Cruise End - Another Chapter at NW Rota-1

Visit the 2010 NW Rota-1 expedition blog at:
http://nwrota2010.blogspot.com/



Chief Scientist Bill Chadwick aboard the R/V Thompson in Guam.

NW Rota 2009 Cruise Summary

Bill Chadwick
Oregon State University

NW Rota-1 submarine volcano is truly unique because it is the only place on Earth where deep submarine volcanic eruptions have been directly observed. In addition, we are discovering that the volcano seems to be continuously active, which is very unusual even for volcanoes on land. What this means is that NW Rota-1 is a fantastic natural laboratory for learning about underwater eruptions, how submarine volcanoes grow, and how they affect the ocean environment.


One aspect of working here that continually amazes me is how close we can get to the eruptive vent, because the pressure of the ocean above keeps the energy of the eruptions subdued and allows us to have a great view of what is happening in the vent.Some of the most exciting observations we made during this expedition were during the times that we were watching lava slowly get pushed up and out of the eruptive vent.


JASON returning to the deck after exploring the erupting, undersea volcano, NW Rota-1.
As this was happening, the ground in front of us shuddered and quaked and huge blocks were bulldozed out of the way to make room for new lava emerging from the vent. It gave me the distinct impression that there was some powerful monster just below the seafloor trying to get out.The eruptive activity here is extremely dynamic because there is so much gas being released from the lava as it comes out.

We also discovered that the volcano has grown considerably since our last visit in 2006. The eruptive vent is now at the top of a large cone that a new bathymetric survey shows is as high as a 10 story building and as wide as a city block. And that entire cone was not there in 2006! Despite the on-going eruption with ash and rocks falling everywhere and an extreme chemical environment, an ecosystem has developed here that is thriving. In fact, we found this year that the population of animals and microbes had increased dramatically relative to 2006 and had become more diverse, including new species that have not been found anywhere else. Do the animal populations wax and wane in concert with the intensity of the eruptive activity at the vent? Our work is aimed at investigating if such interactions exist between the volcano and the animals that live here.


The R/V Thompson (University of Washington) at sea above the volcano. The ship is a floating laboratory and mini-city, supporting a team of ship's crew, JASON crew and scientists during the expedition.
We will be leaving an array of monitoring instruments to learn more about how the volcano behaves over the next year. A hydrophone will record the sounds of the eruptive activity, chemical sensors will sample the eruptive plume above the summit, and moorings on the flanks will look for landslides and debris flows from the eruptive vent. We plan to be back here next year to continue our investigations at this fascinating place where we have the rare opportunity to study a submarine volcano in action.

In closing, I would like to thank the National Science Foundation for supporting our research here at NW Rota-1. The success of our expedition this year is in large part due to the hard work of the talented team of Jason pilots and engineers who kept the ROV running in top form and allowed our dives to be as productive as possible. We also had outstanding support from the captain and crew of the research vessel Thompson, who are always a pleasure to work with. Finally, I would like to thank my colleagues who have joined me on this trip. It is always a pleasure to go to sea with a diverse group of specialists (geologists, chemists, ecologists, microbiologists, oceanographers) because it expands the scope of what we can learn and accomplish and it allows us to look for linkages between all of our observations and experiments. I can’t wait to see what the volcano is up to next year.


Below are some video highlights from this year's expedition:


video
Jason approaches the Brimstone eruptive vent at the top of the new 40-meter high cone (no audio).


video
Jason prepares to sample the eruption plume as ash rains down on the vehicle. Later a curtain of CO2 bubbles rises in front of the camera during another eruptive pulse.


video
The seafloor shakes and heaves as new lava forces its way to the surface.


videoAsh explosively erupts from Brimstone vent as Jason prepares to place a temperature probe in the plumea temperature of 210° C (410°F) was where measured.

All video copyright by Advanced Imaging and Visualization Lab WHOI

The Chemist's "BEAST"

Extreme Water Sampling at an Underwater Volcano

Dave Butterfield

University of Washington




Intake nozzle on water sampler (the "Beast") coated with sulfur.
What do you think of when someone says “I’m a chemist”? Lab coats, glasses, clean laboratory, test tubes, glassware, sparkling expensive instruments? The picture out here is different. We’re working on a ship in the tropics, wearing shorts and t-shirts, getting dirty, working on deck with tools, doing plumbing on instruments, and staying up all night sampling. It’s certainly not easy, but given the choice between laboratory chemistry and being out here studying how volcanoes work, I want to be out on the ocean.


Re-heating the Beast's wand in Brimstone's vent, an attempt to remove the sulfur clogging the intake valve.

Capturing good samples at underwater volcanoes takes a different set of tools. Because I am interested in a full range of chemistry and microbiology, I developed the Hydrothermal Fluid and Particle Sampler, commonly known as “the Beast”. With an in-line temperature sensor at the tip of the titanium intake nozzle, a flexible Teflon-lined hose, 24 custom exchangeable sample containers, in-situ pH and H2S measurement, data logging, etc., the Beast is definitely more sophisticated than a titanium syringe, which used to be the standard vent sampling tool. The Beast is a great tool for studying the relation between chemistry and microbiology in the submarine hydrothermal environment because it can bring back samples for DNA analysis and culture experiments.



Dave Butterfield holding the Beast's wand after the dive. The yellow sulfur not only coated the outside, but clogged the intake of the fluid sampler.

The eruptive vent here is called Brimstone for good reason. Sulfur is abundant as SO2 gas, fine “smoke” particles, sulfuric acid, and as molten sulfur that periodically erupts in spectacular yellow bursts. While using an extra-long intake nozzle on the Beast to reach into the sulfur-rich volcanic vent at Brimstone, the nozzle got away from us and plunged down into the volcanic sands right in the eruptive vent. The result was instant clogging of the sampler as molten sulfur and tephra were sucked up the nozzle and frozen into a solid plug. In an effort to regain sampling capability, we deliberately laid the entire intake nozzle down on the hot smoking ground to try to re-melt the sulfur in the nozzle while pumping in reverse. That effort was in vain and we ended up with a sulfur-covered mess. The Beast had met its match at Brimstone. Obviously that won’t stop us and the Beast will ride again.


videoJason’s manipulator arm holds a long intake tube designed to sample the hot fluids and gases coming out of the Brimstone eruptive vent. However, boiling seawater and molten sulfur make the sampling difficult.


videoMolten sulfur sticks to the intake tube and has clogged the fluid sampler on this dive. Fluid samples from the eruption plume were successfully collected on later dives.

All video copyright by Advanced Imaging and Visualization Lab WHOI

JASON vs. the Volcano


Tito keeping JASON in position near the exploding plume of Brimstone Pit.

Tito Collasius
JASON Expedition Leader

WHOI

Now, I have to start by saying I have seen some cool things on the bottom of the Ocean. Being a part of the Titanic discovery and finding 3rd century shipwrecks being a couple of the highlights, but now, here I am, sitting center stage in a mostly darkened room, surrounded my innumerable monitors and HDTVs providing the only glow. Sulfur rich smoke, bespeckled with falling ash billows on most of the monitors. The earth pulses, bubbles of CO2 flutter past one camera view, disappear, and float up toward the downlooking camera showing the ROV Jason perched next to a live volcano vent with a huge white plume.

A panorama-view of the front displays in the JASON control van. JASON itself was configured with over 6 cameras and additional cameras are mounted on its tether vehicle, Medea. Also visible in the van are the sonar displays, navigation information and equipment monitors. For each dive the JASON team has a pilot, navigator and engineer working together to bring the ROV safely to the seafloor.

A box reminiscent of a 1980's arcade game console sits on my lap. Anticipation hangs in the air, as scientists, who always fill the room, stare intently at video feeds coming 500 meters up from the ocean floor through a tether. They are all hoping for the vent to exhibit behavior like that of the St. Helen's disaster. I also watch with anticipation, only half cheering for cataclysm. My real concern is keeping the 6 million dollar vehicle that sits less than three meters from this geologic event. My eyes dart to all camera views showing information from dozens of sensors updating me on depth, heading, ambient temperature, amount of thruster force used to keep me on the seafloor.

The earth pulses, shaking the ground and the vehicle. Boulders walk further from the plume and closer to the vehicle’s basket. They are large enough that if they fall, they could lock the vehicle to the ocean floor. They are getting a little too close. Time to move. I pull back on the joysticks, one to fly up, the other to fly back. As I fly backward through the water the action increases. The whole vent cone and surrounding virgin earth starts pulsing faster. Smoke and bubbles blow harder. The ground where I had the vehicle sitting only a moment ago explodes. Boulders shake and fall away. The whole thing shears off. Wow. Careful what you wish for.


video

Time-lapse movie of the seafloor shaking and rocks being shoved away from the eruptive vent just before Jason moved out of the way (speeded up 4 times, no audio).


videoThe same video clip as above at normal speed (with audio).
All video copyright by Advanced Imaging and Visualization Lab WHOI

Shake and Bake

The Earth Moves

Kathy Cashman
University of Oregon


As we watched from the Jason ROV, a spire of lava (to the right of the sulfurous clouds) was extruded from the Brimstone vent.
Our earlier blog “NW Rota-1 is Active!” described NW Rota’s activity primarily from the perspective of the eruptive plume, that is, the gases that are released from the magma as it ascends to the sea floor. During the past few days we have had excellent visibility that has allowed us to watch lava emerging from the active vent, a process that has never been witnessed in this sort of detail in the submarine environment.

But first to define some terms. Geologists use the word “magma” to describe molten rock beneath the Earth’s surface, where it consists of melt with dissolved gases (think of it as champagne in the bottle, before the cork is popped). The word “lava” is used when the magma has reached the surface, by which time it has lost most of its gases. Lava may be either very fluid, and form long thin flows (as in Hawaii), or very viscous (sticky) and form short thick lava flows and domes (as at Mount St. Helens, WA). The rate at which lava comes out of the vent also affects the flow behavior, with lower rates usually leading to shorter flows.

At Brimstone Peak, the magma is moderately viscous and it is coming out of the vent very slowly. Additionally, the seawater cools the lava rapidly. The result is that the lava solidifies as it emerges from the vent to form odd-shaped pillars and bulbous protrusions. Although from our viewpoint the emerging lava is usually veiled in plumes of sulfur ‘smoke’, we see evidence of its presence. New lava degasses vigorously for several minutes, thus the location of active lava extrusion can be tracked by watching the regions of vigorous degassing. Additionally, as the rapidly solidified magma comes out of the vent, it pushes on the surrounding lava, which causes these slightly older and cooler lava blocks to jostle together, move aside, and eventually break into pieces. In this way the ‘new’ lava quickly transforms to rubble that forms a growing apron around the active vent.

Is this how NW Rota grows? The answer to that question appears to be yes, at least over the past several years. We just completed a new high-resolution bathymetric survey of the volcano’s summit, to compare with a similar survey made in 2004. It appears that the vent, formerly known as Brimstone Pit, should now be called Brimstone Peak, because it is now a cone that stands almost 40 m (about 130 feet) high and about 100 m (330 feet) across. This growth has not been steady, however, as observations in 2006 showed that the growing cone had collapsed to produce a slide of loose debris down slope. As we continue to monitor and revisit NW Rota over time, we hope to assemble a more complete picture of the dynamic growth of this underwater volcano.

videoThis time-lapse movie shows lava rising and pushing previously erupted blocks to the side in the vent over a time period of an hour and a half. The areas of the most intense degassing are where new lava is actively erupting (no audio).



videoWatch closely as recently erupted (and already degassed) lava on the right side of the vent is shoved aside as new lava rises behind it and vigorously degasses.
All video copyright by Advanced Imaging and Visualization Lab WHOI

Getting Gas

Collecting Bubbles Under Pressure


Capturing bubbles using an ordinary funnel placed over the gas sampler's intake.


Leigh Evans
Oregon State University


As the 'Fire and Brimstone' blog entry showed, Brimstone Pit releases streams of gas bubbles that are composed mostly of carbon dioxide. They and the fluids they rode in on, can be captured with titanium "gas tight bottles." These specially designed bottles can withstand the pressures of all currently workable ocean depths both from within and without. At the depth of NW Rota-1, gas bubbles should be at a pressure about 60 times atmospheric. The version of the gas tight bottle that catches gas bubbles is outfitted with a kitchen funnel, a rubber stopper, thin plastic tubing and some glue. One hydraulic "arm" of Jason II includes a special hydraulic ram to push the triggering button of the gastight bottle. All we need to do is position the funnel to catch bubbles and trigger the bottle at the appropriate time.


Brimstone's gas bubbles are primarily composed of CO2(90%).

The PMEL Helium Isotope Lab has gathered fluid and separate CO2 rich phases from six volcanoes; four on the Mariana Arc and two on the Kermadec/Tonga Arc. In all but one volcano, the separate phase is gas bubbles. Comparison of the measured concentrations of helium and carbon dioxide to those based on published solubilities revealed that the fluids contained far less gas than one would expect if the bubbles had been the product of the fluid degassing its dissolved contents. It appears that the “extra” gas is coming directly from magma inside these volcanoes, or in the case of NW Rota-1 directly from lava erupting at the surface. In some cases, sub-surface boiling might also be involved. We are collecting additional samples on this trip to try to figure this puzzle.



videoA funnel attached to a “gas-tight” sampler is used to collect gas bubbles rising from the eruptive vent. (no audio)
All video copyright by Advanced Imaging and Visualization Lab WHOI

Shrimp on the Rim

Living on the Edge…of an Active Volcano

Verena Tunnicliffe
University of Victoria


Dense colonies of shrimp near the summit of the volcano. (click images for full size)

NW Rota does not seem to be the best habitat for animals and yet there is a hive of activity buzzing around the summit. Most of these animals are dependent upon the diffuse hydrothermal venting that provides the basic food source: bacteria in the form of filaments on the rocks. Upon our return, my main question was whether there would be any changes in the simple community that we encountered in 2004 and 2006. There is. The major difference is the extent of the animal populations; it appears that the diffuse venting has spread and, with it, the vent animals.



Close-up view of both species of shrimp.


There is now a very large biomass of shrimp on the volcano. Two species are able to cope with the volcano conditions. The “loihi” shrimp has adapted to grazing bacterial filaments with tiny claws like garden shears. The second shrimp is a new species; it also grazes bacteria after the juveniles settle to the volcano. But, as they grow to the adult stage, their front claws enlarge and they become predators. While the second species is able to evade Jason’s suction sampler, we took advantage of its scavenging habits: a trap baited with Spam came back with 4 dozen shrimp.


Limpets and their eggs collected from the rim.


Another new species we found in 2004 is a limpet that was restricted to one small vent. But now it has spread to many different sites on the volcano. How does a limpet “spread”? This animal glues egg cases to the rock where the embryos develop; then, the larvae hatch and swim to a new site. Another surprise is the presence of a barnacle that we never saw before – in fact, I am not sure it is a known species. It is intriguing that NW Rota is attracting more animals even though the volcano went through a very intense eruption cycle. It is impressive that, for some species, the highly unpredictable nature of this site is balanced by conditions that enhance population survival. It remains to be seen whether the next more violent phase of the volcano will eradicate much of the new colonization.

An interesting question to solve at NW Rota is how the shrimp recruit to the seamount. We are collecting samples to examine them in several ways. First, collections can determine the proportion of the populations that are reproductive; there appear to be a lot of juveniles and few adults. Second, plankton tows are searching for the dispersing juvenile phases in the water column. Third, we can examine gene flow with the loihi shrimp we collected at two other seamounts on the Arc and on Loihi Seamount off Hawai’i…a long trek for a shrimp juvenile!


videoA rocky outcrop on a ridge of the volcano provides habitat for two species of shrimp adapted to live at hydrothermal vents. (no audio)

videoThe smaller shrimp species is a grazer while the larger one is a carnivore. The smaller grazers get out of the way as a larger carnivore walks through a crowd. The carnivore species uses its large claws in aggressive displays. (no audio)
All video copyright by Advanced Imaging and Visualization Lab WHOI

Microbes, aka "Bugs"


Diffuse hydrothermal fluids are used to inoculate tubes and vials containing nine different kinds of growth media, which are incubated at four different temperatures (click images for full size)
Life at the Extremes

Julie Huber
Marine Biological Laboratory

While many of the scientists on the Thompson are focused on understanding how submarine eruptions work from a geological perspective, some are interested in the effects of such eruptive activity on biological communities. Previous studies at mid-ocean ridge hydrothermal vents have shown that eruptions are important sources of energy for life, especially microbial life. As a refresher, all of life on earth is divided into 3 domains- Bacteria, Archaea, and Eukarya. Bacteria and Archaea, also called microbes, are single celled organisms with no true nucleus, no membrane-bound organelles, and they divide by binary fission. They are very very small- invisible to the naked eye- whereas most eukaryotes tend to be bigger things, like humans, tigers, shrimp, and fish. We have scientists on board who are interested in both the big stuff and the small stuff, and for all organisms, their survival is intimately connected to the volcanic activity. Microbial communities in particular thrive from the combined input of heat, water, and chemical energy in volcanic rocks. Chemicals like sulfur and hydrogen are being created at NW Rota, and microbes are harnessing that energy to make a living. And from our previous expeditions to NW Rota, it is clear that the microbes are having no problem making a good living!


White microbial biofilms bathed in vent fluids make their living from the chemicals in the warm water and can also use rust colored iron oxides (seen here) as an energy source

Diverse microbial communities are found everywhere on the volcano, including in the warm acidic vent fluids and coating all sorts of surfaces like rocks and sediments in microbial mats or biofilms. The vents at NW Rota are teeming with microbes, both archaea and bacteria, despite the harsh dynamic conditions created by the eruptive volcano. In fact, the microbial communities at NW Rota are more diverse and variable than microbes we find at other types of underwater volcanoes, like mid-ocean ridges or hot spot volcanoes. We’re still trying to understand why, but one hypothesis is that places like NW Rota have really complex hydrothermal chemistry and because of the extremely dynamic nature of the eruptive cycle, a lot of different niches or habitats are created for diverse microbial communities to exploit.


Without the ability to bring a high-powered microscope to sea our only indicator for growth of microbes is “turbidity”, or cloudiness, of the growth medium. The vial on the left will contain somewhere between 107-108 cells per ml of fluid.

In addition, eruptions are a great way to also sample what is happening within the seafloor, or in the subseafloor, because the fluids are forced out of the seafloor and when collected, provide a glimpse into organisms that normally live in the crust. Eruptive events are a great source of novel organisms and so when we can, we try to catch these events to also catch the novel microbes. We’ll spend the next 2 weeks trying to capture these diverse microbial communities and try to figure out who they are, how they make a living, and how they interact with and are impacted by the eruptive volcano.


videoVarious types of filamentous microbial mat wave in the current on a vertical cliff near the summit of NW Rota-1. (no audio)
All video copyright by Advanced Imaging and Visualization Lab WHOI

Fire and Brimstone

NW Rota-1 is Active!

Kathy Cashman
University of Oregon




The Volcano is active! Large plumes continuously billow up from Brimstone Pit. Plumes carry CO2 bubbles and ash particles. (click image for full size)


As the time approached for our first Jason dive, the anticipation in the air became p
alpable. We had been preparing for this dive for two years, and during this time had been monitoring the volcano’s activity through glimpses provided by other cruises in the area. In February 2008, a hydrophone and plume sensor were deployed on a mooring at the summit of NW Rota-1 volcano, with the help of the US Coast Guard ship Sequoia. The mooring stayed down for a year and was retrieved in February 2009. The data from both the hydrophone and plume sensor clearly showed that the volcano had been very active from February through August 2008 and less active from August through February 2009.


Ash from plume after a large burst of activity, covers the basket of instruments in front of ROV Jason.
Just after the hydrophone was recovered, the Japanese research vessel Natsushima sent their ROV Hyperdolphin to have a quick look, and they found the volcano in a state of low level eruptive activity. But volcanoes are notoriously fickle and unpredictable. What would we find when Jason reached the bottom on this visit?


Our first Jason dive confirmed the previous day’s evidence from the CTD survey that Brimstone Pit, the active eruptive vent, is still active and well named. It sits southwest of, and slightly below, the volcano’s summit and is currently at a depth of 522 m below sea level, almost 40 m higher than it was when we last visited it three years ago. The vent is about 2 m across and formed by a loose pile of lava blocks. It appears to be continuously active, emitting billowing ‘clouds’, large bubbles of gas, and an episodic rain of small lava fragments. Unlike volcanic plumes on land, however, the ‘clouds’ are not formed of steam but instead are composed of tiny dispersed droplets of molten sulfur, or brimstone, an ancient name for sulfur. The bub
bles are filled with CO2, all that remains of the magmatic gas after the original water and sulfur have condensed to liquid (water) or solid (sulfur) phases. The lava fragments provide hints of what is happening in the vent, behind the curtain of sulfur clouds.

My personal reaction to my first glimpse of Brimstone Pit was not only excitement but also amazement and awe. I am a volcanologist who has spent my career traveling the world to study active volcanoes. But this was my first experience with a volcano erupting under the ocean – an ocean that on the surface, looks unremarkable, with no hint of what is happening below. My reaction was to try to understand the activity that I was seeing on the video monitors by comparing it with volcanoes that I have studied on land, particularly the volcano Stromboli in Italy, which is also perpetually active.



'Within the 'smoke', many gas bubbles of CO2 can be seen. Typically after bubbles appear, activity at Brimstone would increase, actually shaking the ROV. (click image for full size)
Volcanic eruptions occur when magma rises from depth to the surface. On land, eruptions are explosive when magma rises fast enough for the dissolved gases to form bubbles within the magma, and then expand violently to erupt a mixture of gas (from the bubbles) and magma (which cools to form solid fragments). A common analogy for this process is the explosive opening of a pressurized bottle of champagne. In contrast, when magma rises slowly, the bubbles can escape freely and magma erupts passively to form lava flows and domes. Underwater, conditions that produce explosive eruptions are probably similar to those that operate in terrestrial environments, as evidenced by the presence of large, submarine, pumice-filled calderas, such as those south of Japan. However, when magma ascent is slow, as is the case at Brimstone Pit, the seawater alters volcanic activity in important ways, particularly because of the capacity of cold seawater to absorb heat. This has the dual effect of causing rapid condensation of many gas species (as described above) and rapid quenching of lava, which causes the magma to shatter into the small, angular fragments that we have seen raining down from the volcanic plume. The weight of the overlying water also helps to limit the energy of the activity, which allows Jason to view and sample the vent activity at close range (from only 1 or 2 meters away), closer than we will ever be able to approach explosive volcanic vents on land!


Thus, our first glimpse of Brimstone Pit on this trip shows a volcano in continuous activity, with a vent that has built to a height almost equal to the volcano’s summit and producing a eruption plume composed primarily of particulate sulfur, CO2 bubbles and lava fragments. How representative is this snapshot of the volcano’s normal range of eruptive activity? We’ll find out over the next few weeks!


Volcano Observation Videos:
All video copyright by Advanced Imaging and Visualization Lab WHOI

video
White billowing eruptive plume full of sulfur and ash coming out of Brimstone vent (no audio).



video
Clear bubbles rising from the eruptive vent are mainly CO2, while the white cloud is dominated by sulfur from SO2 (no audio).

Mapping Volcano 'Smoke'

An Eruptive Plume Above the Volcano

Sharon Walker
NOAA Vents Program





Turbidity data from the CTD tow (black sawtooth line) show a cloudy eruption plume over the volcano (reds) and clearer water elsewhere (blues). (click image for full size)


Before our first Jason dive we conducted a detailed survey of the water column with a CTDO (conductivity-temperature-depth-optical) instrument package that includes 20 large bottles for sampling the water. We want to measure the physical properties of the ocean surrounding the volcano, as well as map the extent of any plumes generated by eruptive activity and sample the water for chemical analyses. The optical sensor tells us where the most particle-laden parts of the plume are. We also have sensors that give us a general indication of the chemical variability within the plume (for pH and oxidation-reduction potential), and others that measure particle sizes. We raise and lower the CTD through the water as we tow it to distances up to 4 km away from the


Deployment of CTD on ship. Gray cylinders are water sampling bottles triggered by scientists at specific depths.
(click image for full size)
summit.

On our first CTD tow we found an intense plume over the summit, similar to what we've seen during our past visits when the volcano was erupting. This plume is so full of particles that our measurements reach values near the upper limit of our optical sensor each time we've passed near Brimstone Pit, the active eruptive vent. Our chemical sensors respond strongly near the summit too - another indication the volcano is still active. This is the first evidence on this expedition that the volcano is probably still erupting!

In addition to mapping and sampling the eruptive plume over the summit of the volcano, we are interested in finding out what is happen
ing deeper along the flanks. In 2004 and 2006, we observed multiple layers of turbid, particle-laden water surrounding the volcano at depths much deeper than the eruption site. We believe these particles were transported there due to landslides. We know that freshly erupted material accumulates on the steep slopes around the active vent and can become unstable. When it becomes unstable it slides down the flanks of the volcano, sending clouds of finer particles off into the surrounding ocean. It is interesting that we have not seen any deep particle layers so far during our CTDO tows this visit, suggesting that no slides have happened recently.

We don't know how often these slides occur or
what sorts of events trigger them, but we've come this time prepared to try to answer that question. We will be deploying instruments that will stay here for the next year and measure any turbidity layers deep along the flanks that might develop. Current meters will monitor the currents around the volcano and a hydrophone will let us know when eruptions occur and how intense they are. We hope we will catch one or more slide events in the act and be able to find out what triggers them.

View a slide show of the CTD instrument being launched from the R/V Thompson:

video

Departure from Guam




Tumon Bay, Guam

After months of preparation, we left Guam this morning on the R/V Thompson headed to NW Rota-1 volcano where we will be making dives with the Jason ROV or the next 2 weeks. The first thing we will do is to deploy transponders (acoustic beacons that help Jason keep track of its location on the seafloor). Next we will resurvey NW Rota-1 with the ship's multibeam sonar system to look for any depth changes since our last survey in 2006. A previous comparison between bathymetric surveys in 2003 and 2006 showed up to 40 m of depth change from the accumulation of deposits downslope of the eruptive vent. After that, we will collect the first of many tows with a CTDO (Conductivity, Temperature, Depth, Optical) sensor, an instrument package that shows us if there is an eruptive plume above the summit and/or any deeper turbidity plumes from any recent landsliding of eruptive deposits down the flanks (both of which we have seen during previous visits). Finally, we will make our first dive with the Jason ROV to see what the volcano is doing now. Will it be erupting? Or slumbering? We all hope it will be the former, but won't know until then.

Science Meeting:


University of Guam Student Visit:

Dr. Verena Tunnicliffe, a deep-sea vent animals expert (University of Victoria), discusses the upcoming expedition with the students in the Computer Lab of the R/V Thompson (above). Dr. Bob Embley (NOAA Vents Program) who has been studying the geology of this area with ROVs and sonar systems since 2003, arranged the visit with Dr. Ernie Matson of the University of Guam Marine Lab.

Cruise Plan


The plan for this cruise is quite simple: we will be studying a submarine volcano named NW Rota-1, located about 100 km (60 miles) north of Guam, who's summit is at a depth of 520 meters (1700 feet) below the ocean surface. This submarine volcano is very unique because it has been found to be actively erupting every time it has been visited (about once a year) since 2003. In fact, this is the only site in the world where deep underwater eruptions have been directly observed and recorded by hydrophone. The pressure at this depth makes it safe to study the eruptive activity up-close. With support from the US National Science Foundation, we hope to take advantage of this extraordinary opportunity to learn more about how submarine eruptions work and how they effect the surrounding ocean environment. Incredibly there are hydrothermal vent animals that live on top of the volcano in the midst of these eruptions.
We do not know exactly what we will find when we visit the volcano between April 3-17, 2009, but we have an extraordinary team of scientists and engineers poised to make the most out of this scientific opportunity. We hope you will follow along on this exciting adventure!

- Bill Chadwick, Chief Scientist, Oregon State University

Videos from the Expedition



video
White billowing eruptive plume full of sulfur and ash coming out of Brimstone vent (no audio).



video
Clear bubbles rising from the eruptive vent are mainly CO2, while the white cloud is dominated by sulfur from SO2 (no audio).



video
Various types of filamentous microbial mat wave in the current on a vertical cliff near the summit of NW Rota-1. (no audio)



videoA rocky outcrop on a ridge of the volcano provides habitat for two species of shrimp adapted to live at hydrothermal vents. (no audio)



videoThe smaller shrimp species is a grazer while the larger one is a carnivore. The smaller grazers get out of the way as a larger carnivore walks through a crowd. The carnivore species uses its large claws in aggressive displays. (no audio)



videoA funnel attached to a “gas-tight” sampler is used to collect gas bubbles rising from the eruptive vent. (no audio)



videoThis time-lapse movie shows lava rising and pushing previously erupted blocks to the side in the vent over a time period of an hour and a half. The areas of the most intense degassing are where new lava is actively erupting (no audio.





videoWatch closely as recently erupted (and already degassed) lava on the right side of the vent is shoved aside as new lava rises behind it and vigorously degasses.



video

Time-lapse movie of the seafloor shaking and rocks being shoved away from the eruptive vent just before Jason moved out of the way (speeded up 4 times, no audio).




videoThe same video clip as above at normal speed (with audio).



videoJason’s manipulator arm holds a long intake tube designed to sample the hot fluids and gases coming out of the Brimstone eruptive vent. However, boiling seawater and molten sulfur make the sampling difficult.



videoMolten sulfur sticks to the intake tube and has clogged the fluid sampler on this dive. Fluid samples from the eruption plume were successfully collected on later dives.



video
Jason approaches the Brimstone eruptive vent at the top of the new 40-meter high cone (no audio).



video
Jason prepares to sample the eruption plume as ash rains down on the vehicle. Later a curtain of CO2 bubbles rises in front of the camera during another eruptive pulse.



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The seafloor shakes and heaves as new lava forces its way to the surface.



videoAsh explosively erupts from Brimstone vent as Jason prepares to place a temperature probe in the plumea temperature of 210° C (410°F) was where measured.

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