ON THE MORNING OF JANUARY 14, I led a convoy of a half-dozen jeeps west out of Pasto. Seventy-five scientists would be working around Galeras that day, but ours was the only group that would study the crater itself. The temperature was in the forties, and thick clouds drifted slowly across the mountaintops. About 3,000 feet from the summit we entered a national park, the mountainside thick with frailejon, a succulent with silvery-green leaves and vivid yellow flowers. Before entering the clouds, I caught a final glimpse of Pasto a few thousand feet below. Above the red tile roofs, wisps of smoke drifted from the chimneys.
The convoy parked at a small, stucco police station perched on the rim surrounding the volcano's amphitheater. I'd stood here many times: Standing at the police post, you gaze down at the active volcano, its crater lip 300 feet below. In the center of the amphitheater rises the present cone of Galeras, 1,500 feet in diameter, and in its center, 450 feet above the amphitheater floor, is the active crater. To get from the police post to the crater you descend the declivitous wall of the old volcano, with its layers of hardened lava at the top and scree at the bottom. Then you cross 150 feet of amphitheater floor before reaching the cone, whose scree slope rises at a 45-degree angle. An old wooden soccer goal sits in pieces at the base of the cone, placed there by soldiers who once played on what was undoubtedly the world's most dangerous soccer field.
The 16 of us—13 scientists, a two-man Colombian television crew, and our driver from the observatory, Carlos Estrada—moved to the lip of the scarp. Geoff Brown checked his gravimeter. Igor Menyailov peeked into his box of sampling tubes. José Arlés Zapata made the sign of the cross. Around 10 a.m. we began to descend the amphitheater wall, holding on to a thick, yellow nylon rope for the initial 100-foot drop. The clouds were still dense, and after a few dozen yards the rope disappeared into a gray void.