Woods Hole Oceanographic Institution

Author Archive for Rebecca Carey

Driving the ROV Jason

During ROV Jason operations on the seafloor there can often be ‘spare time’ when we’re waiting for a measurement to complete or when we’re traversing between locations for geological observations. Recently there was one such time when we were waiting for a measurement of heat flow to be finished. So I jumped in the driving seat of the ROV Jason!

With the offer to give Jason a quick spin on the seafloor I promptly replied, “I was very good at computer games as a child so I’m sure I’m not going to destroy the Jason!” Was this welcome news for the Jason operations team? I’m not so sure…

Piloting Jason was partly like playing a computer game and partly like using a flight simulator. But driving Jason is especially dynamic and challenging because the driver has to coordinate with two other engineers to move the ship and monitor Jason’s tether to its partner vehicle Medea and the boat.

Jason weighs about 5000 kilograms, yet is able to hover and move in all directions on the seafloor just like a helicopter in the air. I was tasked with the job of traversing laterally (i.e., moving to the side while facing a hill) while looking at the rocks. The outcome of my driving time was that I didn’t bump into anything, but I was about 45 degrees off the planned direction!

Jason can not only move around in any direction, but can also sit on the seafloor or hover in mid-water and use its manipulators to pick up rocks and our measuring equipment. The manipulators work like a human arm, with joints that permit separate movement of the upper or lower arm. Jason has a shoulder, elbow and wrist joint, but unlike the human arm Jason’s hand can spin continuously. This is of real benefit when we need to drill into volcanic deposits with our corers. The joystick for the manipulator arms is a miniature replicate of the real manipulators – so its relatively quick to adapt to. Using the manipulators was really fun – the idea that I was moving the Jason’s arms at more than 1000 meters (about half a mile) below sea level was aweing.

One significant benefit of driving Jason was realizing just how skilled the ROV pilots are. It has helped me to plan missions and sampling tasks while on the seafloor to make operations easier for the ROV pilots.

Thank you Jason team!

Dance of the Underwater Robots

Research ships like Revelle map seafloor volcanoes with sophisticated sonar-type equipment and can produce topography maps of the seafloor. In 2002 Havre volcano was mapped by the National Institute of Water and Atmospheric Research (NIWA) vessel, Tangaroa.

After the 2012 eruption the ship remapped the volcano, and by comparing these two maps we were able to determine the new (in 2012) eruption products. I’ve been staring at these maps for the past two years and now I get to use the AUV Sentry and ROV Jason to do some underwater geology. Read More →

Once More Into the Deep

By James White

On Friday (New Zealand time), R/V Roger Revelle sailed from Auckland and we’re on our way to Havre Seamount to make seafloor observations and take samples from this newest known submarine volcanic deposit. This is my third trip, widely spaced over two decades, to study deposits of volcanic eruptions on the seafloor, but my first in which the team will deploy a remotely operated vehicle (ROV). It will also be, by a wide margin, the youngest eruption deposits that I will have seen on the seafloor.


James White on deck with ROV Jason.

My first trip, in 1995, was led by a scientist named Rodey Batiza and was among the earliest to employ the submersible Alvin to conduct a focused study of physical eruption processes. We made nine dives on that trip onto a small area of a volcano called Seamount Six to look at and sample a deposit type called “hyaloclastite,” which is made predominantly of small, angular chunks of basaltic glass only one or two millimeters across. Among these miniscule glass fragments are a small proportion of particles broken from very thin glass sheets, which were bent and twisted as they formed. The aim of the cruise was to test the predictions of a model from Rodey’s previous work that suggested these glass sheets are solidified remnants of fluid basaltic magma that was torn apart in submarine lava fountains.

To test this, we looked for the distinctive features of lava-fountain deposits on Hawaii, which are progressively thinner and made of smaller particles at greater distances from the fountain. These deposits also have an elliptical shape when viewed on a map and are elongated in the direction that the wind was blowing during the eruption.

Seamount Six deposits are estimated to be about 2 million years old, but the glassy particles are very fresh beneath, and partly held together by, a centimeters-thick layer of seafloor manganese, which looks like bulbous black moss or mold covering the deposits.

What we found over the course of nine Alvin dives was not what we anticipated. Instead of deposits that became thinner and composed of smaller particles at greater distances from what we inferred to be the source of the lava fountain at the top of the volcano, we found many small patches of deposits, all with about the same thickness and composed of roughly similar-sized grains, over distances of more than a kilometre. This told us that the deposits could not have been formed and dispersed from a single lava fountain.

We then looked for evidence of small lava-fountain sources, particularly small cones of “spattered lava in or near the individual deposit patches, but found none of these, either. Everybody agreed that the most likely origin for all of the blocky glass fragments forming 90 percent or more of the material in the deposits was quench-shattering of hot lava as it cam in contact with cold seawater, but we had no source for the small proportion of small glass sheets that were curved and twisted, even folded, that we thought came from lava fountains.

In one of our many interesting discussions, we realized that these small glassy sheets had a lot in common with much larger, but still very thin and glassy, sheets of basalt that form along the coast at Kilauea where water gets trapped in lava. The trapped water expands as it boils, blowing big bubbles, or balloons, of basalt that pop to form the thin glass sheets. Volcanologist Ken Hon named these formations limu o’ Pele when he wrote about the activity and described how they formed. Deep-sea limu are much smaller than those found on the coast because the great water pressure at Seamount Six depths (1700 to 2000 meters) prevented the boiling water trapped in its basalt bubble from expanding very much at all. It was an interesting and unexpected outcome of my first trip to the ocean floor, and I immediately began trying to arrange another submarine project.

My second trip was over a decade later, in 2006, and was led by Bruce Houghton, who had joined the University of Hawaii from New Zealand just as Rodey left Hawaii for a new position on the mainland. Bruce, a PhD student I was supervising in New Zealand, and I made series of dives with a different small research submarine, Pisces IV, operated by the Hawaii Undersea Research Lab, onto the surface of Loihi seamount. Loihi is the youngest Hawaiian volcano lies lies underwater a few tens of kilometers southeast of the Big Island’s Kilauea volcano. On that cruise, we revisited seafloor deposits where another volcanologist, Dave Clague, had described layered outcrops of volcanic particles that found in small hills built on top of Loihi. Our aim was to sample the outcrops very systematically and then look at the internal textures of the particles to determine how the deposits formed. Rebecca Carey, the cruise co-chief scientist for the Havre expedition we are on now, also took part in the dives.

In one deposit on Loihi, we found more limu associated with a very thin lava flow, but the main samples we took were bubbly basalt glass fragments a few centimeters across. By measuring the volume, shapes, and sizes of the bubbles in different fragments; examining the shape of small grains with a scanning electron microscope; looking at the shapes of tiny crystals; and analyzing the chemistry of the glass, the crystals, and of small blebs of glass that had gotten trapped inside crystals as they grew before the eruption, my student Ian Schipper was able to determine that different small hills were cones from different eruptions. He also showed how the different eruptions behaved, and that, for at least one of, them magma-water explosions must have broken up the erupting magma. The Loihi deposits don’t have thick manganese layers, and are generally much fresher than those at Seamount Six, and, though we don’t know the deposit ages, it is inferred that these deposits are young—perhaps hundreds to a few thousands of years old considering how quickly Loihi has been growing—and much younger than at Seamount Six.

This trip we’re on now to Havre will be a great adventure, but if I hadn’t had the opportunity to study those other submarine volcanoes, I doubt I would be here. There are not a lot of physical volcanologists who study submarine volcanoes, and there have been very few submarine eruptions that we know of historically. This isn’t because there are very few eruptions–in fact, most of Earth’s volcanic activity occurs underwater—it’s because the ocean is vast and seawater covers these volcanoes obscuring eruptions from us on the surface, even if someone is in the vicinity.

The story elsewhere on this site, about how people found out about the Havre eruption, provides a great illustration of how different it is to study submarine volcanoes compared to those on land. And now, after I’ve worked with a 2-million-year-old deposit, and one perhaps only hundreds or thousands of years old, I’ll finally get to look at a fresh one, from an eruption that we know quite a bit about already. This time, however, we won’t be collecting samples from a, so I won’t get another visit to one of Earth’s least-visited realms, but the ROV is much more efficient. Watching the big screens from the ship’s control room will actually provide a better view than you get “live” looking out of the portholes of a research submarine—plus you don’t have to hold your bladder for six or eight hours!

Getting Ready

Over the last few days, the science party, vehicle operators, and ships crew have been working feverishly to prepare for departure from New Zealand. The transformation of the research vessel Roger Revelle from its previous cruise to MESH has been dramatic and has included the addition of five container vans, an ROV (Jason), an AUV (Sentry), a crane, miles of wires and cables, hundreds of boxes and equipment cases, and (of course) new people.

Both Jason and Sentry arrived at the ship entirely assembled, but numerous small modifications and extensive testing must take place before they are ready to get wet. We had to develop a plan for configuring Jason‘s science basket, with its sampling equipment and sensors. Jason can carry 400 pounds of gear and samples, but the placement of equipment in the basket thought through ahead of time according to the order and manner it will be used. At the same time, the Sentry team was busy tweaking the vehicle’s command and control software and sensor payload for the upcoming missions we have planned for it.

Installation of the acoustic equipment that will track both vehicles while they are underwater has also taken place. This ultra-short baseline (USBL) system is installed in a well that passes through the ship’s hull and pings the vehicles in the water so that we know their position relative to the ship at all times.

The researchers on board have likewise been busy preparing laboratory spaces to process and describe rock samples, assembling gear, and getting computers hooked up to the ship’s network.

Yesterday evening, we also had a visitor to the ship, Richard Wysoczanski of New Zealand’s National Centre of Water and Atmospheric Research (NIWA). Richard was one of the first scientists to recognize the eruption at Havre and conducted initial sampling of the volcanic deposits. He gave a short presentation to describe the mapping and sampling he has done, which spurred vigorous discussions of what we might find once we get to the site.

All of this activity has helped build anticipation of the work ahead, and we are set to get underway at mid-afternoon (New Zealand time). Stay tuned!

Havre at Ground Zero!

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A quick examination of the weather forecast (surface pressure and wind) in the Havre region reveals… eeeek! .. a significant low pressure system that looks cyclonic! We’re definitely keeping an eye on weather systems for the next few weeks to come, and thinking about doubling the quantity of ginger tablets to combat seasickness during our expedition!