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Geysers of the World   

Geysers of Yellowstone   



  West Triplet
Feature Type: Geyser
Geyser/Spring Type: Fountain geyser

Upper Geyser Basin
Grand and Castle Group

Because of its nearness to the boardwalk and the fact that it often plays just prior to or after an eruption of Grand, West Triplet is a fun and relatively easy geyser to watch. Long eruptions of West Triplet can delay Grand but this relationship may or may not be seen from one year to another. Grand has a better chance of erupting if it follows soon after West Triplet starts. A relationship which doesn't seem to have changed in recent years is that West Triplet often precedes an eruption of Rift Geyser.

West Triplet is a fountain-type geyser, erupting through a funnel shaped pool. The maximum height is about 10 feet. Durations range from minutes to hours. Intervals range from hours to days.

What to look for:
Prior to an eruption, water slowly rises in West Triplet. The water level may drop some at about the time Turban erupts but will rebound. Eventually, the water over the vent begins to pulsate and low thumping noises may be heard. Sometimes the eruptions starts before overflow is reached other times it overflows before it erupts. At times, it can overflow for a long period and then drop without erupting.

The sound and pulsing are the most enjoyable part of the eruption.

Electronic Monitor Files
West Triplet Eruptions in 2002.txtWest Triplet Eruptions in 2003.txt
West Triplet Eruptions in 2004.txtWest Triplet Eruptions in 2005.txt
West Triplet Eruptions in 2006.txtWest Triplet Eruptions in 2007.txt
West Triplet Eruptions in 2008.txtWest Triplet Eruptions in 2009.txt
West Triplet Eruptions in 2010.txt 

Some of the temperature data used to derive the eruption times and durations used in this section were collected by Ralph Taylor under a National Park Service research permit, and the remainder was collected by personnel working for the Geology Department of the Yellowstone Center for Resources (including Ralph Taylor). The loggers are a combination of loggers owned by the NPS and Ralph Taylor. Analysis of the raw temperature data to extract the eruption data was performed by Ralph Taylor. The eruption time files on this website may be used provided that Yellowstone National Park is credited for the temperature data and Ralph Taylor is credited for the eruption times.

Activity Recorded by Data Logger - by Ralph Taylor  

When some additional data loggers became available in the late summer of 2002 we deployed one on Rift Geyser and one on West Triplet Geyser.

West Triplet Geyser is located to the southwest of Grand Geyser a few meters from the boardwalk and is known to be one of the interconnected geysers of the Grand Geyser complex. Other members of the complex are Grand Geyser, Turban Geyser, Rift Geyser, Percolator Geyser, and Vent Geyser.

The sensor for West Triplet is located a few meters downstream of the geyser formation in the runoff channel. Start times for West Triplet on the data logger lag visual times by a few minutes since no overflow occurs until the geyser has been in eruption for a few minutes.

I have written software to determine the end times for West Triplet's eruptions, but because of the gradual trailing off of the eruptions, the end times (and therefore durations) are not as accurate as the start times. At this time I do not have a quantification of the error in durations derived from logger data.

Activity in 2010  
The full statistics for 2010 are shown at West Triplet Geyser 2010 Statistics.

The first graph shows the eruption intervals for 2010 plotted against the eruption start time and date. Many of the eruptions occur in pairs separated by an hour or so.
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The next graph shows the intervals over the past three months.
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The distribution of the intervals for 2010 to date along with the most recent month and week are shown in the histogram at the right. The intervals around 3h00m are the double eruptions, the ones between 5 and 10 hours are the longer intervals between pairs of eruptions.

Note that in this and the other histograms displayed here the labels shown on the X-axis represent the upper boundary of the class, not the midpoint. Geyser times are traditionally truncated. The graph at the right has class widths of 30 minutes. The bar appearing above the label "5:00," for example, contains intervals from 4h31m through 5h00m.

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The next graph shows West Triplet's durations plotted against time and date of the eruption start.
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The next graph shows the West Triplet Geyser eruption durations for the past three months.
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The duration distribution histogram is another look at the pattern of durations. The labels shown on the X-axis represent the upper boundary of the class, not the midpoint. The durations represented by the bars over the label 1:20, for example, represents the percentage of durations between 1h15m and 1h20m.
Click for a larger image

Activity since 2002  
The graph at the right shows all of the electronically recorded intervals for West Triplet Geyser. The long gap in the spring of 2005 resulted from a logger failure. Note the gradual decline in the intervals, especially the longest intervals, between 2002-3 and 2005-6.
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The next graph shows the moving 1-week median intervals. this graph suppresses the extreme values and gives a somewhat clearer picture of the changes.
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The next graph shows the monthly minimum, mean, median, and maximum intervals.
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The final graph shows the monthly minimum, mean, median, and maximum durations. As with the interval statistics, there has been little change since 2002.
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Activity in 2009
Activity in 2008
Activity in 2007

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Please note - this site is currently under constuction. Please visit for more information.  Last update 01-29-2017

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