There are 12 levels of upgrades for the Volcano

Multiplier at max level: x4096


Upgrade Cost
More Lava 600,000,000
Huge Eruptions 6,000,000,000
Volcano Farm 60,000,000,000
Larger Volcanoes 600,000,000,000
Insane Eruptions 6,000,000,000,000
Unbelievably Explosive 60,000,000,000,000
Even More Lava V1 600,000,000,000,000
Even More Lava V2 12,000,000,000,000,000
Even More Lava V3 240,000,000,000,000,000
Even More Lava V4 4,800,000,000,000,000,000
Even More Lava V5 96,000,000,000,000,000,000
Even More Lava V6 1,920,000,000,000,000,000,000