(gentle upbeat music)
Hi everybody, I'm Mike Poland scientist-in-charge
of the Yellowstone Volcano Observatory.
This is the YVO monthly update
for April 1st of 2021, no fooling.
Now, before we talk about what happened in Yellowstone
over the past month, I thought it might be fun
to talk about what else YVO looks
at in terms of volcanic activity even though we're
the Yellowstone Volcano Observatory.
We also have the responsibility for monitoring the volcanoes
of the Southwestern United States
in the four corners region, Utah,
Colorado, Arizona and New Mexico.
And in fact, there is young volcanism in this area.
For example, the Black Rock Desert Volcanic Field
in central south central Utah has had an eruption
about 10,000 years ago or so.
The Zuni Bandera volcanic field West of Albuquerque
in New Mexico had an eruption about 3000 years ago.
And the youngest eruption
in the region was out of Sunset Crater near Flagstaff
in the San Francisco Volcanic Field.
And that was just a little over 900 years ago.
So in fact, it's more likely that magma will reach
the surface in the Four Corners area than it will
in the Yellowstone area.
Where the most recent magmatic eruption
was 70,000 years ago.
So we do keep an eye on these volcanoes down
here using a combination of techniques.
And we do see activity from time to time.
Although we haven't seen anything
that suggests that magma is on the move.
Now, for example, this is a map of seismicity
in Utah over the last week, basically late March of 2021.
And there's this seismic swarm right down here
in sort of southern Utah.
This is sort of on the border
of the Black Rock Volcanic Field,
but it has all of the characteristics
of a tectonic earthquake swarm.
And that's because this entire area
of the western U.S. is stretching.
You can see it in the topography
with all these alternating valleys and mountain ranges.
And that's a sign
that the whole region is being pulled apart.
We see lots and lots of earthquakes.
In fact, just a year ago, almost a year ago today
we had the magnitude 6.5 earthquake in central Idaho.
And that was also related
to this tectonic extension of the western United States.
So we can tell from the type of seismicity
this is tectonic seismicity, tectonic earthquakes
but of course we keep an eye on it
just to make sure that there's no magmatic component to it.
Okay, well, now that you know a little bit more
about YVO's background and what else we monitor,
let's talk about what happened
in Yellowstone during the month of March.
There was no particularly noteworthy activity
in the Yellowstone region during the month of March.
The University of Utah Seismograph Stations
which is responsible for the maintenance
and operation of the Yellowstone seismic network located
105 earthquakes during the month,
which is pretty much average.
The largest was only a magnitude 2.4 located right here
in the northern part of the Park.
There were also a couple of small swarms
in the Old Faithful region,
but that's again pretty average about 50%
of all the seismicity
in Yellowstone occurs as part of swarms.
In terms of deformation we haven't seen changes
in several years now.
This is the last two years of vertical deformation
at the White Lake GPS station,
which is on the east side of the caldera
at the Sour Creek resurgent dome.
Each one of these dots is a day of data.
And when you see the trend going down that means subsidence
and up means inflation or uplift.
And you can see over the last two years
there's been this overall subsidence trend of
just a couple of centimeters about an inch
so per year interrupted by little seasonal variations
which we see every year.
And this has been ongoing since 2015.
If we go over to the west side
of the caldera and the Mallard Lake resurgent dome
this is a GPS station located near Old Faithful.
And that same pattern of overall subsidence
for the last couple of years is apparent there as well.
Again, happening at couple of centimeters
about an inch or so per year.
Finally, if we go over to the Norris Geyser basin
that had been uplifting between 2015 and 2018,
but that paused in late 2018, we didn't see much change
through 2019 bit of subsidence at the end of 2019
and there's been really nothing since the beginning of 2020.
So deformation at Norris continues
to be pretty flat, no real changes there.
And then of course, turning to everyone's favorite geyser,
Steamboat Geyser in the Norris Geyser basin
that has had three water eruptions
in the month of March, one here on March 3rd
one here on March 18th and another on March 27th.
This is the temperature record
in the Steamboat outlet channel.
All of this minor activity leads up to a major
and then everything decreases
as there's no more eruptive activity all.
Then we get to more minor activity.
And this pattern has been going on now
for a couple of years with these three eruptions in March
that brings the total number of eruptions of Steamboat
for 2021 to seven.
Well, that does it for the YVO monthly update
for April 1st of 2020.
Now, remember if you have any questions
you can email us anytime yvowebteam@usgs.gov.
Take care, stay safe,
and we'll see you next month, bye bye.
(soft upbeat music)