Volcanic activity on Mercury stopped some 3.5 billion years ago suggesting that the planet has had a long quiet period geologically as compared to Venus, Mars and Earth.

Researchers from North Carolina State University used crater size-frequency analysis to carry out their research because of absence of any physical samples of the innermost planet of our Solar System. In the crater size-frequency analysis technique, researchers place the number and size of craters on the planet’s surface are placed into established mathematical models to calculate absolute ages for effusive volcanic deposits on Mercury. Data from NASA’s MESSENGER mission was used for the study.

Researchers found that major volcanism on Mercury stopped at around 3.5 billion years ago, in stark contrast to the volcanic ages found for Venus, Mars and Earth. The findings indicate a huge geological difference between Mercury and its nearby planets. Mercury has had a much smaller mantle and because of this it lost most of its heat earlier. This effectively forced the planet to contract and the crust essentially sealed off any conduits by which magma could reach the surface.

For those of you who are not aware about volcanic activity – they are of two types: effusive and explosive – both of which are currently present on Earth. Explosive volcanism is often a violent event that results in large ash and debris eruptions, such as the Mount Saint Helens eruption in 1980. Effusive volcanism refers to widespread lava flows that slowly pour out over the landscape — believed to be a key process by which planets form their crusts.

Determining the ages of effusive volcanic deposits can give researchers a handle on a planet’s geological history. For example, effusive volcanism was active a few hundred million years ago on Venus, a few million years ago on Mars, and it still takes place on Earth today. Until now, the duration of effusive volcanic activity on Mercury, made of the same materials as these other planets, had not been known.