Volcanoes are basically the mountains from which hot lava, volcanic ash and gases can escape a planetary object which is burning inside through a rupture in its crust. Our home, the planet Earth has hundreds of active and inactive volcanoes. They occur because the planet’s crust is broken into 17 major rigid tectonic plates that float on a hotter, softer layer in the planets mantle. The largest volcano discovered on Earth to date is called Tamu Massif. This monster volcano is classed as a shield volcano and is around the same size as the British Isles.
Tamu Massif is 400 miles wide but only about 2.5 miles high and around 100,000 square miles in diameter. This volcano erupted for a few million years during the early Cretaceous period about 144 million years ago and has been inactive since then. This giant was discovered under the Pacific ocean about 1000 miles east of Japan. Tamu Massif dwarfs the largest active volcano on Earth which is Mauna Loa in Hawaii which measures about 2000 square miles.
However, Earth cannot be given the credit for having the largest volcano in the solar system. This has to be given currently to our neighboring red planet the Mars and the largest volcano it has is called ‘Olympus Mons’ and is also a shield volcano. The cliffs leading up to this monstrous volcano are over 5 miles high and these are just the foothills. ‘Olympus Mons’ towers around 16 miles above the surrounding plains and stretches across 374 miles which is roughly the size of Arizona state. The crater alone is over 52 miles wide and we could fit the entire chain of Hawaiian Islands inside of it.
‘Olympus Mons’ is around 25% larger than Tamu Massif and is 3 times the height of the tallest mountain on Earth the Mount Everest. However, unlike Everest, ‘Olympus Mons’ has a very gentle slope which is made as a result of thousands of basaltic lava flows over millions of years. The extraordinary size of this volcano has been attributed to the lack of tectonic plate movement on the planet. This lack of movement allows the Martian crust to remain fixed in place over a magma hotspot allowing repeated large lava flows which results in the creation of massive volcanoes like ‘Olympus Mons’.
The crater counts taken by high-resolution images returned by the Mars Express spacecraft in 2004 seem to show that flows on the northwestern flank, range in age from 2 million years old to 115 million years old. Since these flows are geologically young, it may indicate that the volcano is still active. However, it also may have died within the last 3 million years. Massive volcanoes like ‘Olympus Mons’ would have also helped Mars to create an atmosphere, allowing rivers, lakes and oceans to flow across the surface which may have resulted in the possibility of Martian life existing. However, these hotspots below the giant volcano have cooled and no volcanic activity has ever been recorded on Mars.