[Text by MAB]
Like many of the Norris geysers, Vixen's activity varies from year to year. Waiting one hour or more for a single eruption was common during 2011-2013. Late in 2013 the activity (and water chemistry) changed with frequent majors producing runoff in all directions, rapidly depositing sinter and changing
the look of the surrounding area. These eruptions maintained 3-8 minute intervals throughout 2014-2015, with many “major” eruptions lasting more than 20 minutes. The classic “Vixen Drain,” in which the pool would drain completely following an eruption (often with bathtub-drain-like gurgling noises at depth), changed in 2015, with drains not occurring after each eruption, but mostly occurring after very long duration majors.
Following the September 2015 Disturbance, Vixen began fascinating cyclic behavior, consisting of four identifiable phases: Initial, Decreasing Intervals, Frequent Intervals, and a Slow Down period. Frequent eruptions are about 40% of the total elapsed time, followed by longer intervals “slowing down”, then a longer wait for an “Initial” as the pool slowly fills. This is followed by Decreasing Intervals as it speeds up. Suddenly the frequent intervals will resume and the cycle repeats itself.
Throughout 2016 and early in 2017, the classic “Vixen Drain” with noise usually occurs after very brief durations (less than 30 seconds) and the water level bounces back up after the drain noise.
Research is underway to determine if Vixen had similar cyclic activity documented in the past. For now, the rapid deposition of sinter is fast changing the surrounding formation. Perhaps similar water
chemistry in the distant past built the smaller platform we had known for decades. This interesting
cyclic action may continue, or may stop as suddenly as it began in fall of 2015.
|Two descriptions are given here, one reflecting current (post-2015 Disturbance) behavior and one the historic (until mid-2015) Vixen. Current description: Eruptions at the end of the Frequent Eruptions and Slow Down phase will start from within the vent, or a quick fill just prior to the bursting start. During the longer intervals (the Initial and the Decreasing Interval set) eruptions will begin from a full or nearly full platform; watch for larger bubbles and boiling convection. Some eruptions from a full pool are a complete surprise with no warning!
Older version: With Vixen, the question is not so much what to "look for," as what to listen for. When in an active period, Vixen chugs and gurgles underground in a way that is clearly audible from the adjacent boardwalk. As an eruption approaches, the gurgling gets more vigorous and can be clearly heard to be rising in the plumbing system. Finally, the commotion pushes water to the surface, and within seconds, the eruption is on.