2020 Volcanic Eruption Leads to Hours-Long Thunderstorm
Boulder, Colo., USA: A study conducted by scientists at the U.S. Geological
Survey, the National Oceanic and Atmospheric Administration, and Vaisala
Inc., published yesterday in the Geological Society of America’s journal Geology, discusses how advances in global lightning detection have
provided novel ways to characterize explosive volcanism. Lead author Alexa
Van Eaton says, “It’s the perfect storm—explosive eruptions can create
lightning that is detected around the world.”
The January 2020 eruption of Taal volcano in the Philippines showed how a
powerful volcanic eruption becomes electrified, giving off thousands of
cloud-to-ground lightning strikes over several hours. Those flashes allow
scientists to shed light on the eruption’s behavior. “As soon as the
volcanic ash plume rose high enough to freeze, its electrical activity lit
up our sensors,” says Van Eaton.
Radio waves produced by lightning travel at the speed of light, so, unlike
other remote sensing tools with longer lag times, “we can receive the
lightning data super-fast,” explains Van Eaton. The scientists also used
satellite images and hundreds of photos shared on social media. “The
eruption took place in a major urban area, so people posted pictures of
volcanic lightning as it was happening.” Those photos and videos, Van Eaton
and colleagues write, “reveal a highly electrified region at the base of
the umbrella cloud.”
“Much more can be done to characterize an eruption when there are camera
perspectives from all angles,” says Van Eaton. And understanding the
evolution of volcanic lightning helps us recognize the early warning signs
of ash hazards to aircraft.” However, remote-sensing studies like this one
“only provide a broad-brush picture of an eruption,” says Van Eaton. “It is
clear that nothing can replace the work of local geologists who know the
area like the backs of their hands.”
An area of interest for future study, notes Van Eaton, is the miniature
sparks they observed in photos of the ash plume. “We were surprised to find
the high-altitude umbrella cloud crawling with these tiny, blue streamers,” which are distinct from lightning because they are
discharges of cold plasma, rather than hot. “It’s still an enigma how these
little ribbons of ionized air relate to powerful lightning.”
Note: On Sat., 15 Jan. 2022, a massive volcanic eruption from the submarine
volcano in Tonga known as Hunga Tonga-Hunga Ha'apai occurred. It sent a
tsunami across the entire Pacific Ocean while a giant ash cloud spread out
overhead, producing record-breaking amounts of volcanic lightning. Van
Eaton and colleagues’ Geology paper explains how such water-rich
volcanic plumes become electrically charged.
FEATURED ARTICLE
Eruption dynamics leading to a volcanic thunderstorm—The January 2020
eruption of Taal volcano, Philippines
Alexa Van Eaton; Michael Pavolonis; Ryan Said; Cassandra Smith
Contact: Alexa Van Eaton, avaneaton@usgs.gov, U.S. Geological Survey,
Cascades Volcano Observatory, Vancouver, Washington
https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G49490.1/610898/Eruption-dynamics-leading-to-a-volcanic
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https://geology.geoscienceworld.org/content/early/recent
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