For Atlas Obscura: Why Scientists Are Worried about a Landslide No One Saw or Heard
Here’s the lead (er, lede) I pitched to Atlas Obscura, which (to my delight) they ran unchanged, giving me a welcome chance to write an interesting story I learned about at the AGU Fall Meeting from Kevin Krajick of the Lamont-Doherty Earth Observatory:
If a steep mountainside in a remote national park gives way and drops 200 million tons of rock into deep glacial water, will anyone hear?
In the case of the massive landslide that fell into Taan Fjord, Alaska, the answer was no—and yes.
No one heard the mountainside fall into the fjord on a rainy night on October 17, 2015. No one saw an almost unimaginably huge and powerful wave crest at 600 feet and sweep down the inlet. The tsunami obliterated forests on both sides of the inlet, and its rush to the sea dragged an iceberg over a marine spit and out into coastal Icy Bay. The enormous wave, an estimated 60 feet high in the middle of the inlet, traveled eight miles to open water and made it all the way to about five miles north of Icy Bay Lodge.
Thousands of miles away, at Columbia University’s Lamont-Doherty Earth Observatory north of New York City, a pair of geologists noticed an unusual squiggle on a seismograph. The team of Göran Ekström and Colin Stark has in recent years pioneered a new method of detecting unusual seismic events that don’t send out the fast-moving compressional waves characteristic of earthquakes. Instead they look for subtler surface waves, or undulations, that radiate much more slowly through the surface of the earth. These are the kinds of waves sent out by collapsing volcanoes, calving ice sheets, and massive landslides.
“There are not that many landslide detections by us in a given year, maybe just half a dozen,” says Ekström. “We now know that when we detect something, it is often spectacular. We had just detected another landslide in the Yukon a week earlier, and had it confirmed, so I was quite excited when I saw another detection in the Saint Elias range, especially since it was not detected by anyone else, and because it was so large.”
Story looks great (sez me). Thanks to the photographer Bjorn Olson and the scientists at Ground Truth Trekking for the photos and for taking time out from vacations in exotic places with little connectivity for taking the time to talk to me, such as the wonderfully articulate expedition leader Bretwood “Hig” Higham.
Here’s the rest of the story, with a favorite photo, of the Taan Fjord and Mt Saint Elias. Please read!