No. 71: Sep-Oct 1990
"Eruptions of Old Faithful Geyser are generally perceived as extremely regular events, with variation of eruptive interval being attributed to random noise. The governing equations for such a hydrothermal system are highly non-linear, therefore it is reasonable to assume that such systems are capable of operating in regines that display chaotic behavior. Three-dimensional state-space reconstruction of eruption time data provides strong evidence of a strange attractor quite similar to the Rossler attractor. Establishing the system as chaotic indicates that while one can predict eruptive intervals in the short term, long term predictions regarding Old Faithful's eruptive behavior are impossible, no matter how carefully and accurately the system is modeled. The mean eruptive interval of Old Faithful has changed over time. This is consistent with the behavior of a chaotic system, which by definition must be nonstationary in the mean. Seismic activity is believed to be a perturbation shifting Old Faithful into a new chaotic state with a different shape to the strange attractor. A simple non-linear dynamic model of geyser behavior is proposed that leads to chaotic behavior and is consistent with the observations of eruption interval data for Old Faithful." (Nicholl, Michael, et al; "Is Old Faithful a Strange Attractor?" Eos, 71:466, 1990.)
Comment. "Strange attractor" is a specialized term employed in chaos analysis. So, Old Faithful is not really faithful; neither are the planets in their orbits (see under Astronomy). Is there nothing left in Nature that is reliable -- just about everything is non-linear and therefore a candidate for chaotic behavior.
Reference. An entire setion on geyser phenomena may be found in GHG in our catalog: Earthquakes, Tides. To order, visit: here.