Ancient Mars Was a Blast: Scientists Find Evidence of Martian Supervolcanoes

The entire universe in blog form
Oct. 3 2013 8:00 AM

Ancient Mars Was a Blast: Scientists Find Evidence of Martian Supervolcanoes

Eden Patera
An ancient supervolcano? Topography of Eden Patera; dark and blue areas are depression, reds and yellows higher elevations (though still lower than the Martian average; note the color bar for scale).

Photo by NASA/JPL/GSFC/Arizona StateUniversity, from the paper

We’ve known for a long time that Mars has volcanoes; after all, Olympus Mons on the Martian Tharsis shield is the largest volcano in the solar system.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

But there may have been a more powerful menace lurking just below the red planet’s surface eons ago. A paper just published (though the authors first reported about it at 44th Lunar and Planetary Science Conference) claims to have found evidence of supervolcanoes on Mars.

Advertisement

On Earth, a supervolcano is far larger than a regular volcano; they have huge chambers of magma that can be dozens of kilometers across (like under Yellowstone). They build slowly over hundreds of thousands of years, and erupt catastrophically, and can change the landscape and climate of nearly the entire planet.

In the northern hemisphere of Mars is a series of craters that have been thought to be from impacts. Mars is littered with impact craters, since it has little atmosphere and no running water to erode away ancient features. But the craters in question, most notably Eden Patera (85 x 55 kilometers in size, or 53 x 34 miles), are a bit odd. The entire area is actually lower than average, literally sunken, which is consistent with a supervolcano; once the magma under the surface erupts out, the ground around it collapses to fill the empty space.

Eden Patera
An oblique view of Eden Patera, using the European Space Agency's Mars Express images and elevation data.

Photo by ESA/Mars Express/Freie Universitat Berlin

Other features make it suspiciously un-impact-like. The crater isn’t round, it has no rim, no ejecta (material blasted out from impact), and no central peak (which are common in large craters, like Tycho on the Moon). There are substantial flows of lava around the area, and more evidence of ancient volcanism. Also, benches, or flattened rings around the inside of the crater, are present, and these are common in volcanoes as lava lakes subside.

If Eden Patera (and several other craters seen in the Arabia Terra region of Mars) are in fact supervolcanoes, this changes how we see ancient Mars. Olympus Mons, for example, probably built itself up over eons with big eruptions, but not catastrophic enough that it blew itself apart. That’s why it grew to such enormous size; 600 km (370 miles) wide and 22 km (14 miles) tall— Mars also lacks plate tectonics, so a single volcano can just sit in one spot and grow ever larger.

But supervolcanoes explode. Gas dissolved in the magma is pressurized underground, but once it hits the surface it expands violently, creating a massive explosion. This would have distributed volcanic output like ash for thousands of kilometers across the planet. In fact, fine-grained volcanic deposits have been found across the equatorial regions of Mars that are most likely from volcanoes, but no source volcano has ever been found. Moreover, the deposits are layered, which is expected as well from episodic supervolcano explosions. Similar features are seen on Earth.

It’s not certain that these craters are in fact supervolcanoes, but it would explain a lot. As we investigate more of Mars we’re sure to find features that were previously unknown, and our view of the red planet will no doubt continually evolve. Perhaps we’ll find evidence to support this idea of supervolcanoes; perhaps we’ll find contradictory data. Either way, the only way we’ll know is to keep exploring, keep looking around, and keep learning.

TODAY IN SLATE

History

The Self-Made Man

The story of America’s most pliable, pernicious, irrepressible myth.

Does Your Child Have Sluggish Cognitive Tempo? Or Is That Just a Disorder Made Up to Scare You?

Mitt Romney May Be Weighing a 2016 Run. That Would Be a Big Mistake.

Amazing Photos From Hong Kong’s Umbrella Revolution

Rehtaeh Parsons Was the Most Famous Victim in Canada. Now, Journalists Can’t Even Say Her Name.

Television

See Me

Transparent is the fall’s only great new show.

Doublex

Lena Dunham, the Book

More shtick than honesty in Not That Kind of Girl.

What a Juicy New Book About Diane Sawyer and Katie Couric Fails to Tell Us About the TV News Business

Rehtaeh Parsons Was the Most Famous Victim in Canada. Now, Journalists Can’t Even Say Her Name.

  News & Politics
Damned Spot
Sept. 30 2014 9:00 AM Now Stare. Don’t Stop. The perfect political wife’s loving gaze in campaign ads.
  Business
Moneybox
Sept. 30 2014 11:25 AM Naomi Klein Is Wrong Multinational corporations are doing more than governments to halt climate change.
  Life
Atlas Obscura
Sept. 30 2014 10:10 AM A Lovable Murderer and Heroic Villain: The Story of Australia's Most Iconic Outlaw
  Double X
Doublex
Sept. 29 2014 11:43 PM Lena Dunham, the Book More shtick than honesty in Not That Kind of Girl.
  Slate Plus
Behind the Scenes
Sept. 30 2014 10:59 AM “For People, Food Is Heaven” Boer Deng on the story behind her piece “How to Order Chinese Food.”
  Arts
Brow Beat
Sept. 30 2014 10:48 AM One of Last Year’s Best Animated Shorts Is Finally Online for Free
  Technology
Future Tense
Sept. 30 2014 7:36 AM Almost Humane What sci-fi can teach us about our treatment of prisoners of war.
  Health & Science
Bad Astronomy
Sept. 30 2014 7:30 AM What Lurks Beneath the Methane Lakes of Titan?
  Sports
Sports Nut
Sept. 28 2014 8:30 PM NFL Players Die Young. Or Maybe They Live Long Lives. Why it’s so hard to pin down the effects of football on players’ lives.