Interesting fact: A volcano is not just the cone you see. Its total mass includes buried lava, ash, rock layers, and deep plumbing built over many eruptions.
The answer: A volcano can weigh billions to trillions of tons depending on its height, width, and internal structure. The exact answer depends on its total rock volume and the density of that volcanic material.
Volcanoes are weighed by estimating their volume from topography and geologic modeling rather than by direct measurement. Their mass matters because it affects slope stability, flank collapse risk, magma pressure, and even how the crust responds underneath them. Large volcanoes are essentially mountains assembled by repeated eruptions over very long timescales.
