Old Faithful, one of the icons
of Yellowstone National Park
and probably the most famous geyser in the world.
But how faithful is it really?
Well, that's the question we're gonna tackle
on today's June 1st, 2023 update
of the Yellowstone Volcano Observatory.
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Old Faithful is actually not faithful
in three different ways.
Today it erupts every 94 minutes,
give or take about 10 minutes or so.
That happens 98% of the time.
The other 2% of the time,
there's just 65 minutes between eruptions.
That happens after very short duration eruptions
almost like Old Faithful doesn't completely empty itself.
When that happens, there's a shorter time between eruptions.
So if you happen to be here
and see a maybe an unimpressive eruption,
wait around 65 minutes or so
and you might see a more impressive one.
Another way in which Old Faithful is not entirely faithful
is in looking over the decades.
Now when Old Faithful was first scientifically documented
in the 1870s, it was erupting every 60 to 70 minutes,
but as we just discussed now, it's every 94 minutes.
What happened?
Up until the 1950s, that 60 to 70 minutes was maintained.
But there were a series of earthquakes
that caused the time period to lengthen.
The 1959 magnitude 7.3 Hebgen Lake earthquake.
The 1975 Norris Earthquake, 6.1.
And the 1983 Borah Peak earthquake in Idaho,
that was a magnitude 6.9.
After that, the Old Faithful eruption interval increased
by almost 10 minutes.
So that earthquake sort of changed the plumbing system
a little bit and can cause the interval between eruptions
to lengthen or shorten.
A third way in which Old Faithful is not entirely faithful
is looking over centuries.
There's actually evidence that trees were growing
in the Old Faithful mound.
Now clearly, nothing's growing there today,
and for good reason.
Nothing can grow in all that hot water
so the fact that there were trees growing at one time
means that Old Faithful must not have been erupting.
Now, by dating those trees,
we know that they grew from about 650 to 800 years ago.
So there was a time period, hundreds of years ago,
when Old Faithful must not have erupted at all.
Now, this corresponds to a time period of great drought
in the west and southwestern U.S..
In fact, it affected many Indigenous cultures at the time.
So it appears that during time periods of drought
when there's not much water available,
Old Faithful might go completely dormant,
not erupting at all.
This is actually reasonable given what we see today
when rivers are running high and there's a lot of water,
the interval between Old Faithful eruptions
is a little bit shorter than if the rivers are lower
and there's not as much water,
only by a few seconds to minutes
but water availability clearly makes a difference.
Well, that's the story of Old Faithful.
Now let's talk about what happened during the month of May
in terms of seismic deformation
and geyser activity in Yellowstone.
Well, there's been some interesting hydrothermal activity
in the area of Geyser Hill, which is near Old Faithful,
over the past few weeks.
There's been a general increase in the temperatures
of the features and in fact,
a new hydrothermal feature formed
unfortunately right next to the boardwalk
and it's thrown some mud and hot water onto the boardwalk.
So the portion of the trail there has been closed
in order to ensure visitor safety.
This is not unlike what happened in 2018
in the exact same area when we saw increase in temperatures,
some new features formed,
and that was the year of a rare eruption of Ear Spring.
That eruption was noteworthy because it brought decades
of human garbage up to the surface; coins, hats,
a cinder block, cans with pull tabs, even a baby's pacifier,
things that had either been thrown in
or fallen in over the years.
This really emphasizes the dynamic nature
of Yellowstone's hydrothermal system.
These systems are always changing
and so the kinds of activity that we see this year of 2018,
that kinda thing happens all the time throughout the park.
So we'll report on this further
in the months to come as it evolves.
Turning now to earthquake activity,
we've seen background levels of activity
throughout the month of May
when the University of Utah located 148 earthquake events.
The largest event of the month
was a magnitude 2.8 earthquake that occurred in late May,
about halfway between the Norris Geyser Basin
and Mammoth Hot Springs area and the area near Grizzly Lake.
Now this has been an area of constant seismicity
for the better part of the past year.
During the past month, 34 earthquakes were added
to the swarm activity in this area.
There was also a swarm to the northeast of West Yellowstone.
There were 28 earthquakes that occurred
as part of this swarm.
And there were two other swarms during the month,
both down by West Thumb near Yellowstone Lake.
One of these occurred on May 5th,
there were 19 events
and then another 12 events occurred on May 29th.
And this is pretty common activity for Yellowstone.
This swarm activity is about 50% of all earthquakes
that are located in the region
over the course of a given year
so background levels of seismicity.
Turning now to ground deformation,
this is the last two years of vertical deformation
at the White Lake GPS station,
which is on the east side of the caldera,
Sour Creek resurgent dome.
Each one of these blue dots is one day of data
and downward trends indicates subsidence
while upward trends indicate uplift.
There is an overall trend of subsidence at this site
as we've seen since 2015 at this particular site.
The caldera has been overall subsiding
by a few centimeters per year, about an inch or so per year.
And that's interrupted during the summer months
by a little bit of uplift as water from snow melt and runoff
sort of puffs the ground up
almost like a sponge that gets wet.
And then after the summer months,
we see a resumption of the subsidence.
We might be seeing the turnaround to a little bit of uplift
just now, and that's occurring as all of that runoff
from a really heavy snow year starts to percolate
into these subsurface.
We see the same sort of patterns at Old Faithful
which is on the west side of the caldera,
in the Mallard Lake resurgent dome.
Over the course of the last two years,
there is an overall subsidence,
you can see it really well here from October of 2022
to the current times
and we might start to be seeing that reversal now
into the summertime,
subsidence pause or possibly a little bit of uplift
as that groundwater percolates into the subsurface.
And now looking at the Norris Geyser Basin,
we've seen not a whole lot of change
over the last couple of years.
There's that summertime uplift in 2022
and then since October of 2022,
there's been about two centimeters,
that's less than an inch of subsidence.
We haven't seen much in the way of other changes
except for some snow storms during the winter
that covered the antenna and caused these brief periods
of artificial subsidence.
These are all artifacts.
Finally, turning to everyone's favorite geyser,
Steamboat Geyser, the tallest geyser in the world
in Norris Geyser Basin.
We finally got the temperature sensor back online in May.
Unfortunately, the temperature sensor itself was not working
but that was corrected right at the end of the month
in time to record some minor activity of the geyser.
Now looking back at past records
that we were able to collect recently,
we saw that the geyser erupted on March 11th
and it also erupted on May 7th.
So there have been four eruptions of the geyser
so far this year and with this sort of minor activity
we're seeing now, it looks like the geyser is still active
and so we can expect an eruption
perhaps in the days and weeks to come.
Hopefully, we'll see an eruption here coming in June.
Well, that's it
for the June 1st Yellowstone Volcano Observatory update.
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And if there are any questions you have,
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Our address is yvowebteam, all one word, @usgs.gov.
We'll be back next month, so stay tuned, stay safe,
stay healthy, and we'll see you next time.
Bye-bye.
(bright upbeat music)