Before and after a catastrophic volcanic eruption
BY RICHARD EMANUEL
Kasatochi Island in the central Aluetians is less than two miles across, with a thousand-foot volcanic cone crowned by a crater cradling a lake of shifting colors. Before 2008, the island was an emerald jewel, set in rich seas supporting a thousand sea lions and a quarter-million seabirds that bred on the island in boisterous abundance.
Scientists had based a summer field camp on Kasatochi, part of the Alaska Maritime National Wildlife Refuge, for a dozen years to monitor the plants and wildlife under the refuge’s care.
“It was beautiful,” assistant refuge manager Jeff Williams says. “It’s just one part of our vast and amazing refuge, but anywhere else, it would be a national park.”
A Treasure House Laid Waste
In late July 2008, two biologists camped on Kasatochi began to feel earthquakes, which on volcanoes can be a sign of magma moving underground. The jolts grew in strength and frequency until the Alaska Volcano Observatory, tracking with satellites and other instruments, urged refuge managers, “Get your people off that island!”
A fishing boat from Adak, 50 miles to the west, took four hours to reach Kasatochi and evacuate the endangered biologists. Twenty minutes later, the volcano exploded in shrouds of ash, lightning, and shattered rock. Plumes of fine ash and sulfur dioxide shot to 50,000 feet and circled the globe. Roiling clouds of toxic gas, ash and lava, called pyroclastic flows, laid down deposits that pushed the southern shoreline
a quarter-mile seaward. In just 24 hours, Kasatochi was laid waste, buried in blistering mud and debris in places a hundred feet deep.
Two weeks later, Williams beheld an altered landscape.
“Whole sections of the crater rim were blown out,” he says.
Lower down, thick, gray deposits dotted with steaming fumaroles lay strewn with “huge boulders the size of cabins. It was mindboggling.”
Nothing green was seen.
The Aleutian Islands are products of geologic calamity. Raised from the seafloor by volcanic eruptions, islands are ravaged by earthquakes, tsunamis, and volcanic blasts. Life always returns.
In fall 2008, Williams and the wildlife refuge mustered a team of experts from sister science agencies and academia to chronicle life’s return to Kasatochi.
First back were Steller sea lions. Feeding at sea, all they need from land is somewhere to haul out, socialize, and breed.
“Sea lions were on the island within two weeks,” Williams reports. A decade later, seabirds, too, have largely recovered. Auklets, the island’s signature birds, winter at sea, and those that fled the explosion stayed at sea until spring.
“Crested and least auklets came back in 2009,” Williams says.
“They mate out in the water, so they had eggs. They had to go somewhere.”
Auklets are crevice-nesters, returning to rookeries in cliffs and talus slopes, but these were covered by ash and mud.
“The birds were so confused,” Williams recalls. “They would fly in these magnificent murmurations, big, huge swarms that are choreographed.”
Eggs lay everywhere on bare ground, a feast for gulls. No auklets were successful in 2009, but things improved as Aleutian storms washed out crags and clefts. An avalanche in 2010 opened a fresh boulder field. That year, “maybe ten auklets were able to breed,” Williams says. “The next year, maybe hundreds, then thousands, and by year six or seven, there were tens of thousands.”
Plants remain sparse, but they too, are returning to the island.Thought sterilized by pyroclastic flows hot enough to melt aluminum, mats of rootstock sheltered by overhanging cliffs sprouted hardy patches of grass. Botanists call these legacy plants, regrown from roots that survived the cataclysm. Colonial plants are also gaining footholds, washed ashore riding kelp or driftwood. A century may pass before biologists again wade through lush greenery to visit raucous rookeries, but revegetation has begun.
A decade on, other signs of recovery may be seen. Loose volcanic deposits are eroding, sculpting new landscapes. Seabird guano is pumping nutrients onto the island, building soil and fertilizing auklet colonies, now green with plants and algae.
Kasatochi’s story is already shedding light on life in the Aleutians. In the 1,200-mile archipelago, one or two volcanoes erupt per year. Earthquakes and tsunamis also afflict the Aleutians, all produced by jostling plates of the planet’s crust. Has Aleutian life adapted to upheaval? Williams and colleagues think so.
Where seabirds nest, their poop fertilizes their rookeries.
“Eventually, it creates this solid mat that covers everything,” Williams says. “They crap themselves out of a home.”
Or rather they would, if volcanoes and earthquakes didn’t generate fresh nesting grounds.
“There’s probably a Goldilocks effect,” Williams says, “not too much disruption, not too little. You need just the right amount.”
Kasatochi’s 2008 eruption was awesomely destructive. But life in the Aleutians may sometimes depend on calamity.
Richard Emanuel is a science and nature writer who came to Alaska as a geologist 40 years ago. He loves volcanoes and earthquakes and lives in Anchorage with his wife and daughter.