Lost in the fog of a cosmic storm Floating on
whimsical wavelengths is the norm Dancing through
the stars, chasing spectrums of light Waves that
are just out of sight For me, as a volcanologist,
it has to be because of the two active volcanoes,
Kilauea and Mauna Loa, that are accessible through
the national park. For me, that's enough right
there. But it also has mind -blowing microclimates,
different ecological zones with different species.
The island laid back culture, too. It's also
on the front line of what happens when a new
species is introduced into systems they didn't
evolve with. Some areas, you might need to sleep
with earplugs on the Big Island Hawaii because
of the koki frogs. We're back, audio -wise anyway,
to visit Kilauea Volcano due to a recent paper
published that I became aware of on LinkedIn.
Where to start the intro? Well, Kilauea has been
in a near -constant state of unrest my entire
life. It is also one of the best -studied volcanoes
in the world. It is well monitored from the ground
through gas geochemistry, seismic stations, permanent
GPS stations, tilt meters, and a variety of other
direct measurements. All this is augmented with
remote sensing data as well from space. It's
a highly studied place, and there is so much
we don't know. So a bit of context and details
to make the conversation with today's guest more
intelligible. for all the non -volcanically obsessed
individuals listening. Normally, we volcanologists
think about eruption dynamics. We think about
changes near the surface and how it affects other
magma storage in the system. You can think of
it in terms of pressure. Erupting one batch of
magma lowers the pressure, potentially causing
more material to erupt. You can think of it a
bit like a cascade of effects. This is a top
-down view. It makes sense to think of it this
way for volcanoes with long periods of being
dormant. It does not mean that mantle dynamics
don't have any effect. It's just what happens
there does not directly affect the volcanic behavior
at the Earth's surface, as far as we can tell,
at least normally. In my opinion, Kilauea is
a very special volcano. It is a hotspot volcano
sitting over what we conceptualize as a mantle
plume. This is where hot mantle rocks, carrying
heat slowly rise from near the core of the planet
towards the lithosphere, the solid part of the
Earth that we all live on. As that material,
even though it's solid, it can still flow. As
it begins to rise, the pressure on it begins
to drop, which changes its melting point. Once
that material, which is slowly flowing through
viscous flow, it's not really a liquid. It's
just deforming due to stresses. Once it hits
a threshold, it can melt. It's a combination
of the heat it's carrying and being brought to
a level closer to the Earth's surface, which
reduces pressure. Remember water? It has a different
boiling point and freezing points, for that matter,
at different pressures. Like on top of a mountain,
it boils at a lower temperature than at sea level.
Magma is no different. Okay, so today's topic
is Kilauea's magma system, looking at a simplified
model that shows sometimes its bottoms up. So
please welcome someone who started in Italy at
the University of Bologna and is now a PhD candidate
at Rice University, Gaetano Ferranta. That's
good, that's good, yes. I got it close enough
to correct. No, no, no, it's very close. Well,
thanks for being here. And I guess we always
kind of start with a little bit about who you
are as a guest and how you ended up in the science
field. So how did you end up in STEM as a PhD?
Was it a childhood dream or was it like something
that came much later? That's a very good question.
Well, first of all, Jeff, thanks for having me.
It is my first podcast, so I'm quite excited
about this. Well, and to be fair, I jumped at
the opportunity because your paper came in actually
in my feed and LinkedIn. Yeah. Me being a volcanologist,
having worked at Kilauea and Mauna Loa. And I
was like, this is cool. I want to talk about
this. And so I reached out to you and here you
are. So this is awesome. Maybe it's just because
I wanted to nerd out real hard, but that's part
of the reason why I have the podcast. But let's
go back to how you ended up as a PhD first. That's
a very tough question. I don't think it was a
childhood dream. I've always been interested
in science, but I didn't know necessarily what
to do with my career up until the very end of
my high school. To be honest, I was really drawn
into STEM because of earth science, even if I
took an unusual path because I studied physics
first for my undergrad. But in reality, I went
to Bologna because there was a master's program
there called Physics of the Earth System. So
that's actually what I was really interested
in. And I decided to study physics for my undergrad,
but I already knew at that time that I was going
to pivot. to the earth signs, let's say. But
no, not necessarily a childhood dream. One could
say that probably living near volcanoes my whole
life has kind of shaped that idea in my subconscious,
even if I didn't know. But yeah, I discovered
it quite late. So I guess you just mentioned
Italy is full of volcanoes. I have yet to be
there. That is on my bucket list from Etna to
Stromboli to Vesuvius. There's just so many,
so many stories, so many dynamic systems. So
which one did you grow up near or was it just
more of in the culture of Italy? Because I know
Italy is not, I mean, yes, Canada and US is way
bigger than Italy, but it's not like there's
volcanoes everywhere throughout Italy. And then
secondly, it's like, why? Why go from there with
all of these volcanoes steeped in history to
Kilauea? Like, how did you make that transition
and jump? Yeah, so I actually did live near a
volcano because I come from a very small town
in the south called San Potito San Nitigo, which
is an hour away from Naples. And so Vesuvius
was the closest one, but also Campi Flegrei,
which is probably less towering, but as dangerous,
if not more. Yeah, scarier. Yeah, much scarier.
So definitely did live near a volcano. I always
wanted to study abroad, and I never really had
the chance to, partly because when I really made
up my mind and decided I wanted to do that, COVID
hit, and so I was actually stuck. So I finished
my master's in Italy, and then I was considering
doing a PhD in the US. And I started looking
at different programs and my advisors back then
helped me a lot. And at some point I stumbled
into what eventually became my current project.
And I started learning more about Hawaii. And,
you know, I had never thought about potentially
working on Hawaii, let alone going to Hawaii.
So for me, it was a whole new thing. And I was
very, very intrigued. And I eventually decided
to do that. So during my first year, I had the
chance to go there for the first time. I spent
a week on the Big Island and then a month in
Honolulu while my advisor was doing a sabbatical
there. And it was just a life -changing experience.
Yeah, for sure. I don't know. I can't sing the
praises of the Big Island enough. Now, I will
say the one thing, the only thing, and I do mean
the only thing that drove me crazy about... mainly
the big island was how much drinking and driving
actually occurs because people show up to the
beach with a case of beer and then they drive
home that's a good point i actually never thought
of that but yeah it must be a big problem yeah
i don't know if it's a big problem it's just
something i noticed everywhere okay but i mean
like the laid -back atmosphere the whole different
micro climbs just the the people generally are
just so laid back and chill There's some caveats
to that, of course, but that's caveats to everywhere
in this planet Earth that you can find special
people. But let's dig into the paper in Kilauea
more specifically instead of reminiscing about
my time on the Big Island, how I miss it. So
the paper is Bottoms Up, Coupling vs. Decoupling
Within Kilauea's Magmatic System. Before we get
into the science science part, perhaps we should
start with, is Kilauea normal? I think Kilauea
is quite special. Well, it is for sure special
to me, but I also mean it from a volcanological
perspective. In the simplest sense, we have so
much data from Kilauea, and it's erupting all
the time, that it's hard not to consider it as
a special volcano, because it really... improved
our understanding of volcanoes in general so
much by just erupting all the time and giving
us all this data and all these opportunities
to actually learn more about the dynamics of
magma supply and volcanic eruptions in general.
So I think it's very special. There are other
volcanoes in the world that might be considered
similar to Kilauea. But we're talking just a
handful, right? That's true. You can almost count
on... Not quite, but you could almost count on
one hand persistently active volcanoes, those
that erupt all the time. Maybe you need two hands
for the whole globe, but it's really a small
handful of volcanoes. It's a small handful, and
out of all of those, Kilauea is definitely the
one that's most monitored and most studied. So
it's definitely a special volcano. Yeah, this
is more of a comment from me to say, you know,
you look at media, you look at everywhere, like
everyone compares whatever they're seeing to
Kilauea. Like Kilauea is like the stand -in volcano
that everything's compared to. Yet at the same
time, you really can't compare Kilauea to anything
other than the other Hawaiian volcanoes is kind
of where I'm going because it is so special.
yeah how much does it erupt like year on year
on year on after year after year after year is
just like the from the sea floor to where its
current summit is like you you can't really compare
it to anything other than another hawaiian volcano
yeah that's true yeah i agree But yeah, we learn
so much from looking at, if we want to get really
nerdy and talk about geodesy, so the deformation
and gravitation of the Earth to just the chemical
products to the gas geochemistry to earthquakes.
Yeah, it is so wired. Yeah, and even just how
volcanoes grow. How do they evolve? Yeah. Looking
back at the Hawaiian archipelago, we can sort
of look back in time. uh and uh or forward uh
and see how eventually these volcanoes will uh
will evolve and uh and look in the future so
it's uh yeah it's quite special yeah that's it
listeners there is a lot we don't know about
the past and how these volcanoes grow mainly
because they bury everything and so we don't
get access to the younger versions of themselves
Okay, but we're going to cover a lot of different
things about Kilauea and hopefully get into some
nitty gritty details. And hopefully I remember
to use words that is not going to confuse everyone
else because it's two volcanologists here having
a chat and there's lots of jargon in the way
here. So we'll do our best. But to understand
the paper and Kilauea's magmatic system, what
are the main parts we should really be thinking
about here? Well, I think the... One very important
thing to keep in mind while we talk about this
paper is that one of the reasons why Kilauea
is special is that it's not only erupting all
the time, but it's also being supplied by magma
all the time. So what we think is that magma
is almost constantly being replenished from depth,
from almost 100 kilometers depth where magma
first forms. beneath Hawaii to the shallow magma
chambers, which are around two kilometers depth.
So magma is always flowing in this system, and
this is very important. And as a consequence
of that, we think that there's some sort of pathway
that connects the region where magma forms to
the shallow magma chambers, and that pathway
can stay open for long, long time scales. to
allow these magma to flow and to allow the volcano
to be persistently active. So I think those are
two very special elements of Kīlauea and two
very important things to remember in order to
understand this paper and the questions that
this paper tried to answer. Yeah, I guess this
is kind of a little bit of inside baseball because
we understand this pretty well that magma cools.
and so to be able to consistently be able to
erupt means like over decades and decades and
decades and decades means you have to have some
way of getting material in somewhat of a constant
way to the earth's surface and there's not many
volcanoes out there that can do this and so being
able to keep things open is very very difficult
when everything wants to cool you get viscosity
so viscosity increases as it cools it doesn't
want to flow and then it clogs up the pipes and
That's how most volcanoes work, but Kilauea is
a little different. One of the things I wanted
to really drill into is the shallow magmatic
system a little bit before we go deep. Looking
a bit from the top, so you said there's... Now,
I'm not... meaning to contradict anything you
say. It's just I think we want to get a little
bit deeper. So the way I understand it, which
can also change, like from the last time I was
at HBO, things can also change in the mindset
of those that are studying it. So feel free to
correct me. Absolutely. But you can think of
the shallow system as the pipe in from the base.
So that's from the deep mental source. And then
you have a larger summit magma chamber. in the
southern part of the caldera and it tends to
be the larger one you have a shallower one underneath
uh which is a pit crater in the summit which
i don't know if that's still legit anymore because
now it's erupting and yeah it's changed it's
changed shape it's also collapsed in that amount
of time and then you have the rift zones and
at least at one time because you could track
the deformation down the rift zone towards where
Pu 'u 'o 'o was erupting. So the shallow magmatic
system is, I guess, bifurcated in some respects,
that you have some kind of connection to the
individual rift zones, which the east rift zone
and the southwest rift zone, and as well as,
at least there used to be, two summit magma chambers.
Does that kind of still sum up what we think?
Yeah, that's correct. And they're super dynamic.
they're super dynamic there might be even more
and there are definitely more areas of magma
accumulation even in the summit itself the two
ones like you like you said that are usually
most active are the Halema 'uma 'u reservoir
in the south caldera and we still don't fully
understand the connection between all these magma
chambers and to the rift zone also i think because
the connection is not static connection changes
with time. So maybe during an eruption, the connection
will be different than during another eruption.
And maybe you can reach pressure threshold where
new connections can open up. So yeah, it's all
correct. Yeah. But as far as this particular
paper goes, yes, the two main reservoirs that
we need are the Halema 'uma 'u Reservoir and
the South Caldera Reservoir. Right. So one is
The Halema 'uma 'u one is shallower. But I wanted
to get, before we look at the bottom processes,
I kind of wanted to look at the top -down processes,
because these are the ones that if you are sitting
there by the computer watching the data coming
in from the USGS, looking for your chance to
rush out for the next episodic fountaining eruption,
you're going to be paying attention to those
shallow subsurface... activities and stuff like
that. So what are some of the examples that you
might see in the data? Yeah, I mean, shallow
processes are what we are naturally driven to
look at. For example, in the current eruption,
during an eruption itself, magma empties out
while erupting at the surface, and then at some
point it empties out the reservoir so much. that
it just cannot erupt anymore and so now the eruption
stops and the magma chambers need to replenish
until they can erupt again or in 2018 so much
magma was emptied from the magma chamber that
the caldera collapsed and the caldera collapse
actually drove the whole eruption which otherwise
would have stopped much earlier if that didn't
happen so there are a lot of processes shallow
processes that can actually drive eruptions and
so not everything is driven from the bottom But
what I wanted to convey through this paper is
that sometimes not everything is driven by the
top either. Exactly. Now, I'm going to maybe
diverge a little bit here, but it's interesting.
I came to this topic from a very different perspective
because in my master's, I worked on top -down
processes. I think in my master's paper, there's
top -down in the title. So there's a back story
of the title. Yeah. it's a very different process
though um so in my masters i was very interested
in understanding why uh volcanoes in in continental
rifts change their locations over time and so
eventually what we discovered is that the stress
field generated by the deepening of the continental
rift basin over time as it becomes deeper and
deeper changes the stress field in the crust
and when magma ascends to the surface in the
form of dikes, of hydraulic fractures, the trajectory
that these dikes follow are very sensitive to
the stress field. And so their location changes
over time according to the stress field generated
by these very shallow processes. So this is sort
of like the definition of a top -down process.
But this is, again, a very different process.
And it sort of answers your question of why Kilauea
is so special, right? Kilauea is erupting all
the time. We're not creating, sometimes we are
creating new fractures, but these deep pathways
thought to be a very well -established pathway
that just feeds magma from tens of kilometers
of depth to the surface, and it's very stable.
Okay, so I want to take one short deviation only
because I have some background knowledge because
otherwise I would have no idea this exists. And
then we'll get to those deep ones, those much
more stable, and we'll explore that a little
bit. But when we think about the shallow stuff,
we're usually thinking about differences in pressure.
So usually to do with the volatile. So any longtime
listener should know that volcanoes erupt. Yes,
you need a certain amount of heat. Yes, you need
this, you need that. But fundamentally without...
volatiles it'll never erupt you'll never get
a density lower than the rocks it's pushing up
through so when we're starting to look at a lot
of these shallow processes our understanding
is that a lot of it's to do with pressure with
the volatiles and the rocks or the chamber itself
how much can that chamber hold before having
that either fail or push the magma into another
location And so in Kilauea, we see a lot of these
things and they use terminology like DI or ID
or DID events. And that stands for deflation
and inflation, the D and the I. So the idea is
just before a large eruption at the summit where
they have the fountaining, you'll get a quick
deflation where the whole ground is actually
deforming kind of downwards. It's deflating as
the pressure is rising to the Earth's surface
to cause that eruption. you empty the magma chamber
and that's what that deflation is that magma
chamber emptying and then once it's empty and
the eruption has stopped it starts to refill
again which then inflates and so you can actually
get these over the course of 24 hours even without
an eruption especially during the puo times and
there's just so many different shallow processes
that happen as these pressure pulses that have
been created by the gas or the volatiles instead
of what's down at depth because what we down
at depth in general we don't get to directly
see and so that's where this story really turns
because now we're going to talk about the deep
section so what about the deep part more generally
besides it's stable like how do we even know
that something changes down there it's so far
away that it's not like our tilt meters or gps's
it's we can't see it directly can we That's true.
No, we cannot see it directly. We can use some
proxies. One very useful data sets that volcanologists
in Hawaii use to track changes and what happens
at depth is CO2 emission rates. So magmas, when
they form at depth, they contain dissolved CO2
and other volatiles. But CO2 is interesting because
it has a very low solubility. meaning that it
wants to come out of the solution, it wants to
come out of the magma and form bubbles at very
large depths. So for Kilauea, for the composition
of the magma that is erupted at Kilauea, we think
that at depths of about 35 kilometers, CO2 starts
to come out of the magma and form bubbles. Wow,
35 kilometers? That's extremely deep. Oh my goodness.
Not all of the CO2 will come out there, but it
will start coming out. yeah as the solubility
decreases as it gets to lower pressures but 35
kilometers damn yeah just for context i think
the magma forms around 65 kilometers depth if
i remember correctly for hawaii so you're you're
you're not even halfway there and you're starting
to lose volatiles i guess that's also yeah that
must come into the whole processes of deep right
like The whole rise rates, do they pick up after
about 35 kilometers? Does the magma start to
accelerate because the density is starting to
drop? Well, not necessarily. That's a very good
question. It kind of gets in the details of how
we perceive magma flow. But at those, the speeds
at which magma ascends, given our estimates of
supply rate, are actually quite high. And so
the difference in velocity between the gas and
the melt is actually not that great. So the magma
is already quite fast. Why would it be quite
fast at that? Is it density driven? Heat driven?
It's mostly pressure driven. Okay. So we can
get into detail. Of course. Talk nerdy to us.
Well, let me finish about CO2 first. So if CO2
tracks the amount of magma that's coming out
from depth, then changes in CO2 at the surface
are usually interpreted as changes in the rate
at which magma is supplied to the shallow plumbing
system. And that's essentially what happened
in the early 2000s. Measurements of CO2 prior
to that were actually very rare. also because
it was not changing a lot. And if you plot CO2
emission rates as a function of time, it's almost
a flat line because the magma supply rate was
thought to be almost constant. But at some point,
there was a big bump in 2003 that lasted up until
2007. And so that was interpreted as a change
from depth, as a change in the rate at which
magma was supplied from depth. So like you mentioned,
we cannot directly see what's happening there,
but we can use proxies to understand if something
is changing. Now I've forgotten what the other
part of the whole thing I was getting. Oh, speed.
That's what I was going to. Yes. Yeah. You were
going to go into the details. Yeah. So as I said,
one main thing to understand the paper is the
fact that magma is constantly flowing. Another
thing is to think about is pressure. If there
is a big, well -developed conduit that's feeding
magma to the volcano up to tens of kilometers
of depth to the surface, which is implied by
the fact that melt is always being produced and
it's always being transported, then what is the
pressure in that conduit? So as far as I see
it, there's two really main end members. One
is that the pressure follows the weight of the
magma itself. So it's a magma static pressure
profile. That's a mouthful. Yeah, it is, it is.
A magma static pressure profile. That's true,
yeah. So for someone who... If you can think
of, I guess we're going to go back to hydrostatic
just because that's something everyone who's
listening probably understood. You go deeper
into the pool, you have more pressure on your
ears. Exactly. In this case, we're just saying
the deeper down the tube or system, you have
more magma above you creating that pressure,
magma static pressure. Is that what you're saying?
Exactly. That's true. Yeah. So the pool is made
of magma. as as magma actually flows upwards
the pressure decreases decreases because mostly
of two reasons one is that you're reducing the
weight of the magma column because you're now
up higher the second one is because you're using
some of the pressure that you had to overcome
friction this goes drag so if the pressure inside
the magma was only due to the weight of the magma
itself, then it means that the pressure that
you lose because of viscosity needs to be negligible.
And that will happen, for example, if you have
a big pipe. The viscous pressure loss, this is
how it's usually called, becomes smaller and
smaller as the conduit that your fluid is flowing
through becomes larger. So if you had a big pipe,
then you can actually sustain a magma static
pressure. uh with depth the problem with that
is that the density of the magma is lower than
the density of the rocks especially if you go
to the mantle where rocks become very very dense
and so at depths of about 40 kilometers let's
say which for kilauea is when we think that magma
becomes channelized into one individual pathway
we would expect very, very high pressure differences
between the magma and the rocks. So it's hard
to think of how this can be possible. Well, one
option is that it is actually not possible and
this pathway will close up. The pressure will
eventually close the pipe up or close it up to
a point where the pressure balances the pressure
outside. Another possibility is that actually
the flow of magma, since the magma is hot, will
keep melting the surrounding rocks and the rocks
will push inward and so you reach a balance between
the melting of the walls and the closure of the
pipe to where the pathway can stay open even
if the pressure is very low. But I think there's
another problem with that because at Kīlauea
we have a lot of deep earthquakes. And a lot
of these deep earthquakes are thought to be due
to magmatic intrusions. They're not thought to
be of tectonic origin. So we think that magma
is maybe opening up new pathways or moving up
through new pathways and breaking rock. And the
breaking of those rocks creates new earthquakes.
But in order for the magma to break rock, the
pressure in the magma needs to be at least the
same. as in the surrounding rocks, if not higher.
And so even if we can keep a pathway open with
a lower pressure than the surrounding rocks,
I think it's much more reasonable to think that
the pressure inside the pathway is at least the
same as in the surrounding rock. And so I will
introduce a new term and call this lithostatic.
So it's the same as before. We're in a pool,
but instead of a pool of water or of magma, it's
a pool of rocks. And the pressure will be high.
Right. Let's just, I just want to, I understand
everything. I just want to make sure that listeners
are following along. You're using the word pressure,
but you could term it differently and use force
and due to things like buoyancy, right? That's
true. Yeah. Okay. Just to make sure that those
are following along, we could be talking about
a buoyancy force instead of a pressure, but we
obviously... In this sphere of research, we use
pressure because it's much easier to deal with
than 10 to the 16 or 10 to the 32 newtons of
force or whatever the heck it would be. Pressure
is just a little easier to deal with. That's
true. That's true. And so to connect it with
the velocity, the reason why I went through this
tangent, which is actually not a tangent. It's
not a tangent at all. It's really the heart of
the conceptual model of this paper. if you have
a such a high pressure gradient because now we're
assuming that the pressure inside the magma is
the same as the surrounding rocks then you have
a high driving pressure and your flow rate through
this conduit will be high and so the velocity
can be very high and this makes sense because
first of all we can now maintain an open pathway
by simply matching the pressure or the force
that the surrounding rocks are exerting on the
conduit with the pressure that the magma is exerting
on the conduit walls, but in the opposite direction.
But then we can also maintain flow. We can keep
this flow going, which is what we need at Kilauea
because we know that magma is being constantly
replenished. Yeah, it also makes a lot more conceptual
sense than trying to melt the wall rocks because
you... need to have something that is steady
state exactly and melting is not something you
do particularly quickly and so how can you keep
that as a steady state but this isn't always
steady state and that's where this whole paper
got born from was the change to that steady state
in 2003 so how would that if you all of a sudden
had some more material coming up through that
narrow Because it is a narrow pipe, right? That's
true. So what changes do you expect? Can you
have the pipe collapse due to the increase or
decrease in pressure? What kind of things should
we be looking for for changes in the volcanic
activity at the Earth's surface? Well, this is
a very good question. So our idea for that is
that if you have more material coming through,
then the pressure... inside the pipe needs to
increase. But if this pipe is very narrow, then
if the pressure increases, then the dimensions
of the pipe will increase as well. And if these
changes are not too big, we can assume that to
first order the response of this pipe is elastic.
And this is an important part of the model because
that's what eventually will lead to our our final
conclusion but let's stay here for a moment so
if the if more magma comes through then the pressure
increases and the pathway will essentially deform
it will become more spacious to accommodate that
new magma and both of these all of these three
things that we mentioned so flow rate pressure
And this increase in the size of the conduit
will propagate upwards and eventually reach the
shallow magmatic system. And so in the data,
we see that as an increase in CO2 emission rates,
like I mentioned before, and also an inflation
of the shallow magma chambers. So there's a lot
of GPS stations on top of the summit and along
the rift zones of Kilauea that can measure how
ground moves. And sometimes these stations go
up, sometimes they go down. And in 2003, correspondingly,
the GPS stations went up. So the volcano inflated.
More magma was supplied to these balloons, to
these magma chambers as it was erupted. And so
they started to inflate. Yeah. Yeah, that was
a wild time. I was actually there for the tail
end of that as a volunteer at the Hawaiian Volcano
Observatory, taking those differential GPSs,
I think they're called Leica systems, and you
have them on these little tripods with little
buttons so you can quickly level them. And so
one of these shallow events... did or a di event
would start and uh i don't know why but uh mike
poland who's now the scientist in chief at yellowstone
observatory he was the geodisy person at hbo
at the time he trusted me to be able to gather
the gear up and go by myself into the caldera
and just start like running through all the benchmarks
with these to try to capture these events to
try to help with the the permanent stations so
that was uh really interesting A fun time for
sure. And it was really like, I don't know how
to describe it, but I always like as a young,
hopefully to be in grad school at the time, I
just kind of, I knew that the volcano had changed
over time. So like you could go before Pu 'u
O 'o and Kilauea wouldn't erupt for a few years
and then it would have these fairly, well, large
for Kilauea eruptions and you had Mauna Ulu in
the 60s and then... Pu 'u O 'o started and then
it was just constantly erupting. So to kind of
track back this a little, probably way further
than your paper, really, can you look through
time, even though we don't have the CO2 measurements
required, but could you go back casting to see
how some of these events may or may not have
been affected by deeper processes? Well, that's
a very good question. One thing I want to say,
it's probably not answering your question, but
I think it's needed first, is that we forgot
to mention one important thing, which is that
this change that happened in 2003 happened during
a period that was extremely stable. So as you
mentioned... All of Pu 'u O 'o's eruptions were
really stable. Like for 30 years, it was pretty
stable. Exactly. But on the ground, you didn't
notice that, though. You can only really see
how stable it was when you have the chance to
step back and look. Exactly. Because when you're
on the ground, there's all the shallow activity
that's happening. That's true. And it's constant.
You get earthquake swarms. You're getting inflation,
deflation events. You're getting south. You're
getting the south where you're having this constant
slip along the decalment plane, which I'm adding
more terminology, basically. Kilauea has a mobile
south flank, and occasionally you're going to
get intrusions into there. And all of this is
happening at the same time as these deeper sources.
So on the ground, I guarantee you there was some
chatter in the background about increasing CO2
and stuff. But the day -to -day science just
kept rolling, and nobody really gave it too much
of a thought until you could look back. Yeah,
that's true. Yeah, because, yeah, as you said,
the scales matter a lot. If you're sitting there
like you were, you would have probably felt a
lot of changes. Oh, yeah. If you zoom out at
the lithospheric scale, which nobody can until
we actually get the data, you would have probably
noticed, oh, actually things were not that crazy
as I thought. Well, it depends on what your scale
is, because if you're thinking about like, oh,
yeah, we're going through the prairies. in north
america over to kilauea and all of a sudden you're
like wow so this was like a fairly large hill
and now it's a giant hole in the ground yeah
what happened to you like you know like the the
drastic changes there over the times that i've
been there like holy smokes yeah yeah it's crazy
To answer your question, you can actually backtrack
changes in magma supply rate even when you don't
have CO2 emission rates. Because at the end of
the day, it's a mass balance problem, right?
The mass that comes in the shallow reservoirs
is equal to the mass that comes out plus the
change in the mass in the shallow reservoirs.
Over long time scales. That's true. That's true.
You can't do it over the course of a year. Yeah,
that's how they would estimate supply rate in
the absence of CO2 emission rates. So you have
to average it over a longer timescale. It cannot
be a measurement that you make at the scale of
the individual CO2 emission rate measurements.
Right. But you can have estimates over longer
periods of time. All right. Well, we've had a
meandering tale of... Kilauea's magmatic system,
which I'm so glad you came on the podcast for.
I am totally nerding out over all of it. But
how does that fit in with today's activity? We're
back to that same steady state that was there
before 2003, or are we at a different level?
Well, this is very interesting. There seems to
be a steady state right now. The eruption is
very interesting because it's clearly periodic.
It erupts, the volcano erupts for a few hours,
and then it doesn't erupt for a few days, and
then it erupts again. So it seems like it's very
irregular, but in reality, if you average over
a long time period, there seems to be a balance
between what's supplied and what is erupted.
So there seems to be actually some sort of statistical
steady state meaning that over a short time span
it's things seems to be very very dynamic and
changing quite quickly but if you average them
over a longer time then they're actually not
changing a lot so if we go a little bit back
in time and see how we got here this in 2003
there was this big change there was more magma
being supplied to the volcano and that drove
a series of changes in the shallow magmatic system.
There was a big eruption in 2007, then the volcano
started inflating again dramatically up until
2018 where the big eruption in the lower East
Rift Zone happened that most people remember.
So for me the main upshot of this paper and what
we tried to convey is that there's a very big
difference in behavior. from processes that occur
at the bottom and then propagate to the top and
processes that happen at the top so if we think
of what we were talking about before the fact
that if you have more magma being supplied then
the pressure increases and the size of the conduit
increases okay so if you increase the pressure
and you increase the size at depth both of these
processes have the effect of increasing the rate
at which magma ascends through this conduit because
you're increasing the driving force which is
the pressure and you're increasing the size of
this pathway and so you have a lot more magma
coming through so any change at the bottom will
significantly affect the top on the other hand
at the top we have sort of a negative feedback
so if we change the pressure at the top let's
say we increase it we are reducing the pressure
the driving force because now there's a lower
pressure difference to drive the flow. But we
are also increasing the size of the conduit again.
And so these two processes actually compensate
each other. And they do not result in big changes
in magma supply rate. So why is this important?
For example, in 2018, there was a big eruption.
People think that the summit reservoirs decompressed
of about... 20 megapascals. There's a lot. It's
a lot of magma being evacuated and it's a lot
of decrease in pressure. And so everyone was
expecting something to happen. A new increase
in magma supply because we have now decreased
the pressure at the top and so we can drive more
magma in. But in reality, gravity measurements
that have been conducted after the eruption didn't
really show any change. And so this conceptual
model of pressure changes being associated with
changes in the size of the pathway and that leading
to a difference between bottom -up processes
and top -down processes can reconcile the fact
that there were no changes observed in the rate
at which magma was supplied to the volcano after
2018. Crazy. I just had a random thought that
came to me and it's probably useless, but this
is how I conduct science and also my life, which
drives people crazy. I throw darts at a dartboard
and more than half the ideas are bad or wrong.
But is there any way that this process is that
you're describing about creating this pathway
and having it? you said elastically deform to
open a little wider is it any possibility that
some of these deformations become more permanent
like it can't fully go back to the same shape
which if you think about it if they have to stay
steady state and now the whole thing is a little
bit bigger you're potentially increasing the
magma flow rate or the magma supply rate to the
volcano. We've always had this problem of trying
to understand why Mauna Loa, Mauna Kea, Kilauea
are all so large. How did their magma supply
increase to the point where they can actually
get that big? So is there a mechanism here that
as it continues to open up, it just continues
to add more supply? Yeah, I think there could
be. I mean, this is a very interesting question
and something that I would like to actually pursue
in the future. As we mentioned before, what I
considered in this particular case was a purely
elastic response. So as the pressure went back
to what it was before this change in magma supply
rate, then the shape of the conduit also went
back. But that was also because the changes occurred
in a short time relative to the... relaxation
time of of the rocks but if this relaxation time
is just for everyone else is like the ability
to come back to the same shape so if your relaxation
time is a lot longer that means to come back
to that same shape takes a lot longer so like
a billiard ball the reaction time is like instantaneously
whereas this is obviously going to have some
time to flow back if you want to say it in a
viscosity sense to its original shape sorry i
just didn't think anybody was following along
just in case no no exactly and uh and sometimes
the response of a material can be different according
to the how fast the force is applied to that
material. If I apply a force very fast to silly
putty, it will deform in an elastic way. But
if I apply it slowly, then it will flow. And
this is also true for earth materials. So the
deformation that we're talking about here happened
over a few years. And given the possible viscosity
range of rocks there at depth, even if they're
hot, an elastic response is reasonable. But if
those changes happened over a longer timescale,
then it would be more reasonable to assume that
there's also a viscoelastic component, a viscous
component. So viscous component is non -recoverable.
Once you deform something, it stays that way.
It cannot go back. And so I think that answers
your question. It definitely can. You can have
deformations that will alter. the shape of this
conduit and therefore supply of magma over long
time scales. Wow. So I guess that's where the
future of this will go. I mean, you said this
is an avenue that you want to investigate a bit
further. So is that... Yeah. Yeah, I would really
like to. Like you said before, the puzzling thing
about thinking of... any other solution to the
problem of how this pathway stays open is that
you need to be on in a steady state because over
the time scales that we've observed it seems
that the volcano is sort of behaving very stably
so i really want to go a little bit deeper into
the the problem of coupling the flow of magma
with the heat that the magma is moving around
and losing by conduction to the surrounding rocks
How is it possible that we are in such a steady
state, even though there's so many things going
on at the same time, including, again, changes
in the flow rate, which will drive changes in
the rate at which heat is transferred through
the system? So I would really like to address
that in the future. It's definitely on my bucket
list. Yeah, and if you somehow manage to link
that to long -term magma supply rate, changing
the shape of that, that's a nature paper or a
science paper, my friend. Yeah, yeah. And also...
If you manage it, you've got to come back on
to talk about it, though, okay? Oh, 100%. 100%.
I will. Yeah. And another question that I really
find interesting is that we've been talking about
this change that happened in 2003, right? And
we've just been assuming that it's more magma
coming into the system, but actually we don't
really know why there was more magma coming in
the system, right? If for 30 years things had
been quite stable, What changed in 2003 that
drove those transient modifications to the system?
Was there simply more magma being produced because
maybe it was hotter? Maybe a new portion of the
pathway connected to the main pathway and released
a pulse of magma that then ascended towards the
surface? Those are really interesting questions
for me, but they are still open. And it's harder
to constrain because... again like you mentioned
we cannot really see down there so there's only
so much that we can say yeah all we have is the
chemistry of the rocks that come out yeah okay
well uh i guess it's call out time because we
yeah future work colleagues whatever you want
however you want to wrap this together before
we hit the infamous last question okay okay well
uh again like i mentioned at the opening this
is This was my first podcast, so I feel I should
do a shout -out to my parents, who will not be
able to understand this because they don't speak
English. But I'll definitely translate it for
them and let them know that I mentioned them
on that. This is a good segue here because, actually,
if you go to YouTube, because you can send it
out on YouTube, and because I have a transcript,
you can actually do the closed captioning in
a whole bunch of different languages. Okay, that's
great. It does it automatically. I have looked
at this because my wife speaks Farsi, and so
it does translate it to Farsi. So they can understand
it. I cannot because I get automatic transcripts.
I don't go hand -edit them, so maybe the translation
may be missing in a few spots. But nevertheless,
you can do that. this is great this is great
because they're very curious about my work but
of course you know i write in english my papers
are in english and you know it takes some effort
to translate everything and so yeah this is amazing
so shout out to my parents i'll uh i'm happy
that you will finally be able to uh to hear me
in uh or to understand what i say in italian
yeah amazing yeah uh i guess There's people that
listen to this podcast all over the world. And
so if you want your friend to follow along, maybe
the closed captioning is the way to go. I don't
know. I don't think I'll be translating this
into other languages. Yeah, that takes a lot
of effort. Yeah, well, AI is getting pretty good.
Yeah, that's true. But I don't know. A problem
for another time, because we've come to the last
question. The one I ask every guest, and if a
guest comes on twice, they'll have to come up.
ideally with a new joke what yeah is your favorite
science joke so when okay i'll tell you this
this is a joke that i heard in my grad school
geodynamics class it's very short so uh someone
asks a geophysicist or a geodynamicist they ask
them what's up And the geodynamicist answers,
well, perpendicular to the geoid. Oh, my goodness.
For those that are not following along, the geoid
is a way of mapping the mean sea level. It's
the lines of equal potential energy of the gravitational
field, which can deviate in different spots that
doesn't have to be parallel to the ground surface.
And so what is up? perpendicular to those lines
of equal potential energy. Yeah, I thought you'd
appreciate it. I did. You've done work on gravity.
That was awesome. Know your host. Okay, well,
thank you so much for coming on. And absolutely,
if you get into the weeds and further down this
rabbit hole and produce another paper, reach
out. I'd happily have you back on. Thank you
so much. It was great to be there. Thank you,
Jeff. That was a real treat. Hopefully for you
as well. It was great to reminisce a little bit
about Hawaii and get into some brand new research.
Awesome. Just awesome. Alright, there will be
more news about the end of Season 2 as we move
a little further forward. And I'll see you guys
in two weeks. So chaotic, so misbehaved Echoes
of melodies remind us it's always Colors weave
stories painting the sky Swaying to rhythms as
the galaxies fly by our bones through this melodic
maze our minds explore change