Abstract
It seemed probable that as a geyser builds up toward eruption, it should send out detectable pressure waves, which might make it possible to predict the time of eruption. Waves produced by Old Faithful Geyser in Yellowstone National Park were detected by a sensitive microbarograph at various surface locations within a few hundred feet of the geyser vent. The waves occur in bursts, and tend to increase about 50 per cent in amplitude within five minutes prior to an eruption, and to decrease about 20 per cent in period within two minutes before an eruption. However, changes in amplitude and period within bursts of waves are great enough to obscure the longer-time variations, and to make it impossible to predict eruptions in the field by this method.
