GoKawiilIn the summer of 1912, word reached Robert Fiske Griggs that the apocalypse had arrived on Kodiak, an inhabited island off the coast of Alaska. The following year, Griggs, a botanist at the University of Ohio, led the first of several expeditions to the island, where he and a team glimpsed a disquieting sight: Kodiak was shrouded in a full foot of ash. And it wasn’t just the island. On the mainland on a formerly multi-peaked volcano called Mount Katmai, the soot-covered landscape was still venting noxious gas.
The environs of Mount Katmai had been home to a lush river valley. Griggs later wrote that on his surveying missions, he found that it “was full of hundreds, no, thousands — literally, tens of thousands — of smokes curling up. … Some were sending up columns of steam which rose a thousand feet before dissolving.” The site, which bubbled and hissed for decades, is still called the Valley of Ten Thousand Smokes.
Griggs and his fellow expeditioners were walking through the aftermath of the 20th century’s most prolific act of volcanism — a 60-hour frenzy that smothered much of the Pacific Northwest in onyx snow. Aerosols released by the eruption lingered for so long in the atmosphere that average temperatures in the Northern Hemisphere dropped by 1 degree Celsius for over a year.
The eruption did more than cool the skies and scorch an entire network of valleys. It also collapsed two of the three peaks of Mount Katmai into a single pit 1 kilometer deep and 2.5 kilometers across. At the time, it seemed obvious what had happened: Katmai had unleashed most of its magma, and it had left a giant chasm in its wake.
But the truth isn’t always obvious. In the 1950s, detailed geologic mapping of Katmai and its surroundings by Garniss Curtis, a geologist at the University of California, Berkeley, revealed that the eruption had emerged not from the now-collapsed peaks of the volcano, but from an opening in Earth’s crust 10 kilometers to the west that had never been seen before.
After extensive fieldwork, scientists reached a conclusion: Two-thirds of Katmai had disappeared because this opening had stolen Katmai’s magma. The idea was controversial, because volcanoes were always thought to act independently, tapping their own supplies of molten, eruptible rock. But Katmai and the opening, dubbed Novarupta, offered the first real clue that volcanoes could be connected, or “coupled.”