(upbeat guitar music)
Hi, everybody, I hope you're having a great summer.
I'm Mike Poland, I'm the Scientist-in-Charge
at the Yellowstone Volcano Observatory, and I'm here today
with the update for July, when we look back at data
that we collected over the month of June
and the activity that occurred in Yellowstone.
But before we dive into the data,
I wanted to look at some Steamboat eruptions.
Steamboat had a record setting month.
As you may have heard, there were seven water eruptions
over the course of June and, in fact,
they were the shortest interval between Steamboat eruptions
that had ever been recorded, just a little over three days.
So, a really spectacular month for Steamboat
and really wowing visitors to Yellowstone National Park.
If you've wondered what Steamboat looks like
to a seismologist, this is the seismic signal
for the June 28th Steamboat eruption.
So this is a seismometer that is located
at the Norris Museum building in the Norris Geyser Basin.
All of this noise at the top and the bottom of the screen
are the people, basically walking around
the geyser basin during the daytime.
And then this quieter time is at night
when there are fewer people around.
And that's when Steamboat started to erupt,
at 11:44 p.m. on June 28th.
You see how it comes on strong
and then over the course of the next half-hour
or 45 minutes or so, it gradually fades.
We can also see Steamboat in the temperature records
from the thermal data loggers that are in the runoff channel
for the Steamboat Geyser and in the Tantalus stream gage
which is where all the water
from these Steamboat eruptions ultimately drains.
So, there's a lot of neat ways to look at Steamboat.
Seismic is one of the cool ways of doing.
You can see this on the YVO website,
or at the University of Utah Seismograph Stations' website
you can get this particular data recorder.
All right, so let's check out the data.
During the month of June, the University of Utah
Seismograph Stations, which is responsible for the operation
and maintenance of the Yellowstone seismic network,
located only 73 earthquakes in the Yellowstone area.
You can see that they were widely distributed
across the region.
The largest earthquake occurred on June 14th.
It was only a magnitude two,
located a few miles north of West Yellowstone, Montana.
There were also two small seismic swarms in the region,
which is pretty common for Yellowstone.
One swarm occurred on June 13th and the other on June 19th.
Both of them occurred just a few miles south of West Thumb
within Yellowstone National Park.
In terms of deformation, we haven't seen any big changes
at Yellowstone over the last several months,
or years in some cases,
aside from some minor seasonal variations.
For example, the time series here
shows the vertical deformation near Old Faithful,
which is on the Mallard Lake resurgent dome.
It's a GPS station.
Each one of these dots is a daily position
showing the vertical deformation.
Downward in this case is subsidence,
and upward would be uplift.
Over the past two years,
the Old Faithful site has shown dominantly subsidence.
There was a bit of an uptick in the subsidence rate
in the late winter and early spring of 2019,
and that sort of bounced back.
So, this in all likelihood is a seasonal variation
due to changes in snow melt.
We can also look at deformation
on the Sour Creek resurgent dome, which is on the other side
of the caldera, near Yellowstone Lake.
The White Lake GPS station shows the same trend
of subsidence over time as we saw at Old Faithful,
although the rate is a little higher,
maybe two to three to four centimeters a year or so.
There's been a slight uptick in terms of a bit of uplift
over the last few weeks, but that's the sort of thing
we expect to occur in the spring and early summer.
You can see, back in May of 2018,
we had the exact same little uptick.
So, these sorts of seasonal variations
that interrupt the normal subsidence,
which has been ongoing since 2015, are the sorts of things
that happen due to snow melt and changes in lake level.
We would expect to see that maybe roll
back over into a normal subsidence in the next month.
At the Norris Geyser Basin,
we haven't seen any significant up or down motion,
really, since October of 2018.
Norris had been uplifting, as you can seen in this plot
that goes back the last two years,
until about October of 2018.
At that point, the trend sort of flattened out.
We've seen possibly a little down dropping
of maybe a centimeter since October, but it's very difficult
to say, given how noisy the GPS data are.
So, there really hasn't been much
in the way of deformation at Norris in many, many months.
I'd like to remind you that if you're interested
in more information about Yellowstone, you can always go
to the Yellowstone Volcano Observatory website.
There, you'll find our monthly update.
You can also see links to Yellowstone Caldera Chronicles,
which is our weekly article posted to our website
every Monday, and there's also a way
to count eruptions of Steamboat Geyser.
We have every eruption in the last sequence,
going back to March 15th of 2018 listed here.
And also show ways that you can follow along
with Steamboat's activity, looking at the seismic station
or discharge that's measured in the stream gage,
and even temperature data,
when the temperature stations are operational.
Well, that's it for the July update.
Thanks very much for joining us,
and we'll see you at the beginning of August.
Take care.
(upbeat guitar music)