01 Sep 2014

Open University discovers young volcanoes on Mercury

Bright deposits around a 400km line of explosive volcanic vents

Bright deposits around a 400km line of explosive volcanic vents

Violent volcanic eruptions on the planet Mercury happened much more recently than previously believed, new research from The Open University reveals.

Published in Geophysical Research Letters this week, the paper concludes that explosive eruptions continued on the planet until a billion years ago, much later than previously thought, showing that Mercury has been volcanically-active through much of its history.

Kuniyoshi, a fresh crater on Mercury < 1 billion years old

Kuniyoshi, a fresh crater on Mercury < 1 billion years old

Authors of the new research, OU PhD student, Rebecca Thomas and her supervisors Professor David Rothery, Dr Mahesh Anand and Dr Susan Conway used detailed images from NASA’s MESSENGER spacecraft, which has been orbiting the planet since March 2011. They located 150 sites where volcanic vents are surrounded by characteristic deposits of red material exploded out of the vent, more than doubling the number previously known. Among the new examples, they found two where even younger volcanic vents occur inside ‘young’ impact craters.

Rebecca Thomas said:
“Most volcanic activity occurred three to four billion years ago, but the crisp state of preservation of these two impact craters dates them to about a billion years ago.

“This relatively recent volcanism is a really exciting discovery as Mercury, being a much smaller planet than Earth, should have cooled much more since its formation. It’s also a sign that the gases necessary to power these eruptions have been available within the planet for all that time. We used to believe Mercury was depleted in the elements that make up these gases; this evidence means scientists need to rethink these theories.”

Professor of Planetary Geosciences, David Rothery, said:
“You don’t get explosive volcanism without something to drive the explosion, which means magma containing plenty of gas able to expand violently as it approaches the surface. There are several other indications that Mercury is rich in volatile materials.

“This was unexpected of a planet so close to the Sun, and makes Mercury’s origin a mystery that we are keen to solve.”

For a copy of the research paper, entitled ‘Long-lived explosive volcanism on Mercury’, visit

Notes to editors

About the authors
The paper is Thomas, R. J., D. A. Rothery, S. J. Conway, and M. Anand (2014), Long-lived explosive volcanism on Mercury, Geophysical Research Letters, 41, doi:10.1002/2014GL061224.
Rebecca Thomas is a PhD student supported by a grant from the Science and Technology Facilities Council.
David Rothery heads the European Space Agency’s Mercury Surface & Composition Working Group and is the Lead Scientist on the only UK instrument for Europe’s BepiColombo mission to Mercury, due to be launched in 2016, and is supported by the UK Space Agency and the Science and Technology Facilities Council. He is Professor of Planetary Geosciences at the Open University.

About The Open University
The Open University (OU) is the largest academic institution in the UK and a world leader in flexible distance learning. Since it began in 1969, the OU has taught more than 1.8 million students and has more than 200,000 current students, including more than 15,000 overseas.
The OU is rated in the top ten of UK universities for student satisfaction in the National Student Survey, since the survey began in 2005. In 2013/14 it had a 91% satisfaction rating. Over 70% of students are in full-time or part-time employment, and four out of five FTSE 100 companies have sponsored staff to take OU courses.
In the UK’s latest Research Assessment Exercise (RAE 2008) The Open University was ranked in the top third of UK higher education institutions. More than 50% of OU research was assessed in the RAE as internationally excellent, with 14% as world leading.
The OU has a 41 year partnership with the BBC and has moved from late-night lectures in the 1970s to co-producing prime-time series such as Frozen Planet, Bang Goes the Theory, Britain’s Great War, I Bought a Rainforest and Business Boomers. Regarded as Britain’s major e-learning institution, the OU is a world leader in developing technology to increase access to education on a global scale. Its vast ‘open content portfolio’ includes free study units on OpenLearn, which received 5.2million unique visitors in 2012/13, and materials on iTunes U, which has recorded more than 66 million downloads.
For further information please visit

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