bottoms of the legs were smeared with mud that had a strange bluish cast to it. A miner’s hardhat sat on his head, and his face was covered by what Pitt took for a mask with a breathing filter. He clutched a bundle under one arm. “I understand you’re interested in our mining operation,” he said quietly.
“Yes. My name is—”
“Names are unimportant. We don’t have much time if you are to leave the island with the fishing fleet.” He unfolded a jumpsuit, a respirator mask and a hard hat and handed them to Pitt. “Put these on and follow me.”
Pitt said nothing and did as he was told. He did not fear a trap. The security guards could have taken him anytime since he set foot on the dock. He dutifully zipped up the front of the jumpsuit, tightened the chin strap of the hard hat, adjusted the respirator mask over his face and set out after a man he hoped could show him the source behind the violent killings.
Pitt followed the enigmatic mining engineer across a road into a modern prefabricated building that housed a row of elevators that transported the workers to and from the diggings far below. Two larger ones carried the Chinese laborers but the smaller one on the end was for the use of company officials only. The lift machinery was the latest in Otis elevator technology. The elevator moved smoothly, without sound or sensation of dropping.
“How deep do we go?” asked Pitt, his voice muffled by the breathing mask.
“Five hundred meters,” replied the miner.
“Why the respirators?”
“When the volcano we’re standing in erupted in the distant past, it packed Kunghit Island with pumice rock. The vibration that results from the excavating process can churn up pumice dust, which raises hell with the lungs.”
“Is that the only reason?” asked Pitt slyly.
“No,” replied the engineer honestly. “I don’t want you to see my face. That way, if security gets suspicious, I can pass a lie-detector test, which our chief of security uses with the frequency of a doctor giving urine tests.”
“Dapper John Merchant,” Pitt said, smiling.
“You know John?”
“We’ve met.”
The older man shrugged and accepted Pitt’s claim without comment.
As they neared the bottom of the run, Pitt’s ears were struck by a weird humming sound. Before he could ask what it was, the elevator stopped and the doors slid open. He was led through a mineshaft that opened onto an observation platform perched fifty meters above the vast excavation chamber below. The equipment at the bottom of the pit was not the typical type of machinery one might expect to encounter in a mine. No cars filled with ore pulled over tracks by a small engine; no drills or explosives, no huge earth-moving vehicles. This was a well- financed, carefully designed anal organized operation that was run by computers aided in a small way by human labor. The only obvious mechanization was the huge overhead bridge with the cables and buckets that lifted the diamond-bearing blue rock-clay to the surface and carried it to the buildings where the stones were extracted.
The engineer turned and stared at him through green eyes over the mask. “Mason did not tell me who you are or who you represent. And I don’t want to know. He merely said you were trying to trace a sound channel that travels underwater and kills.”
“That’s true. Untold thousands of various forms of sea life and hundreds of people have already died mysteriously in the open sea and along shorelines.”
“You think the sound originates here?”
“I have reason to believe the Kunghit Island mine is only one of four sources.”
The engineer nodded knowingly. “Komandorskie in the Bering Sea, Easter Island, Gladiator Island in the Tasman Sea, being the other three.”
“You guessed?”
“I know. They all use the same pulsed ultrasound excavation equipment as we do here.” The engineer swept his hand over the open pit. “We used to dig shafts, in an attempt to follow the largest concentration of diamonds. Much like miners following a vein of gold. But after Dorsett scientists and engineers perfected a new method of excavating that produced four times the production in one third the time, the old ways were quickly abandoned.”
Pitt leaned over the railing and stared at the action across the bottom of the pit. Large robotic vehicles appeared to ram long shafts into the blue clay. Then came an eerie vibration that traveled up Pitt’s legs to his body. He gazed questioningly at the engineer.
“The diamond-bearing rock and clay are broken up by high-energy pulsed ultrasound.” The engineer paused and pointed to a large concrete structure with no obvious windows. “See that building on the south side of the pit?”
Pitt nodded.
“A nuclear generating plant. It takes an enormous amount of power to produce enough energy at ten to twenty bursts a second to penetrate the rock-hard clay and break it apart.”
“The crux of the problem.”
“How so?” asked the engineer.
“The sound generated by your equipment radiates into the sea. When it converges with the energy pulses from the other Dorsett mines scattered around the Pacific, its intensity increases to a level that can kill animal life within a large area.”
“An interesting concept as far as it goes, but a piece is missing.”
“You don’t find it plausible?”
The engineer shook his head. “By itself, the sound energy produced down below could not kill a sardine three kilometers from here. The ultrasound drilling equipment uses sound pulses with acoustic frequencies of 60.000 to 80,000 hertz, or cycles per second. These frequencies are absorbed by the salts in the sea before they travel very far.”
Pitt stared into the eyes of the engineer, trying to read where he was coming from, but other than the eyes and a few strands of graying hair that trailed from under the hard hat, all he could readily see was that the stranger was the same height and a good twenty pounds heavier. “How do I know you’re not trying to throw me off the track?”
Pitt could not see the tight smile behind the respirator mask, but he guessed it was there. “Come along,” said the engineer. “I’ll show you the answer to your dilemma.” He stepped back into the elevator, but before he pushed the next button on the panel, he handed Pitt an acoustic-foam helmet. “Take off your hard hat and set this over your head. Make certain it’s snug or you’ll get a case of vertigo. It contains a transmitter and receiver so we can converse without shouting.”
“Where are we headed?” asked Pitt.
“An exploratory tunnel, cut beneath the main pit to survey the heaviest deposit of stones.”
The doors opened and they stepped out into a mineshaft carved from the volcanic rock and shored up with heavy timbers. Pitt involuntarily lifted his hands and pressed them against the sides of his head. Though aft sound was muffled, he felt a strange vibration in his eardrums.
“Do you hear me all right?” asked the engineer.
“I hear you,” answered Pitt through the tiny microphone. “But through a humming sound.”
“You’ll get used to it.”
“What is it?”
“Follow me a hundred meters up the shaft and I’ll show you your missing piece.”
Pitt trailed in the engineer’s footsteps until they reached a side shaft, only this one held no shoring timbers. The volcanic rock that made up its rounded sides was almost as smooth as if it had been polished by some immense boring tool.
“A Thurston lava tube,” Pitt said. “I’ve seen them on the big island of Hawaii.”
“Certain lavas such as those basaltic in composition form thin flows called pahoehoe that run laterally, with smooth surfaces,” clarified the engineer. “When the lava cools closer to the surface, the deeper, warmer surge continues until it flows into the open, leaving chambers, or tubes as we call them. It is these pockets of air that are driven to resonate by the pulsed ultrasound from the mining operation above.”
“What if I remove the helmet?”
