Page 41 of Eruption
Rick and Kenny walked over to Mac; Mac could see the concern on Rick’s face.
“Mac,” Rick said, “you know what you’re saying, right? You’re talking about making this volcano explode.”
“You know something, though? It just might work,” Kenny said.
“And that’s exactly what I’m afraid of,” Rick said. “We’re talking about trying to make anuée ardente. An avalanche of fire. The most dangerous volcanic phenomenon there is.”
“Pretty much,” Mac said.
CHAPTER 26
Glowing volcanic avalanches had destroyed Pompeii in AD 79 and had flattened whole islands near Krakatoa in 1883, but they remained a phenomenon unknown to science until 1902, when the volcano Mount Pelée erupted on the Caribbean island of Martinique.
Pelée had been restless for months, but no one was prepared when, at 7:52 a.m. on May 8, 1902, an avalanche of red-hot gas and ash roared down the mountain at five hundred kilometers an hour; it destroyed the town of Saint-Pierre and most of the ships anchored in the harbor.
Twenty-nine thousand people died, many almost instantaneously.
The handful of surviving eyewitnesses—the lucky ones on boats far enough out to sea to avoid the gas cloud—described a scene of hellish destruction. Photographs of the town reduced to smoking ruins made the front pages of newspapers around the world.
The avalanche that had caused this instantaneous destruction was termed anuée ardente,or “fiery cloud.” It ripped through three-foot-thick concrete walls, smashed whole buildings, toreheavy cannons from their mountings, and snapped a lighthouse in half like a twig.
These avalanches were now termedpyroclastic flowsand were the focus of intense study by volcanologists. Numerous attempts had been made to model their behavior in laboratories. Jenny Kimura had worked on it one summer at the Osservatorio Vesuviano near Naples, part of a team that made models of hot lava flows in a sloped laboratory tank, and she had also done computer modeling of these flows. She knew more about pyroclastic flows than anyone at HVO, including Mac, but she didn’t say anything at first. It was one of the things Mac liked about her, sometimes loved. Jenny let the game come to her.
“Okay, let’s think this through,” Rick said. “Let’s say you succeed. Then what?”
“Then we’ll have blown open the vent and released the lava,” Mac said.
“And sent a pyroclastic flow racing toward Hilo.” Rick pointed down the mountain.
“It’ll never get there.”
“You hope.”
“Rick, I’m telling you it won’t,” Mac said. “The slope is too gentle; the avalanche can’t sustain. It’ll die out in three or four kilometers.”
“But isn’t how far it goes a function of the initial blast, Jen?”
Mac wanted to smile. Rick was challenging them the way Mac always challenged him.
Jenny shook her head. Now she was ready to engage. “Mac’s right. It’ll never get to Hilo.”
“For now,” Briggs said, “we don’t want Dr. MacGregor to just tell us how his plan might work. We want him to show us. With the understanding that we in the United States Army have not ruled out the building of walls at this time.”
“Fair enough. Follow me,” Mac said. He was the one giving the orders now.
Mac led them all over jagged lava fields for half a mile, then got down on his hands and knees in front of a hole that was just big enough to squeeze through.
“This one’s a typical lava tube opening,” he said to the group. “Just be careful when you come through. And don’t keep going forward. Move to the right.”
He crawled through the hole, and the others followed him one by one.
Once inside, Mac switched on his phone’s flashlight app because the tube was pitch-black. As the others came through, they switched on their phones. Yellow beams crisscrossed like searchlights.
They found themselves in a domed pocket the size of a high-school gym. The ceiling was smooth, almost shiny, but the floor was rough black lava.
“This is a typical air chamber,” Mac said, his voice echoing. “It’s a bit like being inside a bubble. The magma releases gases as it rises, and if those collect in a big bulge, you get this smooth surface that you see above us. The lava flows continuously beneath this air pocket and often forms a second and even a third chamber. The ceilings of those chambers may break open, making a large pit. If you move carefully forward, you can see down into the pit here. Just don’t get too close to the edge—it’s thin. And it’s a long drop.”
“That’s putting it mildly,” someone behind him said, shining the light down.