Fire Ice (NUMA Files 3)

"Almost a mirror image. The fatality and injury rate was lower in my town, thank goodness. There was another important similarity. Both waves seem to have been caused by huge underwater slides. There was no doubt that an earthquake caused the Grand Banks disaster. The oceanic cables were broken in dozens of places." He paused. "Here's where they were different: The Rocky Point slide seems to have been caused without a quake."

"Interesting. Were there any seismic readings?"

"I checked with the Weston Observatory outside of Boston. The Grand Banks quake had a ma

gnitude of 7.2. So we know something of that magnitude will cause a tsunami. The Rocky Point readings were more muddled." He paused. "There was a shock, but it didn't fit the classic pattern for a quake."

"Let me see if I'm clear on this. Are you really saying the Rocky Point slump was not from an earthquake?"

"I think that can be fairly well established. What I can't say is what actually caused the landslide." Yaeger looked over the tops of his granny glasses. "Which came first, the chicken or the egg?"

"Something like that. I had read about the methane- hydrate deposits found off the continental slope and wondered if instability in those pockets of gas could have caused the slump."

"It's certainly possible," Reed said. "There are huge pockets of the stuff off both coasts. We've found major deposits off of Oregon and New Jersey, for instance. You've heard of the Blake Ridge?"

"Sure. It's an undersea promontory a couple of hundred miles southeast of the U.S."

"Off the North Carolina coast, to be exact. The ridge is loaded with methane hydrate. Some people think the ridge is a 'pressure cooker.' Surveys have found craters pockmarking the ocean floor where the stuff has melted and seeped out, releasing methane gas."

Jenkins scratched his head. "I'm sorry to say I don't know a lot about hydrates. I try to keep up through the professional journals since leaving the university, but what with the lobstering and so on, I never seem to have enough time."

"It's a comparatively new area. You're familiar with chemical composition of hydrate?"

"It's made up of natural gas molecules trapped in ice."

"That's right. Someone dubbed it 'fire ice.' It was discovered in the nineteenth century, but our knowledge has been pretty sketchy. The first natural deposits were under the permafrost in Siberia and North America -they called it marsh gas – then in the 1970s, a couple of scientists from Columbia University found pockets under the seafloor when they were doing seismological studies at the Blake Ridge. In the 1980s, the Woods Hole submersible Alvin found stone undersea chimneys formed by escaping methane. I was on the first big survey back in the mid-1990s. That's when we discovered the deposits in the Blake Ridge. They're only a fraction of what's out there. The potential is vast.”

"Where are the major deposits?"

"Mostly along the lower slopes of the world's continental shelves, where the seabed drops from four hundred feet or so into the abyss several miles deep. There are major pockets off both U.S. coasts. As I said, you can find them in Costa Rica, Japan, India, and under the arctic permafrost. The sheer size of the deposits is astounding. The most recent estimates are ten thousand gigatons. That's double the total amount of all known reserves of coal, oil and natural gas."

Jenkins let out a low whistle. "Waiting there to be tapped when we suck our petroleum reserves dry."

"I wish it were so easy," Reed said with a sigh. "A few technical problems have to be ironed out before extraction is practical."

"Is it dangerous to drill?"

“The first time a ship drilled into a pocket was in 1970. Nothing happened, but drillers were afraid for years afterward that they'd get blown out of the water. Eventually, a few experimental bores showed that research drilling was safe. Getting hydrates to the surface to heat your home or run your SUV is another question. The environment is extremely hostile in the deep water where hydrates are found, and the stuff simply fizzes when we bring it up. The deposits may be another few hundred feet below the seafloor."

"That sounds like a tough neighborhood for rigs to operate in.”

"Absolutely. A number of countries and companies are working on the problem, though. One method is pumping steam or water down the drill hole. This melts the hydrate and releases methane. Then you pump the methane to the surface of the seafloor through another drill hole. Next comes the question of what you do with it. When you remove the hydrate, the seafloor destabilizes."

"There goes your expensive pipeline."

“A good possibility. Which is why engineers have come up with a scheme to put a production facility on the seafloor. You pump the hydrate out and combine it with water. The mix goes into big tanks shaped like dirigibles. Submarines would tow them to the shallows, where the hydrates would be safely broken down into fuel and water."

"With any of those methods, it sounds like mining hydrates is going to be like walking on eggshells."

"Even more difficult. Now back to your original question."

"About hydrates as a source of earthquakes and big waves."

"It's highly possible. There is evidence that the natural melting has destabilized seafloor slopes. They've found massive submarine landslides off the U.S. East Coast, Alaska and other countries. The Russians found unstable hydrate fields off Norway. They think one of the biggest releases ever recorded caused the Storrega submarine landslide: Eight thousand years ago, more than a thousand cubic miles of sediments slid for miles down the slope of the Norwegian continental slope."

"I' m acquainted with Storrega," Jenkins said. "Then you'd know that the huge mud slide caused unimaginable tsunamis. The Grand Banks and Rocky Point would have been bathtub waves by comparison."

Jenkins nodded. "What about man-made landslides. Possible?"