Rapid Response Oceanographic Expedition Dispatched to Chile Earthquake Site

Scientists funded by the National Science Foundation (NSF) and affiliated with the Scripps Institution of Oceanography (SIO) at the University of California at San Diego are undertaking an expedition to explore the rupture site of the 8.8-magnitude Chilean earthquake.

The quake is one of the largest in recorded history.
The scientists hope to capitalize on a unique scientific opportunity to capture fresh data from the event. They will study changes in the seafloor that resulted from movements along faults and submarine landslides.
The "rapid response" expedition, called the Survey of Earthquake And Rupture Offshore Chile, will take place aboard the research vessel Melville.
The Melville was conducting research off Chile when the earthquake struck.
"This rapid response cruise is a rare opportunity to better understand the processes that affect the generation and size of tsunamis," said Julie Morris, NSF division director for Ocean Sciences. "Seafloor evidence of the quake will contribute to understanding similar earthquake regions worldwide."
An important aspect of the rapid response mission involves swath multibeam sonar mapping of the seafloor to produce detailed topographic maps. Data from mapping the earthquake rupture zone will be made public soon after the research cruise ends, Morris said.
The new data will be compared with pre-quake data taken by scientists at Germany's Leibniz Institute of Marine Sciences (IFM-GEOMAR).
Several years ago IFM-GEOMAR researchers conducted a detailed multibeam mapping survey off Chile. Their data will be valuable for comparisons with the new survey to expose changes from the earthquake rupture, say researchers.
"We'd like to know if the genesis of the resulting tsunami was caused by direct uplift of the seabed along a fault, or by slumping from shaking of sediment-covered slopes," said Dave Chadwell, an SIO geophysicist and chief scientist of the expedition.
"We will look for disturbances in the seafloor, including changes in reflectivity and possibly shape, by comparing previous data with the new [rapid response] data."
The rapid response cruise is possible because the vessel Melville is currently in Chilean waters, where a research team has been conducting an investigation of the geology and biology of the Chilean margin.
"This is a unique case in which we have the shipboard assets, the scientific agenda and the funding all in place," said Bruce Appelgate, associate director for Ship Operations and Marine Technical Support at SIO. "The earthquake was a tragedy for the people of Chile, but we hope this opportunity enables important new discoveries that can help us plan for future events."
The logistical details of undertaking the expedition are enormous and constantly evolving due to uncertainties regarding transportation infrastructure in Chile.
Port facilities are limited due to widespread earthquake devastation, making fueling and provisioning the ship difficult.
Chadwell and SIO scientist Peter Lonsdale, along with graduate students Jared Kluesner and Ashlee Henig, and Scripps Geological Data Center analyst Aaron Sweeney, will be aboard Melville for the eight-day expedition.
The scientists, along with Scripps researchers Mike Tryon and Mark Zumberge, also will deploy depth sensors on the seafloor to record possible abrupt vertical motions over the next year.
The U.S. scientists will be joined by Chilean researchers Juan Díaz and Matias Viel González from Universidad Católica in Valparaíso, as well as scientists from IFM-GEOMAR.

Deepest Explosive Eruption on Sea Floor: Underwater Remotely Operated Vehicle Jason Images Discovery

Oceanographers using the remotely operated vehicle (ROV) Jason discovered and recorded the first video and still images of a deep-sea volcano actively erupting molten lava on the seafloor.

Jason, designed and operated by the Woods Hole Oceanographic Institution for the National Deep Submergence Facility, utilized a prototype, high-definition still and video camera to capture the powerful event nearly 4,000 feet below the surface of the Pacific Ocean, in an area bounded by Fiji, Tonga and Samoa.

"I felt immense satisfaction at being able to bring [the science team] the virtual presence that Jason provides," says Jason expedition leader Albert Collasius, who remotely piloted the ROV over the seafloor. "There were fifteen exuberant scientists in the control van who all felt like they hit a home run. "

Collasius led a team that operated the unmanned, tethered vehicle from a control van on the research vessel and used a joystick to "fly" Jason over the seafloor to within 10 feet of the erupting volcano. Its two robotic arms collected samples of rocks, hot spring waters, microbes, and macro biological specimens.

Through its fiber optic tether, ROV Jason transmitted-high definition video of the eruption as it was occurring. The unique camera system, developed and operated by the Advanced Imaging and Visualization Lab at WHOI, was installed on Jason for the expedition to acquire high quality imagery of the seafloor. The AIVL designs, develops, and operates high resolution imaging systems for scientific monitoring, survey, and entertainment purposes. AIVL imagery has been used in several IMAX films and hundreds of television programs and documentaries.

The video from the research expedition, which departed Western Samoa aboard the RV Thomas Thompson on May 5, 2009, was shown for the first time at the American Geophysical Union fall meeting in San Francisco.

"Less than 24 hours after leaving port, we located the ongoing eruption and observed, for the first time, molten lava flowing across the deep-ocean seafloor, glowing bubbles three feet across, and explosions of volcanic rock," reported Joe Resing, a chemical oceanographer at the University of Washington and NOAA, and chief scientist on the NOAA- and National Science Foundation-funded expedition.

For more than a decade, monitoring systems have allowed scientists to listen for seafloor eruptions but there has always been a time lag between hearing an eruption and assembling a team and a research vessel to see it. This has meant that scientists have always observed eruptions after the fact.

"We saw a lot of interesting phenomena, but we never saw an eruption because it happens so quickly," said Robert Embley, a NOAA PMEL marine geologist and co-chief scientist on the expedition. "As geologists, you want to see the process in action. You learn a lot more about it watching the process."

The scientists involved in the expedition had praise for the people and the technology that helped bring that dream to fruition.

"I don't think there are too many systems in the world that could do what Jason does," said Embley. "It takes a good vehicle, but a great group of experienced people to get close [to an eruption], hold station, and have the wisdom to understand what they can and cannot do."

The Jason team maneuvered the vehicle to give scientists an up-close view of the glowing red vents explosively ejecting lava into the sea- often not more than a few feet away from the exploding lava -- and the ability to take samples.

Enhancing the experience was the ability to view the eruption in high-definition video. Designed to operate at depths of up to 7,000 meters, the unique still and video camera system acquired 30-60 still images per second, at the same time generating motion, high def video at 30 frames per second. The system uses a high-definition zoom lens -- nearly twice the focal length of Jason's present standard definition camera -- that enables researchers to see up-close details of underwater areas of interest that they otherwise could not see.

"We were lucky to have those cameras on the vehicle. They are important to the science," said Tim Shank, a WHOI macro-biologist on the expedition. "We use the high def cameras to try to identify species. They allow us to look at the morphology of the animals -- some smaller than 3 or 4 inches long."

"In terms of understanding how the volcano is erupting, the high frame rate lets you stop the motion and look to see what is happening," said Resing. "You can see the processes better."

The National Science Foundation funded the installation of the camera system for this expedition. The system is being tested in advance of a permanent upgrade in 2010 to the cameras on Jason as well as the manned submersible Alvin. Maryann Keith, of WHOI's AIVL, Shank, and other scientists operated the camera system with the assistance of the Jason team during the expedition.

In addition to the benefits to science, the cameras will serve the added purpose of giving the public more access to seafloor discoveries.

"Seeing an eruption in high definition video for the first time really brings it home for all of us, when we can see for ourselves the very exciting things happening on our planet, that we know so little about," Embley said.

Great Indian Ocean Earthquake Of 2004 Set Off Tremors In San Andreas Fault

In the last few years there has been a growing number of documented cases in which large earthquakes set off unfelt tremors in earthquake faults hundreds, sometimes even thousands, of miles away.

New research shows that the great Indian Ocean earthquake that struck off the Indonesian island of Sumatra on the day after Christmas in 2004 set off such tremors nearly 9,000 miles away in the San Andreas fault at Parkfield, Calif.

"We found that an earthquake that happened halfway around the world could trigger a seismic signal in the San Andreas fault. It is a low-stress event and a new kind of seismic phenomenon," said Abhijit Ghosh, a University of Washington doctoral student in Earth and space sciences.

"Previous research has shown that this phenomenon, called non-volcanic tremor, was produced in the San Andreas fault in 2002 by the Denali earthquake in Alaska, but seeing this new evidence of tremor triggered by an event as distant as the Sumatra earthquake is really exciting," he said.

Ghosh is to present the findings Dec. 17 in a poster at the American Geophysical Union annual meeting in San Francisco.

The Indian Ocean earthquake on Dec. 26, 2004, was measured at magnitude 9.2 and generated tsunami waves that killed a quarter-million people. It was not known, however, that an earthquake of even that magnitude could set off non-volcanic tremor so far away.

The San Andreas fault in the Parkfield region is one of the most studied seismic areas in the world. It experiences an earthquake of magnitude 6.0 on an average of every 22 years, so a variety of instruments have been deployed to record the seismic activity.

In this case, the scientists examined data from instruments placed in holes bored in the ground as part of the High-Resolution Seismic Network operated by the University of California, Berkeley, as well as information gathered by the Northern California Seismic Network operated by the U.S. Geological Survey.

Signals corresponding with non-volcanic tremor at precisely the time that seismic waves from the Indian Ocean earthquake were passing the Parkfield area were recorded on a number of instruments as far as 125 miles apart.

"It's fairly obvious. There's no question of this tremor being triggered by the seismic waves from Sumatra," Ghosh said.

Scientists have pondered whether non-volcanic tremor is related to actual slippage within an earthquake fault or is caused by the flow of fluids below the Earth's surface. Recent research supports the idea that tremor is caused by fault slippage.

"If the fault is slipping from tremor in one place, it means stress is building up elsewhere on the fault, and that could bring the other area a little closer to a big earthquake," Ghosh said.

Monitoring tremor could help to estimate how much stress has built up within a particular fault.

"If the fault is closer to failure, then even a small amount of added stress likely can produce tremor," he said. "If the fault is already at low stress, then even high-energy waves probably won't produce tremor."

The work adds to the understanding of non-volcanic tremor and what role it might play in releasing or shifting stress within an earthquake-producing fault.

"Our single-biggest finding is that very small stress can trigger tremor," Ghosh said. "Finding tremor can help to track evolution of stress in the fault over space and time, and therefore could have significant implications in seismic hazard analysis."

Co-authors of the poster are John Vidale, Kenneth Creager and Heidi Houston of the UW and Zhigang Peng of the Georgia Institute of Technology. Funding for the work came from the National Science Foundation.

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Adapted from materials provided by University of Washington.

Deep-sea scientific drilling program to study volatile Earthquake zone launched

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) gets underway September 21, with the Japanese drilling vessel Chikyu departing from Shingu Port with scientists aboard, all ready to log, drill, sample, and install monitoring instrumentation in one of the most active earthquake zones on Earth।

The vessel's launch starts the first of a series of scientific drilling expeditions that will retrieve geological samples and provide scientific data from the Nankai Trough fault zone for the first time. Situated off Japan's southwest coast, the Nankai Trough has reliably generated large-scale earthquakes and tsunamis for millions of years, including historic earthquakes in 1944 and 1946, which measured 8.1 and 8.3, respectively, on the Richter scale.
The NanTroSEIZE expeditions are supported by the Integrated Ocean Drilling Program, a marine research initiative jointly funded by Japan, the United States, a consortium of European countries, the People's Republic of China, and South Korea.
NanTroSEIZE scientists are prepared to drill deeply into the Earth to observe earthquake mechanisms in a well-known subduction zone. The process of subduction occurs when tectonic plates collide and one plate slides beneath another. Geological samples will be collected from the subduction zone, so that IODP scientists can analyze them and study the frictional properties of the rock.
Later, sensors are to be installed deep beneath the sea floor- in the seismogenic fault zone-to monitor development of earthquakes at close range। These sensors and data collected from cored samples are expected to yield new insights into naturally occurring processes responsible for earthquakes. IODP scientists anticipate that the new data also will help them understand water motion and how water affects subduction zones.

Ocean Drilling Program Director James F. Allan of the U.S. National Science Foundation (NSF) characterized the first NanTroSEIZE expedition as an important milestone. "NSF welcomes the beginning of a new tomorrow, where the Chikyu enables us to explore the origins of devastating earthquakes at their source, study Earth history through coring of unstable, thick sediment sections, and investigate the fundamentals of ocean crust formation. These new capabilities," Allan notes, "complement those provided by the U.S. scientific ocean drilling vessel and European mission-specific platforms, which also support IODP scientific investigations, and that have investigated the subseafloor biosphere and Earth's dynamic climate with great success."
The full range of NanTroSEIZE investigations will occur in four stages:
Stage 1, now underway, calls for drilling and sampling at six drill sites to characterize the region's geology and provide geotechnical information for subsequent deep riser drilling (see Figure 1).
Stage 2 involves drilling the first of two deep holes, using Chikyu's unique riser drilling technology to target the mega-splay fault zone (where an array of faults occur) at ~3,500 meters below the seafloor.
Stage 3 focuses on 6,000-meter deep drilling into the seismogenic zone and across the plate interface into subducting crust.
Stage 4 includes installing long-term observatory systems in two ultra-deep boreholes.
During Stage 1, drill targets are
1) the incoming sediment of Shikoku Basin and the underlying oceanic crust,
2) the frontal thrust system at the toe of the accretionary wedge (where sediment is added to tectonic plates through frictional contact),
3) the mid-wedge multiple-fault system (mega-splays), and
4) two, approximately 1,000-meter deep holes at sites identified for later deep penetration into seismogenic zone faults.
The current Stage 1 expedition will continue until November 16. The following Stage 1 expedition will sail from Nov. 17-Dec. 19, 2007, with new scientist participation.
Logging While Drilling (LWD) investigations will occur at all Stage 1 drill sites. LWD operations consist of continuously drilling one or more holes at each site by drilling down at a controlled rate, with logging tools incorporated into the bottom-hole assembly, a relatively short distance (tens of meters) behind the drill bit. Log data are acquired very soon after the hole is cut, providing the best possible data quality. LWD operational and science data are crucial for optimizing subsequent Stage 1 expeditions and future drilling stages.
The current NanTroSEIZE expedition is led by Co-Chief Scientist Harold Tobin, a marine geologist on the faculty of University of Wisconsin-Madison, and Co-Chief Scientist Masa Kinoshita, a marine geophysicist at the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), a leading research institution in Japan.
"A fundamental goal of the NanTroSEIZE expedition," says Dr. Tobin, "is to put long-term monitoring instruments down inside the earthquake fault, so we can look at the physics of the fault process. We will be able to determine whether earthquakes actually have precursory signalsþuthings that happen before the earthquakesþuwe can measure that will provide early warning systems for people on land."
Co-chief scientist Dr. Kinoshita explains that to people in Japan, earthquakes and tsunamis are serious matters. "Consequently, it is logical and relatively easy to excavate into the earthquake source to learn about its mechanism," he says. The NanTroSEIZE science party will excavate 6,000 meters below the 2,000-meter deep oceanic bottom to meet the expedition's scientific objectives.
Prior to its role in NanTroSEIZE, the Chikyu underwent a full schedule of systems integration testing near Shimokita Peninsula and in-situ testing of its drilling, coring, and navigation systems. Sea trials for the custom-built drilling vessel began in 2005 and concluded more than two years later. The Chikyu is the first riser-equipped scientific research vessel in the world.
Its high-tech laboratories are specifically designed for core retrieval, description, and analysis. Complex data sets are assembled onboard and entered into a vast IODP database. Daily and weekly logs are posted online from the ship for access by a global community of research scientists eager to glean news of these ground-breaking investigations.
Stage 1 NanTroSEIZE expeditions are managed by JAMSTEC's Center for Deep Earth Exploration (CDEX) on behalf of the Integrated Ocean Drilling Program (IODP), an international marine research program dedicated to advancing scientific understanding of Earth by monitoring and sampling subseafloor environments.
IODP has operated since 2003, extending the research legacies of the previous Ocean Drilling Program and the Deep Sea Drilling Project. IODP, led by the United States National Science Foundation (NSF) and Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT), currently has 21 member countries. Its Associate Members include ECORD (European Consortium for Ocean Research Drilling); China's Ministry of Science Technology; and the Republic of Korea.
Note: This story has been adapted from material provided by Integrated Ocean Drilling Program Management International.

Fragmented Structure Of Seafloor Faults May Dampen Effects Of Earthquakes

Many earthquakes in the deep ocean are much smaller in magnitude than expected। Geophysicists from the Woods Hole Oceanographic Institution (WHOI) have found new evidence that the fragmented structure of seafloor faults, along with previously unrecognized volcanic activity, may be dampening the effects of these quakes.

Examining data from 19 locations in the Atlantic, Pacific, and Indian oceans, researchers led by graduate student Patricia Gregg have found that “transform” faults are not developing or behaving as theories of plate tectonics say they should. Rather than stretching as long, continuous fault lines across the seafloor, the faults are often segmented and show signs of recent or ongoing volcanism. Both phenomena appear to prevent earthquakes from spreading across the seafloor, thus reducing their magnitude and impact.

Gregg, a doctoral candidate in the MIT/WHOI Joint Program in Oceanography and Oceanographic Engineering, conducted the study with seismologist Jian Lin and geophysicists Mark Behn and Laurent Montesi, all from the WHOI Department of Geology and Geophysics। Their findings were published in the July 12 issue of the journal Nature.

Oceanic transform faults cut across the mid-ocean ridge system, the 40,000-mile-long mountainous seam in Earth’s crust that marks the edges of the planet’s tectonic plates. Along some plate boundaries, such as the Mid-Atlantic Ridge, new crust is formed. In other regions, such as the western Pacific, old crust is driven back down into the Earth.

If you imagine the mid-ocean ridge as the seams on a baseball, then transform faults are the red stitches, lying mostly perpendicular to the ridge। These faults help accommodate the motion and geometry of Earth’s tectonic plates, cracking at the edges as the different pieces of rocky crust slip past each other.

The largest earthquakes at mid-ocean ridges tend to occur at transform faults. Yet while studying seafloor faults along the fast-spreading East Pacific Rise, Gregg and colleagues found that earthquakes were not as large in magnitude or resonating as much energy as they ought to, given the length of these faults.

The researchers decided to examine gravity data collected over three decades by ships and satellites, along with bathymetry maps of the seafloor. Conventional wisdom has held that transform faults should contain rocks that are colder, denser, and heavier than the new crust being formed at the mid-ocean ridge. Such colder and more brittle rocks should have a “positive gravity anomaly”; that is, the faults should exert a stronger gravitational pull than surrounding seafloor region. By contrast, the mid-ocean ridge should have a lesser gravity field, because the crust (which is lighter than underlying mantle rocks) is thicker along the ridge and the newer, molten rock is less dense.

But when Gregg examined gravity measurements from the East Pacific Rise and other fast-slipping transform faults, she was surprised to find that the faults were not exerting extra gravitational pull। On the contrary, many seemed to have lighter rock within and beneath the faults.

“A lot of the classic characteristics of transform faults didn’t make sense in light of what we were seeing,” said Gregg. “What we found was the complete opposite of the predictions.”

The researchers believe that many of the transform fault lines on the ocean floor are not as continuous as they first appear from low-resolution maps. Instead these fault lines are fragmented into smaller pieces. Such fragmented structure makes the length of any given earthquake rupture on the seafloor shorter—giving the earthquake less distance to travel along the surface.

It is also possible that magma, or molten rock, from inside the earth is rising up beneath the faults. Earthquakes stem from the buildup of friction between brittle rock in Earth’s plates and faults. Hot rock is more ductile and malleable, dampening the strains and jolts as the crust rubs together and serving as a sort of geological lubricant.

“What we learn about these faults and earthquakes underwater could help us understand land-based faults such as the San Andreas in California or the Great Rift in eastern Africa,” said Lin, a WHOI senior scientist and expert on seafloor earthquakes। “In areas where you have strike-slip faults, you might have smaller earthquakes when there is more magma and warmer, softer rock under the fault area.”

The findings by Gregg, Lin, and colleagues may also have implications for understanding the theory of plate tectonics, which says that new crust is only formed at mid-ocean ridges. By traditional definitions, no crust can be created or destroyed at a transform fault. The new study raises the possibility that new crust may be forming along these faults and fractures at fast-spreading ridges such as the East Pacific Rise.

“Our understanding of how transform faults behave must be reevaluated,” said Gregg. “There is a discrepancy that needs to be addressed.”

Funding for this research was provided by the NSF Graduate Research Fellowship Program, the WHOI Deep Ocean Exploration Institute, the NSF Ocean Sciences Directorate, and the Andrew W. Mellon Foundation Awards for Innovative Research.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.

Note: This story has been adapted from a news release issued by Woods Hole Oceanographic Institution.

Massive Coral Death Attributed To Earthquake

Scientists have reported what is thought to be one of the world's greatest mass death of corals ever recorded as a result of the earthquake in Aceh, Indonesia on 28 March 2005. Researchers say 300 kilometers of sea floor heaved more than a meter upwards.

The recent survey by scientists from the Wildlife Conservation Society - Indonesia Program and the Australian Research Council Centre of Excellence for Coral Reef Studies (ARCCoERS) investigated the condition of coral reefs in Pulau Simeulue and Pulau Banyak off Aceh, Indonesia, in March 2007.
The surveys covered 35 sites along 600 kms (372 miles) of coastline, have documented, for the first time, the effects of earthquake uplift on coral reefs. The entire island of Simeulue, with a perimeter of approximately 300 km (186 miles), was raised up to 1.2 m (3.9 feet) following the 28 March 2005 earthquake, exposing most of the coral reefs which ringed the island.
Dr Stuart Campbell coordinator of the Wildlife Conservation Society --Indonesia Marine Program reports: "This is a story of mass mortality on a scale rarely observed. In contrast to other threats like coral bleaching, none of the corals uplifted by the earthquake have survived".
Dr Andrew Baird of ARCCoERS says: "Amazingly, the uplifted corals are so well preserved we could still identify each species, despite these colonies having been exposed for two years. Some species suffered up to 100 percent loss at some sites, and different species now dominate the shallow reef." "This is a unique opportunity to document a process that occurs maybe once a century and promises to provide new insights into coral recovery processes that until now we could only explore on fossil reefs" says Dr Baird.
Dr Campbell adds "The news from Simeulue is not all bad. At many sites, the worst affected species are beginning to re-colonize the shallow reef areas. The reefs appear to be returning to what they looked like before the earthquake, although the process may take many years.
"The challenge now is to work with local communities and government agencies to protect these reefs to ensure the recovery process continues," he says. The team found coral reefs ranging from highly diverse assemblages of branching corals in sheltered waters to vast areas of table corals inhabiting surf zones. The team also documented, for the first time in Indonesia, extensive damage to reefs caused by the crown-of-thorn starfish, a coral predator that has devastated reefs in Australia and other parts of the world.
"Finding the starfish damage is particularly important" says Dr Baird. "Most observers would attribute damage on this scale to more common reef threats in Indonesia such as cyanide fishing or bleaching. People monitoring Indonesian corals reefs now have another threat to watch out for, and not all reef damage should be immediately attributed to human influences."
Many other reefs, particularly in the Pulau Banyak, continue to be damaged by destructive fishing including bombing and the use of cyanide. These practices are now illegal in Indonesia, and need immediate attention.
Dr Campbell concludes "While reef condition in south-western Aceh is generally poor, we have found some reefs in excellent condition as well as and evidence of recovery at damaged sites. This gives some hope that coral reefs in this remote region can return to their previous condition and provide local communities with the resources they need to prosper. The recovery process will be enhanced by management that encourages sustainable uses of these ecosystems and the protection of critical habitats and species to help this process."
Note: This story has been adapted from a news release issued by Wildlife Conservation Society.