Our first proper sunset! / Getting to know: Update

After a few rougher days of weather, the sun finally came out!
/ Victoire and Sam finish their mission!

By Sam Mitchell

Sunrise? Sunset? Who can tell?!

We're about a week into the expedition now, and yet we hadn't really seen a nice sunset... until today! We just about got the timing right - a few rough days and big swells had prevented some of us from venturing up on deck. However, today graced us with a nice, calm, crisp evening with few clouds and a good view of the setting sun. So, a few members of our evening crew headed up towards the bow of the ship to enjoy some well-deserved fresh air in the middle of the ocean! We hope to see many more!

Adrien, Massimo, Axelle and PSO Lluiva enjoy some time in the sun

In other news....

Victoire and Sam finished their mission to collect pictures of everyone on board for the final ship roster! Now we can get to learning everyone's names and positions quickly. The last few were a struggle for us to find (hiding in parts of the ship we didn't even know existed!), so one of the on-board science officers helped us source our final faces. We could just learn people's names the normal way.... by asking them... but this gave us a fun challenge and goal which - with a little help - we finally pulled off!

Our masterpiece!

Meet the Science Party! Matthew Griffiths

WHERE ARE YOU BASED?
I am in between; I have finished my Masters, and am starting my PhD this fall. I'm based in Ottawa, Canada with Carleton University and the Geological Survey of Canada.

WHAT IS YOUR AREA OF RESEARCH?
Geophysics: The combination of physics, going outside and treasure hunting I guess make it the most fun activity. I'm particularly interested in geophysical characterization of groundwater.

WHAT IS A FIRST TIME FOR YOU ON THIS EXPEDITION?
Being this far away from shore.

WHAT ARE YOU EXCITED TO LEARN/DISCOVER?
I'm quite excited to learn about the surveying equipment: What the source and streamers are like; how they are attached / deployed. Then I'm also excited to see some 3D processing.

WHAT DO YOU LOVE ABOVE GEOSCIENCE?
To elaborate on my research interest, I really like when mathematics describes nature and the understanding that comes with it. This is true for most scientific disciplines, but what makes marine/geoscience special is the scale of the subject. The subject (be it the ocean or geology) is on tangible scales we experience and see in the everyday. Whereas subjects like quantum physics / astrophysics are either too small or too far away.

TELL US SOMETHING ABOUT YOURSELF.
I am an excellent multi-tasker; I rarely watch a movie without sleeping.

Meet the Science Party! Morgane Goulain

Hello everyone, I'm Morgane and I am doing my Master's in Science and Executive Engineering at Mines Paris Tech, a French school.

WHAT IS YOUR AREA OF RESEARCH?
My courses includes physics, mathematics and even social sciences. I chose to follow the Geoscience program that focus among others on soil resources, energy supply and natural hazards. The latter particularly interested me as well as the geophysics course. In September, I will start a 6-month internship doing seismic data analysis of the Merapi volcano in Indonesia.

WHAT IS A FIRST TIME FOR YOU DURING THIS EXPEDITION?
This expedition is my first scientific mission abroad, my first time in the United States, and my first seismic cruise! However, not my first time at sea, I really love being on a boat, feeling the wind on my face and looking at the sea. I particularly enjoy sailing and jump at any chance to be out at sea!

WHAT ARE YOU EXCITED TO LEARN/DISCOVER ON THIS CRUISE?
So far, I have only had theoretical courses in geophysics, I'm here to discover how it works in real life! I want to assist the deployment of OBS, to see the devices recording signals and learn how to process data. I'm very excited to be here with people more experienced than I am or specialized in a field I don't know. My wish is is to talk with all of them and to learn new things about Geosciences I didn't learn in class.

WHAT DO YOU LOVE ABOUT THE GEOSCIENCES?
I think I love geosciences for two reasons. First, I'm fascinated by all these phenomena that one could hardly handle. How is a mountain formed? How does a volcano work? How do tsunamis propagate? Such power in the nature that we can barely understand! Moreover, I feel better when I am outside and not stuck in an office or in front of a computer. I love climbing mountains, walking in the forest, being at sea... I really like breathing fresh air, that's why geoscience is a field I particularly appreciate.

TELL US SOMETHING ABOUT YOURSELF!
Australia is my favourite country: I love the atmosphere and its beautiful landscapes from red centre to the Great Barrier Reef. Moreover, I really love cooking and I'm quite gourmand, I have even baked cookies, biscuits and pancakes on a small sailing boat!

Objective #1: What is actually going on in there?!?

By Annie Kell

Our 3D survey has the first objective of imaging Axial volcano is to see the details of the main and satellite magma chambers. Though we have this idea that volcanoes hold magma in a single and simple reservoir of magma and where there is no variation in the types of magma melt, the reality is that volcanoes have a more complicated system! There are many arms and pathways inside the system and there are variations of the actual chemical composition of magma.

The magma body:

When we think volcano and magma chamber, we think of it like a single tank underground with an opening on top, like what is illustrated in the first figure below. In this mental picture, pressure builds and the magma either blows or seeps out of the top of the “tank.”

In an idealized setting, the volcano is very simple with one magma chamber and one vent.

https://alchetron.com/cdn/magma-chamber-a949bbe6-88eb-4aa1-8875-1c337c7c633-resize-750.jpg

In observations of volcanic systems, the tank that holds the magma is complicated. It can be a combination of small chambers that are connected through fractures or conduits. The chambers can be mostly vertical, called dikes, or can be more horizontal, called sills (see the next image). Because there are few examples of the “text book” magma chamber, a lot can be learned by seeing an actual system and by seeing that system in 3D. The AXIAL3D Expedition will answer the fundamental questions that cannot be answered with 2D data and that are still lingering about this system. By seeing the large and small paths that make up the magma chamber, we can see how melt is stored in reality. The magma is moving from beneath the crust, within the crust and then to the surface of the earth. We will get to see that path! And in 3D! 

Observations actually show that volcanoes are complicated structures with many chambers and many vents. This survey will image the internal workings in 3D.

 https://ai2-s2-public.s3.amazonaws.com/figures/2017-08-08/929455c9e325f50322e86e5501344b24d502faad/5-Figure1-1.png

Some of these magma are not like the others:

Not all magma is the same. Magma is a variable material! Some magma is very melted, meaning it has a larger proportion of liquid. In other systems and (as we are learning) sometimes within the same system, the magma is more crystalized. More crystalized means the material is not as melted but rather has some “solidus” in the melt.  Within the Axial magma chambers, there are pockets where magma is more melt rich and where there is more crystallization. How do we tell this?!? The magma is deep within the earth so we cannot sample it! This is where the seismic data comes in.

As mentioned earlier, we record reflections of seismic waves off of all the material deep underground. Depending on the material, the amplitude of the reflected wave changes. Seismic data shows variations in the recorded amplitudes and we can plot those variations in many different ways. In order to distinguish areas that are more crystalline from areas that are more melted we conduct a type of seismic analysis called Amplitude Versus Offset or AVO. Offset is simply the distance between the seismic source to the seismic receiver. We look at the dependencies between the amplitude of the returned wave and the offset from the source. The cartoon image of a 2D profile below gives a bit of a picture of how offset and amplitude change along the length of the receiver array. AVO analysis can give a lot of details about a materials density, fluid percentage (thus melt variation) and material porosity.

This cartoon illustrated the changes in offset along the length of a receiver array.

http://www.subsurfwiki.org/300x251xthumb.php,qf=Seismic_acquisition_cartoon_marine.jpg,awidth=300.pagespeed.ic.XyTkU4dvxO.webp

So depending on HOW we analyze the data, we can tell the internal structure AND we can get indicators of material composition. All from the same data collection! These 2 direct uses of the seismic data are the first learning objective for this study. We will cover more about further objectives later.