Open University’s volcanic findings from outer space


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

PhD student, Rebecca Thomas, with and her supervisors Professor David Rothery, Dr Mahesh Anand and Dr Susan Conway, have had a paper published in Geophysical Research Letters.

They claim 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.

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.”

Mercury is the smallest planet in the solar system and is the closest planet to the sun. Its surface area is about a tenth of Earth.

Professor Rothery, professor of planetary geosciences, 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