A new study in the Journal of Geophysical Research: Planets highlights the possible importance of small volcanoes on Mars. Most of us are familiar with the gigantic Olympus Mons that dominates the Martian landscape. It’s the tallest volcano in our solar system, reaching up a staggering 23 kilometers. And it’s not alone. There are three other giant volcanoes nearby in the Tharsis Montes. Much of the planetary science work done on volcanic Mars has focused on these titans.

The Tharsis Montes are part of the Tharsis Volcanic Province, and this research team, led by Jacob Richardson, identified over 1,000 small volcanic vents and cinder cones in this area about the size of Africa. These fissures and cones could be analogs to the ones we’ve been watching on YouTube over in Iceland. And they range in age from three billion years to 250 million years, suggesting that a new volcanic vent formed every three million years or so.

Now, Mars doesn’t have plate tectonics as we do here on Earth, and these vents don’t follow Earth formation rules. Here, vents and cones tend to be connected to a larger volcano, forming on its flanks or very close by. If you look at the shield volcanoes of Hawaii or the peaks of the Andes, you can see these vents and cones everywhere. On Mars, however, the vents and cones are not on the flanks of those giant volcanoes; instead, they are scattered to the east and may have had their own source. In fact, they could have contributed as much lava by volume as the bigger volcanoes did!

The difference in formation may have to do with existing fractures in the crust. It appears that the larger volcanoes formed where there were huge fractures, so the magma had clear pathways to the surface. Meanwhile, the volcanic field is not very fractured, so the volcanoes are small. And all of this information helps give us a clearer understanding of Mars’s mantle and possibly even a start on explaining why Earth was the only one of Venus, Mars, and Earth to develop plate tectonics.

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“Small Volcanic Vents of the Tharsis Volcanic Province, Mars,” J. A. Richardson, J. E. Bleacher, C. B. Connor, and L. S. Glaze, 2021 February 3, JGR Planets