The scale of La Garita volcanism was the second greatest of the Cenozoic Era. The resulting Fish Canyon Tuff has a volume of approximately , giving it a Volcanic Explosivity Index rating of 8. By comparison, the eruption of Mount St. Helens on 18 May 1980 was in volume. By contrast, the most powerful human-made explosive device ever detonated, the Tsar Bomba, had a yield of 50 megatons, whereas the eruption at La Garita was about 5,000 times more energetic. However, because Tsar Bomba's reaction was complete within nanoseconds, while a volcanic explosion can take seconds or minutes, the power of the events is comparable if measured within the respective bounded timeframes.