but now they followed them excitedly. Nothing was sacred to the modern scientific mind, not even fear. Deep-sea monsters had become man's favourite playthings, the soft toys of science.

Except one.

It struck fear into the most rational mind. Rising up from the sea to sweep over the land, it brought with it death and destruction. It owed its name to the Japanese fishermen who had been spared its horrors out at sea, but had returned to their villages to find their homes devastated, their families dead. The word they used to describe it meant 'wave in the harbour'. Tsu for harbour; nami for wave.

Tsunami.

Alban's decision to plot a course for deep water showed that he knew the monster and its habits. Seeking the supposed protection of the harbour would be fatal.

While the Thorvaldson was battling its way through the choppy seas, the continental shelf and slope slid further into the depths. The downward pull lowered the sea level over a vast area. The water around the plummeting mass rose up, surging outwards in a wave that radiated across the ocean. Near the site of the slide, covering an area of several thousand square kilometres, the wave was so flat that its presence went undetected amid the raging storm. Its height above water reached scarcely a metre.

Then it hit the shallow water of the shelf.

Over the years Alban had learned what distinguished a tsunami from a normal surface wave. Ocean swells were usually the result of movement in the air: solar radiation warmed the atmosphere, but the warmth wasn't distributed equally across the surface of the planet so the heat was transferred by winds, which swept over the ocean, ruffling the water and creating waves. The water rose barely fifteen metres, even in a hurricane. Giant waves were the only exception. Normal surface waves reached a maximum speed of ninety miles an hour, and the effect of the wind stayed on the surface. Just two hundred metres lower, the water would be calm.

But tsunamis didn't form on the surface: they originated in the depths. They weren't the result of high winds: they were created by a seismic shock – and seismic shock waves travelled at entirely different speeds. Worst of all, the energy of the tsunami was transmitted throughout the water column all the way to the seabed. No matter how deep the ocean was, the wave was always in contact with the seabed. The entire mass of water was in motion.

The best demonstration that Alban had ever seen of a tsunami wasn't a computer simulation but something much more basic. Someone had filled a pail with water and rapped the bottom. Concentric rings had rippled through the water. To picture a tsunami, he had merely to imagine it several million times bigger.

Merely.

Triggered by the landslide, the tsunami propagated outwards at a speed of 700 kilometres per hour. The crest of the wave was long and flat. It carried a million tonnes of water and was laden with energy. Within a few minutes, it had reached the spot where the shelf had snapped. The water became shallower, acting as a brake. The wave front slowed, but lost little energy. The mass of water pushed onwards, but because it was slowing, it began to stack up. The shallower the water became, the higher the tsunami towered, while its length shrank dramatically. Normal surface waves joined in, riding on its crest. By the time it reached the platforms on the North Sea shelf it had decelerated to 400 kilometres per hour, but it was already fifteen metres high.

Fifteen metres was nothing to an oil platform – providing the wave was just normal surface swell.

A seismic wave that stretched from the seabed to the surface, carrying a fifteen-metre mound of water and travelling at four hundred kilometres per hour, had the momentum of a speeding jumbo jet.

GULLFAKS C, Norwegian Shelf

For a second Lars Jörensen thought he was too old to endure the final months on Gullfaks. He was trembling so much that the platform seemed to be vibrating with him. In all other respects he wasn't feeling too bad. A little depressed, maybe, but not ill.

Then it dawned on him that the platform was shaking, not him.

He stared at the derrick, then back out to sea. The sea was raging, but he'd seen worse and it had never affected the platform. Jörensen had heard of platforms shaking: it happened when a drilling operation triggered a blow-out, causing oil or gas to shoot up at high pressure. The whole platform could shudder back and forth. But that was impossible on Gullfaks, where the reserves were half empty, and the oil was pumped into sub-surface tanks. Besides, extraction took place at a distance, not under the platform.

The offshore industry had its own top ten of greatest risks. Struts within the steel framework that supported the platforms might collapse. Freak waves, massive surges of water caused by a combination of current and wind, were the industry's equivalent of a maximum credible accident. Pontoons that broke free or tankers with engine failure were dangerous too. But near the top of the hit parade of horror was the gas leak. Escaping gas was almost impossible to detect. In most cases it was only noticed when it was too late and fire had broken out. In incidents like that the platform exploded: more than 160 people had died on the British Piper Alpha, the biggest disaster in the history of the industry.

But a seaquake was the ultimate nightmare.

And this, Jörensen realised, was a quake.

Anything could happen now. When the ground shook, events spun out of control. Metal warped and snapped. Leaks sprang up and fires broke out. If the tremor was enough to rattle the platform, they could only hope that things wouldn't get worse, that the seabed wouldn't cave in or slump, and that the rig's foundations would withstand the shock. But in addition to all that, another problem was associated with quakes, which no one could do anything about.

And it was about to hit the platform.

Jörensen saw it coming and knew that his chances were nil. He turned and made for the steel steps, trying to escape his lofty perch.

It happened quickly.

He lost his footing and fell. Instinctively his fingers clutched the metal grating beneath him. An infernal noise broke out, a roaring and cracking as though the platform were breaking apart. There was screaming, a deafening bang, and Jörensen was tossed against the railings. Pain seized him. As he hung there in the metalwork, the sea reared up out of nowhere. He could hear the shriek of tearing metal and realised that the whole platform was tilting. His mind shut down. Now he was just a panic-stricken body, making futile attempts to crawl away from the approaching water. He dragged himself up the slope that, seconds before, had been a floor, but the incline was getting steeper.