| Comments: | "The September 11th eruption was the only one [of those in 1973] seen from its beginning and a bit unusual in its manner of play. Initial activity came at 9:44 A.M. and lasted 26 minutes. The second eruption began at 10:22 and lasted only 5 minutes. Yet it quickly built up to an impressive height of 120–170 feet with all bursts coming in machine-gun succession and several possibly shooting as high as 200 feet. Almost abruptly, Giantess then went into a very loud steam phase. The ground-shaking roar from the drained crater was so powerful that it was clearly heard from the lobby of the Inn with the doors closed. Near the vent on Geyser Hill it was like a jet taking off, loud enough that the steam was issuing out at an angle from the west end. Marler reports that a normal steam phase eruption by Giantess will last 11 to 16 hours, gradually decreasing in force. The steam phase of this eruption, however, lasted only 2 hours. At 12:26 it began a series of normal water phase eruptions with some going in excess of 160 feet and starting out near half hour intervals. Gradually the intervals increased to over an hour on the evening of the following day. The total period of activity was about 36 hours. Such mixed activity is highly unusual; only 2 similar eruptions were observed in 1969." |