Hi, everybody.
Hi, everybody.

I'm Mike Poland, the scientist-in-charge
I'm Mike Poland, the scientist-in-charge

of the Yellowstone Volcano Observatory.
of the Yellowstone Volcano Observatory.

And this is the monthly update for November 1st, 2021.
And this is the monthly update for November 1st, 2021.

Coming to you today from a very snowy Norris Geyser Basin.
Coming to you today from a very snowy Norris Geyser Basin.

And we're looking at Porkchop Geyser.
And we're looking at Porkchop Geyser.

Now Porkchop was named in the sixties
Now Porkchop was named in the sixties

because it looked like a pork chop.
because it looked like a pork chop.

It was really just sort of a thermal pool,
It was really just sort of a thermal pool,

but in the seventies and into the eighties,
but in the seventies and into the eighties,

it started having these intermittent geyser eruptions.
it started having these intermittent geyser eruptions.

It became Porkchop Geyser. And in the mid-eighties,
It became Porkchop Geyser. And in the mid-eighties,

it started having these perpetual geyser eruptions.
it started having these perpetual geyser eruptions.

In fact, there's some really spectacular photos from
In fact, there's some really spectacular photos from

the eighties, especially in the winter - days like today
the eighties, especially in the winter - days like today

where large mounds of ice would form over the geyser
where large mounds of ice would form over the geyser

as the water that was coming out,
as the water that was coming out,

as the steam condensed very quickly into ice crystals,
as the steam condensed very quickly into ice crystals,

you got these very spectacular ice mounds.
you got these very spectacular ice mounds.

And Porkchop was becoming more and more active
And Porkchop was becoming more and more active

through the late eighties
through the late eighties

until on September 5th, 1989, it actually exploded.
until on September 5th, 1989, it actually exploded.

The vent for the geyser became so constricted
The vent for the geyser became so constricted

that pressure built up and it blew it up.
that pressure built up and it blew it up.

And rocks were actually thrown 200 feet distant from there.
And rocks were actually thrown 200 feet distant from there.

In fact, all those upturned rocks
In fact, all those upturned rocks

that you see around Porkchop now were formed
that you see around Porkchop now were formed

during that explosion.
during that explosion.

And there were a bunch of people in the geyser basin
And there were a bunch of people in the geyser basin

that day who witnessed it.
that day who witnessed it.

So we have a very good record of the Porkchop explosion.
So we have a very good record of the Porkchop explosion.

This is an example of a hydrothermal explosion,
This is an example of a hydrothermal explosion,

a relatively small one,
a relatively small one,

but this is one of the hazards that we have in Yellowstone.
but this is one of the hazards that we have in Yellowstone.

And one of the reasons that we need
And one of the reasons that we need

to monitor the thermal basins like we do.
to monitor the thermal basins like we do.

So since that explosion in 1989,
So since that explosion in 1989,

Porkchop's been a relatively calm pool.
Porkchop's been a relatively calm pool.

You can see the nice blue color there.
You can see the nice blue color there.

We actually monitor the temperature
We actually monitor the temperature

with one of our thermal data loggers
with one of our thermal data loggers

And you can find that information
And you can find that information

on the Yellowstone Volcano Observatory website.
on the Yellowstone Volcano Observatory website.

So, really cool feature here on a wonderful day
So, really cool feature here on a wonderful day

in Norris Geyser Basin.
in Norris Geyser Basin.

All right, now let's talk about what happened in Yellowstone
All right, now let's talk about what happened in Yellowstone

during the month of October, with respect to earthquake
during the month of October, with respect to earthquake

and deformation activity.
and deformation activity.

Seismic activity during the month of October
Seismic activity during the month of October

in the Yellowstone region was pretty typical
in the Yellowstone region was pretty typical

of normal background levels.
of normal background levels.

The University of Utah Seismograph Stations,
The University of Utah Seismograph Stations,

which is responsible for the operation
which is responsible for the operation

and maintenance of the Yellowstone seismic network,
and maintenance of the Yellowstone seismic network,

located 267 earthquakes in the region during the month.
located 267 earthquakes in the region during the month.

The largest was a magnitude 2.6,
The largest was a magnitude 2.6,

located just off to the east of the Norris Geyser Basin.
located just off to the east of the Norris Geyser Basin.

That occurred on October 4th, local time.
That occurred on October 4th, local time.

There were also three swarms in the region.
There were also three swarms in the region.

One that was sort of north of the Old Faithful area.
One that was sort of north of the Old Faithful area.

That was 109 earthquakes in this swarm here.
That was 109 earthquakes in this swarm here.

That was a continuation of a swarm that started
That was a continuation of a swarm that started

in September and lasted into mid-October.
in September and lasted into mid-October.

There was a swarm off to the east of Norris
There was a swarm off to the east of Norris

that included the largest event of the month,
that included the largest event of the month,

a little over 20 earthquakes.
a little over 20 earthquakes.

And then there were also a little over 20 earthquakes
And then there were also a little over 20 earthquakes

in the swarm that was off
in the swarm that was off

to the northeast of West Yellowstone, Montana.
to the northeast of West Yellowstone, Montana.

That's also a continuation of a swarm
That's also a continuation of a swarm

that started in September and lasted into early October.
that started in September and lasted into early October.

So normal background seismicity for the month.
So normal background seismicity for the month.

Largest magnitude 2.6 and typical swarm activity.
Largest magnitude 2.6 and typical swarm activity.

Turning now to deformation.
Turning now to deformation.

This is showing vertical deformation at the White Lake GPS
This is showing vertical deformation at the White Lake GPS

station over the past two years.
station over the past two years.

This is on the east side of the caldera
This is on the east side of the caldera

on the Sour Creek resurgent dome.
on the Sour Creek resurgent dome.

Each one of these blue dots represents one day.
Each one of these blue dots represents one day.

And over the entire two year time period,
And over the entire two year time period,

you can see this downward trend overall,
you can see this downward trend overall,

which indicates subsidence.
which indicates subsidence.

There are periods during the summertime
There are periods during the summertime

of pause in the subsidence,
of pause in the subsidence,

even a slight amount of uplift,
even a slight amount of uplift,

and that's caused by seasonal groundwater recharge.
and that's caused by seasonal groundwater recharge.

So no real changes in trend over this time period here.
So no real changes in trend over this time period here.

We're seeing subsidence on the order of a couple
We're seeing subsidence on the order of a couple

of centimeters about an inch or so per year.
of centimeters about an inch or so per year.

If we go to the other side of the caldera
If we go to the other side of the caldera

and the Old Faithful continuous GPS site,
and the Old Faithful continuous GPS site,

this is on the Mallard Lake resurgent dome.
this is on the Mallard Lake resurgent dome.

We see the same overall downward trend
We see the same overall downward trend

with this small interruption during the summertime.
with this small interruption during the summertime.

The trend improves in terms of the precision
The trend improves in terms of the precision

of the data quite a bit here in September of 2020,
of the data quite a bit here in September of 2020,

because some of the trees in the region were cut down
because some of the trees in the region were cut down

because of a nearby fire and the park wanted
because of a nearby fire and the park wanted

to reduce the potential fire load if the fire made it
to reduce the potential fire load if the fire made it

into this area.
into this area.

So with fewer trees in the area,
So with fewer trees in the area,

the GPS signal is a little bit better in that region.
the GPS signal is a little bit better in that region.

Moving to the area of the Norris Geyser Basin.
Moving to the area of the Norris Geyser Basin.

Over the past two years, there hadn't been much deformation
Over the past two years, there hadn't been much deformation

but it's looking like over the summer, we might start
but it's looking like over the summer, we might start

to see a bit of uplift here in the Norris area.
to see a bit of uplift here in the Norris area.

Over the last few months,
Over the last few months,

this has only amounted to one to one and a half centimeters
this has only amounted to one to one and a half centimeters

or so, less than an inch.
or so, less than an inch.

And this area has been the site of uplift in the past,
And this area has been the site of uplift in the past,

particularly during 2013 to 2014.
particularly during 2013 to 2014.

And again, from 2015 to 2018.
And again, from 2015 to 2018.

So Norris may be going back into a period of uplift
So Norris may be going back into a period of uplift

after a few years of no deformation.
after a few years of no deformation.

And finally, now turning to everyone's favorite geyser,
And finally, now turning to everyone's favorite geyser,

Steamboat Geyser.
Steamboat Geyser.

It remains active.
It remains active.

We've seen two eruptions during the month of October.
We've seen two eruptions during the month of October.

This is the temperature trend measured
This is the temperature trend measured

in the outlet channel of Steamboat.
in the outlet channel of Steamboat.

So these up and down variations
So these up and down variations

are just the normal daily variations.
are just the normal daily variations.

And then we see a lot of this sort of noise in here.
And then we see a lot of this sort of noise in here.

Those are minor eruptions that culminate in a major.
Those are minor eruptions that culminate in a major.

So here's a major eruption on October 13th.
So here's a major eruption on October 13th.

Then it goes quiet again, not much activity,
Then it goes quiet again, not much activity,

more minor activity,
more minor activity,

and then another major eruption on the 25th.
and then another major eruption on the 25th.

So Steamboat had these major eruptions
So Steamboat had these major eruptions

on October 13th, October 25th,
on October 13th, October 25th,

and we're seeing more minor activity now.
and we're seeing more minor activity now.

So there'll probably be another major eruption sometime
So there'll probably be another major eruption sometime

in the next few days, to a week or so.
in the next few days, to a week or so.

So Steamboat remains active so far during the year 2021.
So Steamboat remains active so far during the year 2021.

We have seen 17 eruptions of the geyser.
We have seen 17 eruptions of the geyser.

Well, that does it for the monthly update
Well, that does it for the monthly update

for November 1st, 2021.
for November 1st, 2021.

Now remember, if you have any questions,
Now remember, if you have any questions,

you can email us anytime at yvowebteam,
you can email us anytime at yvowebteam,

that's all one word, @usgs.gov.
that's all one word, @usgs.gov.

We'll be back next month.
We'll be back next month.

So until then, stay safe,
So until then, stay safe,

stay healthy.
stay healthy.

We'll see you soon.
We'll see you soon.

Bye, bye.
Bye, bye.