Thank you again for joining us.
As usual, this session is being recorded,
and I'm going to ask that participants under the age of 13
have a parent of guardian present with them
during this session.
As you all may know, we are doing this
as preparation and as...
in addition to the Let's Talks Science Challenge.
which is a weekly quiz. Quiz 4
is tomorrow, May 7th.
So the English version is offered Thurs-
well tomorrow, on Thursday from 10:00 to 11:00 am
Eastern Time, and 1:00 to 2:00 pm Pacific Time.
As well as there's a French quiz being offered
tomorrow at 2:00 to 3:00 [pm]
Eastern Time.
So this week's topic centred around Earth Sciences.
So in keeping
with that, we'll be looking at things such as the structure of the Earth,
continental drift and plate tectonics,
minerals and rocks,
mines...we'll also be looking a bit at
mining. So as you all may
recognize the Let's Talk Science website
which gives you a breakdown of what will be covered in the quiz.
Just take a look at the structure of the Earth.
So we'll be looking at things such as the layers of the Earth,
the Earth's core,
looking at the different layers
of the Earth.
If you back up a bit now, things such as
continental drift, which a lot of you may have
come across in your
school.
Looking at concepts such as Pangea,
fossil evidence and what not.
I won't go into too much detail because I know our speaker today has
a lot to tell us about that.
So,
without further adieu, allow me to introduce
our speaker
today,
Dr. Bhairavi Shankar.
who has a Ph.D in Planetary Science,
is the founder of
and CEO of Indus Space.
So Indus Space provides educators and youth the tools
needed to be innovative.
And promotes things such as logical
reasoning, critical thinking,
and analysis. So, please join me in welcoming, Bhairavi.
Thank you, Adisa! Hi everyone,
I'm so excited to participate with all of you
and share a little bit about this week's topic.
I'm going to just quickly share my screen and then we can get started.
Alright, I'm hoping you can see my title slide!
Yes? Thumbs up, maybe? Adisa?
Okay, great. Okay.
So,
thanks for that intro. My name is Bhairavi Shankar.
I have a Ph.D in Planetary Science
and Geology. So I am
You can think of a geologist who
typically works on Earth, but now can actually
start to look at data and understand
the geological history of any other
area of our solar system. So for this week
I was asked to talk about tectonism on Earth
What does that mean and how
can we tell? And I'll also end off by
adding a little bit about how we see the evidence
of tectonics in other parts of our solar system.
This might be a very familiar
photo to all of us. It's
a nice ball. There are some continents
in there, there are the oceans, and there are the clouds.
And this is [what] we often think of when we talk
when we talk about Earth from afar,
looking at it from afar. But really
all we're seeing in this mode is just the
top parts of our
planet.
Our planet is after all a sphere
and there are many layers there.
And this is a typical
cut through of Earth.
There are different layers. If we start from the centre
we have our core. The core can be thought of as an
inner core or a rocky inner core,
and there is a more liquid
outer core. And moving away from the
core then we have the mantle. That mantle
can also be split into a lower mantle and
upper mantle.
And then as we get closer to the surface,
that area is more hard rock
that has actually cooled down
and that forms our crust.
And the breakdowns in the sort of distances
just give us an idea of how thick
each of these regions are. So you'll notice that our crust
is really thin compared to the other parts of our
Earth. It varies anywhere from 5
to 50 [km]. But even then
crust can be defined as oceanic crust,
where the oceans are, or continental crust
where a lot of our continents are. The naming
was actually helpful in understanding
just the two different types of crust.
So, what has happened is as the planet
has cooled over billions of years
that cooling process just means that there is a lot of heat,
internal heat, that is escaping from the core
and is moving its way outward. And really where
we see our crust is that response to what happens
when the planet cools. As it cools
it starts to harden and any sort of the liquid that was there before
slowly starts to harden
and [inaudible] over time. And really
that's how we've got our crust.
And that
response of the crust
to continual heating and cooling
is what is known as 'tectonism.'
So, it's the response of what happens
to the crust when it's being...
feels that sort of heat from underneath
from the mantle. And that process
might involve some level of folding, or
some level of faulting. So it's like moving.
I'm hoping this is visible. I'll hold it up real quick
and sort of preview myself.
I have two layers of clay, if you want to consider that
two layers of our crust. And there's an
upper crust, but then right below is what is called
the layer between the mantle and the crust.
So think of them- If you have two of them
what would happen if you start to fold them like push in really
hard. That starts to deform your crust.
Similarly, you might have some in another area
where you're starting to pull apart this whole layer and stack.
That starts to actually make the crust
respond in different ways. And that whole process
and the sort of
evidence that we see is what's known as tectonism.
It has been happening as long as the planet has been around.
So for millions and millions of years.
Scientists and Geologists are sort of
piecing together and trying to figure out what the history is.
So specifics are
think of our mantle area,
the area between the mantle and where it's touching that crust is known as
[inaudible]
the asthenosphere.
That's where the sort or reacting.
This is a very quick overview of how
that structure looks. If you were to cut across
through the Earth.
Now,
when we look at the maps of Earth,
again this might be a very familiar picture
for everyone. It's just a 2D map of our 3D sphere.
You have your continents in certain areas. You can see green land,
you can see the oceans. But really, with tectonics
and our crust, what scientists and geologists have discovered
is that it's not just one comment crust.
In fact, there is what's known as plates.
 
The crust is actually
broken up
along
certain parts
and have moved towards each other. Some
have moved away from each other. And some are actually
just moving along each other. So they are not necessarily
doing much except moving either forward or backward
and in a direction.
This is the basics of
[inaudible] plates.
My next picture will show you how many plates there are.
There are about 9 major plates, and then there are
other smaller plates. But essentially
if you're in the ocean- the ocean has it's crust,
right? So that's like, for example, the Pacific
Ocean lies on the Pacific Plate. Similarly,
the Atlantic Ocean lies on the Atlantic Plate. North America
as a continent is on its own plate. So this
map is showing you just how many plates there are.
And really, these plates a kind of moving towards
or away from each other, which my next slide is going
to go into in a little more detail.
But this is very unique to Earth.
And this was actually, as a theory and as a sort of
hypothesis was only introduced
about 50 years [ago]. So before that, any
geologist who were looking at the rocks were kind of
noticing, "Huh, interesting. I'm kind of noticing some
fossils in Africa." But I'm also-
another person may have actually said, "I'm seeing
the same fossils, but I'm in North America. How did that happen?"
Because, as we know, Africa and North America are really far apart.
And those sort of early observations is what
helped scientists think, "Hey wait!
There might be actually smaller parts of the crust that are
moving." Think of it as
moving on a conveyor belt, and they are kind of
and they are responding by either hitting each other
or moving away from each other. One thing I will also add
is that oceanic plates, or the crust
has a lot more iron. So it's a lot
more dense.
And that's why you don't necessarily- When you step out to the beach
or to the ocean, you don't see the crust right there, right?
It's filled with water. But that's because the water
is over the oceanic crust. But
continental plates are actually less
rich in iron, and so they are less dense,
so they tend to float. Which is why we are able walk
on crust, right? So that's a neat thing
and that actually helps us now visualize how
plates move, and what kinds of plates there are.
So I'm going to move along...and let's hope this works.
The first kind is called a Divergent Plate.
What that means is, think if ocean crust
There is actually magma from the mantle
that is rising up.
And I'm hoping I can play that again...
As it's rising up, it's able to escape
through a little vent and flow out onto the surface
And over time, that
plate is moving. So that's how it's moving away
from that
initial spot. And that process is
known as a divergent plate boundary.
Then, we have what's known as a convergent
plate boundary. Think of an ocean crust
that is now actually meeting a continental crust.
One's lighter, so floating, and the other one's heavier.
And so the one that's heavy starts to actually go
underneath. You can think of like pulling a carpet
and how you pull it down under the continental crust.
And that is known as a convergent boundary. If you
have heard of subduction zones, this is that process
that is allowing you to have subduction zones.
And over the course of time, there
is going to be this sort of
 
shrinking- not shrinking, but
the crust at the top, if you notice, will actually start to
 
push upward and start to fold. Again,
examples like my little clay example that I showed earlier.
So that's the second kind. And then the third
kind is what is known as a transform
plate, where they'e just moving along each other.
They're not necessarily being pulled apart. They're not going
underneath. But they're just kind of saying hi to each other
as they go along. So these are the three kinds
of plate boundaries, and really on Earth,
this is how a lot of those plates
are moving along.
 
Hopefully that is a good visual
that helps you understand the three different kinds of plates.
I will mention at this point, y'know, I talk about
plates moving. These animations appear like they're
moving really fast, but in reality they're not.
They're only moving maybe a few centimetres
in a year. So imagine, take your ruler out,
and 2 cm on average
that is something, that's really tiny.
But this is for a planet that so active, right. So
it kind of gives of perspective of seeing
just how much things move. Geology is a
slow process, but it records everything.
So as a geologist, you go and look a the rocks, you're able to
peel back on all of that evidence and really understand
the history of our own planet and what it's been doing
with regards to plate tectonics.
If- I'm going to ask...I can't see everyone's responses
yet, but hopefully everyone sees
this picture can (a) guess
this is a mountain, but in particular, this is the Himalayas,
or the Himalayan Range out in
Southeast Asia. This is actually a
process where you have two continental plates
hitting each other. So it is that sort of
convergent plate movement.
The Indian plate is meeting up with the
Asian Plate.
What happens when you have two plates that are
the same density? Is one going to sink in?
Or not?
Turns out they're not going to sink in,
they're actually going to start to push
against each other, and that whole process over millions
of years, so this about a 60 million year
animation. But in 60 million years this is how
the Himalayas have formed. And over
the course of- it's still continuing, it hasn't stopped.
The Himalayas are actually growing by about 6 cm
a year. So again, to us
as we look at the mountains they all look tall, but in reality
they are growing.
So,
one of the neat things about observing plate movements
and things is to actually see
how old or not the crust
is. The one
neat thing about plate tectonics is that we can actually start
where things are moving. But
the reality of it is, the subduction area,
because you are actually recycling the crust
that is only giving you a sort of
preview of the last
200 million years. Anything before that,
it's a little hard to find those rocks because they
have either been subducted, or they have kind of been
pushed in towards each other, and we're not necessarily seeing
that pristine rock- that original rock from when it formed.
In some ways it helps, and it some ways it's like, "Huh
if only we can find those early evidence
of what happened in early Earth.
I wanted to highlight that this is the map.
The colours are telling you what the ages are of the ocean floor.
And anything that's red is showing you
very young or very new crust. So they're
along certain areas of our planet
and they are typically called mid-ocean ridges
and that's how the new magma from underneath
kind of comes out and then moves away. But then
areas that are the blues or purples are the oldest
regions. And if you look over here, it's very hard
to see those blues of purples. In fact just
above Africa and Eurasia
that's where there's a little bit of rock
that is about 200 million years old. That's the oldest one.
So this is yet another neat way for us to
look at how old rocks are on our
planet.
I do want to mention, so you must be thinking, "with all of this movement, how
do we- what do we see?" We can see
some evidence in the rocks as they're folded or pulled apart.
But another really good way to know how plate tectonics
is working is by looking at earthquakes. So
everywhere there are
these sort of plate movements where
one's subducting under the other, chances are it's
a lot of friction and a lot of stress that's being built up
in this process. And the only way
that some of the tension can be released is in the form of
earthquakes. So that is why everyone monitors how-
where earthquakes are happening, how far they are,
how far or how deep into the crust
they are happening. This is a great website,
that is you want to take a screenshot and go back
and see what is active. See where are earthquakes happening
on Earth every single day.
We have a similar one for Canada.
You may notice there are lots happening along the
California, Oregon, Washington State,
into Canada around British Columbia,
because that's where we have a lot of these plates moving
towards each other. Some are moving
along each other, some of moving underneath,
so they are being subducted. And that's why- If you keep
hearing about California and the great big one that is
yet to happen, chances are
all of that is leading to the plate movements that
are happening in this general area. So scientists and geologists
and seismologists are like, "wait we are expecting something,"
it's just not happened yet. So every time the Earth is
responding to these tensions, it's coming in the form
of an earthquake.
I realize I am running out of time, so I am going to quickly go through
what do we see in terms of tectonics else where. This is our
moon. Unlike Earth, the Moon has cooled down
very early in its history, so we don't-
Earth is the only one that has these plate movements
as I've explained. But on other surfaces
we are still able to see that sort of tension and stress
signatures on the planet just because of the past
volcanism or impact events, and things like that.
So this is the Moon. There are great missions that are right
now capturing the images of the surface of the Moon.
And they are- This is, for example,
linear features they've observed from a mission
on a part of the Moon that gives them evidence
that we are not seeing active tectonics now
but it did happen on the Moon earlier.
And if you look at the little bar at the bottom
it shows you how wide this image is,
and the image is maybe at most 6 km across.
So you're getting a really close up view of one
part of our Moon.
Venus is similar.
Venus has actually had so much tectonism.
Just because of that movement
of magma under the crust, and that has
meant that the surface has
been responding in really different ways. And
there are missions that went to
Venus back about 30 years ago.
And they have given us all the evidence we need to see
about Venus, and that is on it's own a very
different planet and interesting planet.
Mars is similar. We have-
Mars have Olympus Mons, the largest volcano
in our solar system. But just to,
just off of Olympus Mons, there's this area called Tharsis
and that's where Mars scientists are seeing a lot of the
tectonic evidence. Seeing how the crust is responding to
the weight of all that volcanism
that has come out of, say, Olympus Mons, or any of the other
volcanos that are near by.
I want to leave it off at the other areas in our
solar system that are also equally exciting.
Two of the moons around Jupiter have
shown us a lot of evidence, and everyone
is excited and curious, and maybe you want to go and explore.
The main one I'm going to focus on is Europa
Imagine, Europa and Ganymede are
all these, like,
moons that are so far away from the Sun.
Europa has a crust of ice.
And so this is actually showing pictures of how
tectonics, how the satellite,
or the moon responds to [those] stresses
when you have a thick ice layer on top. It's not
continents and it's not oceans, it's actually ice.
The pictures in here are still showing you how
tectonics can happen on nay surface. It may look like
slightly different, but it is
being recorded and you can look at where they're
cutting across each other or just kind of
 
extending really far out and
helping to understand the history for Europa.
For Jupiter's moon.
I'm going to leave it off- I know there was a question of
how can we look at features on Earth?
I want to highlight and recommend this app. It is
Android and iPhone friendly. It is called
Flyover Country, and you can think of it as
you want to take a road trip or you want to fly over
your location, say Toronto, and into maybe
somewhere in the Grand Canyon. It'll show you
all the geological sites that are of interest
all along that path. So some might be tectonics
related, but some might just be volcanism.
So I will highly recommend, if it's okay with all the adults
in your house, to install this app
and you can look at that area
between California and British Columbia,
and look at what are all the features around there.
I will also say that Google Earth
is another excellent location where you can,
if you've gone to that app and found certain features
you can now come back on Google Earth and zoom in
a little more and see how it actually looks.
Maybe you can get
a surface view of it as well.
For anyone who's interested in, like, STEM
careers related to this sort of topics, these are
the sort of jobs that exist
if you are interested in looking at plate tectonics.
It's such a cool process.
It's a lot of cool evidence you can look at from the rocks.
These are the kind of jobs that exist for that.
And these are the kinds of subjects that we learn
that really help us in understanding
and interpreting what we see when we go out to
to the field. So with that, I'm going to end
and I'm happy to take questions.
I hope this has given you a good introduction
to plate tectonics and tectonics of
of just our solar system.
Thank you so much, Bhairavi. That was amazing.
 
Anyone who has questions, please feel free to put them into the chat.
 
 
 
While we're waiting for some questions to come in...
So with these plate tectonics, [are] there a separate
types of movements that make-
like one might cause a volcano, one might cause an
earthquake? Or do they all cause those?
So typically, earthquakes
are more along subduction zones,
or that area where you're converging.
So you have one plate that is going under the other.
And all along the North America,
like the west coast of North America, even South America.
It's not just North America, right? All of those
are where the Pacific Plate is starting to go underneath
the continental plate, and so those are the
best examples. And in the East side,
or like the Asian side, you have the Pacific Ring of Fire.
Again, if you look at
the West Coast of North America, go over to Alaska,
over to the eastern parts of Asia.
That whole area is a subduction zone
of many plates going underneath, and all of those
areas are really highly populus
with earthquakes.
Which is why you might hear it. But if you-
It's very rare,
but sometimes you might hear of an earthquake in Ottawa,
or Montreal, or something. And that actually is our own
continental crust responding to certain stresses.
Where those stresses are happening from, it really depends
on how deep or not those earthquakes are
that can tell us where or what's causing it.
The same thing with volcanism.
When a plate is going underneath, it's sort of creating
a few cracks. If magma is able to escape it
and come onto the surface, you have a volcano. So
you kind of want to know where you are
in a location before you can understand what's causing it
and what sort of evidence you see. But these are some of the most
common signs and ways.
Okay.
So, I'm going to go to the chat now.
So, I have a question here,
"what is the biggest earthquake that has happened?"
 
I believe
on record, the biggest earthquake happened
early in the 20th century, so in like
early 1900s, 1905.
There was a massive earthquake along the coast of
California.
That is fact was so massive, if I remember
right, it caused a massive fire
around San Francisco. So the history of
San Francisco, when they talk about the big fire
it's referring back to that event. But, that event
happened because of an earthquake.
So I think from memory,
that's sort of the largest that we have observed. But again,
I have the link, and I'm happy to share it later on and you can share it with all
your participants. But that site that is
actively recording everyday earthquakes
is really helping- They look at the frequency.
How fast are these earthquakes happening? How often are they happening?
And how deep or shallow are they happening?
Which part of the crust they are happening.
So by understanding and mapping that out,
they're able to understand just what's happening with the
plate movement and how that stress is building up.
And this is why, again, back to what we started
off with is like, the big one is coming, when is it coming?
We can't really tell. But the more you start to document
how often these are happening, the more it kind of gives them
some idea to say, "okay, let's be-
We got to be mindful, we got to be ready, and we go to let
everyone who lives in those areas know that there is something."
Okay, so something is coming.
Alright, so
we will definitely share that on the site with the participants
Sure.
So I have another question here. When did plate tectonics begin?
Excellent question.
 
Modern plate tectonics, like the one that I showed
the map of with all the different plates,
is thought to have begun
about 200 hundred
odd millions years ago. But that's a modern one.
That's not the only one. For those that know about Pangea
and that whole idea that we were a super continent,
we know that that happened because if you were to retrace
our current continents, they kind of fit into a ball.
And so really, we know
that this has been in some ways, episodic.
So when certain plates
move, it might just mean- Imagine
what would happen if you were to pull a rug. Not the best
analogy. But if you were to pull a rug, eventually
that rug ends. So when that ends,
that means that process has stopped, but that does not mean
that something can't start elsewhere.
It also depends on, what we're seeing right now
is what we've known for the past 100 million years.
But before that, something caused for Pangea
to form. That was actually two different continents, larger
continents, coming together. And so
we think that- This is why we also look at
other planets to see how old
those features are. So we can only infer and assume
Earth had something similar, but we're- Because
Earth is constantly cooling, and there's this
active process of volcanism, release of heat
things like that. That process is sort of constantly
getting updated. So the continents we have right now,
we have for now. But who knows, down the road
there are modellers who try to predict
how long will this go for, or where is there new areas
that might be of interest.
 
Sort of an answer I guess of how much we know.
 
So with that,
would gas giants like Jupiter
have plate tectonics? It's another question from the chat.
Jupiter as a planet wouldn't because it doesn't
because it doesn't have a solid surface. But that's
where the moons of Jupiter have solid surfaces.
 
And that's where we're seeing that evidence of tectonics
and the release of tension in the form of
cracks and things on the surface. So gas giants
don't but satellites might.
So you require a solid surface to have these
tectonics taking place.
Another question here is,
how does the Earth's interior work, and how does it effect the surface?
Okay, so it has to do a bit with- We have a core,
we have a mantle. But in that mantle
is [where] we have molten magma.
And that magma is not static. It's actually moving like a current
 
More heated content
will be more buoyant.
Which means it will want to rise, just cause it wants to reach a state of
equilibrium where it's happy.
Until it reaches that it will keep rising. But at one point
it might rise so far that it's actually colder from the
top so it needs to sink.
And that whole process of convection is what is driving
the magma internally within
our planet. And
tectonics is the response of that
convection happening over the crust.
The crust had solidified millions and billions
of years ago. But because there are these cracks
and things happening, sometimes that heat can
still continue to escape. And when you
have volcanic events, that's more heat escaping
and that's how
it sort of helps our own planet be
dynamically active, and we continue to
have earthquakes, plate tectonic movements,
and things like that.
That was a very short answer. I know that topic
can be on its own.
Years of studying can go towards that for sure.
 
I have a question here from Instagram.
How did you get into studying plate
tectonics of other planets, and could you recommend
any readings?
Great question! So for me
I got interested in plate tectonics as a kid. So
kind of in the grade levels that all of your are, likely.
When my teachers started to introduce the concepts of
plate tectonics, I thought that was fascinating.
Fast forward to grad school, after doing
undergrad and learning the basics of geology,
just understanding geology, like what does that mean?
Plate tectonics is one subpart within
a broad topic of geology. And that's where
it got me more interested. Again, this idea of you can go
and look at a rock. If you know where that rock cam from, you can
kind of figure out what it's history is, is more and more
of what fuelled me to be interested in this.
And this in grad school, I have to say, my Master's,
my research was looking at Venus.
Because we've sent missions and satellites
to explore our solar system
we have a lot of data that is now available
that we can use and understand
without having gone there. We've gone there with robotics
and satellites. We've collected that data
and that helps us right here on Earth figure out what that data is,
what it means, and have we seen something like that on Earth already?
Can we figure out what that is or not?
And so on and so forth. So tectonics is a topic that is
so interesting. Because imagine if you can start to calculate
how fast things are moving and where they are headed
maybe one plate might run itself out.
Like what will happen at that point? Will new things start somewhere else?
All of that really got me interested to continue
the journey of becoming a planetary scientist so that I could
understand
several aspects of
geology across the solar system.
It's like never ending questions, yeah?
It is!
Very interesting.
I have a few more questions here.
 
What's the deepest that humans have
ever gone into the Earth?
It might be just a
kilometre or so in.
And that is mainly through mining projects. So,
the whole mining industry within
the field of geology is going to extract
resources. And when you're going to do that
there are some resources available on the surface, but chances are
the most necessary, main
metals, and minerals and elements
that we need for functioning of technology
needs to be brought from deeper.
The mining profession is where
professionals will go further into the Earth
in order to excavate all of that content. So,
I believe mining projects typically go
at least 1 to 2 km, but I might be
 
on the shorter end of that estimate.
That's about as far as we've gone.
 
 
Is it possible- So I'm going to join to questions together.
So is it possible that plate tectonics might one day stop?
And do plates only
move in one direction?
So the question is, is it possible plate tectonics might one day cease to
happen, and also do plates just move in one direction?
So I believe that the
whole concept of
plates moving
can continue on for the planet
for the rest of the planet's history. But what might
change is what that original crust looks like.
Because often, your crust, once it goes in,
new crust may be forming elsewhere, but then new crust
has a slightly different composition
than what was there before. So it's almost like a recycling
process. But crust is constantly being regenerated
right along the centres of the oceans, right? So in that sense
plate movements will constantly happen, just what
those plates are, or their shapes, or where they are
might change.
So it might move, and might go
and join together and pull apart. Is that what is meant?
Joining together, yeah. So for example
 
think of Los Angeles. Los Angeles is
on the Pacific Plate
interestingly. And San Francisco is
on the North American Plate. So right now
Los Angeles is below San Francisco
if we have the map, right? But over several
millions of years from now
chances are Los Angeles will be over, above,
or further north rather.
So that's neat to know certain movements might happen like that.
So what does that even look like?
But that's because plates are moving.
And that's still happening right now. So that's what...
Sorry, there was another part to the question...
It was just about the direction of the movements.
Does it only move in one direction?
No, they actually move in different directions. It depends on what they're
lining up against. So Pacific Plate right by
South America might move in, let's say, left to right.
But Pacific Plate right by Alaska
might actually move north west, so kind of
diagonal left, right? So it depends on how-
Pacific Plate is an example, but it's the biggest plate
because it has a lot of surface area. So
really how the plate is moving will depend on
really where it's at and what it's against.
And so
plates can move in different directions. Typically along
the ocean floor, like where fresh crust is
forming, it is moving outward.
And there is a feature, I won't get into
all of it, I'll just mention. typically
when new crust is forming on the ocean floor
there is a record of a magnetic
 
record that is locked within the rock.
So for geophysicists who
can interpret that, they will look at just how,
and the information that's locked
is just showing in what direction the North Pole was
relative to the crust. In some ways. I am simplifying this.
But by looking at that and decoding what that is
they can actually figure out in what direction
the crust formed, and where it was heading, and how it was moving.
So those are our little nuggets
of information locked in the rocks that you have to
discover by looking at them.
So fun!
I love it, I always love this!
So in terms of earthquakes
Can you talk a bit about the
way we measure them. Would someone go out
and stick a prob into the ground and measure them?
And what sort of scale would they use?
Right, so earthquakes. That's the whole field
of studying earthquakes and the responses
of say the mantle
and the crust and things. That's under the umbrella
called seismology. That's the main area
that focuses on that. But you're right. A seismologist
will typically want to stick a detector
somewhere in the sort of
in the surface. So it's not sticking out
like our lawn water things. Not like that.
But it's actually in the ground. But
by knowing where they are
and again, placing them in an area of interest
because they want to know where the detectors are. They will actually
record. It's called the
Richter Scale. And so the scale is
the intensity of how
big or small an earthquake is.
Imagine, if an earthquake is happening
at the top parts of the surface
of a crust,
us on Earth as humans who are living
in populated areas will feel it, right?
But the further deeper in the crust that
the earthquake originates from, the less intense we feel it.
So if you hear in the news there's like the Richter Scale
it measured 8 or 9 or something, or even 7 or 5,
all of those are just telling
us how intense they are. But the detectors that are in there
will actually help you
understand just how far in the crust
those happen. And there's the measurement
of what are called P-waves and S-waves that are all
waves moving in the mantle,
these detectors can help decode that.
And by combining all of that information, we kind of know
how intense and earthquake is, where it's happening
and then there's a main earthquake. But the
fault and the sort of
plate movement response is not just one type. There's always
other indicators, right? Like
aftershocks is what they call them, often.
Like after main event they want to see how frequent other ones are.
And they will use all of that
just to know okay, which part of the
plate was moving, where was it moving, was that
sufficient release of energy
that they expected for that area or should they
be waiting for more? This is why they often
let the community know, FYI
this has happened, we're monitoring it, but keep an eye.
Because it might happen again.
So , hope that answered it.
I think that answered a lot of it, for sure.
 
Let's talk about something that has gotten a lot
of traction recently, I'm not sure why.
I have a few questions here in the chat about the shape of the Earth.
So, in your
expertise, can you explain exactly
how the Earth got its shape and
what that shape is.
Okay, again, a very quick answer to that.
Because that is its own topic as well.
It's just like, planets, when they formed,
you can think of the Sun was where it is
but there was a soupy material around it. Like pre
planetary materials that were just clumps.
But over time the clumps started to hit against each other
and that started to grow. And just because of
the role of gravity by default
it's shaped like a sphere. So that is where
with enough momentum and enough movement
and collisions and forming that's
how you start as a proto-planet.
Like a pre-planet.
And over the course of time it grows, but all of that is molten,
it is still spherical.
And then,
as the process continues, that molten material
will cool down
and as it cools down is how you start to get the crust.
But internally, that heat is still there.
There's a lot of heat that went into all of these collisions.
And really what we're seeing again with the Earth
is how that heat is escaping
as the planet continues to cool. We're such a large planet
that we still have a lot of energy left in order to cool down.
Which is why, again, through volcanism,
plate tectonics,
that process is continuing.
But if you look at other planets like Mercury or even
satellites like our moon, they're smaller in size.
So they have lost that ability to do that
for this long. They have just cooled off really early
in it's history.
And, those are all planets that are just one plate.
Nothing ever broke it apart. Like you can't have multiple plates and move
them around, etc. So, in a nutshell, that's how planets are
all shaped round
or spherical, and that's in part from the
gravitational response as its orbiting the sun.
Thank you so much for that answer. And
I think we're going to wrap things up.
But I'm going to ask the one question we ask all of our
speakers.
We all know that we are going through the Corona
pandemic. So I want to know
how you as a scientist have adapted,
and how some of your colleagues have adapted to dealing with this
sort of issue.
I have to admit, it wa-
 
I think very early on we didn't-
We knew it was coming, just kind of seeing how it was in Europe
and other areas of the planet were kind of gearing up for it.
So we knew. I personally kind of anticipated it,
but I don't think I anticipated the length how long
this is now taking.
So that was the initial
adjustment. But,
now we are what? Week 8 into this?
It has become and opportunity to
just reflect on what is, like,
how do we go along our day? We also realize how much we have
been outside a lot. Again, for work and stuff I would
travel a lot. So this is the first time I've been at home.
It's nice to spend time with family. But at the same time
from a work perspective,
moving onto a virtual platform has been sort of the
biggest adaptation, learning curve.
But it is going as well as can be. So I really
hope everyone is staying safe, staying indoors.
And if the weather is improving, just maybe
keep safe distance.
I have to say, I also have two new puppies
in the house, so that has certainly kept me busy.
 
And with that, I would like to thank
Dr. Bhairavi for joining us today. Thank you everyone
for being here. Do you have any quick final words
for everyone in the audience?
I want to say I've enjoyed
this opportunity, so I hope everyone
has also enjoyed and learned a little bit about plate tectonics.
How it matters. What it tells us about our own planet.
It's a very cool area of
interest and research. So I really hope
you enjoyed it and you continue to
tune into other programs where I think many other scientists are
also coming by.
Have a good day everyone,
thank you.
Thank you everyone. Take care, bye!
