EARTH: Is there really a minerals crisis?

China sent the high-tech industry and markets reeling last fall when it blocked exports of raw rare earth minerals to Japan, Europe and the U.S. The sudden severing of rare earths supply was a frightening prospect as the minerals are key ingredients in a broad range of high-tech products, from smartphones to wind turbines and hybrid cars. Although the bans have since been lifted, governments around the world saw the ban as a kind of wake-up call and started looking at ways to develop their own mineral resources – for rare earths as well as basic industry metals like copper and zinc.

As EARTH explores in “Is There Really a Minerals Crisis?” in the August issue, the rare earths scare of last fall prompted scientists from academia, government and industry alike to reconsider the question of the world’s supply of minerals in general – and how governments should, going forward, invest in new exploration. At issue, economic geologists argue, is not whether the geological reserves of these minerals exist. Instead, they say, any shortages have more to do with ongoing sociological and political impediments to minerals exploration and mining.

Read how Europe and other parts of the world are trying to surmount the sociological and political issues surrounding mining. Plus, learn about other topics such as what scientists are finding in mysterious sinkholes beneath the Great Lakes, how the Large Hadron Collider is answering long-standing theoretical physics questions, and how natural gas fracking is affecting well water in the August issue. And don’t miss the cover stories about traveling to Australia and New Zealand.

Underwater Antarctic volcanoes discovered in the Southern Ocean

Scientists from British Antarctic Survey (BAS) have discovered previously unknown volcanoes in the ocean waters around the remote South Sandwich Islands. Using ship-borne sea-floor mapping technology during research cruises onboard the RRS James Clark Ross, the scientists found 12 volcanoes beneath the sea surface – some up to 3km high. They found 5km diameter craters left by collapsing volcanoes and 7 active volcanoes visible above the sea as a chain of islands.

The research is important also for understanding what happens when volcanoes erupt or collapse underwater and their potential for creating serious hazards such as tsunamis. Also this sub-sea landscape, with its waters warmed by volcanic activity creates a rich habitat for many species of wildlife and adds valuable new insight about life on earth.

Speaking at the International Symposium on Antarctic Earth Sciences in Edinburgh Dr Phil Leat from British Antarctic Survey said,

“There is so much that we don’t understand about volcanic activity beneath the sea – it’s likely that volcanoes are erupting or collapsing all the time. The technologies that scientists can now use from ships not only give us an opportunity to piece together the story of the evolution of our earth, but they also help shed new light on the development of natural events that pose hazards for people living in more populated regions on the planet.”

Mantle drilling initial feasibility study completed

The Integrated Ocean Drilling Program (IODP) has announced completion of a feasibility study of drilling and coring activities that would be conducted in an ultra-deepwater environment into very high temperature igneous rocks to reach the upper oceanic mantle.

This initial feasibility study focuses on future requirements for planning, drilling and coring a hole through the 6 km-thick oceanic crust and the crust-mantle interface or “Moho”, then 500 meters into the mantle from three candidate locations in the Pacific Ocean (Cocos Plate, Baja California and Hawaii) and to point out some of the critical issues that need to be resolved before embarking upon such a challenging project. The document was prepared by Blade Energy Partners, U.S. upon request by the IODP-MI.

Challenges of the mantle drilling project include drilling into very hard igneous rocks at extremely high temperatures (i.e., 200-250 °C) using coring tools that are routinely used in less extreme conditions and drilling in deepwater environments (i.e., >4000 meters). Both of these challenges push the limits of current drilling technologies. The main challenges discussed in this study are as follows:

  • Drilling with riser in ultra-deepwater environments with water depths around 4000 meters which will set a new world record.

  • Drilling and coring in very high temperature igneous rocks with bottom-hole temperatures that are estimated to be as high as 250°C which will also set a new world record.

  • Drilling and coring a very deep hole with a total drilled and/or cored interval around 6000 meters in the oceanic crust below the Pacific Ocean seafloor in order to reach the upper mantle which will be a major achievement for the worldwide scientific community.

The report includes discussions and analyses concerning environmental data, marine drilling riser options, deepwater subsea equipment, drill-pipe design, wellbore design, down-hole tools, drilling fluids, various advanced technologies and operational time and costs estimations. The analysis concluded that there are existing available technologies, equipment, and materials in the ultra-deepwater industry that could enable the IODP drilling vessel Chikyu, operated by the Center for Deep Earth Exploration (CDEX) of Japan Agency for Marine-Earth Science and Technology (JAMSTEC), to conduct operations at the candidate locations.

The results of this study show that drilling/coring a scientific hole into the upper mantle is certainly feasible, and that existing solutions are currently available to many of the technological challenges based on work being done in the commercial industries. In addition, technologies and techniques are continuously advancing, and can be expected to continue to close the gap between what is required and what is currently possible.

Geothermal industry to get boost

Jim Faulds, geologist and research professor at the University of Nevada, Reno's Bureau of Mines and Geology, lectures his geothermal exploration class in April at the Fly Ranch Geyser north of Gerlach, Nev. -  Photo courtesy of the University of Nevada, Reno.
Jim Faulds, geologist and research professor at the University of Nevada, Reno’s Bureau of Mines and Geology, lectures his geothermal exploration class in April at the Fly Ranch Geyser north of Gerlach, Nev. – Photo courtesy of the University of Nevada, Reno.

An ambitious University of Nevada, Reno project to understand and characterize geothermal potential at nearly 500 sites throughout the Great Basin is yielding a bounty of information for the geothermal industry to use in developing resources in Nevada, according to a report to the U.S. Department of Energy.

The project, based in the University’s Bureau of Mines and Geology in the College of Science, is funded by a $1 million DOE grant from the American Recovery and Reinvestment Act of 2009. It has reached the one-year mark and is entering phase two, when five or six of the 250 identified potentially viable geothermal sites will be studied in more detail. Some of the studied sites will even have 3-D imaging to help those in the industry better understand geothermal processes and identify where to drill for the hot fluids.

The research aims to provide a catalog of favorable structural elements, such as the pattern of faulting and models for geothermal systems and site-specific targeting using innovative techniques for fault analysis. The project will enhance exploration methodologies and reduce the risk of drilling nonproductive wells.

Jim Faulds, principal investigator for the project, geologist and research professor at the University of Nevada, Reno, has a team of six researchers and several graduate students working with him on various aspects of the project.

“Of the 463 geothermal sites to study, we’ve studied and characterized more than 250 in the past year, either using existing records or on-site analyses,” Faulds said. “We’ll continue to study more of the sites so we can develop better methods and tools for geothermal exploration. Most, about two-thirds, of the geothermal resources in the Great Basin are blind – that is, there are no surface expressions, such as hot springs, to indicate what’s perhaps 1,500 feet below the surface.”

Better characterization of known geothermal systems is critical for new discoveries, targeting drilling sites and development, Faulds said. The success of modeling sites for exploration is limited without basic knowledge of which fault and fracture patterns, stress conditions, and stratigraphic intervals are most conducive to hosting geothermal reservoirs.

“The geothermal industry doesn’t have the same depth of knowledge for geothermal exploration as the mineral and oil industries,” he said. “Mineral and oil companies conducted extensive research years ago that helps them to characterize favorable settings and determine where to drill. With geothermal, it’s studies like this that will enhance understanding of what controls hot fluids in the earth’s crust and thus provide an exploration basis for industry to use in discovering and developing resources.”

Faulds and his team have defined a spectrum of favorable structural settings for geothermal systems in the Great Basin and completed a preliminary catalogue that interprets the structural setting of most its geothermal systems.

“This is the first attempt to broadly characterize and catalogue Great Basin geothermal systems in this way,” he said.

In addition, Faulds has developed and taught a geothermal exploration class, published many papers on his work and presented his work at many conferences, including the World Geothermal Congress in Bali, Indonesia and the GEONZ2010 Geoscience-Geothermal Conference in Auckland, New Zealand.

Faulds also presented information from his study at a session of the National Geothermal Academy today at the University of Nevada, Reno.

“We want to help the industry achieve acceptable levels of site-selection risk ahead of expensive drilling,” he said. “This study costs only $1 million, but it could cost a company several million dollars for drilling at a single prospect in the hopes that they hit a good hot well. Our research will provide the baseline studies that are absolutely needed if Nevada is going to become the Saudi Arabia of geothermal.”

Fewer rain storms across southern Australia

Decreasing autumn and winter rainfall over southern Australia has been attributed to a 50-year decrease in the average intensity of storms in the region – a trend which is forecast to continue for another 50 years.

In an address today to the International Union of Geodesy and Geophysics conference in Melbourne, CSIRO climate scientist, Dr Jorgen Frederiksen, said these changes are due to reductions in the strength of the mid-latitude jet stream and changes in atmospheric temperatures. The jet stream comprises fast moving westerly winds in the upper atmosphere.

“The drop in winter and autumn rainfall observed across southern Australia is due to a large downturn in the intensity of storm formations over at least the last three decades compared with the previous three decades, and these effects have become more pronounced with time,” Dr Frederiksen said.

“Our recent work on climate model projections suggests a continuation of these trends over the next 50 years.”

Dr Frederiksen’s address was based on recent CSIRO and Bureau of Meteorology research that has just been published in the International Journal of Climate Change: Impacts and Responses.

The research, based on observations and climate modelling, centers on the changes in southern Australian winter rainfall linked to atmospheric circulation changes that are directly associated with storm formation, and particularly rain bearing lows and frontal systems crossing southern Australia.

The most important circulation feature associated with winter storm formation is the strength of the sub-tropical jet stream. For example, winter storms give south-west Western Australia much of its rain. Between the 20-year periods 1949 to 1968 and 1975 to 1994 south-west WA rainfall reduced by 20 per cent. In south-east Australia, there were reductions of 10 per cent.

“Our research has identified the historic relationship between the reduction in the intensity of storms, the southward shift in storm tracks, changing atmospheric temperatures and reductions in mid-latitude vertical wind shear affecting rainfall.” Vertical wind shear is the change in the westerly winds with height.

“We expect a continuation of these trends as atmospheric temperatures rise based on projections from climate models forced by increasing carbon dioxide concentrations.

“Trends during the 21st Century are likely to be similar to those observed during the second half of the 20th Century, when we saw substantial declines in seasonal rainfall across parts of southern Australia.

“Indeed, reductions in projected southern Australian rainfall during the 21st Century, particularly over south-west WA, may be as much as, or larger than, those seen in recent decades,” Dr Frederiksen said.

Researchers discover new force driving Earth’s tectonic plates

A view of the bends of the fracture zones on the Southwest Indian Ridge caused by the slowdown of Africa in response to the Reunion plume head. The image shows the gravity field. -  Scripps Institution of Oceanography,UC San Diego
A view of the bends of the fracture zones on the Southwest Indian Ridge caused by the slowdown of Africa in response to the Reunion plume head. The image shows the gravity field. – Scripps Institution of Oceanography,UC San Diego

Bringing fresh insight into long-standing debates about how powerful geological forces shape the planet, from earthquake ruptures to mountain formations, scientists at Scripps Institution of Oceanography at UC San Diego have identified a new mechanism driving Earth’s massive tectonic plates.

Scientists who study tectonic motions have known for decades that the ongoing “pull” and “push” movements of the plates are responsible for sculpting continental features around the planet. Volcanoes, for example, are generally located at areas where plates are moving apart or coming together. Scripps scientists Steve Cande and Dave Stegman have now discovered a new force that drives plate tectonics: Plumes of hot magma pushing up from Earth’s deep interior. Their research is published in the July 7 issue of the journal Nature.

Using analytical methods to track plate motions through Earth’s history, Cande and Stegman’s research provides evidence that such mantle plume “hot spots,” which can last for tens of millions of years and are active today at locations such as Hawaii, Iceland and the Galapagos, may work as an additional tectonic driver, along with push-pull forces.

Their new results describe a clear connection between the arrival of a powerful mantle plume head around 70 million years ago and the rapid motion of the Indian plate that was pushed as a consequence of overlying the plume’s location. The arrival of the plume also created immense formations of volcanic rock now called the “Deccan flood basalts” in western India, which erupted just prior to the mass extinction of dinosaurs. The Indian continent has since drifted north and collided with Asia, but the original location of the plume’s arrival has remained volcanically active to this day, most recently having formed Réunion island near Madagascar.

The team also recognized that this “plume-push” force acted on other tectonic plates, and pushed on Africa as well but in the opposite direction.

“Prior to the plume’s arrival, the African plate was slowly drifting but then stops altogether, at the same time the Indian speeds up,” explains Stegman, an assistant professor of geophysics in Scripps’ Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics. “It became clear the motion of the Indian and African plates were synchronized and the Réunion hotspot was the common link.”

After the force of the plume had waned, the African plate’s motion gradually returned to its previous speed while India slowed down.

“There is a dramatic slow down in the northwards motion of the Indian plate around 50 million years ago that has long been attributed to the initial collision of India with the Eurasian plate,” said Cande, a professor of marine geophysics in the Geosciences Research Division at Scripps. “An implication of our study is that the slow down might just reflect the waning of the mantle plume-the actual collision might have occurred a little later.”

How hot did Earth get in the past? Team of scientists uncovers new information

The question seems simple enough: What happens to the Earth’s temperature when atmospheric carbon dioxide levels increase? The answer is elusive. However, clues are hidden in the fossil record. A new study by researchers from Syracuse and Yale universities provides a much clearer picture of the Earth’s temperature approximately 50 million years ago when CO2 concentrations were higher than today. The results may shed light on what to expect in the future if CO2 levels keep rising.

The study, which for the first time compared multiple geochemical and temperature proxies to determine mean annual and seasonal temperatures, is published online in the journal Geology, the premier publication of the Geological Society of America, and is forthcoming in print Aug. 1.

SU Alumnus Caitlin Keating-Bitonti ’09 is the corresponding author of the study. She conducted the research as an undergraduate student under the guidance of Linda Ivany, associate professor of earth sciences, and Scott Samson, professor of earth sciences, both in Syracuse University’s College of Arts and Sciences. Early results led the team to bring in Hagit Affek, assistant professor of geology and geophysics at Yale University, and Yale Ph.D. candidate Peter Douglas for collaborative study. The National Science Foundation and the American Chemical Society funded the research.

“The early Eocene Epoch (50 million years ago) was about as warm as the Earth has been over the past 65 million years, since the extinction of the dinosaurs,” Ivany says. “There were crocodiles above the Arctic Circle and palm trees in Alaska. The questions we are trying to answer are how much warmer was it at different latitudes and how can that information be used to project future temperatures based on what we know about CO2 levels?”

Previous studies have suggested that the polar regions (high-latitude areas) during the Eocene were very hot-greater than 30 degrees centigrade (86 degrees Fahrenheit). However, because the sun’s rays are strongest at the Earth’s equator, tropical and subtropical areas (lower latitude) will always be at least as warm as polar areas, if not hotter. Until now, temperature data for subtropical regions were limited.

The SU and Yale research team found that average Eocene water temperature along the subtropical U.S. Gulf Coast hovered around 27 degrees centigrade (80 degrees Fahrenheit), slightly cooler than earlier studies predicted. Modern temperatures in the study area average 75 degrees Fahrenheit. Additionally, the scientists discovered that, during the Eocene, temperatures in the study area did not change more than 3 to 5 degrees centigrade across seasons, whereas today, the area’s seasonal temperatures fluctuate by 12 degrees centigrade. The new results indicate that the polar and sub-polar regions, while still very warm, could not have been quite as hot as previously suggested.

The findings are based on a chemical analysis of the growth rings of the shells of fossilized bivalve mollusks and on the organic materials trapped in the sediment packed inside the shells, which was conducted by Keating-Bitonti and her colleagues. Ivany collected the fossils from sediment layers exposed along the Tombigbee River in Alabama. The mollusks lived in a near-shore marine environment during a time when the sea level was higher and the ocean flooded much of southern Alabama. The sediments that accumulated there contain one of the richest and best-preserved fossil records in the country.

“Our study shows that previous estimates of temperatures during the early Eocene were likely overestimated, especially at higher latitudes near the poles,” Keating-Bitonti says. “The study does not mean elevated atmospheric CO2 levels did not produce a greenhouse effect-the Earth was clearly hotter during the early Eocene. Our results support predictions that increasing levels of atmospheric CO2 will result in a warmer climate with less seasonality across the globe.”

To determine the average seasonal temperatures in the study area, Keating-Bitonti sampled the mollusk shells for high-resolution oxygen and strontium isotope analyses, which were done at SU. The Yale team analyzed shells and sediments for clumped-isotope and tetraether-lipid analysis. The results were consistent across all of the independent analytic methods. The scientists believe the multiple methods of analysis have yielded a more complete and accurate picture of ancient climate than previously possible.

The study also marks the first time clumped-isotope analysis has been used alongside traditional oxygen isotope and organic geochemical analyses in paleoclimate work. The research team is currently using the same analytical process to determine Eocene Epoch mean annual and seasonal temperatures in polar-regions.

“Clumped isotopes is a new way to measure past temperatures that offers a distinct advantage over other approaches because the technique requires fewer assumptions; it’s based on well understood physics,” Affek says. “The agreement among different methods gives us confidence in the results and enables us to use these methods in other locations, such as Antarctica.”

Australian volcano eruptions overdue, new study confirms

Latest research into the age of volcanoes in Western Victoria and South Australia has confirmed that the regions are overdue for an eruption, potentially affecting thousands of local residents.

Using the latest dating techniques, scientists from the University of Melbourne’s School of Earth Sciences and the Melbourne School of Engineering have calculated the ages of the small volcanoes in the regions and established the recurrence rate for eruptions as 2,000 years.

With the last volcano eruption at Mt Gambier in South Australia occurring over 5,000 years ago, scientists say the areas are overdue.

The research was presented today by Professor Bernie Joyce of the University of Melbourne’s School of Earth Sciences at the XXV International Congress of Geodesy and Geophysics, in Melbourne.

“Although the volcanos in the region don’t erupt on a regular sequence, the likelihood of an eruption is high given the average gap in the past has been 2,000 years,” Professor Joyce said.

“These are small eruptions and very localised but depending on the type of eruption, they could cause devastation to thousands of people,” he said.

The regions of Western Victoria and adjacent south-eastern South Australia demonstrate a history of activity by young monogenetic (single short-lived activity) volcanoes. Similar young monogenetic provinces are found in northeast Queensland.

Professor Joyce and his colleagues from the University’s School of Earth Sciences have spent years cataloguing the hundreds of small volcanic cones, lava flows and craters in the regions. The distribution of activity including lava flows and ash deposits has been mapped in detail.

The latest findings are due to more recent studies using a range of state of the art dating techniques, which have provided more information on the ages of the individual volcanoes, providing information about the occurrence rates.

Professor Joyce said there are several kinds of eruptions which can cause damage and harm to local communities.

“Among the hazards which may need to be prepared for in this closely-settled region are the localized effects of cone building leading to lava flows which run downhill towards the coast.’

“The long lasting and often extensive lava flows can travel for tens of kilometers, and so would be hazardous to modern infrastructure such as bridges, roads and railways, powerlines and pipelines, as well as being a major fire hazard on the dry grassland plains of summer in Western Victoria.”

“In some cases rising magma can meet ground water and cause steam explosions. This can form wide craters and produce a lot of ash.”

“Depending on where the eruption occurs, ash can cause huge damage to people who are down wind, clogging up streams, road and rail transport and perhaps affecting local air travel,” he said.

The cause of the volcanic activity may be the movement of the Australian tectonic plate, which is moving north.

“The plate is hitting up against PNG, lifting the southern margin upwards. This allows magma to move upwards towards the surface,” Professor Joyce said.

Professor Joyce said communities need to have some knowledge of what to do after an eruption.

“So far we have no action plans in place if eruptions occur. If they happen close to Melbourne or Geelong it could be hugely devastating. It is more likely however, that eruptions would occur further west, closer to areas such as Colac, Port Fairy, Portland and Mt Gambier.”

“We need to note the concerns of other cities such as Auckland in New Zealand which sits on a similar young volcanic region, with a local government which has plans in place to respond if eruptions occur,” he said.

The seasonal potato

The “Potsdam Gravity potato”, as this representation of terrestrial gravity has become known, can for the first time display gravity variations that change with time. The seasonal fluctuations of the water balance of continents or melting or growing ice masses, i.e. climate-related variables, are now included in the modeling of the gravity field. “EIGEN-6C” is the name of this latest global gravity field model of the GFZ German Research Centre for Geosciences. It was recently calculated in Potsdam in cooperation with the Groupe de Recherche de Géodésie Spaciale from Toulouse. This new gravity field model is based on measurements of the satellites LAGEOS, GRACE and GOCE. These were combined with ground-based gravity measurements and data from the satellite altimetry. EIGEN-6C has a spatial resolution of about 12 kilometers. Compared to the last version of the Potsdam potato, this is a four-fold increase.

“Of particular importance is the inclusion of measurements from the satellite GOCE, from which the GFZ did its own calculation of the gravitational field’ says Dr. Christoph Foerste, who together with his colleague Dr. Frank Flechtner directs the gravitaty field work group at the GFZ. The ESA mission GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) was launched in mid-March 2009 and since then measures the Earth’s gravitational field using satellite gradiometry. “This allows the measurement of gravity in inaccessible regions with unprecedented accuracy, for example in Central Africa and the Himalayas” adds Dr. Flechtner. In addition, the Earth’s gravity field in the vastness of the oceans can be measured much more accurately with GOCE than with previous satellite missions such as GFZ-CHAMP and GRACE. Amongst other advantages, this allows a more faithful determination of the so-called dynamic ocean topography, i.e. the deviation of the ocean surface from the equilibrium with the force of gravity. This ocean topography is essentially determined by ocean currents. Therefore, the gravity field models calculated with GOCE measurements are of great interest for oceanography and climate research.

Besides GOCE, long-term measurement data from the twin-satellite mission GRACE (Gravity Recovery and Climate Experiment) of the GFZ were included in the new EIGEN-6C. GRACE allows the determination of large-scale temporal changes in the gravitational field caused for example by climate-induced mass displacements on the Earth’s surface. These include the melting of large glaciers in the Polar Regions and the seasonal variation of water stored in large river systems. Temporal gravity changes determined with GRACE are included in the EIGEN-6C model. Therefore, the new Potsdamer potato is for the first time no longer a solid body, but a surface that varies over time. Particularly in order to record these climate-related processes for the long term, a follow-on mission for the GRACE mission that ends in 2015 is urgently needed. A comparison of the various “Potsdamer potatoes” since 1995 clearly shows the leaps in quality.

Scientists study earthquake triggers in Pacific Ocean

The CRISP research site is located 174 km (108 miles) off the coast of Costa Rica. -  Original is modified by IODP
The CRISP research site is located 174 km (108 miles) off the coast of Costa Rica. – Original is modified by IODP

New samples of rock and sediment from the depths of the eastern Pacific Ocean may help explain the cause of large, destructive earthquakes similar to the Tohoku Earthquake that struck Japan in mid-March.

Nearly 1500 meters (almost one mile) of core collected from the ocean floor near the coast of Costa Rica reveal detailed records of approximately 2 million years of tectonic activity along a seismic plate boundary.

The samples were retrieved with the scientific drilling vessel JOIDES Resolution during the recent month-long Integrated Ocean Drilling Program (IODP) Costa Rica Seismogenesis Project (CRISP) Expedition. Participating scientists aim to use the samples better understand the processes that control the triggering of large earthquakes at subduction zones, where one plate slides beneath another.

“We know that there are different factors that contribute to seismic activity – these include rock type and composition, temperature differences, and how water moves within the Earth’s crust,” explained co-chief scientist Paola Vannucchi (University of Florence, Italy), who led the expedition with co-chief scientist Kohtaro Ujiie (University of Tsukuba, Japan).

She added, “but what we don’t fully understand is how these factors interact with one another and if one may be more important than another in leading up to different magnitudes of earthquakes. This expedition provided us with crucial samples for answering some of these fundamental questions.”

More than 80% of global earthquakes above magnitude 8.0 occur along subduction zones. The Pacific Ocean is famous for these boundaries, known as convergent margins, which are found along the coasts of the East Pacific from Alaska to Patagonia, New Zealand, Tonga, Marianas all the way up to Japan and the Aleutians, making the margins of the world’s largest ocean basin a primary target for research into the triggering mechanisms of large quakes.

During four weeks at sea, the science party and crew successfully drilled four sites, recovering core samples of sand and clay-like sediment and basalt rock. In a preliminary report published this month, CRISP scientists say that they have found evidence for a strong subsidence, or sinking, of the Costa Rica margin combined with a large volume of sediment discharged from the continent and accumulated in the last 2 million years.

“The sediment samples provide novel information on different parameters which may regulate the mechanical state of the plate interface at depth,” said Ujiie. He adds, “knowing how the plates interact at the fault marking their boundary is critical to interpreting the behavior and frequency of earthquakes in the region.”

Vannucchi explains, “for example we now know that fluids from deeper parts of the subduction zone system have percolated up through the layers of sediment. Studying the composition and volume of these fluids, as well as how they have moved through the sediment helps us better understand the relationship between the chemical, thermal, and mass transfer activity in the seafloor and the earthquake-generating, or seismogenic, region of the plate boundary. They may be correlated.”

Cores from the CRISP Expedition are currently being further analyzed by different members of the research party at their home institutions. The scientists will meet beginning August 29 at Texas A&M University to share their initial results.

The CRISP Expedition is unique because it focuses on the properties of erosional convergent margins, where the overriding plate gets “consumed” by subduction processes. These plate boundaries are characterized by trenches with thin sediment cover (less than 400 meters), fast convergence between the plates (at rates greater than 8 centimeters per year), and abundant seismicity.

The seismically active CRISP research area is the only one of its kind that is accessible to research drilling. However, this subduction zone is representative of 50% of global subduction zones, making scientific insights gleaned here relevant to Costa Ricans and others living in earthquake-prone regions all around the Pacific Ocean. The recent Tohoku Earthquake in Japan was generated in an erosive portion of the plate interface.

Other geoscience research drilling programs, such as IODP’s Nankai Trough Seismogenic Zone Experiment (NantroSEIZE), near the southeast coast of Japan, focus on accretionary margins, where the front part of the overriding tectonic plate is built up by the subduction processes (sometimes forming mountains) and the plate boundary input is trench material. In these environments, the trench sediments are significantly thick (greater than 1000 meters or over a half a mile). Accretionary margins are known for their large earthquakes as the 1964 Alaska and the 2004 Sumatra quakes. Japan’s Nankai Trough itself was the center of two magnitude 8 earthquakes in 1944 and 1946.

The CRISP team hopes to return to the same drill site in the future to directly sample the plate boundary and fault zone before and after seismic activity in the region. Changes observed through this work may provide new insights into how earthquakes are generated.