WHEN GALERAS BLEW, roughly 75 scientists, including our team, were on field trips on and around the volcano—on its flanks, in the river valleys running off the mountain, in nearby towns. Besides ours, Marta Calvache's group was closest to the crater itself—perhaps 500 to 800 yards from the top. Marta was born in Galeras's shadow, and she has spent most of her professional life studying it. Her mastery of the volcano would save my life.

As soon as the eruption died down and the projectiles stopped flying, Marta and our colleague Patty Mothes bolted toward their jeep and headed up the mountain.Ash drifted down on the windshield as they sped toward the summit. At the police post, they confronted a grim scene. Volcanic bombs had knocked holes in the roof and walls. White-hot, angular rocks littered the ground. When Patty spat on one, it hissed back at her. The volcano still thrummed, howling like a strong wind.

Andy Adams and Mike Conway—both suffering minor burns and Conway with a broken hand—had made it to the top of the scarp. Luis LeMarie, both of his legs fractured and his clavicle broken, had been helped up the last few meters by Carlos Estrada. Now Marta and Patty, joined by several other rescuers, scrambled down the amphitheater wall. The group found Andy Macfarlane, who had collapsed with a minor skull fracture about 150 yards below, and hauled him up. Then, ignoring radio warnings of another possible eruption, Marta, Patty, and the others raced across the slopes of the still-chuffing volcano in search of more survivors. Somewhere on the lower half of the cone they found José Arlés, his skull cracked open. Patty saw the bodies of two of the tourists, their brains spilled out on the ground. And a few yards away from José Arlés, Marta spotted me. Of the rest—of Igor Menyailov and Nestor García, of Geoff Brown, Carlos Trujillo, and Fernando Cuenca—there was no sign. They had essentially been vaporized.