
Activity Recorded by Data Logger  by Ralph Taylor 



Introduction 
A data logger has been deployed at Artemisia Geyser since October of 2000. We have attempted to obtain a continuous record of Artemisia’s activity since that time, but the record has several gaps caused by equipment failure or our inability to recover the data in wintertime.
The sensor for Artemisia is located in one of the runoff channels about a meter from the edge of the main platform and about five meters from the edge of the pool. The sensor easily detects the temperature rise signifying the wave of hot water resulting from the eruption start. Electronic times are recorded to the nearest minute currently, but in the earlier deployments sample intervals of five minutes were used during the winter and 30 seconds was used in summertime when more frequent downloads were performed.



Activity in 2011 
The overall eruption interval statistics for Artemisia in 2011 are shown at Artemisia 2011 Statistics. A pdf of this summary is at Artemisia Recent Activity Summary.




The activity of Artemisia Geyser in 2011 is shown in the graph at the right. The blue line shows all of the eruption intervals and the green line shows the 1week moving median interval. The straight red line is a linear regression fit, included to show the general trend of intervals. The graphs for the current year are updated about every six weeks from October to June and weekly from June to the end of September. The data ends with the 3 November download because of a logger failure.

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The second graph expands the time line for the past three months.

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The next graph shows Artemisia's activity for the month preceding the last download.

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The next graph shows the interval distribution for 2010. The width of the peak shows the uncertainty in intervals. Blue shows the intervals for the whole year to date, maroon shows the previous month, and yellow the previous week. Note that in this and the other histograms displayed here the labels shown on the Xaxis represent the upper boundary of the class, not the midpoint. Geyser times are traditionally truncated. The graph at the right has class widths of 60 minutes. The bar appearing above the label "22:00," for example, contains intervals from 21h01m through 22h00m.

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The final chart for 2011 shows the monthly statistics for the year to date.

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Activity since October 2000 
One way to present the eruption interval data is to graph the interval as a function of time. The graph shown at the right shows all of the electronically recorded intervals since 2000. The gaps in 2001, 2002, 2003, and 2004 are many weeks long and resulted from logger failures. We were somewhat more successful in 2005 but there is a gap in July caused by yet another failure. The 2007 data is complete and the 2008 data has a 15 hour gap in early January and a six day gap in April when the logger filled. The 2009 data is complete up to the January download. The 2010 data is fragmentary until April due to logger technical issues.

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The interval graph shows the large variation in interval from one eruption to the next. A better idea of the change in intervals over time can be seen from the graph of the 1week moving median intervals, shown at the right. From both graphs the sharp drop in intervals from late winter of 2002 to about June of 2002 shows clearly. Since that time intervals have generally risen to even longer than at the start of the data, and the variation from day to day and week to week has grown substantially since 2005.

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The chart at right shows how the maximum, minimum, mean, and median intervals for each month have changed. Note that since July 2004 Artemisia's intervals have steadily increased until midyear in 2006 when they stabilized. The maximum intervals in 2007 were quite a bit higher than previous years, even in the summer months. The low minimum intervals in July 2005 represents two minor eruptions (see below). The average interval has remained between 18 and 21 hours since early 2006.

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Activity in 2010

Activity in 2009

Activity in 2008

Activity in 2007

Activity in 2006

Activity in 2005
