Energy unleashed by submarine volcanoes could power a continent
From: Leeds University
April
21, 2021 -- Eruptions from deep-sea volcanoes were long-thought to be
relatively uninteresting compared with those on land. While terrestrial
volcanoes often produce spectacular eruptions, dispersing volcanic ash into the
environment, it was thought that deep marine eruptions only produced slow
moving lava flows.
But
data gathered by remotely operated vehicles deep in the North East Pacific and
analysed by scientists at the University of Leeds,
has revealed a link between the way ash is dispersed during submarine eruptions
and the creation of large and powerful columns of heated water rising from the
ocean floor, known as megaplumes.
These megaplumes contain hot
chemical-rich water and act in the same way as the atmospheric plumes seen from
land-based volcanoes, spreading first upwards and then outwards, carrying
volcanic ash with them. The size of megaplumes is immense, with the volumes of
water equivalent to forty million Olympic-sized swimming pools. They have been
detected above various submarine volcanoes but their origin has remained
unknown. The results of this new research show that they form rapidly during
the eruption of lava.
The research was carried out by Dr
Sam Pegler, from the School
of Mathematics and Dr David Ferguson, from
the School
of Earth and Environment and is being
published today in the journal Nature Communications.
Together they developed a mathematical
model which shows how ash from these submarine eruptions spreads several
kilometres from the volcano. They used the ash pattern deposited by a historic
submarine eruption to reconstruct its dynamics. This showed that the rate
of energy released and required to carry ash to the observed distances is
extremely high – equivalent to the power used by the whole of the
USA.
Dr Ferguson said: “The majority of
Earth’s volcanic activity occurs underwater, mostly at depths of several
kilometres in the deep ocean but, in contrast to terrestrial volcanoes, even
detecting that an eruption has occurred on the seafloor is extremely
challenging. Consequently, there remains much for scientists to learn about
submarine volcanism and its effects on the marine environment.”
The research shows that submarine
eruptions cause megaplumes to form but the release of energy is so rapid that
it cannot be supplied from the erupted molten lava alone. Instead, the
research concludes that submarine volcanic eruptions lead to the rapid emptying
of reservoirs of hot fluids within the earth’s crust. As the magma forces its
way upwards towards the seafloor, it drives this hot fluid with it.
Dr Pegler said: “Our work provides
evidence that megaplumes are directly linked to the eruption of lava and are
responsible for transporting volcanic ash in the deep ocean. It also shows that
plumes must have formed in a matter of hours, creating an immense rate of
energy release.”
Dr Ferguson added: “Observing a
submarine eruption in person remains extremely difficult but the development of
instruments based on the seafloor means data can be streamed live as the
activity occurs.
“Efforts like these, in concert with
continued mapping and sampling of the ocean floor means the volcanic character
of our oceans is slowly being revealed.”
Further information
Rapid heat discharge during deep-sea
eruptions generates megaplumes and disperses tephra is
published in Nature
Communications 22 April 10:00 GMT. DOI:10.1038/s41467-021-22439-y.
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