Profile of a grad student

As a kid, Ben Phrampus never imagined going to sea for work.  He grew up in Seguin, Texas, near San Antonio, about 150 miles from the Gulf of Mexico.  This is his fourth cruise.  He’s been offshore the east coast of the U.S., the Gulf of Mexico, and Svalbard.

Ben is on this cruise because he is interested in the heat flow measurements and their interpretation. Although temperature is an important quantity for understanding many processes, research cruises that collect a lot of heat flow data are relatively rare.  He says he jumped at the opportunity for this cruise so that he could learn how to make these measurements and how to analyze the data.  When you collect the data, there is an intimate connection with the science.  This immediacy with data drives Ben’s research.  He likes collecting the data and likes writing computer code that generates models used to understand the data.  This process is a form of puzzle solving that Ben has always been interested in.  Ben’s favorite puzzles as a kid included logic and numbers.

Ben is in his last year of his Ph.D. at Southern Methodist University where he has been studying gas hydrates for his dissertation.  Gas hydrates are an ice-like substance where water molecules form a cage around a gas molecule, mostly methane, CH4.  In the oceans hydrates are mostly found along continental margins and New Zealand has plenty.  The change from the gas phase to the ice-like phase is controlled by temperature and pressure.  He computes the pressure from seismic reflection data and the temperature can be estimated from phase relationships, but more directly from heat flow measurements.  Ben was involved in identifying gas plumes rising from the seafloor due to the dissociation (melting) of the hydrate.  When hydrate melts it releases the trapped gas that can then make it way to up through the seafloor as a bubble.  The melting of gas hydrate has been attributed to the warming of the world’s oceans. Ben plans to take the lessons learned from this cruise and apply to his future gas hydrate studies.

Being young, the internet has always been fast for Ben.  Not so on a ship.  Ben likes escaping his digital presence but also gets frustrated at the slow internet speeds and limited band-width.  It’s a double edged sword he says.

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Back to science!

28 May:  The unimaginable has finally happened – we are down to 2.8m seas! It’s an incredible feeling to be able to walk without the aid of walls and rails. Around midnight was the first time in days that we’ve seen swells under 5m for any period of time and it is a relief in many ways. We were able to launch the seismic line yesterday after lunchtime and we have been running smoothly since. There was a moment at the end of the first survey line where we had to make a decision whether it was safe for the equipment to turn the ship to the next line as it would mean potentially driving in the trough of the swell. I was asleep when the decision was made to continue full steam ahead.  The seismic survey will continue for at least another day before we remove the 800m line that we have been trailing behind us and switch back to heat flow measurements. The upcoming forecast looks fantastic – winds are shifting to onshore (rather than from the south/southwest) and swells should be back down to 1-2m.

Below are a few pictures from a deployment and recovery of the heat flow probe a few days ago.

*see ‘About STINGS’ for more detailed information about seismic reflection and heat flow*

-Nicole

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All hands on deck to deploy the heat probe.

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Deploying the probe. Note the large swell.

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Deploying the probe.

 

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Recovering the probe. Operations are going 24/7.

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Recovering the probe. The rough seas made this a challenging recovery. Drew, our resident technician pictured here steadying the probe, helps make every deployment and recovery a success.

 

 

 

 

 

Weather Hold

Today, 26 May 2015, marks our third science-less day here on the Revelle. Last night brought the largest swells we’ve seen yet (at times, >10m), and it was a workout just to stay in our bunks. At breakfast this morning there was discussion of this storm being the largest low pressure system on the planet right now, with low measuring pressures akin to Hurricane Katrina.

It appears we are on the back edge of it now, and hope to finally start the seismic line tomorrow or Thursday.

-Nicole

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Hard to capture, but here’s a taste of our day yesterday.

 

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A screen grab of an active wind map from the linked article above.

 

Pictures are appearing!

Please check out the previous posts for new photos! I’m finally getting some uploaded. Here is a little eye candy from this evening, along with the swell forcast for tomorrow…

-Nicole

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Incredible sunset this evening – the calm between two storms.

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A few moments later.

 

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This is what we are in store for over the next 2-3 days, starting tomorrow evening. Welcome to life in proximity to the Southern Ocean. Giddy up!

 

Heat Flow

Rob Harris

Oregon State University

I am interested in understanding the energy budget associated with geologic processes.  I think this understanding leads to better insights into how the Earth works.  For example, plate tectonics – the creation, motion, and destruction of plates – reflects Earth cooling.  About 70% of the Earth’s heat loss occurs through the ocean floor which is reflected by the cooling and subsidence of oceanic plates as they move away from spreading centers.  The upper layer of these plates, the oceanic crust, is cooled efficiently by hydrothermal circulation.  It turns out that the entire volume of the global ocean circulates through the oceanic crust every few hundred thousand years.  This hydrothermal circulation is important because it leads to significant exchanges of energy, mass, and solutes between the ocean and crust.  These exchanges modify the chemistry of the ocean, the chemical and physical properties of the oceanic crust, and support a globally significant biosphere.

At many subduction zones, temperatures along the subduction thrust fault appear to play a role in governing the depth extent of seismicity.  Earthquakes represent the release of stress stored in rocks, but once rocks exceed a certain temperature (~350° C) they are too weak to store the elastic stresses required for an earthquake.  It turns out that the deeper an earthquake can nucleate the bigger it can be, so estimating the position of the 350° C isotherm is important for both understanding geologic risks due to earthquakes and also the physics of how earthquakes work.

To estimate temperature along the subduction thrust, we need to know the thermal state of the Pacific plate before it subducts beneath the Australian plate, the geometry of the fault zone, and the long-terms rates at which these plates are moving past each other.  The geometry of the fault zone is illuminated by seismic reflection data that we are collecting, combined with previously collected data.  Deeper in the earth the fault zone is illuminated by earthquakes.  The long-term rate at which these plates move past each other is estimated from geodetic data.  Finally, the thermal state of the incoming Pacific plate is estimated using the heat flow measurements we are collecting.  All of these data are necessary inputs for developing a thermal model used to estimate temperatures along the plate boundary.

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Cross section of a subduction thrust.

 

A second interesting aspect of this system is the Australian margin that overrides the Pacific plate and how it changes along the length of the Hikurangi trench. In the northern region it appears that most of the sediment on the incoming plate is carried down into the subduction zone whereas at the southern portion of the margin some of the sediment is scraped off the incoming plate and accreted to the Australian margin.  Fluid flowing through these sediments plays an important role in their evolution, structure, and deformation, the occurrence of overpressures and also influences the nature of seismicity along the subduction thrust.  Heat flow measurements like those that we are making can be used to detect and trace the flow of fluids.

It’s very exciting to have the opportunity to investigate these questions and to be sailing on the R/V Roger Revelle.  Without ships like these, important science that we and others are doing wouldn’t be possible.

Life on the open ocean

On 16 May 2015, I set foot on an ocean-bound ship – a ship I’d be living aboard for an entire month – for the first time. I had no idea what to expect, save the stories I’d heard from others. We were in port for just over three days before getting underway, and that gave me a time to size up my environment and get used my new schedule.

The co-chiefs split the geophysics team into two 12-hour shifts – noon to midnight and midnight to noon. We did not start those shifts until we were closer to our first waypoint, but our time in port gave us a chance to get on a good eating and sleeping schedule; this is much easier said than done. Meal time are very regimented:  breakfast at 07:30, lunch at 11:30, and dinner at 17:00. There is food available 24/7, however, since not everyone is around for mealtime. In the galley, there is a fridge marked ‘LEFTOVERS’ that is free game. Snacks abound also, should munchies occur at any time. Our port time was a breeze, even though I was in the beginning stages of acquiring my sea legs (the ship is very stable in port, but there is still movement, and my landlocked state noticed every to-and-fro). We ate breakfasts and lunches on the ship, but took advantage of the great food in Auckland for most dinners, especially a great brew pub (Brew on Quay) that was about a five-minute walk from the harbor. Their food was fantastic and they boasted 102 beers and a deep scotch list. Needless to say, we stopped in almost every night (did I mention it’s a dry ship?).

Aside from acclimating to the strict meal times, the transition to ship meals was an easy one as our ship chefs are top-notch. I have heard many tales about ship food – the good and the not-so-good. I would rank this experience so far as very, very good (check back in three weeks). Breakfasts are a spread of eggs (fried, poached, scrambled with cheese), a variety of morning meats, oatmeal, pancakes, and pastry selections such as scones or muffins. Lunches have varied greatly, from soup and grilled cheese, pasta salad, and Salisbury steak. Dinners… Where do I begin? Seared Ahi tuna with wasabi butter, grilled flank steak, sweet and sour chicken, roast pork loin, and prime rib… the list goes on. Every lunch and dinner includes fresh fruit and an ample salad bar – for now. They always put out some sort of dessert, too – the fresh baked chocolate chip cookies were a particular favorite. Marc and Mark have been spoiling us rotten.

It took most of the team and me a few days to get a good night’s sleep. If you are sensitive at all to noise or movement, being underway definitely takes some getting used to. I found that when I was not feeling well, lying down was the best position for me. There is a comfort in the heave, pitch, and roll of the ship – to a point. It’s not uncommon to wake when conditions change, or when the ship begins or ceases a transit. For the most part, I feel very well rested and am thankful. As one of the least experienced scientists aboard, I’m doing my best to be a support and help keep up morale. Running scientific operations in the field is a challenge, and performing it on the open ocean adds another level of stress and intensity. Thankfully, we have an incredible ship crew along with our adept science team. Troubleshooting on the fly is an invaluable skill, and our guys are all skilled problem solvers. Drew Cole, the Revelle’s resident technician, is worth his weight in gold.

-Nicole

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View of the bridge from the bow as we get underway.

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Auckland at sunset from the bay.

 

Two days at sea

Greetings from the R/V Revelle! As it has taken a few days to get this site up and running, I will attempt to summarize the last few days in this post and keep on a somewhat regular schedule. There will be updates from myself and from the other scientists aboard the cruise to share about the project and the experience of living at sea for a month.

Most of us arrived in Auckland a couple of days before boarding the ship, and after boarding on 16 May, had until the 19th before getting underway. We took the time to gather any last minute provisions as well as see as much of the city as possible. Auckland is incredibly beautiful and diverse. The city has a lot of relief, and is comprised of and surrounded by cinder cones and other volcanic features. A group of us traversed 30-plus kilometers (on foot) over the course of two days, taking sites such as the Auckland Museum and hiking to the top of Mt. Eden. Pictures to follow.

At 16:00 on 19 May, the Revelle was underway toward our first heat flow transect waypoint. The transit took 27 hours and was a bit intense for my inexperienced mind and body. I learned quickly that using a computer is similar to reading while in the car for me, and that it is not a good thing while in transit. I also learned that my bed was the dearest friend in the world.

We arrived at the first waypoint at about 19:00 on 20 May and began the process of deploying the heat probe. From then until now (17:00, 21 May) we have moved through 16 waypoints to procure heat flow data just seaward of the trench.  We will then transit for approximately 3 hours to our next transect.

Until next time,

Nicole

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These trees were everywhere along this walk – Pohutukawa trees. They seemed to grow out instead of up .

 

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Co-chief Anne Trehu capturing the view from the top of Mt. Eden .

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Auckland from the top of Mt. Eden.

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Co-chief Rob Harris and Rachel Lauer assembling the heat flow probe.

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Co-chief Anne Trehu, Rachel Lauer, Ben Phrampus, and the ship geoengineers coiling the high resolution seismic reflection line onto the winch.