(upbeat music)
- Hi everyone. I'm Mike Poland,
the Scientist-in-Charge
of the Yellowstone Volcano Observatory.
And this is the monthly update for September 1st of 2022.
We're continuing our three part series
on the different types of thermal features in Yellowstone.
Last month, we were at Mammoth Hot Springs,
looking at travertine springs.
This month,
we're coming to you from Biscuit Basin
in the Upper Geyser Basin near Old Faithful
to talk about neutral chloride features.
Now this is the sort of feature that's associated
with some of the most iconic thermal areas
in Yellowstone like Grand Prismatic Spring
and Old Faithful.
They're formed from water, snow melt, and rainwater
that circulates deep beneath the earth
and becomes heated by the cooling magma body
beneath Yellowstone.
It also picks up some gases from that magma body and
because it's warm, it starts dissolving some of the rock
that's very high in silica beneath the surface.
Now that warm water, then buoyantly rises up to the surface,
even through some of the colder ground water that may be
between that and the surface.
And when it reaches the surface,
it deposits a lot of that silica that it has dissolved
in the rock below.
And that gives you these really beautiful terrace features.
And also some of the cones that make up geysers
like Old Faithful, Castle and Giant.
So neutral chloride features some
of the most iconic features in Yellowstone National Park.
All right, now let's talk
about the deformation, seismic activity,
and geyser activity that occurred
during the month of August.
August seismicity in the Yellowstone region
was pretty typical for the area.
And in fact, it was dominated
by earthquakes that were part of a single swarm.
The University of Utah Seismograph Stations,
which is responsible for the operation and
maintenance of the Yellowstone seismic network,
located 290 earthquakes in the region during the month.
And of those,
221 were part of this earthquake swarm that's occurring
in the northwest part of the park
between Norris Geyser Basin area and Mammoth Hot Springs.
Now, this is the most seismically active area
of the park between Hebgen Lake
and sort of the north, central part of Yellowstone.
So we often see lots of earthquakes in here
and lots of earthquake swarms.
Now this swarm has been flaring up and cooling down,
off and on, since late July of this year.
And it had another little flare up late in August,
which included three magnitude 3 events.
And this is not atypical for Yellowstone
where there can be little bursts like this.
In fact, back in 2021,
there was a burst of earthquakes beneath Yellowstone Lake.
800 events over the course of 10 days
that included several magnitude 3 events.
And you may remember back in 2017,
there were 2,400 earthquakes that occurred
as part of a three-month-long swarm
right in this area again,
between Hebgen Lake and Norris Geyser Basin,
included magnitude 4 events and several magnitude 3.
So this sort of swarm is pretty typical for Yellowstone.
Right on the very last day of the month too,
night of August 31st local time,
there were some earthquakes down near Lewis Lake as well
that included one magnitude 3 event.
So, it may seem like a lot of earthquakes,
a lot of magnitude 3s,
but this is pretty typical for Yellowstone.
We usually see about 10 magnitude 3 events every year.
So far this year, we have six of these events.
So we're right on track for kind of an average year
for Yellowstone seismicity.
Turning now to ground deformation.
This is vertical deformation at the White Lake GPS site.
And this is located on the east side
of the caldera on the Sour Creek resurgent dome.
This plot shows the last two years of vertical deformation.
Each one of these blue dots is a day's worth of data.
And the overall trend here is one of subsidence,
these downward trends indicate subsidence,
But in each summer that's shown here,
summer of 2021 and summer of 2022,
there is a little bit of uplift
or at least a pause in that subsidence.
And that's caused by groundwater
sort of puffing up the ground like a sponge.
And this groundwater comes from recharge due to rainwater
and snow melt that is percolated into the subsurface.
Now this trend of subsidence has been ongoing
since 2015 at rates of about one to two inches per year.
And every summer it's interrupted
or paused slightly by this little bit of uplift
caused by the groundwater recharge.
And that little bit of uplift amounts
to less than an inch per year, overall rate.
If we look on the west side of the caldera
near Old Faithful,
we see the exact same trends.
Overall subsidence over time with an interruption
in those subsidence trends during summer months,
as we're seeing here in 2021 and again, here in 2022.
Now, looking at the Norris Geyser Basin,
things have been relatively flat there
over the last couple of years.
This big deviation here in late 2021 is caused
by snow that covered the GPS antenna
and created this strange signal.
And as soon as the snow left the antenna,
melted away from the antenna, we got back to normal.
But you see the same overall trend
of a little bit of uplift during the summer months.
So this is affecting everywhere
in the park that water can percolate
into the subsurface and cause it to puff up
a little bit as groundwater accumulates.
Finally, we go to the world's tallest geyser,
Steamboat Geyser,
which had been enjoying a real nice surge in activity
since 2018.
This is the temperature in the outflow channel
of Steamboat Geyser.
And you can see these relatively hot temperatures
bouncing up and down quite a bit.
That's evidence that there's a lot
of minor eruptive activity at the geyser
and that often precedes a major eruption.
Now this actually went throughout the month.
We don't have any data in the last week of the month
because unfortunately internet has been out
to the Norris Museum where we collect the data.
But we know from actual observations
of the geyser that this activity has continued.
Now, hopefully that means we're in store
for a major eruption sometime soon.
The last major eruption of Steamboat was June 20th.
So we've had a few months of no major eruptions
but lots of minor activity.
Now, hopefully this minor activity means though,
that Steamboat's not quite done putting on a show
for us and maybe he'll give us one or two more
big eruptions before the end of the season.
Well, that does it for the monthly update
for September 1st, 2022.
Now, remember if you have any questions at all,
you can feel free to email us anytime at yvowebteam,
that's all one word, @usgs.gov.
Next month, we're gonna come to you
from some of the acidic thermal features in Yellowstone.
Until then, stay safe, stay healthy.
We'll see you next month.
(upbeat music)