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September 24, 2012

Today we returned to West Mata for the second dive of this expedition to explore in more detail and collect additional samples. It was two years ago at this site that we observed actively erupting volcanic vent sites, Hades and Prometheus. When the ROV reached the ocean floor, we saw sands, rocky fragments and talus shoots, and in-place pillow lavas.  We observed the rim of the new Hades pit and now have evidence that strongly suggest that the pit was formed by collapse due to shut off of the magma supply, rather than an explosive crater-forming event. We also observed rubble, fresh pillow lavas, and steep remnant volcanic crags colonized by large numbers of shrimp. Evidence of slope failure was also seen, along with in-place young pillow lava overlying older rock. Vertical dikes, breccia pipes and horizontal lava flows gave us a first rate “cut-away” view of the inside of a volcanic vent complex. Lava samples, water and sediment samples, and shrimp were collected.

 


 

Snails, crabs and scale worms on a chimney at Mata Tolu.

Snails, crabs and scale worms on a chimney at Mata Tolu. Click image for larger view and image credit.


September 23, 2012

We found an array of beautiful features during our visit. We discovered an active hydrothermal system surrounded by a large area of currently inactive chimneys that covered an area roughly the size of an American football field.  Some formed tall individual spires and others in clusters like the roof line of a gothic cathedral. Pockets of extensive biological colonization included crabs, snails, shrimps, fish, and worms around some of the chimneys. This dive had something for everyone, and the ROV team showed their skill as usual, as they collected a wide array of geological, hydrothermal and biological specimens for the Submarine Ring of Fire NE Lau Basin 2012 Expedition team.

 


 

Beautiful large tubeworms, some of which we collected were a meter in length and an centimeter in diameter at the opening to their tube, were seen for the first time at this site.

Beautiful large tubeworms, some of which we collected were a meter in length and an centimeter in diameter at the opening to their tube, were seen for the first time at this site. Click image for larger view and image credit.


September 22, 2012

We visited both the deepest and shallowest volcanoes of our expedition on the dives to Mata Fitu (2600m depth) and Niua North (700m depth); we were approximately 1.5 miles deep in the ocean at the first site, while less than a half a mile deep at the second. Mata Fitu appears to be split down the middle by a large fault created by movement of the ocean crust, while Niua N. is an arc volcano that has forced its way up through much older crust. Even more striking than the differences in geological settings were the observations made when we arrived on the seafloor. Mata Fitu exhibited a stunning display of high temperature hydrothermal activity, with pagoda-shaped chimneys everywhere. Niua N., on the other hand, had no chimneys. Instead it had jets of sulfur shooting out from many holes in the sediment-covered seafloor. When the sediments were disturbed, carbon dioxide was released into the water column as small droplets of liquid that rose up slowly above the remotely operated vehicle. Although both sites hosted biological activity, there were great differences between them. These two sites were as different as any two explored on our voyage of discovery.

 


 

September 21, 2012

Mata Fitu Volcano is the northernmost of the Mata chain. Following a tow-yo and camera tow in 2010, clear evidence of a strong hydrothermal, including high temperature black smokers, had been identified on the southeast flank at about 2600m depth. Using the Quest 4000 ROV, we planned to sample the volcanic rocks forming the deep flank of the structure, and then move shallower to intercept the strike of the putative vent sources. In the result, the plan worked perfectly: fresh pillow lavas and tubes, then highly varied chimneys ranging from low temperature shimmer through squat chimneys emitting clear fluids at ~50°C, to slender towers up to 18m tall jetting black smoke accompanied by flashing at the vents, with orifice temperatures of at least 350°C were found there. The fauna surrounding these vents is diverse; including barnacles, anemones, holothurians, shrimp, crabs, and fish. Chimneys within meters of each other support markedly varied permutations of these colonisers.

 


 

Video showing black smoker chimneys found on the second dive at Mata Ua.

camera icon Video showing black smoker chimneys found on the second dive at Mata Ua.


September 20, 2012

Scientists celebrated today as the hydrothermal vent sources of the large plume on the northwest slope of Mata Ua were successfully located as a result of many long hours conducting CTD tow-yos, vertical hydrocasts and analyzing the resulting water column data collected over the past 24 hours. The CTD data helped narrow our search area using the Quest 4000 ROV and we discovered a large vent field of black smoker chimneys. The chimneys displayed a wide range of sizes, shapes and colors. Similarly, some chimneys were densely colonized by vent organisms while others were less so. Not previously seen on this expedition to date were dense clusters of stalked barnacles on the seafloor and on the chimneys. Many other organisms were observed within each barnacle cluster. Close-up views of the barnacles gracefully filter-feeding on the sides of the black smoker chimneys was truly stunning. Please stay tuned!

 


 

Dense concentrations of shrimp, many of which were gravid (egg bearing) at West Mata.

Dense concentrations of shrimp, many of which were gravid (egg bearing) at West Mata. Click image for larger view and image credit.


September 19, 2012

Today, we returned to West Mata, the volcano that exploded violently in 2009, enabling scientists to witness, for the first time, lava actively spewing from sources deep within the Earth. Pillow lava tubes and angular lava rocks were seen along the steep, unstable summit slope. Large vertical dikes were also seen nested within the summit wall. The collapse of the southeast side of the summit, which scientists expect is the “major event” known to take place here in the past year and a half and are hopeful is recorded on the hydrophone recovered two days ago, produced a large pit crater on the summit. The once very focused volcanism witnessed here in 2009 has been replaced by diffuse flow of hydrothermal fluid, evidenced by the types of organisms observed here now. Later in the dive, the ROV came upon extremely dense concentrations of shrimp – perhaps some of the most dense concentration of shrimp observed at a hydrothermal vent site exhibiting diffuse flow such as that found at West Mata today. Many of the shrimp were gravid (egg bearing). Where did they come from? How did they get here? How long have they been here? Biological, geological, water and chemical samples were collected to help us answer some of these – and many other - questions.

 


 

The tops of two active chimneys discovered at Niua South.

The tops of two active chimneys discovered at Niua South. Click image for larger view and image credit.


Niua volcano proposed remotely operated vehicle dive sites indicated by black circles. 200 meter contour interval. EM300 and EM122 multibeam bathymetry grid cell size is 35 meters.

Niua volcano proposed remotely operated vehicle dive sites indicated by black circles. Click image for larger view and image credit.


September 18, 2012

After two days of bad weather when we couldn’t dive, the Quest 4000 ROV got back in the water today and made a dive at Niua South Volcano, the northern-most in the Tofua arc. The ROV explored a crater that was about 200 meters across and about 30 meters deep. At the center of the crater was a large sulfide mound, about 20 meters high and 50 meters wide, representing deposits formed during many years of high-temperature hydrothermal venting at this site. Most of the mound is now inactive but at the top we found a spectacular black-smoker vent, consisting of a cluster of about 20 active chimneys that had all grown together. The ROV sampled the vent fluids and gases coming out of the chimneys as well as a few pieces of the sulfides. Animals living at the vent included at least two species of shrimp, scaleworms, crabs, eelpouts, and barnacles.

 

 

 

 

 


 

Scientists and crew on starboard side of R/V Roger Revelle standing by to recover the buoy and mooring to which the hydrophone and other instrumentation is attached near W. Mata.

Scientists and crew on starboard side of R/V Roger Revelle standing by to recover the buoy and mooring to which the hydrophone and other instrumentation is attached near W. Mata. Click image for larger view and image credit.


September 17, 2012

Weather again precluded a dive for the ROV Quest 4000. To maximize the use of limited time at sea, the decision was made to recover a “hydrophone” or underwater microphone and other instruments on a vertical mooring deployed near W. Mata almost two years ago. Hydrophones are designed to listen for the range of sounds typically given off by underwater volcanoes. Scientists are especially excited about the data collected by the hydrophone recovered today because they know that the volcano underwent a major event sometime in 2011 and are hopeful that it contains critical new information about the nearby submarine volcano, West Mata. Analyses of the hydrophone recordings at the lab will hopefully reveal the critical information the scientists are looking for. CTD and multibeam mapping continued to further refine what we know about the ocean floor in this most intriguing area of volcanism in the NE Lau Basin.

 


 

Mata Tolu at about 1,820m depth is one of the shallowest of the Northern Matas.

Mata Tolu at about 1,820m depth is one of the shallowest of the Northern Matas. Click image for larger view and image credit.


September 16, 2012

Inclement weather prevented the Submarine Ring of Fire NE Lau Basin 2012 Expedition team from diving with the Quest 4000 ROV today on Mata Tolu (number 3 in Tongan), the shallowest of the Northern Matas. A towed camera that passed over Mata Tolu in 2010 revealed some large sulfide chimneys and swarms of shrimp near the summit at about 1820m. The day was spent conducting multibeam mapping and CTDs, catching up on logging entries and some data analyses. Mata Tolu is our next planned exploration dive site, but if the current weather pattern causes more loss of dives, we could be forced to reevaluate dive site priorities.

 


 

We have at least three targets in the northern Matas which are named consecutively from south to north by their Tongan “number” name, i.e., Mata Taha (one), Mata Ua (two), etc.  To date we have identified at least 5 active hydrothermal systems on these small volcanoes using a towed CTDO and camera systems.  Seafloor images of active vents, biology and hydrothermal deposits have been taken on three of them (Mata Ua, Mata Tolu and Mata Fitu).

We have at least three targets in the northern Matas which are named consecutively from south to north by their Tongan “number” name, i.e., Mata Taha (one), Mata Ua (two), etc.  To date we have identified at least 5 active hydrothermal systems on these small volcanoes using a towed CTDO and camera systems.  Seafloor images of active vents, biology and hydrothermal deposits have been taken on three of them (Mata Ua, Mata Tolu and Mata Fitu). Click image for larger view and image credit.


September 15, 2012

The Quest 4000 made it first dive on one of the small volcanoes in the northern Matas which are named consecutively from south to north by their Tongan “number” name, i.e., Mata Taha (one), Mata Ua (two), and so on. Today’s dive was at Mata Ua Volcano and was the deepest dive of the expedition so far. Mata Ua has never been explored by an ROV before, but a survey two years ago found an intense hydrothermal plume just below the summit. The purpose of today’s dive was to try to find that hydrothermal vent site. Elongated pillow lava, rocks and the cloudy water of the plume transitioned to sediment with white deposits, which was evidence of recent hydrothermal flow. As we continued to search for active venting, the summit became so steep that at times the ROV was rising up a vertical wall.

As the ROV descended down slope to another search area, the water began to appear uniformly cloudier, indicating that we were returning to the depth interval of the plume. Towards the end of the dive, we started to get more indications of proximity to the vent source(s), including squat lobsters, polychaetes, eelpouts (deep-sea fish from the Family Zoarcidae) and a synaphobrachid eel (a deep-sea fish from the Family Synaphobrachidae). Small sponges and surpulid worms, typical of the type seen on the outskirts of vent systems, were also observed. Unfortunately, we ran out of time and had to end the dive before we found the source(s) of the venting. A scientist from within the ROV van remarked after one of the last observations of the organisms at the site, “If only they could tell us which way to go…..”.

The Mission Log of the dive at Mata Ua will be posted on the website tomorrow. In today’s log, we have more to share about Volcano O! Please stay tuned.

 


 

Clusters of what appear to be polysaccharide sacs on the seafloor seen at the beginning of the dive at Volcano O.

Clusters of what appear to be polysaccharide sacs on the seafloor seen at the beginning of the dive at Volcano O. Click image for larger view and image credit.


September 14, 2012
1619 GMT
Wind – NE @ 5 kts
Air Temperature - 25.9°C (78.7°F)
Sea State – 2.2 m

The Submarine Ring of Fire 2012 NE Lau Basin exploration team onboard the R/V Roger Revelle explored Volcano O today, one of the largest submarine calderas discovered on Earth to date. Shortly after arrival on the seafloor with the Quest 4000 ROV, we observed what appeared to be rubble held together by gelatinous mats which gave a carpeted appearance to the seafloor. What appeared to be clusters of polysaccharide sacs were also observed. Particulate sulfur formed a fog which was suspended over the seafloor in some areas. The ROV flew over an area on the western flank that appeared to have downward flows of recent molten sulfur. Once reaching the summit of the cone, we observed extremely intense clouds of sulfuric gases venting from the large pit at the top of the cone. Multiple attempts were made to enter the pit with the ROV to identify the source(s) of the sulfuric gases, however, the “smoke” was so thick and widespread that we were unable to locate the potential source(s) before the end of the dive. What was also interesting about this site is that very little macrofauna was observed as compared to previous dives, likely due to the caustic environment at this site.

 


 

Map of Vai Lili dive and sample sites. The black lines are contours representing depths in meters. Bathymetry resolution is 0.5 meters.

Bathymetric map showing main features of Volcano O. Click image for larger view and image credit.


September 14, 2012

Volcano O -This is one of the largest submarine calderas discovered to date, measuring about 10 km with 500 m of relief. A caldera is a large depression, usually circular or sub-circular, formed by collapse of the summit of a volcano following a large eruption of lava and/or explosive products. The “O” caldera is circular, with several very distinct concentric ring structures within the primary high relief walls.  Linear “rift” zones extend SW and N, respectively, from near breaches in its southwest and northern outer walls.  Extensive lava flows, defined by high acoustic backscatter zones, extend up to 10 km from the breaches.  High- temperature, sulfide-depositing hydrothermal systems occur at and near the intersection of the inner ring faults with the north and south rift zones. Vigorous sulfur-rich diffuse venting occurs at the summit of a young constructional post-caldera cone near the center of the caldera. Our first dive will investigate this intriguing feature and its ecosystems.

 


 

Large chimneys discovered at Fonualei Rift. The site was named Laloa Kakai today by the Submarine Ring of Fire 2012 exploration team, which translates to “tall people” in Tongan.

Large chimneys discovered at Fonualei Rift. The site was named Laloa Kakai today by the Submarine Ring of Fire 2012 exploration team, which translates to “tall people” in Tongan. Click image for larger view and image credit.


September 13, 2012

The Submarine Ring of Fire 2012 NE Lau Basin exploration team onboard the R/V Roger Revelle dove at Fonualei Rift today. Shortly after arriving on the seafloor, small lava towers approximately 5-10 m in height with steep walls rising from the seafloor came into view. A second exploration area revealed large expanses of dead mussel shells (the majority with valves closed) and gastropods shells at the base of several sulfide chimneys.  At the final area explored at Fonualei South, we observed white bacterial mats, overlaying mixed lavas and sediment with occasional pillow lava formations. Shimmering water was also observed in a few places, and generally, the water appeared to be murky. As the Quest 4000 continued to explore the site, a most spectacular vent field came into view with large chimneys reaching 35-40 m in height in proximity to each other at a depth of 1,555 m. The site was given the name today of Loloa Kakai, which means “tall people” in Tongan, evocative of the thin, tall chimneys formed near each other found there.

 


 

September 12, 2012

The Submarine Ring of Fire 2012 NE Lau Basin exploration team onboard the R/V Roger Revelle continues towards its second target site, S. Fonualei. A live webcast was conducted from the ship with The Exploratorium in San Francisco, a world-renown museum of science, art, and human perception. The webcast highlighted the reasons for exploring the most volcanically-active region of innerspace, the ocean, with the Quest 4000. This webcast followed a series of webcasts conducted by The Exploratorium focusing on the Mars Rover, curiosly, as it explored the surface of Mars.

Later in the morning, the science team met with the ROV team for an overview of the capabilities and assets of the vehicle, as well as a brief on the display screens in the ROV Video Viewing Lab and the ROV Van. Using multibeam sonar today, a new underwater caldera was discovered and dubbed First Volcano. The water column above the caldera was sampled with the CTD.

Scientists map a new underwater caldera, dubbed First Volcano, discovered using multibeam sonar.

Scientists map a new underwater caldera, dubbed First Volcano, discovered using multibeam sonar. Click image for larger view and image credit.


The science team meets with the ROV team to discuss video and navigation displays for the Quest 4000 ROV.

The science team meets with the ROV team to discuss video and navigation displays for the Quest 4000 ROV. Click image for larger view and image credit.


September 11, 2012

The Submarine Ring of Fire 2012 NE Lau Basin exploration team onboard the R/V Roger Revelle arrived at its first dive target Vai Lili, on the Valu Fa ridge, in the Lau Basin in the early morning hours of September 11th.  The ROV Quest 4000 was successfully deployed off the stern of the ship and arrived on the seafloor at a depth of 1,741m (5,710 ft) at 2208 GMT (0800 local Samoa time) for the first dive of the expedition. A total of three sites were visited, where successful collections of bacterial mats, sediment, temperature, gases, and water samples were made. The Quest 4000 was secured on deck at 0720 GMT (2020 local Samoa time).  Sample processing continued throughout the evening as the ship transits for its second dive site of the expedition, S. Fonualei.

Orange and black materials are iron-oxide and manganese encrusted microbial mats, respectively.

Orange and black materials are iron-oxide and manganese encrusted microbial mats, respectively. Click image for larger view and image credit.


Bathymetric map of Fonualei Rift and Spreading Center.

Bathymetric map of Fonualei Rift and Spreading Center. Click image for larger view and image credit.


 


 

Map of Vai Lili dive and sample sites. The black lines are contours representing depths in meters. Bathymetry resolution is 0.5 meters.

Map of Vai Lili dive and sample sites. The black lines are contours representing depths in meters. Bathymetry resolution is 0.5 meters. Click image for larger view and image credit.


September 10, 2012

The Submarine Ring of Fire 2012 NE Lau Basin exploration team continued its transit onboard the R/V Roger Revelle towards its first dive target, Vai Lili.  A science team meeting was held to discuss dive sites and sampling regime needs of each science team. The University of Bremen-based ROV team continued preparations of the ROV for the first dive and scientists began preparation of specialized sampling tools to collect sediment and bacterial mat samples at Vai Lili.

 


 

The Fijian and U.S. flags fly high atop the mast of the R/V Roger Revelle while in port in Suva, Fiji.

The Fijian and U.S. flags fly high atop the mast of the R/V Roger Revelle while in port in Suva, Fiji. Click image for larger view and image credit.


September 9, 2012
0202 GMT
Wind – E @ 5 kts
Air Temperature - 25.7°C (78.2°F)
Sea State – 1.3 m

The Submarine Ring of Fire 2021 NE Lau Basin exploration team departed Suva, Fiji at 0400 GMT for their first target, Vai Lili, to explore bacterial mats and collect water samples from hydrothermal vent sites at Vai Lili, a vent field located on the central Valu Fa Ridge in the Lau Basin. There, they will collect samples of Mn- and Fe-encrusted microbial mats from the vicinity of diffuse flowing hydrothermal vents in the southern most region of the exploration study area. The day before departure, students from the University of the South Pacific joined members from the U.S. Embassy and the U.S. Ambassador for a tour of the R/V Roger Revelle and conversations with the scientists on board. They also got a first-hand glimpse of the Quest 4000, a remotely operated vehicle owned by the University of Bremen in Germany that will be used to explore the most volcanically-active area of the planet.

 


 

 

 

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