HIGH ABOVE ROSS ISLAND, THE VOLCANO’S FULMINATING lava lake seethed and bubbled and abruptly shot a dollop of molten rock into the sky with a belch of pressurized gas. Trailing smoke and licks of flame, the red-hot ejecta hurtled toward the rim of the summit cone, and over it, and then smacked into the mountainside a mile away. It was larger than a howitzer round, and its ballistic impact threw a cloud of ash, snow, and ice crystals up from the crater’s rim.

There the plastery magma bomb hardened in the supercooled air to lay among countless other chunks of igneous debris tossed across the slope.

While signs of the eruption traveled across many miles in this frigid and barren land, they drew only a scattering of attention.

It was heard clearly by National Science Foundation vulcanologists working on the mount’s upper elevations, and produced a tremor that rattled the equipment in their mobile apple huts. Its sonic precursors (vibrational pulses that signal an impending eruption) and signature oscillations (harmonic changes that indicate a discrete eruption, or series of eruptions, in progress) were registered by seismometers and broadband microphones that the researchers had installed and maintained with steady diligence throughout the Antarctic summer.

Ten thousand feet below on another corner of the island, the discharge and resultant concussion would be audible as two dull, thudding blurts of sound to McMurdites who took notice. Few did, however. The continuous volcanic output had never inflicted damage on the station, and was for them little more than background noise.

Eastward across the Transantarctic Mountains, the seismic precursors were detected in instantaneous-wave readouts from sensors on Erebus’s flank that had been well camouflaged from the NSF research team. As the sound of the explosive outbursts carried to Bull Pass, bouncing faintly between its craggy walls, hidden men and equipment went into clockwork action.

Three thousand feet underground, a boom-mounted drill came alive with a percussive jolt, its tungsten carbide bit boring into solid rock. Protected from its deafening clatter inside their safety cabin, the drill controller and his assistants breathed filtered air behind the face shields of their high-efficiency, closed-circuit respirator helmets.

Two thousand feet underground, a large jaw crusher began grinding and smashing the contents of its mineral fill chamber, the first stage in the yield’s multistage separation process.

A thousand feet higher, a pair of specialized trolley-assisted haul trucks, slung low for tunnel clearance, started forward on an inclined concrete ramp. On a stone shelf several levels beneath the surface, their semiprocessed loads would be stored in excavated pockets until ready to be moved into the open and rigged for helicopter airlift to the coast.

Soon after Erebus quieted, the trucks ceased to roll.