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In My Words: ​How Kilauea eruption fits into our geological heritage

In this column distributed by the Elon University Writers Syndicate, Dave Gammon provides historical context for the recent eruptions of the Kilauea volcano in Hawaii. 

This column was distributed by the Elon University Writers Syndicate and was published in the Greensboro News & Record. Views expressed in this column are the author's own and not necessarily those of Elon University.

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By Dave Gammon

The recent eruption of Kilauea volcano was its biggest in decades. It spewed steam and ash more than five miles into the air, caused more than 2,000 people to evacuate and has destroyed dozens of homes.

As devastating as Kilauea’s eruption has been, history reminds us of geological events even more explosive, and science provides clues about why they happen.

The biggest volcanic eruption of the last several centuries took place in 1815 when Mount Tambora blew its top. Lying on a small Indonesian island where two oceanic plates crash into each other, Tambora’s explosion was orders of magnitude more powerful than Kilauea’s recent hiccup.

Ash from Mount Tambora dispersed throughout the world. For several months the resulting yellowish atmospheric haze obscured sunlight worldwide.

Historians called 1816 the “year without a summer.” During June, July and August, snow and freezing temperatures punished New Hampshire and Vermont. In France and the United Kingdom, widespread crop failures and loss of livestock led to food riots.

New Englanders fled failed farms in droves to settle places like upstate New York and the upper Midwest, thus contributing to the settlement of the American interior. “Frankenstein” and “Dracula” both emerged from the pens of writers who were stuck inside that fateful summer.

Deeper in the past, even more explosive volcanoes emerge. Yellowstone charms millions each year with hot springs and geysers, belying a much more violent past.

Just below Yellowstone in the upper portion of the Earth’s mantle lies enough magma to cover most of the United States in several inches of ash. Every few hundred thousand years, the caldera releases an eruption 10 times as explosive as Tambora, with 10 times as much ash.

Supervolcanoes like Yellowstone have erupted throughout the Earth’s 4.6 billion-year history. One of the biggest occurred 200 million years ago at the end of the Triassic Period. Pangea was just starting to rip apart, with what is now the eastern United States splitting from northwest Africa. A series of violent eruptions began in what is now Morocco and wreaked havoc on the Earth for thousands of years, darkening the skies, altering the climate and acidifying the oceans.

Fossilized lava ash from several locations in the eastern United States suggests the Triassic supervolcano released more than a million cubic kilometers of magma. For perspective, Mount Tambora released a mere hundred cubic kilometers. Catastrophic consequences followed. More than half of the Earth’s species went extinct, clearing the way for dinosaurs to dominate the next 135 million years.

Like a giant battery slowly leaking its power, the Earth has been dissipating geothermal heat energy for ages. Smaller spheres in space, like Mercury and our moon, no longer experience active volcanoes because their heat battery became empty long ago.

Slightly larger planets like Mars, a planet with one-ninth the mass of Earth, are now experiencing the last gasps of tectonic activity before they too become inert rocks in space. Billions of years from now the Earth will join the club of geologically dead planets.

But where did the Earth’s heat come from?

As gravity formed the Earth billions of years ago, meteors and other matter bombarded our planet. Imagine the kinetic energy of a rock that traveled thousands of miles per hour before it slammed into the proto-Earth. All that kinetic energy cannot simply disappear. Instead it transformed into an incomprehensible amount of heat that continues to leak out through volcanoes, deep sea vents, and other fissures in the Earth’s crust.

Additional geothermal heat comes from the presence of heavy radioactive elements. These elements traveled to the early Earth after yet another colossal explosion – the supernova of a star at least eight times as massive as our own Sun.

Even further back in time, all the Earth’s matter, all the matter of the stars, and heck, all the matter of the cosmos, originated from the mother of all explosions – the Big Bang!

So next time Kilauea or any other volcano erupts, remind yourself it is all part of an incredible series of explosions dating to the dawn of time – our geological heritage.

 

Owen Covington,
Staff
6/15/2018 1:45 PM