“Peering Beneath a Source of El Capitan’s Deadly Rockfalls”
by Katherine Kornei
The New York Times, May 20, 2019
[Kornei notes: I attended a European Geosciences Union meeting in April 2019 and found this story by sitting in on a talk I hadn’t planned to attend. I pitched this story to two other outlets who ended up saying no, and I hadn’t worked with this editor before.
There was a hitch during my reporting: the researchers had a manuscript about these results in review for publication. They were hesitant to share their manuscript with me, and my editor and I went back and forth a lot about what to do. We decided that I’d write the story based on what had been presented at the conference, which had no embargo.]
I’m a freelance science journalist who regularly writes for Science, Scientific American, and Eos. [Redacted] gave me your contact information.
I’m pitching a story for Trilobites. These results were presented last week at the General Assembly of the European Geosciences Union, which I attended in Vienna, Austria.
The sheer granite face of Yosemite’s El Capitan rises over 1000 meters above the valley floor, a playground for the world’s best climbers. But rockfalls, like the one in September 2017 that killed one person and injured another, are common, particularly near large sheets of rock known as “flakes.” Now, Swiss and American researchers have imaged El Capitan in infrared light and shown that hidden “rock bridges” determine the stability of its flakes.
The scientists found that two features called Boot Flake and Texas Flake were always colder than their surroundings, consistent with air circulating around the sheets’ backsides, the researchers reasoned. The flakes’ thermal signatures also revealed where they were connected to the face of El Capitan. Based on the thermal data, the researchers calculated the sizes of these unseen “rock bridges.” Boot Flake’s rock bridge makes up about 6.8% of the sheet’s surface area, the scientists showed, and this feature is likely stable. But Texas Flake’s rock bridge is proportionally much smaller: only about 0.8% of the sheet’s surface area, which makes it unstable, the researchers concluded. This technique can be used to identify rock features on El Capitan and elsewhere that are particularly at risk of producing rockfalls, the scientists suggest.
Conference abstract: https://meetingorganizer.copernicus.org/EGU2019/EGU2019-14179.pdf