Inside USGS, No. 4, Robert B. Smith

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Robert B. Smith of the University of Utah has been collaborating with USGS scientists on Yellowstone geologic topics since the 1960’s. In this interview Bob describes nuances of the Yellowstone volcano story. He shares details of his past and present work and explains how the University of Utah and USGS have a long history of working together on Yellowstone geology.


Date Taken:

Length: 00:24:02

Location Taken: US


Describe your area of interest in Yellowstone.

Bob Smith:
My area of interest follows my background.

I’ve had degrees, a PhD in geophysics and
degrees in geology and I studied mathematics

and computer science.

So, my areas of interest in Yellowstone have
been focused using earthquake studies, seismology,

I’m a seismologist but they move into the
areas of deformation using global positioning

system, they move into the areas of understanding
the dynamics and the chemistry of the system.

And I integrate these together to solve a
single problem.

That is I never just use seismology to attack
the problem.

I rely very much on the geologic history that’s
been well documented in Yellowstone.

I rely on the geochemistry that other people
have done.

Because we have to understand the one big
basic thing is heat.

It’s a very high heat flow area because
heat’s coming off of a young and active

magma reservoir.

That heat leads to earthquakes.

The heat leads to deformation.

The heat leads to of course heating the ground
that creates the geysers, fumaroles and hot


And so this is roughly six gigawatts a year
that come out of the earth from Yellowstone.

Enough to electrify a modern city.

That is kind of the basic, primeval that drives
and is responsible for the other components.

What excites you about working on Yellowstone


Bob Smith:
I’ve gone back now for fifty something years

and I’ll be honest every year we’re discovering
something new.

Either the caldera’s going up or it’s
going down.

We’ve had big earthquakes we’ve had interactions
of earthquakes with geysers and things.

And it’s always looking, always finding
out that you’re seeing processes that are

active today.

Many geologists in their careers work on rocks
that are millions and millions of years old.

I like work on Yellowstone because what’s
happening it’s real time, it’s today.

So, it’s real time geology and that’s
what makes it exciting for me.

Is to look at the processes we can from studying
Yellowstone and then apply those processes

to other places in the earth where there’s
volcanoes and there’s big faults and earthquakes.

But, Yellowstone truly is a window into the
earths processes.

It’s really an active geologic laboratory
and the laboratory is alive.

How did you get hooked on earth science?

Bob Smith:
I was off studying mathematics or physics

at the time at Utah State University.

But as I got more and more into these topics
I got more and more interested in in earth


And then in 1959 we had the occurrence of
the magnitude 7.5 Hebgen Lake earthquake just

on the west side of Yellowstone.

And we went up immediately as students and
faculty and I had relatives there to see this

giant earthquake.

Well it turns out it killed 28 people.

It’s the biggest normal faulting earthquake
that’s occurred in historic times in the

basin and range.

At the time I’d been changing the seismogram
records at the university to help pay for

my little scholarship.

And when I saw that earthquake I said wow
that’s what I want to study and that coupled

back with my experience in Yellowstone, trying
to understand how all that heat was being

manifest I said to myself, did the Hebgen
Lake earthquake have anything to do with this

Yellowstone Volcano?

And that really turned me into taking a degree
in geology a bachelors degree with studies

in math and computers at Utah State.

And that moved me on into geophysics following
my master’s degree and that’s where I’ve

been ever since.

When did you begin studying seismology in

the park?

Bob Smith:
Following my military career I came back with

my PhD.

Then I went back and started thinking about
Yellowstone again.

Nothing had been done there in the way of

So, I started installing portable seismographs
all around the park different places for different

periods of time for about 2 to 3 years and
then we mapped out the seismicity.

We mapped out the active faults.

We mapped out the relationships between the
earthquakes and the volcanic features that

were in Bob Christiansen’s work.

And then that then turned this into “Let’s
get a permanent network”.

Well the USGS installed a permanent network
in ’73 they gave it up in 1980 and said

to me “Bob you take over the Yellowstone
network, you have the drive and the Interest”.

I said “I’ll take it over if I can grow
it to my own dimensions and reliability.

Yellowstone operations are not California

It costs a lot more to have reliable equipment.

And they agreed to pay for it.

We expanded the Yellowstone network in the
80’s and then in the late 80’s GPS started

to come in and so we started doing portable
GPS studies and integrating the two right


University of Utah is the base of operations
for all of the Yellowstone earthquake volcano

or deformation monitoring.

That’s an important feature that Bob Christiansen’s
always said.

And it’s true.

So, we had all this data coming in together
and then we began to evolve, modernize as

more and more digital equipment came in as
bigger and better computers would come in

bigger and better data bases would come in.

And so, that came up through the 80’s I
had funding from the NSF to start the GPS,

NSF funding start the seismic, got USGS funding.

We upgraded the seismic network.

The Park Service has always been very very
helpful with us providing us all kinds of

logistical support.

How is new technology helping to conduct earth


Bob Smith:
Well certainly when I first began studying

in Yellowstone the instrumentation, for example
the seismographs were very crude they were

recording on paper , smoked paper drums or
on inked drums, we had no GPS, the actual

sensors were very low magnification would
only detect relatively moderate to large earthquakes.

Well it’s because of computational methodologies
the whole area of seismic monitoring has evolved

greatly so that in currently we now have seismographs
that are now capable of magnifying ground

motion even from as small as a magnitude zero
earthquake to a magnitude 8 earthquake and

remain on scale.

Space technology came in the mid-80’s.

We have GPS so we’re using GPS to actually
measure a point on the ground and if we measure

with time it represents ground motion and
so it’s just like a seismograph.

And so these new technologies primarily GPS
and high quality broad band seismology that

we receive funding by the way from the USGS
to upgrade to the newest system.

We now have in Yellowstone a network of 39
seismographs putting out a hundred channels

of real time data and about 25 GPS systems
putting about 60 or 70 channels of real time


All of the data are recorded digitally that
means they have high fidelity they’re very

reliable but they’re in real time.

That means they get to my laboratory here
at the University of Utah the same time that

it gets anywhere on the web.

So, anybody can have access to our data any
time they want.

Describe your collaboration with Bob Christiansen

Bob Smith:
Bob and I worked together for years, very

closely I would spin off geophysical findings,
he would spin off geological findings and

how they fit was uncanny amazing.

I mean he’d talk about the volcanic history
of a flow and I’d say well here’s the

gravity signature of that flow that tells
us how deep it is.

Or the seismic data here tells you something
about a fault that’s there that you’ve

got on your map.

So, I worked really close with Bob Christiansen
and his thoughts pervaded my basic interpretations.

So, I think, his mapping, his ideas of the
caldera formation.

My ideas of the processes of the magma chamber
how they were formed.

How big earthquakes occur and map out the
faults that are related to the magma chamber

really fit together.

I worked to a certain degree with Bob Fournier
because I was bringing my information to bear

on hydrothermal systems, geysers, hot springs

So, I got to know Bob very well and so I worked
with Bob for several years.

And I still am in touch with he and Bob Christiansen.

And it’s always been very rewarding to put
all of our ideas together, you get a better

solution, you get a broader solution to a
problem in the case of Yellowstone.

When we bring the volcanologists together
with the geophysicists we one can constrain

the other data.

The earthquake information can constrain the
size of a magma body.

The size of the magma body tells the volcanologist
how much magma there is that could be exploded.

It tells the geochemist what percent volume
of melt to solid rock in the case of a partial


These things are done by people working together
and collaborating and talking to one another

routinely and that’s the part that I would
say in the last part of my career that’s

been so fun.

Because I get, I learn new things all the
time and so productive.

How did road surveys help clarify the story?

Bob Smith:
I knew from the earthquake data, Yellowstone

was really active.

And yet you continue measuring earthquakes
and I said to myself, what we ought to do

is measure the ground motion well back in
the 70’s the only way your could do that

was with leveling that is engineering spirit

And so we formed a team that was funded by
the USGS and a leveling team came from the

USGS topographic division came out and we
began leveling.

Now before that I went to the Washington archives
and got the old benchmark descriptions when

they built the roads in 1923 and we were,
we were going to the same bench mark the same

roads, we were half way across Hayden Valley
and as you go along you calculate you know

you’re walking so you can calculate what
the elevation was in 23 and what it is today.

And we got further and further and we kept
getting further and further in the numbers.

I finally got half way and I said to M. David
Cummings, the surveyor, we’ve got a big


We need to go back and resurvey this whole
thing because we’re off two feet.

He says ‘I’m not off two feet”.

“I might be off one or two millimeters but
not two feet”.

We finished the survey, came back to the university,
I spent an entire year and a PhD thesis trying

to take these data and prove they were wrong.

They weren’t wrong.

We had measured 750 mm of uplift, almost one
full meter between 1923 and 1976 in the middle

of the caldera.

That’s when we discovered Yellowstone had
this very very high uplift rate.

And it’s because we were being very careful
we were scrutinizing the data we worked very

hard to prove it was wrong.

And we couldn’t.

And now you use GPS?

Bob Smith:
Now we use GPS.

And we have 25 permanent GPS stations that
we run in Yellowstone plus we go back into

areas of Yellowstone another 30 points are
measured annually, we call them annual measurements

to fill in, get more detail.

But the GPS is now giving us full pictures
of the whole caldera.

And we’re supplementing that now with INSAR
that is satellite radar information, actually

it takes a picture of the whole caldera and
you have a pass every two weeks.

And then the sentinel satellite is just going
to come on board next month for Yellowstone.

We’re going to be able to get a picture
once every two weeks.

The problem with the INSAR satellite is it
measures the top of the ground if there’s

snow it measures the top of the snow so it
doesn’t work in winter.

And that’s where the GPS is continuous.

And our GPS receivers are now so accurate
they measure the height change within millimeters

and the distance change within millimeters
per year.

That’s the width of your it’s an amazing

But, they all have to be worked together.

But, like I said INSAR, GPS, earthquake data
they have to be interpreted together.

One constrains the other.

Describe how you work with the new generation

of scientists like Jake Lowenstern.

Bob Smith:
He and other people of this next generation

are going to be using new techniques I’m
sure built upon what we’ve done.

And there will be another generation after

Because science develops new things and that’s
always guaranteed.

How does plate tectonics relate to Yellowstone?

Bob Smith:
One of the basics of Plate Tectonics are plumes,

one of the four, you know subduction zones,
extension, strike slip and plumes.

Well that’s what’s happened at Yellowstone.

So, I made up some conceptual models for Yellowstone
in 1969 on how a plume could come up and well

magma up and give us the heat that we’re
seeing at Yellowstone as a hot spot.

So, I published that paper, gave the oral
version, ’69.

Published it in ’70, first started to publish
in ’71, ’72, ’73, ’74 so we had it

all down then.

We didn’t have the new tomography, we didn’t
have the new GPS, these were conceptual models,

they were based on earthquake distribution
topography and geology.

So, plate tectonics had a profound effect
and that’s when I named it the Yellowstone

Hot Spot and that it was a mantle plume.

I didn’t say it was a deep mantle plume
I said it was a magma plume.

Now we know it’s a relat…it’s an upper
mantle plume, goes down to about mid-mantle.

How does Yellowstone volcanism compare to


Bob Smith:
The difference between Hawaii and Yellowstone

is the following.

The crustal structure of oceanic plates are
much thinner and they’re much younger so

the magma’s that come up from the mantle
have a much shorter distance to burn through

and create the volcanoes.

Moreover the continental crust is much thicker
much older and contains much larger components

of silicic rocks.

Old old rocks from evidence of billions of
year old rocks so when you heat those up you

not only bring up basalts from the mantle
the mantle in turn burns the lower crust,

mid crust was a lot of silicic material you
get rhyolites.

So, in the case of Yellowstone the rocks that
come out are rhyolitic.

And they are the first, they are the flows
that we see in the Yellowstone Snake River


They’re followed by the primary basalts
after the plate is moved over the hot spot

but the difference being one is a ocean plate
of pure basalt one is a continental plate,

big thick and cold that mixes in the magma
adds in the silicic component that creates

the rhyolites, the granites we see at the

How does the University of Utah work with

Yellowstone National Park?

Bob Smith:
The park interacts with us because all of

the data we have here we send back to them
in real time.

So, they have access to all of our seismic
data, our GPS data just as fast as we have


The park doesn’t have professional seismologists
or geodesists so what they rely principally

upon us for is a level, is interpretation
of the data.

So what they call upon us is what does this

What does this swarm of earthquakes mean,
where is it.

And so we provide the basic data, the meta
data and then, for the park, and then provide

interpretational data and maps and create
images for them of our data that they use

for their own teaching and for their emergency

So, the big, the very important issue in Yellowstone
is public safety and the Yellowstone Volcano

Observatory is set up to provide data for
public safety and management of hazard issues.

Talk about the more recent lava flows in Yellowstone

National Park.

Bob Smith:
There’s been about fifty or sixty post caldera

flows dominantly of rhyolite there was some
basalts, these are flows that come out not

necessarily explosively or catastrophically
they may cover only two or three or four square

miles they are only a few hundred meters thick
at most and they generally don’t leave the


They don’t leave the actual caldera or the
volcanic plateau.

So, these are not deemed to be a national
threat but these are the types of features

that have followed the super eruption of 640
thousand years ago.

Well the youngest of these is 70,000 years
at the south end of Yellowstone, it’s called

the Pitchstone Plateau flow and it is right
at the very south edge and it’s a high piece

of topography around the caldera rim and that’s
the youngest and we’ve seen nothing since


Any epiphanies related to Yellowstone National


Bob Smith:
The occurrence of the Hebgen Lake Earthquake

was an epiphany, the discovery of this gigantic
uplift of the caldera to 1985 followed by

an ’86 earthquake swarm.

Wow that was something that really got us
tuned in.

And then the caldera went down, in 2010 it
went back up again.

We had an accelerated uplift from 2004 to
2010 called it accelerated uplift it was going

up at, it went up 25 centimeters, a quarter
of a meter.

While you don’t see it in your footsteps
you know that those are rates that are higher

then geologic rates, or higher than, faster
than San Andreas Fault is loading.

Now this last week, we just discovered now,
very carefully, that the caldera is now returning

back to uplift and it’s going up at 40 cm’s
a year.

So, we view this caldera as this living breathing
thing and I argue that all these little earthquake

swarms that we have are really just relief
valves so if we have a lot of swarms that

tells us fluids are squirting out of the magma
body and if we keep having swarms and squirting

out we’re fine if we stop that process this
magma body is going to inflate and we could

have an eruption.

So, keeping track closely of the GPS, measure
ground deformation with the seismic activity

in the swarms is helping us to understand
the state of the system in terms of its capability

and whether it’s an immanent threat or not.

And I’ve had epiphanies my whole damn career
up there.

How else is this information shared?

Bob Smith:
I had an NSF sponsored workshop on Yellowstone

and we had teachers K through 12.

These people saw all the data.

They took the data away to use as teaching.

So, what I do with my teaching and all the
information I get my books my talks I give

all my figures away to teachers to National
Park Service Rangers.

We give everything we have to the park service
interpreters who meet millions of people a

year so I view it as a multiplying factor.

By doing this and providing it I can multiply
my thought, by thousands, by giving this information


And I see it come back years later all over
the web of the idea and the map that I made

that I gave to somebody and then give it to
somebody else so it got passed around and


So, to me that’s what distribution of information
is about.

And that’s what education bases itself on.

How has public interest in Yellowstone changed?

Bob Smith:
It was 2004 when the public became aware of

Yellowstone globally that’s when the BBC
produced the super volcano and we were consultants.

And that documentary was actually correct.

They just took a very rare feature and made
it assume it was immanently going occur.

Well that brought alive the fact that Yellowstone
is a geologic park.

Before that they didn’t think of it.

They thought it was an elk park and fish park
and geyser park.

Now people understand it’s a geologic park
and now people are understanding not only

that it has magma chamber it has a plume and
it’s a major element of plate tectonics.

It’s truly a living breathing shaking caldera.

And this all comes back to the idea what are
the processes.

What are the physics of the motions.

What are the chemistry of the fluids.

How do they work together?