IN-SITU OBSERVATIONS OF OLD-FAITHFUL GEYSER

In a series of experiments from 1983 to 1993, four probes were careful ly lowered into Old Faithful Geyser Yellowstone National Park, Wyoming , At different times, these probes variously recorded pressure-tempera ture-time conditions (to nearly 22 m depth), and video probes showed t he conduit geometry and processes of recharge (to 13 m depth), Tempera tures recorded were, within experimental error, the same as those reco rded in 1942, with a peak bottom temperature (T) of 118 degrees C, Pro cesses observed include fog formation in the upper levels of the condu it owing to wind and entrainment of cool air; ''bank storage'' of hot water that splashes to high levels, cools, and recharges; recharge of cooler ground water into the conduit; superheated steam expansion into the conduit (T = 129.5 degrees C); periodic temperature fluctuations; and exsolution of bubbles of noncondensable gas, which we propose are CO2.