The Hunga Tonga-Hunga Ha'apai volcano's underwater eruption last year
produced the most powerful lighting show ever recorded as well as a
supercharged storm.
Why it matters: According to the study's authors, observations of the
eruption-induced storm might aid future efforts to use real-time lightning
data to monitor the risks posed by volcanoes.
Information: The submarine eruption produced a plume of volcanic gas,
water, and ash that rose 58 km (approximately 36 miles) into the
stratosphere.
The plume then grew into an umbrella cloud, producing strong gravity waves
that rippled outward from it. This was followed by lightning strikes in a
similar ring-shaped pattern, which the researchers were able to observe by
integrating data from radio wave and light sensors.
Lightning struck the volcanic cloud at a height of 20 to 30 kilometers
(about 12 to 18.5 miles), according to a study
published
in Geophysical Research Letters.
The storm lasted 11 hours and produced more than 2,600 lightning flashes
per minute at its highest intensity, "an astonishing rate of volcanic
lightning" and "the most intense lightning rates ever documented in Earth's
atmosphere," they wrote.
According to the experts, the unusual occurrence was caused by a
combination of a very high eruption rate, a rapidly growing umbrella cloud,
and evaporated saltwater in the plume.
It "eventually formed electrifying collisions between volcanic ash,
supercooled water, and hailstones," according to a
press statement.
The intrigue: The significant lightning strike shows lightning can be
sparked in circumstances not frequently observed on Earth.
This eruption's volcanism, known as phreatoplinian, included magma erupting
through water. According to the announcement, up until now, only geological
records have proven its existence.
According to the study's lead author, volcanologist Alexa Van Eaton of the
United States Geological Survey, "it was like unearthing a dinosaur and
seeing it walk around on four legs."
