What was once assumed to be a large crater found on the surface of Mars has now been re-identified as evidence of a “supervolcano.” The term supervolcano is used to informally refer to a vast volcanic eruption that shoots out more than 1000 cubic kilometers of rock and ash. Any volcanic event referred to with this monicker is thousands of times the size of normal volcanic events in Earth’s recent history. Events such as these haven’t happened on Earth for thousands of years, however there is plenty of evidence that they have occurred. The Yellowstone National Park in Wyoming, United States, sits atop the remnants of an ancient supervolcano.
Until now, Mars researchers have been looking in the wrong part of the Red Planet for the wrong kind of volcanoes. Joseph Michalski, the Mars researcher responsible for the discovery of supervolcano evidence, admits that scientists have mostly been searching for shield-type volcanic evidence instead of the explosive volcanic evidence that his team has pinpointed on the surface this week. Michalski works at the Planetary Science Institute in Tucson, Arizona, as well as London’s Natural History Museum in England.
According to Michalski, the evidence of explosive types of volcanoes is more difficult to find than smaller types, which explains why the supervolcanic evidence has remained undiscovered for so long. The aftermath of an ancient supervolcano such as that found by Michalski’s team looks just like an impact crater, which cover the surface of Mars and all planets. Even Earth, under the thin cover of flora and fauna, is as pock-marked as the moon. The key to the discovery that this crater, known to scientists as Eden Patera, was actually a supervolcano in disguise was its pattern of erosion. Impact craters and the crater caused by a supervolcano both leave a raised, circular edge which erodes over time. Given the estimated age of such a crater, it should be relatively shallow under the surface: Eden Patera is remarkably deep. The depth of the crater told Michalski and his crew that this was no normal impact crater.
The research team used data collected from the Mars Global Surveyor spacecraft, as well as the Mars Odyssey orbiter and the Mars Reconnaissance Orbiter. They hope that two of the Mars rovers left on the planet’s surface could help to support their claims of supervolcanic activity. In fact, they have posited that the dust deposits found by the Mars Curiosity and the Opportunity could actually be ash remnants from the Eden Patera eruptions.
Michalski believes that the supervolcano was active within the first million years of Mars’ existence as a fully-formed planet. If this is true, it sheds some much-needed light on the mysteries of Mars’ geological history. Scientists have suspected for some time that volcanic eruptions could have been the source of the fine-grained deposits in the Arabia Terra region of the planet, but they could find no evidence for such volcanic activity nearby. The intense eruptions of a supervolcano at Eden Patera could explain those very deposits and provide a theoretical basis for future geologic research on Mars.
by Mandy Gardner