(upbeat music)
Hi, everybody.
I'm Mike Poland, the scientist-in-charge
of the Yellowstone Volcano Observatory,
and this is the monthly activity update
for February 1st of 2022.
We thought that this month,
it might be kind of fun to start out with the story
of one of the iconic photographs
from the history of Yellowstone National Park.
Now at first glance,
this may look like some tourists
that are posing in front of Minerva Terrace,
in Mammoth Hot Springs.
But in fact, this is an army unit.
This is the all volunteer bicycle corps
of the 25th infantry regiment.
Now, the 25th was one of four regiments in the army,
in the late 1800s,
that were composed entirely of African-American soldiers,
the so-called Buffalo Soldiers.
And at this time, this photograph was taken in 1896,
the army was testing out the utility of bicycles,
potentially for use in combat as a cavalry tactic,
instead of say horses.
So, this wasn't just going to Yellowstone
and showing off their bicycles.
They actually were based in Fort Missoula, the 25th was,
and they rode 300 miles over eight days,
from Missoula to Mammoth Hot Springs in Yellowstone.
After a couple of days to refit and re-provision,
they went on a four-day, 132-mile tour around Yellowstone,
stopping in the Lower Geyser Basin,
the Upper Geyser Basin, West Thump,
and also the Grand Canyon of the Yellowstone,
before returning to Mammoth,
spending another couple of days
where they took some photographs,
showing the bicycles on Mammoth Hot Springs,
obviously not something we would do today,
but cruising around the inactive part of Minerva Terrace,
and then going back another 300 miles to Fort Missoula.
And even that was really just a warmup
for a much bigger jaunt that happened in 1897,
and that was a 1900 mile bicycle trek
from Fort Missoula to St. Louis, took 40 days.
Now, it may not seem like that big of deal
to cruise around on your bike in Yellowstone,
but remember back in 1896,
these bicycles were one speed, 30 pound bikes.
They were also carrying all of the repair parts they needed,
bedroll, tent, their weapons and ammunition, food, utensils,
everything you would need to survive
and repair your bicycle along the way.
And of course, none of the roads were paved.
So imagine that,
a one speed bike with dozens of pounds of equipment
on an unpaved road, all throughout Yellowstone,
a pretty incredible adventure.
And then, the next year going all the way
from Missoula to St. Louis in the same sorts of conditions.
All right,
now let's talk about the activity that we observed
during the month of January in Yellowstone,
in terms of earthquakes and deformation,
and geyser eruptions.
Activity in the Yellowstone region,
during the month of January,
was at its normal background levels.
The University of Utah Seismograph Stations,
which is responsible for the operation
and maintenance of the Yellowstone seismic network,
located 105 earthquakes during the month of January.
The largest was a magnitude 2.5,
located just to the south of Mammoth Hot Springs
in Yellowstone National Park.
And in fact,
this earthquake was part of a sequence of earthquakes,
a small swarm of 42 events that occurred between January 5th
and January 31st.
Swarms like these are very common, and in fact,
about 50% of all earthquakes occur as part of swarms
in Yellowstone.
The rest of the earthquakes during the month
were distributed throughout the region.
Turning now to surface deformation,
this is vertical deformation recorded
at the White Lake GPS station,
which is on the east side of the caldera,
the Sour Creek resurgent dome.
Each one of these blue dots is one day of data,
and the entire plot spans two years.
Downward trends indicate subsidence
and upward trends indicate uplift.
The overall trend is subsidence,
at about two to three centimeters or one inch a year.
There are little bits of uplift recorded during the summers
or pauses in the subsidence,
and that's caused by groundwater recharge
as water from snow melt percolates into the subsurface
and the subsurface sort of soaks it up like a sponge.
You can see those since September,
the end of this past summer,
we've had a resumption of the normal subsidence trend.
If we go to the other side of the caldera
and the Mallard Lake resurgent dome,
this is GPS data from the Old Faithful site.
Same overall trend is apparent, of subsidence
a couple of centimeters per year.
The signal gets a little better here in September of 2020,
because some trees near the site were cut down
to reduce the fire load.
There was a wildfire nearby the site,
and there was some concern
if there were too many trees in the region,
it might feed a bigger fire.
So, the signal got better once those trees were removed.
Still have that summertime pause in subsidence,
slight amount of uplift,
and then back to subsidence after the summer's over.
There's a bit of an anomaly right here in mid-December,
and that was caused by heavy snowfall,
which covered the antenna,
but once the snow melted off,
you can see we're back to that normal trend.
And now,
looking at the GPS site near the Norris Geyser basin,
there really hasn't been a whole lot of deformation
over the last two years.
You can see the trend is pretty flat.
But right here, again in mid-December of 2021,
we have that anomaly caused by the heavy snow,
so that snow covered the antenna,
but once it melted off, we got back to the usual trend.
So, no real deformation in the area
of Norris Geyser basin over the last two years.
And finally turning to Steamboat Geyser,
everyone's favorite geyser,
that had one eruption during the month.
This is the temperature that's measured
in the outflow channel below Steamboat Geyser.
All of this little up and down motion
is caused by temperature fluctuations
due to small minor eruptive activity.
It culminated in a major eruption,
right here on January 23rd,
and after that,
we saw the temperatures drop down
to their normal daily variations.
It's looking like we're starting to see
a bit more of that minor activity right here
at the end of the month.
So hopefully, Steamboat is not yet done putting on a show.
It's certainly backed off,
in terms of the frequency of eruptions.
And nothing like it was over the previous few years,
but not over quite yet.
Well, that does it for the monthly update
for February 1st, 2022.
Now remember, if you have any questions at all,
you can feel free to email us anytime.
Our email address is yvowebteam, all one word,
at usgs.gov.
Thanks very much.
Take care, stay safe.
We'll see you next month,
bye-bye.
(upbeat music fades)