Myths about volcanoes
WITH HAWAII’S KILAUEA MAKING HEADLINES ALL OVER, IT’S TIME TO SET THE RECORD STRAIGHT ON JUST HOW VOLCANOES OPERATE
■ News reports often relay bulletins like “volcano erupts sending smoke 30,000ft into air,” as one UK newspaper recently did.
A travel writer who visited Japan’s Mount Sakurajima in 2014 noted that “ash and smoke easily reached up to 5,000 feet,” and a news agency claimed in 2010 that Indonesia’s “Mount Merapi was clouded with smoke” during an active period.
For volcanologists like me, the word “smoke” is deeply frustrating, because it elides some of the real harm volcanoes can do.
Few geologic events capture the imagination like an erupting volcano. We thrill at the image: Hot, molten rock comes bursting out of the ground, destroying most everything in its path. Volcanoes can cause massive disasters that kill tens of thousands, and they can produce amazing sights like hypnotic lava fountains. With an eruption like the one we all witnessed at Hawaii’s Kilauea, volcanoes are the news of the moment. But it’s usually full of errors about volcanoes and how they operate. ■ VOLCANOES CAN BE ‘OVERDUE’ FOR AN ERUPTION VOLCANOES CONTRIBUTE MEANINGFULLY TO CLIMATE CHANGE
Volcanoes produce many kinds of gases, among them carbon dioxide. That has made them a target for deniers of man-made climate change. In 2010, an opinion writer for the Australian Broadcasting Corporation claimed that a single “volcanic cough” can add more CO2 to the atmosphere “in a day” than humans have in the past 250 years. And in 2015, another expert proposed that “the elimination of essentially every automobile would be offset by one volcano exploding.” No.
Given that rates of volcanic activity aren’t rising, there is no reason more carbon dioxide would be added to the atmosphere from volcanic eruptions today than at any time in the past.
Also, the amount of carbon dioxide produced by humans each year is more than 100 times greater than that produced by volcanoes, according to research by volcanologist Terry Gerlach.
So, annually, all the volcanoes in the world produce roughly the same amount of carbon dioxide as the state of Ohio. Volcanoes can affect the Earth’s climate, but not typically by warming it. Particulates of sulphur dioxide from a major eruption can rise high into the stratosphere and prevent the sun’s energy from reaching the surface. ■ ■
VOLCANOES AND EARTHQUAKES IN THE ‘RING OF FIRE’ ARE CONNECTED
We hear it all the time: Volcanoes are erupting in the “Ring of Fire,” an area of intense tectonic activity around the Pacific Ocean.
News articles tend to lump geologic events in the area together, as Channel NewsAsia did in January, when it reported, “Volcanic eruptions and earthquakes in Asia and Alaska over two days show that the Pacific Ring of Fire is ‘active,’” suggesting that they are linked, even if they are halfway around the globe from one another. Other times, sites will speculate that the events are leading to something larger: “[All] eyes are on the Pacific Ring of Fire, as a growing list of volcanic eruptions and tectonic tremors are pointing to a potentially major event.”
The phrase “Ring of Fire” is evocative, but that is about as far as it goes.
Geologically speaking, the “Ring of Fire” isn’t anything more than a coincidence of volcanoes and earthquakes. The supposed ring doesn’t even encircle the whole Pacific Ocean; sometimes it includes locations beyond the Pacific, such as Indonesia.
Underneath all these regions, large tectonic plates interact as they move on the Earth’s mantle. But the volcanoes and earthquakes in the “Ring of Fire” are not directly linked, so when eruptions or earthquakes occur simultaneously in Japan and Chile, it’s not because they are triggering each other.
In fact, there is very little evidence that earthquakes or other volcanoes can cause a volcano to erupt. ■ Eric Klemetti, an associate professor of geosciences at Denison University, writes the Rocky Planet blog for Discover and covers volcanic eruptions around the world on Twitter. ■