Marsquake! (4 page)

But if shaking you out of a sound sleep was the worst that could happen, well, Sean could live with that. He closed his eyes, and before long he fell asleep again, this time without dreaming.

As it turned out,
Dr. Ellman wasn’t at school the next day. He had council business, so Lieutenant Mpondo took over. Unlike Ellman, who was a stickler for keeping
with the day’s lesson plan, Mpondo didn’t mind getting sidetracked a bit, especially when practically the whole class wanted to know what the quake meant and what might happen next.

“Okay,” Mpondo said with a smile. “Let’s do a little vulcanology. Everyone, I’m going to take over your monitors and give you a quick sketch of what makes a volcano. Save what you’re working on.”

Sean hadn’t really started his lesson, so he just waited until Mpondo patched in the volcano module. “Okay,” Mpondo said, “look at the screen.”

It showed Earth as seen from space. Then the view zoomed down through the atmosphere to a mountainous region, looking wrinkled from a high altitude, but breaking up into fault lines, peaks, and valleys as the view moved closer. “This is a fault area on Earth. You’ve learned about tectonics, right?”

Patrick, off to Sean’s left, spoke up at once: “Right. Earth’s crust is broken up into plates. These sort of drift around on the, uh, the asthenosphere—did I say that right?”

“You said it as well as I could,” Mpondo replied. “But what causes the drift? What’s the force shoving the plates around?”

Sean knew that one. “Convection currents deep in the earth. Magma—that’s rock so hot that it’s liquid—wells up, and in some places, like the mid-Adantic Ocean, it breaks through and creates new sea floor. The Atlantic gets wider as new sea floor expands out both east and west of the mid-Adantic ridge. That pushes the plates apart.”

“Right again,” Mpondo said. “Now watch the screen. This shows part of the west coast of North America. What’s happening there is that one plate is grinding underneath another one. The Pacific seabed gets shoved down under the North American plate. Watch what happens.”

On the screen, the view changed to a cross-section of Earth’s surface. The Pacific plate came in from the west and got pressed down under the North American continent. As it went down, its movement generated heat, and that heat melted pockets of rock into glowing red magma. The magma expanded,
pressing upward until it found passageways to the surface, and then a volcano erupted. The animation continued, showing how the plate movement eventually dragged the volcano away from the hot spot, and then it died. But a new volcano formed right away.

“Who can tell me how the volcanoes on Mars are different from these?” Mpondo asked.

Elizabeth knew. “There’s no plate tectonics on Mars,” she said. “So a volcano, like Olympus Mons, doesn’t move away from the hot magma that created it. Instead of a row of volcanoes, you get just one huge one.”

“In fact, the biggest one in the solar system,” Mpondo confirmed. “Okay, then. The volcanoes of Mars all seem to be extinct—though we can’t be absolutely sure of that. The heat that drove them has cooled over millions of years. Now the magma chambers seem to be so far beneath the surface that there’s no way they can break through the crust in an eruption. However, as you know, lava flows in strange ways. There are vast underground caverns around the edges of Olympus Mons, places that once were
reservoirs of magma until it broke through and ran off as lava. Sometimes these caverns collapse, and that’s one source of marsquakes. But what’s probably happening is a miniature version of plate tectonics. As Elizabeth said, Mars doesn’t have plates, but it does have varying kinds of bedrock, and fault lines can develop between the different rock zones. Olympus Mons, for example, is a different kind of rock from the bedrock around it. There’s a boundary between the two different kinds of rock, and while the magma chamber doesn’t have the oomph to force its way out in an eruption, it just might have enough power to push some layers of rock past others, and that results in marsquakes.”

“How dangerous are they?” Jenny asked.

“No one knows,” Mpondo told her. “There’s never been a marsquake strong enough to threaten us, though we’ve been monitoring seismology on the planet from early in the twenty-first century and on. In fact, the strongest seismological event occurred more than seventy years ago, as a level six, and that turned out to be a meteorite impact. There have
been no aftershocks to this latest quake—not even ones so small they’d only register on a seismograph. It might have been a subterranean cave-in. Doesn’t seem like anything to worry about.”

“That’s a relief,” Elizabeth said.

“Happy to have made you feel better,” Mpondo said. “Now, everyone—back to your lessons!”

As they found out
a week later, Tim Mpondo had not been entirely correct. Sean had just come off his work schedule in the greendomes when Alex spotted him. “Heard the news?”

Sean got himself a tall glass of synthetic chocolate milk. He took a long, cool drink and asked, “What news?”

Alex pulled up a chair. “The scouting parties have found a major new system of lava tubes. Remember the quake we had?”

“Hard to forget,” Sean said with a grin.

“Well, what evidently happened is that a big underground magma chamber collapsed, just like Tim—I mean Lieutenant Mpondo said. Now, the interesting thing is that when the roof of that chamber fell in, it left another opening. And leading in and out of that new opening is a maze of new lava tubes.”

“How’d that happen?” Sean asked, frowning.

Alex shrugged. “I’m not exactly sure, but as I understand it, the big chamber resulted from volcanic activity a billion years ago. Later eruptions covered it over, and new lava flows came across the top of it half a billion years ago. The lava tubes that have opened up came from that second period.”

“In other words, you don’t know.”

Alex nodded, not at all insulted. “Pretty much. Anyway, the entrance to the lava tubes is only about eighty clicks to the north. Close enough to serve as the base for a new branch of the colony if we decide to begin branching out.”

Sean finished his drink. “I don’t want to make any decisions before I have my shower,” he said firmly.
“I’ve waited for it, I’ve earned it, and now I’m gonna have it.”

He had developed a special technique for taking a Martian shower. Water rationing meant that he could turn the water on for only about two minutes. Most colonists did a frantic kind of scrub-and-rinse, trying to get all the soap off before the water ran out. Sean’s method was a little different, because he liked the hot rush of water and didn’t want to work so hard at scrubbing that he missed it.

So he began by turning on the water for one quick fifteen-second blast. That got him wet, head to toe. Then he used a liquid soap both to shampoo and to soap up his whole body. And once that was done, then came the best part. He turned on the hot water and rinsed, enjoying more than a minute and a half of sheer luxury.

By the time he had finished his shower and dressed in fresh clothes, the others had gathered in the common area. Patrick had brought a holomap in, and when he activated it, everyone crowded around the
table. “Here it is,” he said, adjusting the map controls. The base of Olympus Mons was an escarpment, a sheer cliff that was itself taller than most mountains back on Earth. South of the escarpment was a range of rounded hills, the remnants of lava flows. Some were miniature volcanoes themselves—fumaroles—which once had vented hot steam and mud from the interior of Mars.

One of the hills showed a dark opening at its base. “This is where the collapse occurred,” Patrick said. “This cave mouth is about twenty meters in diameter, but as you go back, it widens out pretty rapidly. Then you hit the lava tubes. Half a dozen of them at least, leading back toward Olympus Mons and south toward us.”

“Creepy,” Roger Smith said. “And there might be bats!”

“Shut up, Roger. Is it stable?” Mickey asked.

Patrick shrugged. “Seems to be. The seismologists think the collapse happened because water vapor got into the cracks in the rock and expanded when the weather turned colder. It was going to happen soon,
anyway, but the water vapor that’s been added to the atmosphere sped things up.”

“So are we going to explore those tubes?” Mickey asked.

“I’d rather do that than go through tubes that have already been mapped,” Patrick said. “This way, we’re explorers. The other way, we’d just be tourists!”

“What’s the term?” Roger asked, wrinkling his forehead. “Spe-something, isn’t it? Spelologists? Something like that?”

“Spelunkers,” Sean told him. “Cave explorers.”

“Great!” Roger said. “I hope those tunnels are deep and twisty and full of surprises!”

Mickey grunted. Sean looked at the older boy, wondering what was bothering him. Mickey could be a pain—his sense of humor leaned toward sarcasm—but Sean knew from experience that he didn’t lack courage.

Alex was leaning so close to the holographic map that he was almost poking his nose into the cavern. “Man, I can’t wait,” he said. “I thought we were going to be zipped up in this dump all winter long. And winter’s
twice
as long here as it was in South Africa!”

“Great,” Mickey said, looking a little green.

“Hey, you’ll never guess what I heard,” Patrick said suddenly. “There are going to be, like, nine teams, right? Well, guess who’s going to be leading them.”

“Um, Snow White, the Seven Dwarfs, and Santa Claus,” Mickey said. “How can we guess? Give!”

Patrick gave him a superior smile. “Remember the jailbirds? The colonists who were in the brig for fighting?”

“Really?” Mickey said suspiciously. “No way.”

“They’ve been tapped as team experts,” Patrick said. “Some punishment, huh?”

“Man,” Alex said. “I know I don’t want to be on Rormer’s team. That is one seriously janked guy.”

“Who?” Sean asked.

“Pavel Rormer,” Mickey said shortly. “Got a buzz in his hive about anyone who’s not European. What I heard, he was the ringleader behind the fight. He started it all.”

“Good meteorologist, though,” Roger said.

“But a yurk, too,” Alex insisted. A yurk was an
idiot who didn’t know when to quit, the kind of guy who if you told him your computer was on the verge of burning out, would say, “You’re kidding.” And then he would turn on your computer anyway, just to check, and kill it dead.

“He should’ve gone home on the
Argosy,
” Mickey said. “I’ve heard that whenever the council wants a meteorological reading before an expedition, Rormer’s always the one who comes up with a thousand reasons why the weather’s too bad to do anything.”

“Maybe he’s just cautious,” Sean said.

“Maybe he’s just a yurk,” Mickey responded in a tone that closed the subject.

Sean didn’t say anything, but he felt a little twinge of guilt. Letting the prisoners have first crack at getting outside the domes—well, the order was coming from the council, true, but it had been his idea.

And if it went wrong, he reflected, it would be his fault, too.

Only three days later
everything changed. Sean had finished school, and he had taken time for a snack before reporting to Sam Mackenzie, a botanist and one of the directors of the farming program in Marsport. Greenhouse 7 was operating at only half its summer capacity, but still there was work to be done, and that afternoon Sam and Sean were setting up hydroponic frames that would support soybean plants.

The quake came with no warning.

“Hey!” Sam yelled as they were making the last hydraulic connection to the big hydroponic drum. “What’s that?”

Sean felt the vibration too, and then he heard the low rumble, so low that it seemed to be in his bones. “Quake!” he yelled.

Then he was staggering as the ground underfoot tossed and heaved. He heard things crashing—light
fixtures falling, the hiss of a broken water connection. “Emergency suits!” Sam bellowed, reeling toward a compartment at the end of the row of hydroponic tanks.

Sean followed him, fighting for balance. Then everything went dark, and a reverberating
crack!
echoed in the dome. Sean heard the whoosh and rush of air, felt the wind in his face. The dome had ruptured. Air was rushing out of it.

Sam had wrestled the compartment open and tossed Sean a dark green pressure suit, with a slim yellow oxygen “candle” attached. Then he pulled out one for himself.

Already the air felt thin. Sean could hear twangs and pops as parts of the dome hull blew outward, losing their battle against air pressure. He pulled the pressure suit on with haste. Like all the colonists, he had drilled for emergencies like this. But his lungs were burning by the time he got the oxygen flow started, and when Sam switched on his suit light, Sean realized that dark splotches were dancing in front of his eyes. He fumbled with numb fingers, found the light switch, and turned on his light too.

Sam was giving him a palm-up gesture—sign language for “okay?”

Sean nodded and gave him a thumbs-up sign. The quake had ended. Cold was flooding into the dome.

Turning back to the compartment, Sam wrestled out an emergency light, a large one, and got that turned on too. Holding its portable generator in one hand, he turned the beam toward the inner surface of the dome. Sean’s eyes followed the light, and he felt his chest clench. A twenty-meter-long rip, at least a meter across at the widest part, snaked up from the far side of the dome. The plants that the light touched were already dead, frosted and glittering in the cold semivacuum.

Sam turned and motioned with his head. The emergency suits had radio connections, but they didn’t have time to turn them on. The suits wouldn’t hold body heat for very long. Already the temperature in the dome had dropped to twenty below zero. They had to move quickly or die.

They reached the airlock into the connecting corridor, and Sam cycled it. They both crowded in. The
door closed, air rushed in, and with it came a return of warmth that brought stabs of pain to Sean’s toes and fingers. He hadn’t realized how cold he had been.