Volcanic eruption creates moveable islands of pumice

earthsky.org | 9/18/2019 | Eleanor Imster
jenn1020 (Posted by) Level 3
Click For Photo: https://en.es-static.us/upl/2019/09/ocean-pumice-raft-satellite-300x225.jpg

Satellite image of a pumice raft floating near the Kingdom of Tonga. Image via NASA Earth Observatory.

In early August 2019, an unnamed volcano in the South Pacific Ocean near the Kingdom of Tonga erupted roughly 130 feet (40 meters) underwater. As lava spewed from the volcano, it cooled into pumice — porous rock filled with gas bubbles — and floated to the surface. This volcanic debris, with some fragments tiny and some as large as beach balls, aggregated into pumice rafts spanning an area of about 60 square miles (200 square km) — almost as big as Washington, D.C.

Islands - Rock - Currents - Wind - Waves

These temporary islands of volcanic rock are shaped and moved by ocean currents, wind, and waves, and provide a literal toehold for marine life, such as barnacles, coral, seaweed and mollusks, say scientists.

Several sailing crews have encountered the rocks. In a video, below, posted on YouTube on August 17, Shannon Lenz said:

August - Pumice - Field - Hours - Time

On August 9, 2019, we sailed through a pumice field for 6-8 hours, much of the time there was no visible water. It was like plowing through a field. We figured the pumice was at least 6-inches thick.

An Australian couple, Michael Hoult and Larissa Brill, were sailing a catamaran to Fiji, when they encountered the raft on August 16. The couple said in a Facebook post:

Rock - Rubble - Slick - Pumice - Stones

We entered a total rock rubble slick made up of pumice stones from marble to basketball size.

Pumice rafts aren’t that common, according to Martin Jutzeler, a volcanologist at the University of Tasmania in Hobart. He told EOS:


We see about two per decade.

Jutzeler told EOS that not...
(Excerpt) Read more at: earthsky.org
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