Durations are about twenty minutes. Major eruptions start from a full pool. There is little warning before the eruption. Only slight bubbling and convection currents can be seen over the vent. A few minutes before the eruption, the boiling increases and then the eruption starts.
Minor eruptions can occur an hour or two after the major eruption.
These eruptions start from an apparently empty crater and last about five minutes. The pool refills and begins quietly overflowing 4-5 hours after the major eruption. The occurrence of minors does not seem to affect the refill rate significantly. Once full, the pool overflows quietly until the next eruption. Big Cone is a large sinter cone that sticks out of Yellowstone Lake near Fishing Cone.