Mine disaster: Hundreds of aftershocks

A study by University of Utah mining engineers and seismologists found 2,189 suspected seismic events before and after Utah's deadly Crandall Canyon coal mine collapse in 2007, and 1,328 of those events have a high probability of being real: 759 seismic events before the collapse (many related to mining) and 569 aftershocks (some related to rescue efforts). The high-probability events shown here reveal seismic activity clustered in three areas, two of which already were known: near the east end of the mine
(right) and where miners were working, toward the west end of the mine (left of center).  But the third cluster, at the mine's west end (far left) was revealed by the new study. It shows the collapse was at least as big and possibly larger than a 2008 University of Utah study that revealed the collapse extended from the east part of the mine to the area where miners were working. For comparison, see other map. -  Tex Kubacki, University of Utah.
A study by University of Utah mining engineers and seismologists found 2,189 suspected seismic events before and after Utah’s deadly Crandall Canyon coal mine collapse in 2007, and 1,328 of those events have a high probability of being real: 759 seismic events before the collapse (many related to mining) and 569 aftershocks (some related to rescue efforts). The high-probability events shown here reveal seismic activity clustered in three areas, two of which already were known: near the east end of the mine
(right) and where miners were working, toward the west end of the mine (left of center). But the third cluster, at the mine’s west end (far left) was revealed by the new study. It shows the collapse was at least as big and possibly larger than a 2008 University of Utah study that revealed the collapse extended from the east part of the mine to the area where miners were working. For comparison, see other map. – Tex Kubacki, University of Utah.

A new University of Utah study has identified hundreds of previously unrecognized small aftershocks that happened after Utah’s deadly Crandall Canyon mine collapse in 2007. The aftershocks suggest the collapse was as big – and perhaps bigger – than shown in another study by the university in 2008.

Mapping out the locations of the aftershocks “helps us better delineate the extent of the collapse at Crandall canyon. It’s gotten bigger,” says Tex Kubacki, a University of Utah master’s student in mining engineering.

“We can see now that, prior to the collapse, the seismicity was occurring where the mining was taking place, and that after the collapse, the seismicity migrated to both ends of the collapse zone,” including the mine’s west end, he adds.

Kubacki was scheduled to present the findings Friday in Salt Lake City during the Seismological Society of America’s 2013 annual meeting.

Six coal miners died in the Aug. 6, 2007 mine collapse, and three rescuers died 10 days later. The mine’s owner initially blamed the collapse on an earthquake, but the University of Utah Seismograph Stations said it was the collapse itself, not an earthquake, that registered on seismometers.

A 2008 study by University of Utah seismologist Jim Pechmann found the epicenter of the collapse was near where the miners were working, and aftershocks showed the collapse area covered 50 acres, four times larger than originally thought, extending from crosscut 120 on the east to crosscut 143 on the west, where miners worked. A crosscut is a north-south tunnel intersecting the mine’s main east-west tunnels.

In the new study, the collapse area “looks like it goes farther west – to the full extent of the western end of the mine, Kubacki says.

Study co-author Michael “Kim” McCarter, a University of Utah professor of mining engineering, says the findings are tentative, but “might extend the collapse farther west.” He is puzzled because “some of that is in an area where no mining had occurred.”

Kubacki says one theory is that the seismic events at the west end and some of those at the eastern end of the mine may be caused by “faulting forming along a cone of collapse” centered over the mine.

Kubacki and McCarter conducted the new study with seismologists Keith Koper and Kris Pankow of the University of Utah Seismograph Stations. McCarter and Pankow also coauthored the 2008 study.

Before the new study, researchers knew of about 55 seismic events – down to magnitude 1.6 – near the mine before and after the collapse, which measured 3.9 on the local magnitude scale and 4.1 on the “moment” magnitude scale that better reflects energy release, Kubacki says.

The new study analyzed records of seismometers closest to the mine for evidence of tremors down to magnitudes minus-1, which Kubacki says is about one-tenth the energy released by a hand grenade. He found:

  • Strong statistical evidence there were at least 759 seismic events before the mine collapse and 569 aftershocks.

  • Weak evidence there were as many as 1,022 seismic events before the collapse and 1,167 aftershocks.

“We’ve discovered up to about 2,000 previously unknown events spanning from July 26 to Aug. 30, 2007,” Kubacki says, although some of the weak-evidence events may turn out not to be real or to be unrelated to the collapse.

The seismic events found in the new study show tremors clustered in three areas: the east end of the collapse area, the area where miners were working toward the mine’s west end, and – new in this study – at the mine’s west end, beyond where miners worked.

“We have three clusters to look at and try to come up with an explanation of why there were three,” McCarter says. “They are all related to the collapse.”

Some of the tremors in the eastern cluster are related to rescue attempts and a second collapse that killed three rescuers, but some remain unexplained, he adds.

Kubacki says most of the seismic activity before the collapse was due to mining, although scientists want to investigate whether any of those small jolts might have been signs of the impending collapse. So far, however, “there is nothing measured that would have said, ‘Here’s an event [mine collapse] that’s ready to happen,” McCarter says.

Kubacki came up with the new numbers of seismic events by analyzing the records of seismometers closest to Crandall Canyon (about 12 miles away). “We took the known seismic events already in the catalog and searched for events that looked the same,” he adds. “These new events kept popping up. There are tiny events that may show up on one station but not network-wide.”

“Any understanding we can get toward learning how and why mine collapses happen is going to be of interest to the mining community,” Kubacki says.

McCarter adds: “We are looking at the Crandall Canyon event because we have accurate logs and very extensive seismic data, and that provides a way of investigating the data to see if anything could be applied to other mines to improve safety.”

Mine disaster: Hundreds of aftershocks

A study by University of Utah mining engineers and seismologists found 2,189 suspected seismic events before and after Utah's deadly Crandall Canyon coal mine collapse in 2007, and 1,328 of those events have a high probability of being real: 759 seismic events before the collapse (many related to mining) and 569 aftershocks (some related to rescue efforts). The high-probability events shown here reveal seismic activity clustered in three areas, two of which already were known: near the east end of the mine
(right) and where miners were working, toward the west end of the mine (left of center).  But the third cluster, at the mine's west end (far left) was revealed by the new study. It shows the collapse was at least as big and possibly larger than a 2008 University of Utah study that revealed the collapse extended from the east part of the mine to the area where miners were working. For comparison, see other map. -  Tex Kubacki, University of Utah.
A study by University of Utah mining engineers and seismologists found 2,189 suspected seismic events before and after Utah’s deadly Crandall Canyon coal mine collapse in 2007, and 1,328 of those events have a high probability of being real: 759 seismic events before the collapse (many related to mining) and 569 aftershocks (some related to rescue efforts). The high-probability events shown here reveal seismic activity clustered in three areas, two of which already were known: near the east end of the mine
(right) and where miners were working, toward the west end of the mine (left of center). But the third cluster, at the mine’s west end (far left) was revealed by the new study. It shows the collapse was at least as big and possibly larger than a 2008 University of Utah study that revealed the collapse extended from the east part of the mine to the area where miners were working. For comparison, see other map. – Tex Kubacki, University of Utah.

A new University of Utah study has identified hundreds of previously unrecognized small aftershocks that happened after Utah’s deadly Crandall Canyon mine collapse in 2007. The aftershocks suggest the collapse was as big – and perhaps bigger – than shown in another study by the university in 2008.

Mapping out the locations of the aftershocks “helps us better delineate the extent of the collapse at Crandall canyon. It’s gotten bigger,” says Tex Kubacki, a University of Utah master’s student in mining engineering.

“We can see now that, prior to the collapse, the seismicity was occurring where the mining was taking place, and that after the collapse, the seismicity migrated to both ends of the collapse zone,” including the mine’s west end, he adds.

Kubacki was scheduled to present the findings Friday in Salt Lake City during the Seismological Society of America’s 2013 annual meeting.

Six coal miners died in the Aug. 6, 2007 mine collapse, and three rescuers died 10 days later. The mine’s owner initially blamed the collapse on an earthquake, but the University of Utah Seismograph Stations said it was the collapse itself, not an earthquake, that registered on seismometers.

A 2008 study by University of Utah seismologist Jim Pechmann found the epicenter of the collapse was near where the miners were working, and aftershocks showed the collapse area covered 50 acres, four times larger than originally thought, extending from crosscut 120 on the east to crosscut 143 on the west, where miners worked. A crosscut is a north-south tunnel intersecting the mine’s main east-west tunnels.

In the new study, the collapse area “looks like it goes farther west – to the full extent of the western end of the mine, Kubacki says.

Study co-author Michael “Kim” McCarter, a University of Utah professor of mining engineering, says the findings are tentative, but “might extend the collapse farther west.” He is puzzled because “some of that is in an area where no mining had occurred.”

Kubacki says one theory is that the seismic events at the west end and some of those at the eastern end of the mine may be caused by “faulting forming along a cone of collapse” centered over the mine.

Kubacki and McCarter conducted the new study with seismologists Keith Koper and Kris Pankow of the University of Utah Seismograph Stations. McCarter and Pankow also coauthored the 2008 study.

Before the new study, researchers knew of about 55 seismic events – down to magnitude 1.6 – near the mine before and after the collapse, which measured 3.9 on the local magnitude scale and 4.1 on the “moment” magnitude scale that better reflects energy release, Kubacki says.

The new study analyzed records of seismometers closest to the mine for evidence of tremors down to magnitudes minus-1, which Kubacki says is about one-tenth the energy released by a hand grenade. He found:

  • Strong statistical evidence there were at least 759 seismic events before the mine collapse and 569 aftershocks.

  • Weak evidence there were as many as 1,022 seismic events before the collapse and 1,167 aftershocks.

“We’ve discovered up to about 2,000 previously unknown events spanning from July 26 to Aug. 30, 2007,” Kubacki says, although some of the weak-evidence events may turn out not to be real or to be unrelated to the collapse.

The seismic events found in the new study show tremors clustered in three areas: the east end of the collapse area, the area where miners were working toward the mine’s west end, and – new in this study – at the mine’s west end, beyond where miners worked.

“We have three clusters to look at and try to come up with an explanation of why there were three,” McCarter says. “They are all related to the collapse.”

Some of the tremors in the eastern cluster are related to rescue attempts and a second collapse that killed three rescuers, but some remain unexplained, he adds.

Kubacki says most of the seismic activity before the collapse was due to mining, although scientists want to investigate whether any of those small jolts might have been signs of the impending collapse. So far, however, “there is nothing measured that would have said, ‘Here’s an event [mine collapse] that’s ready to happen,” McCarter says.

Kubacki came up with the new numbers of seismic events by analyzing the records of seismometers closest to Crandall Canyon (about 12 miles away). “We took the known seismic events already in the catalog and searched for events that looked the same,” he adds. “These new events kept popping up. There are tiny events that may show up on one station but not network-wide.”

“Any understanding we can get toward learning how and why mine collapses happen is going to be of interest to the mining community,” Kubacki says.

McCarter adds: “We are looking at the Crandall Canyon event because we have accurate logs and very extensive seismic data, and that provides a way of investigating the data to see if anything could be applied to other mines to improve safety.”

Helping to forecast earthquakes in Salt Lake Valley

Salt Lake Valley, home to the Salt Lake City segment of the Wasatch fault zone and the West Valley fault zone, has been the site of repeated surface-faulting earthquakes (of about magnitude 6.5 to 7). New research trenches in the area are helping geologists and seismologists untangle how this complex fault system ruptures and will aid in forecasting future earthquakes in the area.

At the annual meeting of the Seismological Society of America (SSA), Christopher DuRoss and Michael Hylland of the Utah Geological Survey will present research today that indicates geologically recent large earthquakes on the West Valley fault zone likely occurred with (or were triggered by) fault movement on the Salt Lake City segment. DuRoss and Hylland consider it less likely that West Valley fault movement happens completely independently from movement on the Salt Lake City segment. This likely pairing has implications for how the seismic hazard in Salt Lake Valley is modeled.

The trenches have also helped the researchers revise the history of large earthquakes in the area, showing that the Salt Lake City segment has been more active than previously thought. Since about 14,000 years ago, eight quakes have occurred on the segment. Depending on the time period, these quakes have occurred roughly every 1300 to 1500 years on average. It has been 1400 years since the most recent large earthquake on the segment. The earthquake history of the West Valley fault zone had been largely unknown, but now four earthquakes have been well dated.

This new fault research contributes to a broader goal of evaluating Utah’s earthquake hazards and risk. For example, this type of information on prehistoric earthquakes will be used by the Working Group on Utah Earthquake Probabilities, formed under the auspices of the Utah Geological Survey and U.S. Geological Survey, to forecast probabilities for future earthquakes in the Wasatch Front region.

Helping to forecast earthquakes in Salt Lake Valley

Salt Lake Valley, home to the Salt Lake City segment of the Wasatch fault zone and the West Valley fault zone, has been the site of repeated surface-faulting earthquakes (of about magnitude 6.5 to 7). New research trenches in the area are helping geologists and seismologists untangle how this complex fault system ruptures and will aid in forecasting future earthquakes in the area.

At the annual meeting of the Seismological Society of America (SSA), Christopher DuRoss and Michael Hylland of the Utah Geological Survey will present research today that indicates geologically recent large earthquakes on the West Valley fault zone likely occurred with (or were triggered by) fault movement on the Salt Lake City segment. DuRoss and Hylland consider it less likely that West Valley fault movement happens completely independently from movement on the Salt Lake City segment. This likely pairing has implications for how the seismic hazard in Salt Lake Valley is modeled.

The trenches have also helped the researchers revise the history of large earthquakes in the area, showing that the Salt Lake City segment has been more active than previously thought. Since about 14,000 years ago, eight quakes have occurred on the segment. Depending on the time period, these quakes have occurred roughly every 1300 to 1500 years on average. It has been 1400 years since the most recent large earthquake on the segment. The earthquake history of the West Valley fault zone had been largely unknown, but now four earthquakes have been well dated.

This new fault research contributes to a broader goal of evaluating Utah’s earthquake hazards and risk. For example, this type of information on prehistoric earthquakes will be used by the Working Group on Utah Earthquake Probabilities, formed under the auspices of the Utah Geological Survey and U.S. Geological Survey, to forecast probabilities for future earthquakes in the Wasatch Front region.

Research aims to settle debate over origin of Yellowstone volcano

A debate among scientists about the geologic formation of the supervolcano encompassing the region around Yellowstone National Park has taken a major step forward, thanks to new evidence provided by a team of international researchers led by University of Rhode Island Professor Christopher Kincaid.

In a publication appearing in last week’s edition of Nature Geoscience, the URI team demonstrated that both sides of the debate may be right.

Using a state-of-the-art plate tectonic laboratory model, they showed that volcanism in the Yellowstone area was caused by severely deformed and defunct pieces of a former mantle plume. They further concluded that the plume was affected by circulation currents driven by the movement of tectonic plates at the Cascades subduction zone.

Mantle plumes are hot buoyant upwellings of magma inside the Earth. Subduction zones are regions where dense oceanic tectonic plates dive beneath buoyant continental plates. The origins of the Yellowstone supervolcano have been argued for years, with sides disagreeing about the role of mantle plumes.

According to Kincaid, the simple view of mantle plumes is that they have a head and a tail, where the head rises to the surface, producing immense magma structures and the trailing tail interacts with the drifting surface plates to create a chain of smaller volcanoes of progressively younger age. But Yellowstone doesn’t fit this typical mold.Among its oddities, its eastward trail of smaller volcanoes called the Snake River Plain has a mirror-image volcanic chain, the High Lava Plain, that extends to the west.As a result, detractors say the two opposite trails of volcanoes and the curious north-south offset prove the plume model simply cannot work for this area, and that a plates-only model must be at work.

To examine these competing hypotheses, Kincaid, former graduate student Kelsey Druken, and colleagues at the Australian National University built a laboratory model of the Earth’s interior using corn syrup to simulate fluid-like motion of Earth’s mantle. The corn syrup has properties that allow researchers to examine complex time changing, three-dimensional motions caused by the collisions of tectonic plates at subduction zones and their effect on unsuspecting buoyant plumes.

By using the model to simulate a mantle plume in the Yellowstone region, the researchers found that it reproduced the characteristically odd patterns in volcanism that are recorded in the rocks of the Pacific Northwest.

“Our model shows that a simple view of mantle plumes is not appropriate when they rise near subduction zones, and that these features get ripped apart in a way that seems to match the patterns in magma output in the northwestern U.S. over the past 20 million years,” said Kincaid, a professor of geological oceanography at the URI Graduate School of Oceanography. “The sinking plate produces a flow field that dominates the interaction with the plume, making the plume passive in many ways and trapping much of the magma producing energy well below the surface. What you see at the surface doesn’t look like what you’d expect from the simple models.”

The next step in Kincaid’s research is to conduct a similar analysis of the geologic formations in the region around the Tonga subduction zone and the Samoan Islands in the South Pacific, another area where some scientists dispute the role of mantle plumes.

According to Kincaid, “A goal of geological oceanography is to understand the relationship between Earth’s convecting interior and our oceans over the entire spectrum of geologic time. This feeds directly into the very pressing need for understanding where Earth’s ocean-climate system is headed, which clearly hinges on our understanding of how it has worked in past.”

Research aims to settle debate over origin of Yellowstone volcano

A debate among scientists about the geologic formation of the supervolcano encompassing the region around Yellowstone National Park has taken a major step forward, thanks to new evidence provided by a team of international researchers led by University of Rhode Island Professor Christopher Kincaid.

In a publication appearing in last week’s edition of Nature Geoscience, the URI team demonstrated that both sides of the debate may be right.

Using a state-of-the-art plate tectonic laboratory model, they showed that volcanism in the Yellowstone area was caused by severely deformed and defunct pieces of a former mantle plume. They further concluded that the plume was affected by circulation currents driven by the movement of tectonic plates at the Cascades subduction zone.

Mantle plumes are hot buoyant upwellings of magma inside the Earth. Subduction zones are regions where dense oceanic tectonic plates dive beneath buoyant continental plates. The origins of the Yellowstone supervolcano have been argued for years, with sides disagreeing about the role of mantle plumes.

According to Kincaid, the simple view of mantle plumes is that they have a head and a tail, where the head rises to the surface, producing immense magma structures and the trailing tail interacts with the drifting surface plates to create a chain of smaller volcanoes of progressively younger age. But Yellowstone doesn’t fit this typical mold.Among its oddities, its eastward trail of smaller volcanoes called the Snake River Plain has a mirror-image volcanic chain, the High Lava Plain, that extends to the west.As a result, detractors say the two opposite trails of volcanoes and the curious north-south offset prove the plume model simply cannot work for this area, and that a plates-only model must be at work.

To examine these competing hypotheses, Kincaid, former graduate student Kelsey Druken, and colleagues at the Australian National University built a laboratory model of the Earth’s interior using corn syrup to simulate fluid-like motion of Earth’s mantle. The corn syrup has properties that allow researchers to examine complex time changing, three-dimensional motions caused by the collisions of tectonic plates at subduction zones and their effect on unsuspecting buoyant plumes.

By using the model to simulate a mantle plume in the Yellowstone region, the researchers found that it reproduced the characteristically odd patterns in volcanism that are recorded in the rocks of the Pacific Northwest.

“Our model shows that a simple view of mantle plumes is not appropriate when they rise near subduction zones, and that these features get ripped apart in a way that seems to match the patterns in magma output in the northwestern U.S. over the past 20 million years,” said Kincaid, a professor of geological oceanography at the URI Graduate School of Oceanography. “The sinking plate produces a flow field that dominates the interaction with the plume, making the plume passive in many ways and trapping much of the magma producing energy well below the surface. What you see at the surface doesn’t look like what you’d expect from the simple models.”

The next step in Kincaid’s research is to conduct a similar analysis of the geologic formations in the region around the Tonga subduction zone and the Samoan Islands in the South Pacific, another area where some scientists dispute the role of mantle plumes.

According to Kincaid, “A goal of geological oceanography is to understand the relationship between Earth’s convecting interior and our oceans over the entire spectrum of geologic time. This feeds directly into the very pressing need for understanding where Earth’s ocean-climate system is headed, which clearly hinges on our understanding of how it has worked in past.”

Natural soil bacteria pump new life into exhausted oil wells

Technology that enlists natural soil bacteria as 21st century roughnecks now is commercially available and poised to recover precious oil remaining in thousands of exhausted oil wells, according to a scientist who spoke here today. His report on a process termed microbially enhanced oil recovery (MEOR) was part of the 245th National Meeting & Exposition of the American Chemical Society, the world’s largest scientific society.

“The idea of using microbes to bring spent oil wells back to life dates to the early 1900s,” said Brian Clement, Ph.D. “That was the era of ‘easy-to-recover’ oil, and when a well played out, you just moved on and drilled another – knowing that 60-70 percent of the oil in that first reservoir remained untouched. We’re in a different era now. Oil is scarcer, and it makes sense to use MEOR. It can put about 10 percent of the oil in exhausted wells into barrels with low capital investment, low operating costs and little environmental impact.”

Clement is a senior scientist at Glori Energy, which is deploying its MEOR technology known as
AEROTM, for Activated Environment for Recovery of Oil. Other companies that have moved the technology to market include DuPont, which offers its MATRxTM MEOR technology and Titan Oil Recovery, Inc., which offers its Titan Process®. Clement’s talk was part of the symposium titled “The Interconnected World of Energy, Food and Water.”

Conventional oil production techniques rely on pressure that exists naturally in an underground reservoir to push oil to the surface, much like the pressure in a bottle of carbonated beverage. Clement explained that the pressure in a reservoir declines over time, and eventually it is too low to force oil to the surface. At that point, as much as 60 to 70 percent of the reservoir’s oil often remains in the ground.

MEOR can retrieve that oil by fostering various changes in the reservoir. Clement explained that the AEROTM System, for instance, piggybacks on waterflooding, a widely used process in which water is injected into the reservoir to force oil out of the well and to the surface. The system adds a customized formula of nutrients to the injection water to optimize its quality and stimulate the growth of native reservoir bacteria.

With the AERO System, microbes thrive and grow to increase oil production using two main mechanisms. First, they break down and metabolize oil at the oil-water interface, allowing the oil to flow more freely. Second, the microbes block existing water channels within the reservoir’s soil, forcing the water into new channels and driving more oil to the surface.

With the AERO System’s MEOR technology, oil field owners and operators can increase production from declining wells without having to invest in expensive, new infrastructure. Clement described tests in which the technology helped produce an additional 9-12 percent of the total oil remaining in reservoirs. The number may sound small, but translates into an additional $10 billion of oil from wells in the United States and more than $165 billion worldwide.

Natural soil bacteria pump new life into exhausted oil wells

Technology that enlists natural soil bacteria as 21st century roughnecks now is commercially available and poised to recover precious oil remaining in thousands of exhausted oil wells, according to a scientist who spoke here today. His report on a process termed microbially enhanced oil recovery (MEOR) was part of the 245th National Meeting & Exposition of the American Chemical Society, the world’s largest scientific society.

“The idea of using microbes to bring spent oil wells back to life dates to the early 1900s,” said Brian Clement, Ph.D. “That was the era of ‘easy-to-recover’ oil, and when a well played out, you just moved on and drilled another – knowing that 60-70 percent of the oil in that first reservoir remained untouched. We’re in a different era now. Oil is scarcer, and it makes sense to use MEOR. It can put about 10 percent of the oil in exhausted wells into barrels with low capital investment, low operating costs and little environmental impact.”

Clement is a senior scientist at Glori Energy, which is deploying its MEOR technology known as
AEROTM, for Activated Environment for Recovery of Oil. Other companies that have moved the technology to market include DuPont, which offers its MATRxTM MEOR technology and Titan Oil Recovery, Inc., which offers its Titan Process®. Clement’s talk was part of the symposium titled “The Interconnected World of Energy, Food and Water.”

Conventional oil production techniques rely on pressure that exists naturally in an underground reservoir to push oil to the surface, much like the pressure in a bottle of carbonated beverage. Clement explained that the pressure in a reservoir declines over time, and eventually it is too low to force oil to the surface. At that point, as much as 60 to 70 percent of the reservoir’s oil often remains in the ground.

MEOR can retrieve that oil by fostering various changes in the reservoir. Clement explained that the AEROTM System, for instance, piggybacks on waterflooding, a widely used process in which water is injected into the reservoir to force oil out of the well and to the surface. The system adds a customized formula of nutrients to the injection water to optimize its quality and stimulate the growth of native reservoir bacteria.

With the AERO System, microbes thrive and grow to increase oil production using two main mechanisms. First, they break down and metabolize oil at the oil-water interface, allowing the oil to flow more freely. Second, the microbes block existing water channels within the reservoir’s soil, forcing the water into new channels and driving more oil to the surface.

With the AERO System’s MEOR technology, oil field owners and operators can increase production from declining wells without having to invest in expensive, new infrastructure. Clement described tests in which the technology helped produce an additional 9-12 percent of the total oil remaining in reservoirs. The number may sound small, but translates into an additional $10 billion of oil from wells in the United States and more than $165 billion worldwide.

Ocean explorers want to get to the bottom of Galicia

Rice researchers who will study the Galicia rift off the coast of Spain this summer are (from left, front) Sarah Dean, Steve Danbom and Mari Tesi Sanjurjo and (from left, rear) Brian Jordan, Dale Sawyer and Julia Morgan. All but Morgan will make the 45-day cruise to map the terrain under the rift. -  Colin Zelt/Rice University
Rice researchers who will study the Galicia rift off the coast of Spain this summer are (from left, front) Sarah Dean, Steve Danbom and Mari Tesi Sanjurjo and (from left, rear) Brian Jordan, Dale Sawyer and Julia Morgan. All but Morgan will make the 45-day cruise to map the terrain under the rift. – Colin Zelt/Rice University

An international team of scientists and technicians led by Rice University will spend 45 days in the North Atlantic this summer to gather the most detailed information ever about the geology of the ocean basin that formed at what was once the center of Pangaea.

Geologists Dale Sawyer and Julia Morgan of Rice and Donna Shillington of Columbia University are leading the $6 million international project to study the Galicia rift northwest of the Spanish coast where, unusually, sediment has not deeply buried formations that have existed at the bottom of the ocean for millions of years.

A National Science Foundation (NSF) grant to Rice of more than $1.2 million will put five faculty members and graduate students on the 50-plus crew aboard the Seismic Vessel Marcus G. Langseth, owned by the NSF and operated by the Lamont-Doherty Earth Observatory.

The Langseth stopped in Galveston last month, where Sawyer took stock of its tools. He and Morgan have been waiting for their ship to come in since proposing the project eight years ago. “We had to wait for other seismic studies, creating a critical mass of work in the Atlantic in order to bring the ship from the Pacific Ocean to the Atlantic,” Sawyer said.

For 45 days the ship will trace a spiraling path — Sawyer compared it to mowing a lawn — over the rectangular 64-by-22.4 kilometer target. Throughout the journey, the 15 scientists and their technicians and students will analyze data and make critical decisions on optimizing data quality.

Sawyer will represent Rice on the ship, joined by graduate students Sarah Dean, Brian Jordan and Mari Tesi Sanjurjo and adjunct faculty lecturer Steve Danbom. All will begin analyzing the massive amount of data the ship will collect while on board, but the results will take years for geologists to fully process and understand, Sawyer said.

“Between 225 and 110 million years ago, the Atlantic Ocean opened up between Africa and North America, and the breakup propagated northward, opening a new ocean and pulling Spain and Portugal apart from what is now Newfoundland,” Sawyer said. “What makes this unusual is that it is a volcanic-starved rift.”

Elsewhere on the planet, lava flowed upward into rifts and created oceanic crust. “We found in the last 20 years that most margins are volcanic-dominated,” he said. “They actually pull apart, lots of magma comes up and the sea-floor spreading process begins immediately. Galicia is at the other end of the spectrum. Volcanic-dominated margins are thought to be caused by unusually high heat in the Earth’s mantle, while magma-starved margins are caused by cooler mantle rocks.

But the volcanic crust hasn’t reached the Galicia, where sections of the Earth’s mantle in the form of peridotite lie just under a thin layer of sediment. At this rift, the crust is neither oceanic nor continental, but of a different type. These formations may tell geologists a great deal about the rifts that appeared when the great continent split and began evolving into the map we know today.

“The sediments are thin,” Sawyer said, “so we can do seismic characterization and potentially drill into these rocks without having to go through 10 or 15 kilometers of sediment.

“One of our objectives with the 3-D survey is to find the best places to drill,” he said. “Now we can see the fans of sediment deposited on the broken and tilted continental crust blocks, but we don’t know when they broke and how quickly.” The images should allow them to gather core samples at the right places. “Then we have paleontological evidence we can date, and then we can start to know.”

To learn all this, the team will make 3-D images of the upper 20 kilometers of the rocks under the ocean. The RV Langseth will tow four cables, each 6 kilometers long, carrying nearly 2,000 hydrophones. The towed cables cover a width of 600 meters as they rake through the water. Constantly on the move, the ship fires an array of compressed air guns towed behind the ship. Airgun shots will be fired every 37 meters (once about every 16 seconds), and the seismometers will sense the reflections that come back from the seafloor and from rock layers. Using sound to see what eyes can’t, the signals are translated into an accurate three-dimensional image of the geological terrain below.

Before the Langseth sails from Vigo, Spain, on June 1, the German Research Vessel Poseidon and scientists from Germany and the United Kingdom will drop about 80 ocean-bottom seismometers in a grid on the same patch of ocean floor that the Rice-led team will survey.

“The ocean-bottom seismometers give us much better information about the speed of sound through the rocks, and that tells us a lot about what kind of rock the seismic wave is traveling through,” Sawyer said.

Several oil companies are interested in this work, Sawyer said. Although the sediments to be studied are thin and unlikely to yield oil or gas, other places in the world with similar magma-starved rifting and thick overlying sediments are virtually certain to contain hydrocarbons. Images taken through the thin Galicia sediments will provide information about what to expect in hydrocarbon-bearing areas elsewhere, he said.

Ocean explorers want to get to the bottom of Galicia

Rice researchers who will study the Galicia rift off the coast of Spain this summer are (from left, front) Sarah Dean, Steve Danbom and Mari Tesi Sanjurjo and (from left, rear) Brian Jordan, Dale Sawyer and Julia Morgan. All but Morgan will make the 45-day cruise to map the terrain under the rift. -  Colin Zelt/Rice University
Rice researchers who will study the Galicia rift off the coast of Spain this summer are (from left, front) Sarah Dean, Steve Danbom and Mari Tesi Sanjurjo and (from left, rear) Brian Jordan, Dale Sawyer and Julia Morgan. All but Morgan will make the 45-day cruise to map the terrain under the rift. – Colin Zelt/Rice University

An international team of scientists and technicians led by Rice University will spend 45 days in the North Atlantic this summer to gather the most detailed information ever about the geology of the ocean basin that formed at what was once the center of Pangaea.

Geologists Dale Sawyer and Julia Morgan of Rice and Donna Shillington of Columbia University are leading the $6 million international project to study the Galicia rift northwest of the Spanish coast where, unusually, sediment has not deeply buried formations that have existed at the bottom of the ocean for millions of years.

A National Science Foundation (NSF) grant to Rice of more than $1.2 million will put five faculty members and graduate students on the 50-plus crew aboard the Seismic Vessel Marcus G. Langseth, owned by the NSF and operated by the Lamont-Doherty Earth Observatory.

The Langseth stopped in Galveston last month, where Sawyer took stock of its tools. He and Morgan have been waiting for their ship to come in since proposing the project eight years ago. “We had to wait for other seismic studies, creating a critical mass of work in the Atlantic in order to bring the ship from the Pacific Ocean to the Atlantic,” Sawyer said.

For 45 days the ship will trace a spiraling path — Sawyer compared it to mowing a lawn — over the rectangular 64-by-22.4 kilometer target. Throughout the journey, the 15 scientists and their technicians and students will analyze data and make critical decisions on optimizing data quality.

Sawyer will represent Rice on the ship, joined by graduate students Sarah Dean, Brian Jordan and Mari Tesi Sanjurjo and adjunct faculty lecturer Steve Danbom. All will begin analyzing the massive amount of data the ship will collect while on board, but the results will take years for geologists to fully process and understand, Sawyer said.

“Between 225 and 110 million years ago, the Atlantic Ocean opened up between Africa and North America, and the breakup propagated northward, opening a new ocean and pulling Spain and Portugal apart from what is now Newfoundland,” Sawyer said. “What makes this unusual is that it is a volcanic-starved rift.”

Elsewhere on the planet, lava flowed upward into rifts and created oceanic crust. “We found in the last 20 years that most margins are volcanic-dominated,” he said. “They actually pull apart, lots of magma comes up and the sea-floor spreading process begins immediately. Galicia is at the other end of the spectrum. Volcanic-dominated margins are thought to be caused by unusually high heat in the Earth’s mantle, while magma-starved margins are caused by cooler mantle rocks.

But the volcanic crust hasn’t reached the Galicia, where sections of the Earth’s mantle in the form of peridotite lie just under a thin layer of sediment. At this rift, the crust is neither oceanic nor continental, but of a different type. These formations may tell geologists a great deal about the rifts that appeared when the great continent split and began evolving into the map we know today.

“The sediments are thin,” Sawyer said, “so we can do seismic characterization and potentially drill into these rocks without having to go through 10 or 15 kilometers of sediment.

“One of our objectives with the 3-D survey is to find the best places to drill,” he said. “Now we can see the fans of sediment deposited on the broken and tilted continental crust blocks, but we don’t know when they broke and how quickly.” The images should allow them to gather core samples at the right places. “Then we have paleontological evidence we can date, and then we can start to know.”

To learn all this, the team will make 3-D images of the upper 20 kilometers of the rocks under the ocean. The RV Langseth will tow four cables, each 6 kilometers long, carrying nearly 2,000 hydrophones. The towed cables cover a width of 600 meters as they rake through the water. Constantly on the move, the ship fires an array of compressed air guns towed behind the ship. Airgun shots will be fired every 37 meters (once about every 16 seconds), and the seismometers will sense the reflections that come back from the seafloor and from rock layers. Using sound to see what eyes can’t, the signals are translated into an accurate three-dimensional image of the geological terrain below.

Before the Langseth sails from Vigo, Spain, on June 1, the German Research Vessel Poseidon and scientists from Germany and the United Kingdom will drop about 80 ocean-bottom seismometers in a grid on the same patch of ocean floor that the Rice-led team will survey.

“The ocean-bottom seismometers give us much better information about the speed of sound through the rocks, and that tells us a lot about what kind of rock the seismic wave is traveling through,” Sawyer said.

Several oil companies are interested in this work, Sawyer said. Although the sediments to be studied are thin and unlikely to yield oil or gas, other places in the world with similar magma-starved rifting and thick overlying sediments are virtually certain to contain hydrocarbons. Images taken through the thin Galicia sediments will provide information about what to expect in hydrocarbon-bearing areas elsewhere, he said.