The reason Olympus Mons is so tall is because Mars has much weaker gravity- - about 38% of Earth’s gravity. This allows mountains on Mars to grow much taller than those on Earth. A volcano that ...
In comparison, Hawaii's Mauna Loa, the tallest volcano on Earth, rises 6.3 miles above the sea floor, but its peak is only 2.6 miles above sea level. The volume contained by Olympus Mons is about ...