Thermal and seismic indications of Old Faithful Geyser's inner workings

Recent temperature measurements within Old Faithful combined with earlier seismic data provide a fairly broad knowledge of the mechanics of the geyser's action. The geyser tube, which is surprisingly deep, probably deeper than 175 meters, fills suddenly shortly after an eruption. Initially the water in the whole tube superheats, but the upper 60 meters soon cools as the boiling works its way downward. Finally, the hotter water below the 60-meter level rises to the top fairly rapidly, again superheating the water in the upper regions, causing the eruption to start. The boiling rapidly cascades downward, thrusting water from the reservoir to continue the eruption.