New report details more geoscience job opportunities than students

This image graphs industries hiring geoscience degree graduates by bachelors, masters and doctoral degree brackets. -  Carolyn Wilson: cwilson@americangeosciences.org
This image graphs industries hiring geoscience degree graduates by bachelors, masters and doctoral degree brackets. – Carolyn Wilson: cwilson@americangeosciences.org

In the American Geosciences Institute’s newest Status of the Geoscience Workforce Report, released May 2014, jobs requiring training in the geosciences continue to be lucrative and in-demand. Even with increased enrollment and graduation from geoscience programs, the data still project a shortage of around 135,000 geoscientists needed in the workforce by the end of the decade.

“Industry has recognized, and is mitigating the upcoming shortage of skilled geoscientists in their employ, but the federal geoscience workforce is still demonstrably shrinking” report author Carolyn Wilson said, noting that the federal geoscience workforce decreased in all sectors except meteorology; this includes geoscientists skilled in the energy, mining/minerals and hydrology fields. Combined with continued unevenness is the workforce readiness of many geoscience graduates and a regionally hot job market, the geosciences are a dynamic component of the U.S. economy.

Employers have appreciably skilled geoscientists to choose from too. Numbers of graduating geoscience majors who started their degrees at a two-year colleges have increased, as have the number of students participating in a field camp experiences-an important facet of a geoscience degree, where students get experience interpreting the landforms critical to determining where energy or water resources exist, as well as interpreting locations susceptible to hazards like flooding or landslides. Most students graduating from a geoscience degree program have taken math courses up to a calculus-II level, but there is still concern from employers over whether these students are graduating with enough quantitative experience to be completely apt for a career in the geosciences.

Employers underscore the necessity of having enough skilled grads to meet vacancies that will exist in the geoscience sector in the upcoming decades.

“It’s important that working knowledge is passed down because losing the institutional knowledge could have negative impacts for the overall productivity of these companies.” Wilson said.

“Most importantly there is incredible potential for institutions to recruit from the diverse talent pools arising at two year institutions, and many career opportunities available to students enrolled in geoscience programs, and early-career geoscientists entering the workforce,” Wilson said. “Plus, this is the first time we have seen a major shift in employment patterns in over a generation, with increasing number of bachelor recipients securing geoscience positions, and newly minted Master’s finding themselves in high demand.”

New report details more geoscience job opportunities than students

This image graphs industries hiring geoscience degree graduates by bachelors, masters and doctoral degree brackets. -  Carolyn Wilson: cwilson@americangeosciences.org
This image graphs industries hiring geoscience degree graduates by bachelors, masters and doctoral degree brackets. – Carolyn Wilson: cwilson@americangeosciences.org

In the American Geosciences Institute’s newest Status of the Geoscience Workforce Report, released May 2014, jobs requiring training in the geosciences continue to be lucrative and in-demand. Even with increased enrollment and graduation from geoscience programs, the data still project a shortage of around 135,000 geoscientists needed in the workforce by the end of the decade.

“Industry has recognized, and is mitigating the upcoming shortage of skilled geoscientists in their employ, but the federal geoscience workforce is still demonstrably shrinking” report author Carolyn Wilson said, noting that the federal geoscience workforce decreased in all sectors except meteorology; this includes geoscientists skilled in the energy, mining/minerals and hydrology fields. Combined with continued unevenness is the workforce readiness of many geoscience graduates and a regionally hot job market, the geosciences are a dynamic component of the U.S. economy.

Employers have appreciably skilled geoscientists to choose from too. Numbers of graduating geoscience majors who started their degrees at a two-year colleges have increased, as have the number of students participating in a field camp experiences-an important facet of a geoscience degree, where students get experience interpreting the landforms critical to determining where energy or water resources exist, as well as interpreting locations susceptible to hazards like flooding or landslides. Most students graduating from a geoscience degree program have taken math courses up to a calculus-II level, but there is still concern from employers over whether these students are graduating with enough quantitative experience to be completely apt for a career in the geosciences.

Employers underscore the necessity of having enough skilled grads to meet vacancies that will exist in the geoscience sector in the upcoming decades.

“It’s important that working knowledge is passed down because losing the institutional knowledge could have negative impacts for the overall productivity of these companies.” Wilson said.

“Most importantly there is incredible potential for institutions to recruit from the diverse talent pools arising at two year institutions, and many career opportunities available to students enrolled in geoscience programs, and early-career geoscientists entering the workforce,” Wilson said. “Plus, this is the first time we have seen a major shift in employment patterns in over a generation, with increasing number of bachelor recipients securing geoscience positions, and newly minted Master’s finding themselves in high demand.”

New study finds Antarctic Ice Sheet unstable at end of last ice age

This is one of many icebergs that sheared off the continent and ended up in the Scotia Sea. -  Photo courtesy of Michael Weber, University of Cologne
This is one of many icebergs that sheared off the continent and ended up in the Scotia Sea. – Photo courtesy of Michael Weber, University of Cologne

A new study has found that the Antarctic Ice Sheet began melting about 5,000 years earlier than previously thought coming out of the last ice age – and that shrinkage of the vast ice sheet accelerated during eight distinct episodes, causing rapid sea level rise.

The international study, funded in part by the National Science Foundation, is particularly important coming on the heels of recent studies that suggest destabilization of part of the West Antarctic Ice Sheet has begun.

Results of this latest study are being published this week in the journal Nature. It was conducted by researchers at University of Cologne, Oregon State University, the Alfred-Wegener-Institute, University of Hawaii at Manoa, University of Lapland, University of New South Wales, and University of Bonn.

The researchers examined two sediment cores from the Scotia Sea between Antarctica and South America that contained “iceberg-rafted debris” that had been scraped off Antarctica by moving ice and deposited via icebergs into the sea. As the icebergs melted, they dropped the minerals into the seafloor sediments, giving scientists a glimpse at the past behavior of the Antarctic Ice Sheet.

Periods of rapid increases in iceberg-rafted debris suggest that more icebergs were being released by the Antarctic Ice Sheet. The researchers discovered increased amounts of debris during eight separate episodes beginning as early as 20,000 years ago, and continuing until 9,000 years ago.

The melting of the Antarctic Ice Sheet wasn’t thought to have started, however, until 14,000 years ago.

“Conventional thinking based on past research is that the Antarctic Ice Sheet has been relatively stable since the last ice age, that it began to melt relatively late during the deglaciation process, and that its decline was slow and steady until it reached its present size,” said lead author Michael Weber, a scientist from the University of Cologne in Germany.

“The sediment record suggests a different pattern – one that is more episodic and suggests that parts of the ice sheet repeatedly became unstable during the last deglaciation,” Weber added.

The research also provides the first solid evidence that the Antarctic Ice Sheet contributed to what is known as meltwater pulse 1A, a period of very rapid sea level rise that began some 14,500 years ago, according to Peter Clark, an Oregon State University paleoclimatologist and co-author on the study.

The largest of the eight episodic pulses outlined in the new Nature study coincides with meltwater pulse 1A.

“During that time, the sea level on a global basis rose about 50 feet in just 350 years – or about 20 times faster than sea level rise over the last century,” noted Clark, a professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. “We don’t yet know what triggered these eight episodes or pulses, but it appears that once the melting of the ice sheet began it was amplified by physical processes.”

The researchers suspect that a feedback mechanism may have accelerated the melting, possibly by changing ocean circulation that brought warmer water to the Antarctic subsurface, according to co-author Axel Timmermann, a climate researcher at the University of Hawaii at Manoa.

“This positive feedback is a perfect recipe for rapid sea level rise,” Timmermann said.

Some 9,000 years ago, the episodic pulses of melting stopped, the researchers say.

“Just as we are unsure of what triggered these eight pulses,” Clark said, “we don’t know why they stopped. Perhaps the sheet ran out of ice that was vulnerable to the physical changes that were taking place. However, our new results suggest that the Antarctic Ice Sheet is more unstable than previously considered.”

Today, the annual calving of icebergs from Antarctic represents more than half of the annual loss of mass of the Antarctic Ice Sheet – an estimated 1,300 to 2,000 gigatons (a gigaton is a billion tons). Some of these giant icebergs are longer than 18 kilometers.

New study finds Antarctic Ice Sheet unstable at end of last ice age

This is one of many icebergs that sheared off the continent and ended up in the Scotia Sea. -  Photo courtesy of Michael Weber, University of Cologne
This is one of many icebergs that sheared off the continent and ended up in the Scotia Sea. – Photo courtesy of Michael Weber, University of Cologne

A new study has found that the Antarctic Ice Sheet began melting about 5,000 years earlier than previously thought coming out of the last ice age – and that shrinkage of the vast ice sheet accelerated during eight distinct episodes, causing rapid sea level rise.

The international study, funded in part by the National Science Foundation, is particularly important coming on the heels of recent studies that suggest destabilization of part of the West Antarctic Ice Sheet has begun.

Results of this latest study are being published this week in the journal Nature. It was conducted by researchers at University of Cologne, Oregon State University, the Alfred-Wegener-Institute, University of Hawaii at Manoa, University of Lapland, University of New South Wales, and University of Bonn.

The researchers examined two sediment cores from the Scotia Sea between Antarctica and South America that contained “iceberg-rafted debris” that had been scraped off Antarctica by moving ice and deposited via icebergs into the sea. As the icebergs melted, they dropped the minerals into the seafloor sediments, giving scientists a glimpse at the past behavior of the Antarctic Ice Sheet.

Periods of rapid increases in iceberg-rafted debris suggest that more icebergs were being released by the Antarctic Ice Sheet. The researchers discovered increased amounts of debris during eight separate episodes beginning as early as 20,000 years ago, and continuing until 9,000 years ago.

The melting of the Antarctic Ice Sheet wasn’t thought to have started, however, until 14,000 years ago.

“Conventional thinking based on past research is that the Antarctic Ice Sheet has been relatively stable since the last ice age, that it began to melt relatively late during the deglaciation process, and that its decline was slow and steady until it reached its present size,” said lead author Michael Weber, a scientist from the University of Cologne in Germany.

“The sediment record suggests a different pattern – one that is more episodic and suggests that parts of the ice sheet repeatedly became unstable during the last deglaciation,” Weber added.

The research also provides the first solid evidence that the Antarctic Ice Sheet contributed to what is known as meltwater pulse 1A, a period of very rapid sea level rise that began some 14,500 years ago, according to Peter Clark, an Oregon State University paleoclimatologist and co-author on the study.

The largest of the eight episodic pulses outlined in the new Nature study coincides with meltwater pulse 1A.

“During that time, the sea level on a global basis rose about 50 feet in just 350 years – or about 20 times faster than sea level rise over the last century,” noted Clark, a professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. “We don’t yet know what triggered these eight episodes or pulses, but it appears that once the melting of the ice sheet began it was amplified by physical processes.”

The researchers suspect that a feedback mechanism may have accelerated the melting, possibly by changing ocean circulation that brought warmer water to the Antarctic subsurface, according to co-author Axel Timmermann, a climate researcher at the University of Hawaii at Manoa.

“This positive feedback is a perfect recipe for rapid sea level rise,” Timmermann said.

Some 9,000 years ago, the episodic pulses of melting stopped, the researchers say.

“Just as we are unsure of what triggered these eight pulses,” Clark said, “we don’t know why they stopped. Perhaps the sheet ran out of ice that was vulnerable to the physical changes that were taking place. However, our new results suggest that the Antarctic Ice Sheet is more unstable than previously considered.”

Today, the annual calving of icebergs from Antarctic represents more than half of the annual loss of mass of the Antarctic Ice Sheet – an estimated 1,300 to 2,000 gigatons (a gigaton is a billion tons). Some of these giant icebergs are longer than 18 kilometers.

Lower mantle chemistry breakthrough

Breaking research news from a team of scientists led by Carnegie’s Ho-kwang “Dave” Mao reveals that the composition of the Earth’s lower mantle may be significantly different than previously thought. These results are to be published by Science.

The lower mantle comprises 55 percent of the planet by volume and extends from 670 and 2900 kilometers in depth, as defined by the so-called transition zone (top) and the core-mantle boundary (below). Pressures in the lower mantle start at 237,000 times atmospheric pressure (24 gigapascals) and reach 1.3 million times atmospheric pressure (136 gigapascals) at the core-mantle boundary.

The prevailing theory has been that the majority of the lower mantle is made up of a single ferromagnesian silicate mineral, commonly called perovskite (Mg,Fe)SiO3) defined through its chemistry and structure. It was thought that perovskite didn’t change structure over the enormous range of pressures and temperatures spanning the lower mantle.

Recent experiments that simulate the conditions of the lower mantle using laser-heated diamond anvil cells, at pressures between 938,000 and 997,000 times atmospheric pressure (95 and 101 gigapascals) and temperatures between 3,500 and 3,860 degrees Fahrenheit (2,200 and 2,400 Kelvin), now reveal that iron bearing perovskite is, in fact, unstable in the lower mantle.

The team finds that the mineral disassociates into two phases one a magnesium silicate perovskite missing iron, which is represented by the Fe portion of the chemical formula, and a new mineral, that is iron-rich and hexagonal in structure, called the H-phase. Experiments confirm that this iron-rich H-phase is more stable than iron bearing perovskite, much to everyone’s surprise. This means it is likely a prevalent and previously unknown species in the lower mantle. This may change our understanding of the deep Earth.

“We still don’t fully understand the chemistry of the H-phase,” said lead author Li Zhang, also of Carnegie. “But this finding indicates that all geodynamic models need to be reconsidered to take the H-phase into account. And there could be even more unidentified phases down there in the lower mantle as well, waiting to be identified.”

Lower mantle chemistry breakthrough

Breaking research news from a team of scientists led by Carnegie’s Ho-kwang “Dave” Mao reveals that the composition of the Earth’s lower mantle may be significantly different than previously thought. These results are to be published by Science.

The lower mantle comprises 55 percent of the planet by volume and extends from 670 and 2900 kilometers in depth, as defined by the so-called transition zone (top) and the core-mantle boundary (below). Pressures in the lower mantle start at 237,000 times atmospheric pressure (24 gigapascals) and reach 1.3 million times atmospheric pressure (136 gigapascals) at the core-mantle boundary.

The prevailing theory has been that the majority of the lower mantle is made up of a single ferromagnesian silicate mineral, commonly called perovskite (Mg,Fe)SiO3) defined through its chemistry and structure. It was thought that perovskite didn’t change structure over the enormous range of pressures and temperatures spanning the lower mantle.

Recent experiments that simulate the conditions of the lower mantle using laser-heated diamond anvil cells, at pressures between 938,000 and 997,000 times atmospheric pressure (95 and 101 gigapascals) and temperatures between 3,500 and 3,860 degrees Fahrenheit (2,200 and 2,400 Kelvin), now reveal that iron bearing perovskite is, in fact, unstable in the lower mantle.

The team finds that the mineral disassociates into two phases one a magnesium silicate perovskite missing iron, which is represented by the Fe portion of the chemical formula, and a new mineral, that is iron-rich and hexagonal in structure, called the H-phase. Experiments confirm that this iron-rich H-phase is more stable than iron bearing perovskite, much to everyone’s surprise. This means it is likely a prevalent and previously unknown species in the lower mantle. This may change our understanding of the deep Earth.

“We still don’t fully understand the chemistry of the H-phase,” said lead author Li Zhang, also of Carnegie. “But this finding indicates that all geodynamic models need to be reconsidered to take the H-phase into account. And there could be even more unidentified phases down there in the lower mantle as well, waiting to be identified.”

The next ‘Big One’ for the Bay Area may be a cluster of major quakes

A cluster of closely timed earthquakes over 100 years in the 17th and 18th centuries released as much accumulated stress on San Francisco Bay Area’s major faults as the Great 1906 San Francisco earthquake, suggesting two possible scenarios for the next “Big One” for the region, according to new research published by the Bulletin of the Seismological Society of America (BSSA).

“The plates are moving,” said David Schwartz, a geologist with the U.S. Geological Survey and co-author of the study. “The stress is re-accumulating, and all of these faults have to catch up. How are they going to catch up?”

The San Francisco Bay Region (SFBR) is considered within the boundary between the Pacific and North American plates. Energy released during its earthquake cycle occurs along the region’s principal faults: the San Andreas, San Gregorio, Calaveras, Hayward-Rodgers Creek, Greenville, and Concord-Green Valley faults.

“The 1906 quake happened when there were fewer people, and the area was much less developed,” said Schwartz. “The earthquake had the beneficial effect of releasing the plate boundary stress and relaxing the crust, ushering in a period of low level earthquake activity.”

The earthquake cycle reflects the accumulation of stress, its release as slip on a fault or a set of faults, and its re-accumulation and re-release. The San Francisco Bay Area has not experienced a full earthquake cycle since its been occupied by people who have reported earthquake activity, either through written records or instrumentation. Founded in 1776, the Mission Dolores and the Presidio in San Francisco kept records of felt earthquakes and earthquake damage, marking the starting point for the historic earthquake record for the region.

“We are looking back at the past to get a more reasonable view of what’s going to happen decades down the road,” said Schwartz. “The only way to get a long history is to do these paleoseismic studies, which can help construct the rupture histories of the faults and the region. We are trying to see what went on and understand the uncertainties for the Bay Area.”

Schwartz and colleagues excavated trenches across faults, observing past surface ruptures from the most recent earthquakes on the major faults in the area. Radiocarbon dating of detrital charcoal and the presence of non-native pollen established the dates of paleoearthquakes, expanding the span of information of large events back to 1600.

The trenching studies suggest that between 1690 and the founding of the Mission Dolores and Presidio in 1776, a cluster of earthquakes ranging from magnitude 6.6 to 7.8 occurred on the Hayward fault (north and south segments), San Andreas fault (North Coast and San Juan Bautista segments), northern Calaveras fault, Rodgers Creek fault, and San Gregorio fault. There are no paleoearthquake data for the Greenville fault or northern extension of the Concord-Green Valley fault during this time interval.

“What the cluster of earthquakes did in our calculations was to release an amount of energy somewhat comparable to the amount released in the crust by the 1906 quake,” said Schwartz.

As stress on the region accumulates, the authors see at least two modes of energy release – one is a great earthquake and other is a cluster of large earthquakes. The probability for how the system will rupture is spread out over all faults in the region, making a cluster of large earthquakes more likely than a single great earthquake.

“Everybody is still thinking about a repeat of the 1906 quake,” said Schwartz. “It’s one thing to have a 1906-like earthquake where seismic activity is shut off, and we slide through the next 110 years in relative quiet. But what happens if every five years we get a magnitude 6.8 or 7.2? That’s not outside the realm of possibility.”

The next ‘Big One’ for the Bay Area may be a cluster of major quakes

A cluster of closely timed earthquakes over 100 years in the 17th and 18th centuries released as much accumulated stress on San Francisco Bay Area’s major faults as the Great 1906 San Francisco earthquake, suggesting two possible scenarios for the next “Big One” for the region, according to new research published by the Bulletin of the Seismological Society of America (BSSA).

“The plates are moving,” said David Schwartz, a geologist with the U.S. Geological Survey and co-author of the study. “The stress is re-accumulating, and all of these faults have to catch up. How are they going to catch up?”

The San Francisco Bay Region (SFBR) is considered within the boundary between the Pacific and North American plates. Energy released during its earthquake cycle occurs along the region’s principal faults: the San Andreas, San Gregorio, Calaveras, Hayward-Rodgers Creek, Greenville, and Concord-Green Valley faults.

“The 1906 quake happened when there were fewer people, and the area was much less developed,” said Schwartz. “The earthquake had the beneficial effect of releasing the plate boundary stress and relaxing the crust, ushering in a period of low level earthquake activity.”

The earthquake cycle reflects the accumulation of stress, its release as slip on a fault or a set of faults, and its re-accumulation and re-release. The San Francisco Bay Area has not experienced a full earthquake cycle since its been occupied by people who have reported earthquake activity, either through written records or instrumentation. Founded in 1776, the Mission Dolores and the Presidio in San Francisco kept records of felt earthquakes and earthquake damage, marking the starting point for the historic earthquake record for the region.

“We are looking back at the past to get a more reasonable view of what’s going to happen decades down the road,” said Schwartz. “The only way to get a long history is to do these paleoseismic studies, which can help construct the rupture histories of the faults and the region. We are trying to see what went on and understand the uncertainties for the Bay Area.”

Schwartz and colleagues excavated trenches across faults, observing past surface ruptures from the most recent earthquakes on the major faults in the area. Radiocarbon dating of detrital charcoal and the presence of non-native pollen established the dates of paleoearthquakes, expanding the span of information of large events back to 1600.

The trenching studies suggest that between 1690 and the founding of the Mission Dolores and Presidio in 1776, a cluster of earthquakes ranging from magnitude 6.6 to 7.8 occurred on the Hayward fault (north and south segments), San Andreas fault (North Coast and San Juan Bautista segments), northern Calaveras fault, Rodgers Creek fault, and San Gregorio fault. There are no paleoearthquake data for the Greenville fault or northern extension of the Concord-Green Valley fault during this time interval.

“What the cluster of earthquakes did in our calculations was to release an amount of energy somewhat comparable to the amount released in the crust by the 1906 quake,” said Schwartz.

As stress on the region accumulates, the authors see at least two modes of energy release – one is a great earthquake and other is a cluster of large earthquakes. The probability for how the system will rupture is spread out over all faults in the region, making a cluster of large earthquakes more likely than a single great earthquake.

“Everybody is still thinking about a repeat of the 1906 quake,” said Schwartz. “It’s one thing to have a 1906-like earthquake where seismic activity is shut off, and we slide through the next 110 years in relative quiet. But what happens if every five years we get a magnitude 6.8 or 7.2? That’s not outside the realm of possibility.”

On the shoulder of a giant: Precursor volcano to the island of O’ahu discovered

Map showing schematically the distribution of the three volcanoes now thought to have made up the region of O'ahu, Hawai'i.  From oldest to youngest these are the Ka'ena, Wai'anae, and Ko'olau Volcanoes.  Upper panel: bold dashed lines delineate possible rift zones of the three volcanoes; also shown are the major landslide deposits around O'ahu.  The lower panel shows how the three volcanic edifices overlap. -  J. Sinton, et al., UH SOEST
Map showing schematically the distribution of the three volcanoes now thought to have made up the region of O’ahu, Hawai’i. From oldest to youngest these are the Ka’ena, Wai’anae, and Ko’olau Volcanoes. Upper panel: bold dashed lines delineate possible rift zones of the three volcanoes; also shown are the major landslide deposits around O’ahu. The lower panel shows how the three volcanic edifices overlap. – J. Sinton, et al., UH SOEST

Researchers from the University of Hawai’i – Mānoa (UHM), Laboratoire des Sciences du Climat et de L’Environment (France), and Monterey Bay Aquarium Research Institute recently discovered that O’ahu actually consists of three major Hawaiian shield volcanoes, not two, as previously thought. The island of O’ahu, as we know it today, is the remnants of two volcanoes, Wai’anae and Ko’olau. But extending almost 100 km WNW from Ka’ena Point, the western tip of the island of O’ahu, is a large region of shallow bathymetry, called the submarine Ka’ena Ridge. It is that region that has now been recognized to represent a precursor volcano to the island of O’ahu, and on whose flanks the Wai’anae and Ko’olau Volcanoes later formed.

Prior to the recognition of Ka’ena Volcano, Wai’anae Volcano was assumed to have been exceptionally large and to have formed an unusually large distance from its next oldest neighbor – Kaua’i. “Both of these assumptions can now be revised: Wai’anae is not as large as previously thought and Ka’ena Volcano formed in the region between Kauai and Wai’anae,” noted John Sinton, lead author of the study and Emeritus Professor of Geology and Geophysics at the UHM School of Ocean and Earth Science and Technology (SOEST).

In 2010 scientists documented enigmatic chemistry of some unusual lavas of Wai’anae. “We previously knew that they formed by partial melting of the crust beneath Wai’anae, but we didn’t understand why they have the isotopic composition that they do,” said Sinton” Now, we realize that the deep crust that melted under Waianae is actually part of the earlier Ka’ena Volcano.”

This new understanding has been a long time in the making. Among the most important developments was the acquisition of high-quality bathymetric data of the seafloor in the region. This mapping was greatly accelerated after UH acquired the Research Vessel Kilo Moana, equipped with a high-resolution mapping system. The new data showed that Ka’ena Ridge had an unusual morphology, unlike that of submarine rift zone extensions of on-land volcanoes. Researchers then began collecting samples from Ka’ena and Wai’alu submarine Ridges. The geochemical and age data, along with geological observations and geophysical data confirmed that Ka’ena was not part of Waianae, but rather was an earlier volcanic edifice; Wai’anae must have been built on the flanks of Ka’ena.

“What is particularly interesting is that Ka’ena appears to have had an unusually prolonged history as a submarine volcano, only breaching the ocean surface very late in its history,” said Sinton. Much of our knowledge of Hawaiian volcanoes is based on those that rise high above sea level, and almost all of those formed on the flanks of earlier ones. Ka’ena represents a chance to study a Hawaiian volcano that formed in isolation on the deep ocean floor.

Despite four different cruises and nearly 100 rock samples from Ka’ena, researchers say they have only begun to observe and sample this massive volcanic edifice. While this article was in press, SOEST scientists visited Ka’ena Ridge again – this time with the UH’s newest remotely operated vehicle, ROV Lu’ukai – and collected new rock samples from some of its shallowest peaks. With these new samples Sinton and colleagues hope to constrain the timing of the most recent volcanism on Ka’ena.

On the shoulder of a giant: Precursor volcano to the island of O’ahu discovered

Map showing schematically the distribution of the three volcanoes now thought to have made up the region of O'ahu, Hawai'i.  From oldest to youngest these are the Ka'ena, Wai'anae, and Ko'olau Volcanoes.  Upper panel: bold dashed lines delineate possible rift zones of the three volcanoes; also shown are the major landslide deposits around O'ahu.  The lower panel shows how the three volcanic edifices overlap. -  J. Sinton, et al., UH SOEST
Map showing schematically the distribution of the three volcanoes now thought to have made up the region of O’ahu, Hawai’i. From oldest to youngest these are the Ka’ena, Wai’anae, and Ko’olau Volcanoes. Upper panel: bold dashed lines delineate possible rift zones of the three volcanoes; also shown are the major landslide deposits around O’ahu. The lower panel shows how the three volcanic edifices overlap. – J. Sinton, et al., UH SOEST

Researchers from the University of Hawai’i – Mānoa (UHM), Laboratoire des Sciences du Climat et de L’Environment (France), and Monterey Bay Aquarium Research Institute recently discovered that O’ahu actually consists of three major Hawaiian shield volcanoes, not two, as previously thought. The island of O’ahu, as we know it today, is the remnants of two volcanoes, Wai’anae and Ko’olau. But extending almost 100 km WNW from Ka’ena Point, the western tip of the island of O’ahu, is a large region of shallow bathymetry, called the submarine Ka’ena Ridge. It is that region that has now been recognized to represent a precursor volcano to the island of O’ahu, and on whose flanks the Wai’anae and Ko’olau Volcanoes later formed.

Prior to the recognition of Ka’ena Volcano, Wai’anae Volcano was assumed to have been exceptionally large and to have formed an unusually large distance from its next oldest neighbor – Kaua’i. “Both of these assumptions can now be revised: Wai’anae is not as large as previously thought and Ka’ena Volcano formed in the region between Kauai and Wai’anae,” noted John Sinton, lead author of the study and Emeritus Professor of Geology and Geophysics at the UHM School of Ocean and Earth Science and Technology (SOEST).

In 2010 scientists documented enigmatic chemistry of some unusual lavas of Wai’anae. “We previously knew that they formed by partial melting of the crust beneath Wai’anae, but we didn’t understand why they have the isotopic composition that they do,” said Sinton” Now, we realize that the deep crust that melted under Waianae is actually part of the earlier Ka’ena Volcano.”

This new understanding has been a long time in the making. Among the most important developments was the acquisition of high-quality bathymetric data of the seafloor in the region. This mapping was greatly accelerated after UH acquired the Research Vessel Kilo Moana, equipped with a high-resolution mapping system. The new data showed that Ka’ena Ridge had an unusual morphology, unlike that of submarine rift zone extensions of on-land volcanoes. Researchers then began collecting samples from Ka’ena and Wai’alu submarine Ridges. The geochemical and age data, along with geological observations and geophysical data confirmed that Ka’ena was not part of Waianae, but rather was an earlier volcanic edifice; Wai’anae must have been built on the flanks of Ka’ena.

“What is particularly interesting is that Ka’ena appears to have had an unusually prolonged history as a submarine volcano, only breaching the ocean surface very late in its history,” said Sinton. Much of our knowledge of Hawaiian volcanoes is based on those that rise high above sea level, and almost all of those formed on the flanks of earlier ones. Ka’ena represents a chance to study a Hawaiian volcano that formed in isolation on the deep ocean floor.

Despite four different cruises and nearly 100 rock samples from Ka’ena, researchers say they have only begun to observe and sample this massive volcanic edifice. While this article was in press, SOEST scientists visited Ka’ena Ridge again – this time with the UH’s newest remotely operated vehicle, ROV Lu’ukai – and collected new rock samples from some of its shallowest peaks. With these new samples Sinton and colleagues hope to constrain the timing of the most recent volcanism on Ka’ena.