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Earth Matters

A Shape-Shifting Volcanic Island

February 2nd, 2017 by Kathryn Hansen

Image courtesy of AVO/USGS.

Looking at Earth from space every day, we notice that nature takes on some curious shapes. (We have found, for example, features that resemble every letter of the alphabet.) The landform in the image above, which looks a lot like a human ear, is actually Bogoslof Island—a volcano in the Bering Sea that has been erupting in recent weeks. But the island didn’t always have an ear-like shape, and it might not look that way in the future.

Bogoslof has been erupting since mid-December 2016. We wrote about it a few weeks ago when satellite imagery showed a plume of steam and ash ejected from the volcano’s vent. Much of the volcano was (and remains) under water, with only a small part of the volcano’s top rising above the surface. Interaction of the vent with seawater was the reason that the plume contained so much steam. But by the end of January 2017, things had changed. The image above, from the Alaska Volcano Observatory (AVO), shows the island’s new shape after an eruption on January 30-31.

The image was described in more detail by Dave Schneider on the AVO website:

“Freshly erupted volcanic rock and ash have formed a barrier that separates the vent from the sea. This is the first time this has been observed since the eruptive sequence began in mid-December 2016. The vent is below sea level, and erosion of the ash deposits by wave or eruptive processes would allow sea water to flow into the vent again.”

Find more information and images describing Bogoslof and its changing form here.