We've been out here is visiting these volcanoes of the Kermadec Arc
for the past 10 or 12 years
and over the course of that time,
we've been able to determine the size of these volcanoes,
whether or not they're hydrothermally active,
and where these hydrothermal vents or hot springs
are located on the seafloor.
What we're endeavouring to do during the course of this cruise
is to find out in much greater detail,
where exactly do these hydrothermal systems lie.
In order to achieve that,
we're going to use some of the most sophisticated deep-sea vehicles
that are currently available in the world.
Initially we start off with the ship's multi-beam,
and that sends out an acoustic ray of signals on to the seafloor
and that will map the surface of the sea floor in great detail,
in fact, that will map it to a resolution of about 25 metres
and that produces these wonderful maps you can see here
of the volcanoes and structures that are occurring on the seafloor.
We also towed behind the ship a magnetometer.
This is measuring the Earth's magnetic field on the seafloor,
and each and every one of these things has a specific magnetic signal.
Another tool is known as a CTD which stands for Conductivity Temperature Depth,
and we fly this package very close to the sea floor
and we measure continuously what's happening in the sea water column.
So we can tell if there's any of this hot water
and we can find it in real time through the course of the survey,
up and over a volcano.
Another great piece of equipment that we have on board
is known as Towcam, this again comes from the
Woods Hole Oceanographic Institution
and it's a very sophisticated high-resolution digital camera
that is flown between three and four metres above the seafloor.
When we want to recover samples from the seafloor,
as you might imagine that's a very difficult task.
Unless we're using manned submersibles or remotely operated vehicles,
the only thing to use is what we call sleds or dredges.
So we can lower this down from the ship,
we can identify specific targets on the seafloor
and we can recover some samples representative of that part of the seafloor
and bring them up onto the ship.
These are some of the samples that we've recovered from the seafloor
In this case we have a mineral called barite which is very heavy
and you can see the crystals of barite in the sample
so we know that we're very close,
in fact this represents hot-springs on the seafloor.
This is a different type of rock that's a representation of the silica
that's in the fluids on the vent floor
and you can see all of these different textures here
which are commonly the result of microbial activity.
Sometimes what we find down there is that we have these really iron-rich fluids
and they commonly precipitate the mineral haematite
and you can see that here in this beautiful red colour.
This is often very late in the history of the system
and this is also full of barite so it's very heavy.
This piece is probably the most exciting piece that we've found thus far
and you might be able to see these very bright brassy yellow colours in here
and this is a mineral called chalcopyrite where much of the world's copper comes from.
This is telling us that the fluids here at some point were quite hot,
probably hotter than 250, maybe as hot as 300 degrees.
If you look here very very carefully,
you can see tiny little areas where the fluid had flowed though the rock.
What I believe these to be is pieces of chimney
that have fallen down, and they've amalgamated
and made what we call a breccia.
This represents an erosion of the chimneys on the seafloor.
The main piece of kit that we have onboard that differentiates this expedition
from any other that's come to the Kermadec Arc
is the vehicle known as SENTRY.
It's a highly sophisticated autonomous underwater vehicle
which means it's not tethered to the ship
and it can be programmed on what to do on the seafloor.
We tell it where to go, we tell it what to measure.
It can fly 30 metres or so above the sea floor,
it can hug the contours of the seafloor,
It can tell us where the hydrothermal vents are,
it can tell us what the magnetisation of the rock is,
it can tell us in acute detail what the topography is like down there.
So it's a very effective tool, enabling us to bring all the pieces
of information that we have from the other tools,
and to lay it out all in one map.
As an example, if you look at one of these bathymetric maps derived from the ship,
you can see the general outline of the volcano,
you can see the boundaries of the caldera rim,
you can see the cone in the middle etc.
If you have a look at the surface derived magnetic map for that volcano,
the areas that are shaded blue show very clearly
those areas which are low in magnetisation.
That means almost certainly in these instances
that we've had a lot of hot water pouring out in that particular area.
So we can use this as a first-order tool
to locate where the hot water is being expelled on the seafloor.
If you now look at the map that's been derived from SENTRY,
which was flying only 30 meters above the seafloor,
Look at the the difference in the detail of the magnetisation
and you can see the so-called burn holes,
these blue circles on the map.
Each and every one of those tells you
where fluids have been flowing up through the top of the volcano.
In the end, like most of these expeditions
when you have a number of professional people working together,
we've been able to pull it all off,
and to achieve all the objectives and the targets that we set out to do.
And the legacy of this expedition is that we're going to have information
that we can provide to various bodies, governments and so on,
and indeed to our children for many years to come.