May 11, 2009

Eruption!!

West Mata is erupting!

Hades eruptive site at West Mata
Joe Resing, Chief Scientist.
West Mata volcano is erupting! We have seen pillow lavas, pyroclastic (magmatic gas breaks apart the lava) and phreatic (lava flows over water which turns into steam which breaks apart the rock), events. It is incredible. Here is one picture; we hope to get some video footage out as soon as possible. This dive is still happening and we have been in the water for about 3.5 hours. Less than 24 hours after leaving port, we have located on the seafloor an ongoing eruption that we first detected several months ago on a water-column mapping cruise (November 2008).

All high-definition video by Advanced Imaging and Visualization Lab, copyright WHOI

We Thought We’d Seen it All

Prometheus eruptive vent at the summit of West Mata (1208 meters)


Bob Embley: Co-Chief Scientist
Joe Resing: Chief Scientist

Five years ago we came across our first view of an active submarine eruption at NW Rota-1 volcano near Guam in the western Pacific. It amazed and astounded us to see volcanic bombs and gas bubbles being injected from Brimstone Pit (the volcanic vent). On our return visit in April of this year, we saw lava being extruded from the pit. We all felt very fortunate to witness these phenomena for the first time.

Hades eruptive vent at the summit of West Mata (1174 meters)

From results of our initial surveys in the NE Lau Basin in November 2008 we suspected something similar was occurring on West Mata, a small submarine volcanic cone in the northern Lau Basin, about 200 km southwest of Samoa. However, nothing prepared us for the sights we saw on the summit of this volcano - our first dive on the site today using the remotely operated vehicle Jason 2 nearly overwhelmed our senses with a collective gasp. Here, at a depth of 1208 meters (almost 4000 feet), we saw for the very first time pillow lavas flowing from a deep submarine volcano at a site we are now calling Hades. In contrast to Brimstone Pit, we could not approach close to this site because it was undergoing violent explosive activity and almost continuously shedding large blocks of lava as well as pillow flows. On our first approach we saw red glows from the extruding lavas up to 5-10 meters away from the vent!

We were due for another surprise. About 100 meters along the summit from Hades our sonar started showing some very strange echo returns from something to the north of us. As we turned toward it there was another billowing plume! Descending to this site another vent revealed itself as a cinder cone spewing volcanic bombs and ash! As we sat there, a red glow appeared and persisted for about 30 seconds as hot magma and gases were expelled. Wow! Have we seen it all yet? I very much doubt it!

Tomorrow we return to explore the site further…. Stay tuned.

All high-definition video by Advanced Imaging and Visualization Lab, copyright WHOI

Biological Discoveries

A biological sorting tray of recently collected specimens, including shrimp, mussels, and crabs.

Tim Shank

Our exploration of the West Mata Volcano during our first two dives yielded exciting new discoveries of active volcanic eruptions, exploding hydrogen, high-temperature venting, and lava flowing downslope as newly-minted pieces of rock debris fell like rain around our vehicle, Jason-2. Normally, venting water contains nutrients that feed thriving oases of diverse forms of life, including large tubeworms, clams, mussels, and crabs. However, at West Mata, there is a notable absence of any attached or even “slow-moving” animals on the seafloor- no tubeworms, no clams, no mussels. The active creation of new seafloor and volcanic activity may prevent these animals from ever establishing themselves here. In fact, even highly-mobile animals like crabs have not been observed (and only two fish, so far). Interestingly, so far, the diffuse venting fluids (~5 to 25°C), issuing through cracks and crevices around the eruptive vents, play host to only one type of vent fauna - shrimp. Hydrothermal vent shrimp are known to inhabit vent sites throughout the world. The two species we have encountered are abundant (analogous to the density of microwave popcorn kernels strewn over a sofa), apparently grazing on microbes growing on the rocks and in the venting fluids, and they appear to be similar to shrimp seen at known vent sites a few thousand kilometers to the south.

Our subsequent exploration of the Northeastern Lau Spreading Center (NELSC) has yielded two active vent fields that host foot long tubeworms, mussels, crabs, several species of small snails and shrimp, as well as vent-endemic fish. While our round-the-clock processing of these collected animals (now more than 700 individual animals from more than 14 species) is less than 48 hours old, our initial examination of these animals suggests that we may have collected organisms that may best be described as new species. One thing that is certain is that each dive has yielded new biological discoveries. As I write, we are planning our third dive to explore the eruptive West Mata volcano for additional biological communities.

A congregation of shrimp at West Mata in an area of diffuse hydrothermal venting.

All high-definition video by Advanced Imaging and Visualization Lab, copyright WHOI

NELSC "Puipui" Eruption


Young curtain lava flow draped and folded over the landscape

The Puipui eruption of Northeast Lau spreading center

Ken Rubin

Most of Earth’s volcanic activity happens beneath the sea, sight unseen, sound unheard. It’s really rare to witness these eruptions, either accidentally or by design, so when marine scientists catch a whiff of one, we’ll go to extraordinary lengths to locate and observe it. Five months after the email message came in that the NOAA Vents group had discovered spectacular particle plumes rising up to 600 m (~2000 ft) above the sea bed at a site in the Northeast Lau Basin, here we are, looking for the eruption that made them. It turned out there were two eruption sites, one of which is still active, at West Mata volcano and one which is not, at the Northeast Lau Spreading Center (NELSC). Both sites are fascinating places to work. At NELSC, where some might see a seemingly endless sheet of dull black rock that isn’t moving and glowing anymore, isn’t venting hot water, and isn’t teeming with animals, the geologist in me sees cascading lava falls and swirling sheets and rivers of liquid hot magma.

We are calling the NELSC lava flow “Puipui”, meaning curtain in Tongan, because of the distinctive way the lava draped and folded itself over the landscape. The Puipui eruption is interesting because of the range of lava forms we observed over short spatial distance, which resulted from a combination of steep topography, gas rich and fluid magma, and what was apparently an intensely fast lava effusion event. Driving Jason along the lava flow, we saw first hand how important the pre-eruption land surface was for controlling where and how the young lava flowed. It only took 4 to 5 feet tall ridges of old rock to dam the Puipui lava flow in places, where it flowed in thin flat sheets between the high ground. Nearer the volcanic vents, which appear to sit along a narrow ridge, lava cascaded 30 feet or more down steep rock faces, forming sheets of lavas that look like curtains draped over the sea floor. In other places, the lava ponded, crusted over on top, and then drained out, leaving collapse pits that reveal hollow chambers roofed by lava shells held up by pillars of fresh lava rock.

We’re done observing Puipui for now, but the real work has yet to come. There are maps to pour over, and a hundred or so pounds of rocks to take back to the lab. The rocks will be used to learn how magmas form in this location and when they erupted, which will help us understand a little more about deep submarine eruptions.

All high-definition video by Advanced Imaging and Visualization Lab, copyright WHOI

West Mata Eruption Comparisons

Dave Clague

The two Jason dives at West Mata volcano discovered not just one active volcanic vent, but two. The first and deeper vent, named Hades vent, on the southwest rift was erupting both effusively and explosively at the same time on both days. Small bursts were occurring at one end of an erupting fissure perhaps 5 meters long while pillow lavas were being extruded from the other end. By the next night the activity had become more vigorous, sometimes blowing glowing bubbles as much as a meter across. The second shallower vent, named the Prometheus, was located very near the summit of the volcano and about 100 meters away from the first vent. The eruption here was entirely explosive with low-level, but nearly continuous fire fountains throwing ejecta into the water during both dives. Both vents were obscured much of the time by billowing sulfurous gas emissions, but bright orange lava was seen in both vents. The orange glowing lava was visible for minutes at a time. Clear carbon dioxide bubbles were not observed at or near the vents, in contrast to their abundance at NW Rota-1 volcano in the Marianas arc, which was visited just last month by many on board this expedition.

West Mata Dive 1

It is 4:00 am and we have arrived at West Mata Volcano and the Jason-2 ROV is in the water. Dive one is under way. We expect to have an 8 hour dive. Everyone is quite expectant. We are less than 24 hours out of port and we are in the water. Amazing. The Jason group has worked very hard. What will we see? Pictures and updates later.

In the picture below the Jason group is busily preparing the robot for deployment.

Farewell Samoa

To Fa Soifua or farewell to Apia Samoa
We have departed Samoa and are underway to explore the two volcanoes, West Mata and the Northeast Lau spreading center. They say time is relative and that is true in Samoa. To leave the harbor we need to hire pilots to steer the ship. Although we were scheduled for 8am, they arrived at 9am. We departed and our pilots have left us. Our next task for this day is to fine tune our navigation so that we can track our robot (remotely operated vehicle or ROV) Jason-2 and our autonomous underwater vehicle (AUV) D. Allan B. We are about to do this now. We will place a sound beacon (transponder) on the seafloor and will then talk to it from the ship, whose position is derived from satellites. We then talk to our beacon while driving a pattern with the ship. This information allows us to determine where the beacon is. After some fancy mathematical calculations have been completed, we will be able to track Jason-2 and D. Allan B using beacons (transponders attached to the vehicles).

The End of The Cruise

The NE Lau Response Cruise Science Party

Joe Resing

This is the end of a very successful cruise. Within an hour or so of our first dive, within 20 hours of leaving port, we made observations never before seen. We witnessed red molten lava flowing on the seafloor. Volcanic rock formations, especially pillow basalts, are one of the most common rock forms on Earth’s surface and, yet, we had never seen their formation in the deep ocean. Volcanic rocks circle the globe along lines of volcanoes called mid ocean ridges and the seafloor has many individual volcanoes as well. In fact, more than 80% of the volcanic eruptions on planet Earth are under water, generally out of sight. For more than 25 years we have been trying to make these observations. Here, in the seven days of this cruise we have finally seen active extrusions of lava on the seafloor. We have seen explosions with flashes of light. We have seen molten rock forming new earth. We have made completely new observations that will allow us to better understand fundamental processes shaping our Earth. Strangely, these new volcanoes and the toxic gasses that they emit are host to organisms and microbes. We collected these biological specimens and look forward to understanding how they cope with this environment.

We have a research mechanism in place called “time critical studies.” We have responded to many eruptions, only to arrive well after the eruptions had ended. The question was asked, “Is there anything else we can learn from these studies?” Our answer today is “Absolutely yes!” It is clear that planet Earth has much left to reveal, and we have much to learn about our home. We live on an amazing planet. It is dynamic and beautiful. But we are not yet finished, and hopefully someday I will again be a part of revealing something new to you.

I would like to thank all those who made this happen so quickly. We discovered this eruption in mid-November of last year by examining the water above the volcanoes. Amazingly, less than six months later we were able to arrange ship time, Jason-2 robotic remotely operated vehicle time, and funding to come out here to make direct observations of the seafloor. We were allowed to move ship schedules and Jason-2 schedules. We were able acquire funding from the National Science Foundation and the National Oceanographic and Atmospheric Administration. Through the Ridge 2000 and Margins Programs we engaged in three months of concentrated effort and community organizing. Was it worth it? Absolutely.

Background


This mission is aimed at exploring the sites of recent eruptions in the NE Lau Basin. The NE Lau Basin is located in the Southwest Pacific within the triangle formed by Samoa, Tonga and Fiji. This area is home to many submarine volcanoes and very few of them have ever been explored. In November 2008, the NOAA-PMEL Vents program discovered two on-going eruptions in this area, one at W. Mata Volcano and the other on the NE Lau spreading center (NELSC). West Mata volcano (~15̊.1 S, 173̊.7 W) appears to have formed on a tear in the ocean's crust, and may represent the initial stage of the formation of an arc volcano. It may also be producing unusual lavas (boninites) that previously have only been observed at old, inactive, volcanoes. The NELSC is a back arc ridge. An eruption along a back arc ridge has never before been detected, making this a valuable opportunity to explore newly formed ocean crust, hydrothermal vents, and biological communities.

We will explore the sites of these two eruptions from May 5th to May 13th, aboard the University of Washington’s Research Vessel T.G. Thompson. We will be using the Remotely Operated Vehicle (ROV) Jason 2 and the Autonomous Underwater Vehicle (AUV) D. Allan B. The Jason 2 will collect samples of rocks, hot spring waters, microbes, and macro biological specimens. The D. Allan B. will deliver high-resolution maps of the eruption sites.

This cruise represents an incredible opportunity to understand some exciting but unknown facets of our dynamic planet, Earth. Our planet is the most dynamic one in the solar system. Active volcanoes constantly build and reshape the Earth’s crust, providing energy and nutrients that nourish life. Strangely, while we visit our Moon, the planet Mars, and other planets, the submarine portions of our planet remain remarkably under-explored and therefore relatively unknown.

West Mata Volcano


West Mata volcano is located in an unusual location between the Tafua arc and the subducting trench. This volcano and its neighbors are elongate with two long rift zones running in the same orientation as the tears in the ocean crust beneath them. In November, W. Mata was draped in fresh clastic debris from its summit to its base, with old lava flows ponded at the ends of each of the rift zones. We are uncertain if magma from the back arc or the volcanic arc feeds W. Mata, although its location closer to the arc front suggests it is the dominant source. A rare lava type called boninite has been recovered in dredges in the area to the northwest of W. Mata. The eruption was discovered by detecting an intense cloud of particles rising ~175 m above its summit at 1200 m depth. We judged the volcano to be actively erupting during our sampling because the cloud contained enormous concentrations of hydrogen (> 9000 nM) and abundant sharp-edged rock shards. Extremely high levels of hydrogen are generated when molten rock and water come in contact. The rocks then explode into countless pieces (or clasts), and the finest of these particles rise with the cloud. The same process forms the ash clouds commonly seen over erupting volcanoes on land. Many of these characteristics are similar to those at NW Rota-1 in the Mariana arc, which has been undergoing continuous submarine eruption for at least 5 years. The summit of W. Mata is about 800 m deeper than NW Rota-1 so eruptive processes are likely to differ due to the greater pressures at W. Mata.

Northeast Lau Spreading Center (NELSC)



The NE Lau spreading center is located on a spreading ridge in a back arc basin and its eruption would represent the first documented eruption in this setting. Our first clues that unusual activity was taking place along this volcanic ridge were the observations of clouds of particles (plumes) rising 800-1000 m above the sea floor. These plume rise heights are a strong indicator of seafloor eruptions, and, as at W. Mata, the plumes contained elevated levels of hydrogen and high concentrations of volcanic glass shards. This site differs from West Mata in that it is part of a semi-continuous system of back-arc “spreading centers” that have been forming in the Lau Basin as the result of the subducting plate to the east pulling away from the Australian plate to the west. These spreading centers generate new ocean crust just as happens along the globe-encircling Mid-Ocean Ridge, but we know little about the volcanic and hydrothermal systems that drive their formation and the biologic systems that feed off the hot hydrothermal effluent. This expedition will be the first to investigate a newly erupted site on a back-arc spreading center where the geologic and biologic “clock” has been “reset” by an eruption, and, like similar studies at the Mid-Ocean Ridge over the past 20 years, we will very likely be surprised and excited by what we will find.


video
3-D fly-through over Northeast Lau Basin. The EM300 bathymetry (colored) were collected on the November expedition. The data are 1.5 times vertically exaggerated. The fly-through starts at the southern end of the NELSC heading north along the spreading center. Then the flight zooms in on West Mata, approached from the south and then circling around to the north. The final image is looking from the north toward the south.

Partipating Organizations

This project is a joint venture between the National Science Foundation (Ridge 2000 and Margins) and the National Oceanographic and Atmospheric Administration (Ocean Exploration and the Pacific Marine Environmental Laboratory). It is a community-wide effort that involves multi-disciplinary and inter-disciplinary discovery and hypothesis testing that meets the goals of each of these programs. A wide range of scientific disciplines are involved in this project including macro- and micro-biologists, rock chemists, water chemists, geophysicists, volcanologists, and oceanographers. Scientists working at many organizations will participate at sea and ashore. The scientists working at sea come from the Monterey Bay Aquarium Research Institute, Woods Hole Oceanographic Institution, The Marine Biological Lab, Pennsylvania State University, Portland State University, Western Washington University, University of Washington, Oregon Sate University, the University of Hawaii, and the National Oceanographic and Atmospheric Administration’s Pacific Marine Environmental Laboratory. Scientists participating in a shore-based capacity are from Harvard University, University of California, Santa Cruz, University of Michigan, University of Tulsa, and Moss Landing Marine Laboratory.