geology – 91̽��News

Ranking: Four 91̽��subject areas place in global top 10

91̽��News staff — Wed, 25 Mar 2026 15:02:14 +0000

The 91̽��is the best in the U.S. and No. 2 in the world for library and information management, according to the 2026 QS World University Rankings by Subject. Three other 91̽��subject areas placed in the top 10 in the world: geology, geophysics and Earth and marine sciences. Photo: Pamela Dore/91̽��

The 91̽�� is the best in the U.S. and No. 2 in the world for library and information management, according to the 2026 released Wednesday. Three other 91̽��subject areas placed in the top 10 in the world: geology, geophysics and Earth and marine sciences.

This ranking tracks an analysis of reputation and research output, conducted by . The consultancy looks at more than 18,300 individual university programs at more than 1,700 universities in 100 locations around the world. The ranking spans 55 academic disciplines across five broad faculty areas including arts and humanities; engineering and technology; life sciences and medicine; natural sciences; and social sciences and management.

The 91̽��has 29 programs in the top 100, 14 in the top 50, and four in the top 10, including:

Library and information management — No. 2
Geology — No. 8
Geophysics — No. 9
Earth and marine sciences — No. 10

Visit the rankings site for .

Ranking: 91̽��library and information management best in the country, second best in the world

91̽��News staff — Fri, 14 Mar 2025 17:59:32 +0000

The 91̽��is the best in the U.S. and No. 2 in the world for library and information management, according to a new global ranking. Four other 91̽��subject areas placed in the top 10. Photo: Mark Stone/91̽��

The 91̽�� is the best in the U.S. and No. 2 in the world for library and information management, according to the released Wednesday. Four other 91̽��subject areas placed in the top 10.

This ranking tracks an analysis of reputation and research output, conducted by , of academic subjects at 5,203 institutions around the world. The ranking consists of 1,747 institutions at 148 locations with more than 55 subjects across five broad faculty areas including arts and humanities; engineering and technology; life sciences and medicine; natural sciences; and social sciences and management.

The 91̽��has 31 programs in the top 100, 16 in the top 50, and five subjects in the top 10, including:

Library and information management — No. 2
Nursing — No. 6
Geology — No. 8
Geophysics — No. 9
Earth and marine sciences — No. 10

Visit the rankings site for .

Ranking: 91̽��recognized as among the best in the world

91̽��News staff — Wed, 10 Apr 2024 19:20:22 +0000

The 91̽��has been named one of the world’s top
universities, according to the QS World University Rankings by Subject. Photo: 91̽��

The 91̽�� has been named one of the world’s top universities, according to the QS World University Rankings by Subject Wednesday.

This ranking tracks an analysis, conducted by , of 16,400 university programs at 1,500 institutions in 96 locations around the world.

The 91̽��has 45 programs in the top 100, and five subjects in the top 10, including:

Library and information management — No. 3
Nursing — No. 4
Geology — No. 8
Earth and marine sciences — No. 10
Geophysics — No. 10

The complete list and more about the methodology can be found .

In the Field: Tracking seismic clues in one of the driest places on Earth

91̽��News staff — Thu, 16 Nov 2023 21:44:35 +0000

91̽��doctoral student Tamara Ará�Բ��ܾ��-�鲹�� collects rock samples on the hills next to a fault in Chile’s Atacama Desert for a pilot study in September 2022. This month she will collect more data to try to reconstruct the history of the formation of these mountains. Photo: Emma Heitmann/91̽��

Unlike the Pacific Northwest, the Atacama Desert in Chile experiences very little rain. But the two regions are both seismically active. Faults in the Atacama Desert are slowly sliding past each other in a way similar to the Seattle Fault in Puget Sound and the San Andreas Fault in California. The Atacama Desert’s lack of rain makes it easier to see how those gradual movements shape the landscape over time.

Alison Duvall, a 91̽�� associate professor of Earth and space sciences, and doctoral student will travel to Chile this month to study landscapes developed along these types of faults. Duvall has previously studied historic landslides at the site of the rainfall-triggered Oso mudslide and how rainfall, earthquake and landslide risks combine in Oregon.

91̽��News asked the two geophysicists about their upcoming trip as part of a new series, “In the Field,” highlighting 91̽��field research.

Where are you going, and when?

Tamara Ará�Բ��ܾ��-�鲹��: We will visit the , in the hyper-arid, or dry, core of the Atacama Desert in Northern Chile. The Salar is a dry lakebed that contains economic resources, in the form of salt, that is extracted from the basin and then exported around the world. We’ll be there Nov. 19-25.

Follow updates Nov. 19-25 on X at and .

We’re interested in this area because it’s extremely dry and has active faults slicing through it. Only a few places on Earth register such low rates of precipitation, offering a landscape that stores climate and tectonic variations from the past 50 million years. At our field site, there are places that haven’t seen a drop of rain in 500 years!

As a result, this is one of the best places on Earth to study how landscapes respond to earthquakes and plate tectonics under hyper-arid conditions. Dry conditions slow down erosion and help preserve landscape form and enable us to observe processes, like tectonic processes, that modify the surface from deeper down.

The Atacama Desert in September 2022. The flat strip of land in the middle is not a human-built road but a strike-slip fault, where two blocks slowly slide past each other. Researchers will travel to the site again this month to learn more about these types of faults. Photo: Tamara Ará�Բ��ܾ��-�鲹��/91̽��

Have you visited this field site before?

TA: I visited this site last fall with , another doctoral student in the Department of Earth & Space Sciences.

Alison Duvall: This will be my first time to this site, to Chile and to South America.

What do you hope to learn there?

AD: We want to learn more about the dynamics of slow faults that move laterally — strike-slip faults, similar to the San Andreas Fault in California — and how these dynamics control the shape of the landscape. In wet places, it’s hard to isolate faults’ effects on the landscape since water is the main agent driving erosion. What we observe on the surface in other places is a combination of tectonics and surface processes. However, thanks to the aridity of this place, it is easier to be confident about what is changing the landscape.

We’re also interested in how this landscape has shifted with a changing climate. This place was wetter in the past, and there is evidence of climate change happening to make the region hyper-arid. So we are also studying how the landscape has adapted to that change.��

What’s something that you enjoy about this field work — especially something that might not occur to most people?

TA: There is a really special feeling when you’re in the driest place on Earth. It almost feels like you’re on a different planet. You don’t see any signs of life — no water, no animals, no plants — but it’s just amazing to feel that nothingness.

Changes in the landscape are so slow that when you visit the site, you know that each step you make, or any perturbation we make to collect our samples, can be one of the biggest modifications to the landscape in hundreds of years.

91̽�� doctoral student Emma Heitmann stands at the bottom of one of the biggest paleochannels in the study area in September 2022. The size of the rocks in the channel provides researchers with information about past wet events that have interrupted the current very dry climate. Photo: Tamara Ará�Բ��ܾ��-�鲹��/91̽��

Anything you’d like to add?

AD: I’m super excited to get to this incredible field site and spend time with Tamara studying it. We have done field work together in New Zealand, and I have done decades’ worth of field work in many different geomorphic settings, but never in a hyper-arid landscape like this one. I can’t wait to see what we find!

Warm liquid spewing from Oregon seafloor comes from Cascadia fault, could offer clues to earthquake hazards

Hannah Hickey — Mon, 10 Apr 2023 22:24:00 +0000

This sonar image of the Pythias Oasis site shows bubbles rising from the seafloor about two-thirds of a mile deep and 50 miles off Newport, Oregon. These bubbles are a byproduct of a unique site where warm, chemically distinct fluid gushes from the seafloor. Researchers believe this fluid comes directly from the Cascadia megathrust zone, or plate boundary, and helps control stress buildup between the two plates. Photo: Philip et al./Science Advances

[Updated 4/18/2023 for clarification:

Scientists are not alarmed at discovering this geologic feature, which does not trigger earthquakes but may regulate friction in the fault zone
This discovery does not change the current risk of a large earthquake on the Cascadia Subduction Zone]

The field of plate tectonics is not that old, and scientists continue to learn the details of earthquake-producing geologic faults. The Cascadia Subduction Zone — the eerily quiet offshore fault that threatens to unleash a magnitude-9 earthquake in the Pacific Northwest — still holds many mysteries.

A study led by the 91̽�� discovered seeps of warm, chemically distinct liquid shooting up from the seafloor about 50 miles off Newport, Oregon. The , published Jan. 25 in Science Advances, describes the unique underwater spring the researchers named . Observations suggest the spring is sourced from water 2.5 miles beneath the seafloor at the plate boundary, regulating stress on the offshore fault.

The team made the discovery during a weather-related delay for a cruise aboard the RV Thomas G. Thompson. The ship’s sonar showed unexpected plumes of bubbles about three-quarters of a mile beneath the ocean’s surface. Further exploration using an underwater robot revealed the bubbles were just a minor component of warm, chemically distinct fluid gushing from the seafloor sediment.

“They explored in that direction and what they saw was not just methane bubbles, but water coming out of the seafloor like a firehose. That’s something that I’ve never seen, and to my knowledge has not been observed before,” said co-author , a 91̽��associate professor of oceanography who studies seafloor geology.

The feature was discovered by first author , who made the discovery as a 91̽��undergraduate student and now works as a White House policy advisor.

Observations from later cruises show the fluid leaving the seafloor is 9 degrees Celsius (16 degrees Fahrenheit) warmer than the surrounding seawater. Calculations suggest the fluid is coming straight from the Cascadia megathrust, where temperatures are an estimated 150 to 250 degrees Celsius (300 to 500 degrees Fahrenheit).

The new seeps aren’t related to geologic activity at the that the cruise was heading toward, Solomon said. Instead, they occur near vertical faults that crosshatch the massive Cascadia Subduction Zone. These strike-slip faults, where sections of ocean crust and sediment slide past each other, exist because the ocean plate hits the continental plate at an angle, placing stress on the overlying continental plate.

Loss of fluid from the offshore megathrust interface through these strike-slip faults is important because it lowers the fluid pressure between the sediment particles and hence increases the friction between the oceanic and continental plates.

“The megathrust fault zone is like an air hockey table,” Solomon said. “If the fluid pressure is high, it’s like the air is turned on, meaning there’s less friction and the two plates can slip. If the fluid pressure is lower, the two plates will lock – that’s when stress can build up.”

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“” | The Oregonian
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Fluid released from the fault zone is like leaking lubricant, Solomon said. That’s bad news for earthquake hazards: Less lubricant means stress can build to create a damaging quake.

This is the first known site of its kind, Solomon said. Similar fluid seep sites may exist nearby, he added, though they are hard to detect from the ocean’s surface. A significant fluid leak off central Oregon could explain why the northern portion of the Cascadia Subduction Zone, off the coast of Washington, is believed to be more strongly locked, or coupled, than the southern section off the coast of Oregon.

“Pythias Oasis provides a rare window into processes acting deep in the seafloor, and its chemistry suggests this fluid comes from near the plate boundary,” said co-author , a 91̽��professor of oceanography. “This suggests that the nearby faults regulate fluid pressure and megathrust slip behavior along the central Cascadia Subduction Zone.”

Solomon just returned from an expedition to off the northeast coast of New Zealand. The Hikurangi Subduction Zone is similar to the Cascadia Subduction Zone but generates more frequent, smaller earthquakes that make it easier to study. But it has a different sub-seafloor structure meaning it’s unlikely to have fluid seeps like those discovered in the new study, Solomon said.

The research off Oregon was funded by the National Science Foundation. Other co-authors are , who did the work as a 91̽��doctoral student and now works as an environmental consultant in Seattle; Emily Roland, a former 91̽��faculty member now at Western Washington University; Masako Tominaga at Woods Hole Oceanographic Institution; and Anne Tréhu and Robert Collier at Oregon State University.

For more information, contact Solomon at esolomn@uw.edu or Kelley at dskelley@uw.edu.

91̽��brings field geology to students with ‘Virtual Field Geology’

Hannah Hickey — Thu, 08 Dec 2022 19:42:51 +0000

The former Bear Valley Strip Mine in Pennsylvania is the site of the “Whaleback anticline,” named because the 30-foot-tall hump of bedrock looks like a whale. Decades of coal mining exposed folds in the bedrock, that offer clues to the landscape’s history. The Virtual Field Geology project uses drone photography to create a virtual field visits on a web browser or virtual reality headset. Photo: 91̽��

91̽�� geologists had set out to create computer-based field experiences long before the COVID-19 pandemic hit. , a 91̽��associate professor of Earth and space sciences, first got a grant from the National Science Foundation to send a former graduate student and a drone to photograph an iconic Pennsylvania geological site and pilot a new approach to field geology.

Her team has now completed a virtual field visit to that site, the , where decades of coal mining have exposed 300-million-year-old folds in the bedrock. A pilot version of the web-based tool was used during the pandemic, and a version that allows people to wear virtual reality headsets to explore the geological site just launched. A 91̽��field class used both tools in an undergraduate summer course that for the first time blended virtual and in-person field trips.

The 91̽�� project has many goals: to make geology field experiences accessible to more people; to document geological field sites that may be at risk from erosion or development; to offer virtual “dry run” experiences that complement field courses and help new students acclimate to the field; and to allow scientific collaborators to virtually visit a field site and explore it together.��

, a 91̽��doctoral student in Earth and Space Sciences, used his background in geology to help develop the virtual field experiences. He is lead author of a published this fall that presents the first two sites: the Whaleback site and a fictional site called “Fold Islands.”

The fictional ‘Fold Islands’ experience is a cartoon-based field geology site that lets students practice their skills using a geodetic compass and other tools of field geology. Photo: Needle et al/Geoscience Communication

“Virtual experiences provide access to more people, they let us visit sites that are completely inaccessible, and we think everyone can benefit from a new way to interact with the tools of field geology,” Needle said.��

Last summer, instead of the traditional 91̽��geology six-week field course in Montana, the department held a hybrid version led by Crider and , a 91̽��assistant professor of Earth and space sciences. It combined classroom teaching and digital experiences with day trips to the many geologic sites within driving distance of the Seattle campus.

“Moving forward, these virtual field trips are likely going to play a key part in making the geosciences more accessible and more equitable,” Condit said. “They provide the opportunity for all students to be able to begin experiencing fieldwork remotely, and learn about how vital the geologic field context is for the geosciences.”

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The pandemic altered the project’s trajectory. When COVID canceled field trips, the team put the virtual reality programming on pause and focused on creating a web-based version that would be accessible most quickly to the most people. Since the site launched, it’s been accessed more than 1,700 times by 91̽��undergraduates and, after sharing among the geology teaching community, around the world. The team recently completed the VR version.

Even though people can now travel and assemble, the team believes virtual experiences could become part of a “new normal” for geology research and education.��

“Part of increasing access to the field is to help people know what to anticipate,” Crider said. “To the extent that we can help students anticipate both the outdoors experience and the science experience, then the uncertainty and maybe anxiety is reduced, and people can focus on the learning goals.”

The virtual experiences allow people to visit the field site and use common geology tools to measure angles in the rock layers or orientation of cracks that explain a landscape’s history. While a virtual option benefits anyone challenged by the travel and access to a remote field site, it also lets all students and researchers have a “dry run” experience and review techniques before reaching the actual location.

In the , keyboard commands let a user walk across the landscape. Users can try various tools to measure distances and angles. Selecting three points creates a virtual plane and displays its orientation. Data can be downloaded into a spreadsheet or directly into a popular geology software program.

“What’s unique about this experience is that it’s open-ended, which allows instructors to tailor the lessons and the goals,” Crider said. “Students decide what to measure, and where to measure, to answer the questions — it’s not predetermined. Making those decisions is an important thing to learn.”

The virtual experience also gives the scientist superhuman powers to instantly swoop from one place to another, zoom in and out to explore a site at different scales.��

“One of the cool advantages of the game is that you can fly. There’s a little jetpack icon and then you go up in the air, and all of a sudden your perspective changes, and you can travel quickly from place to place,” Needle said.��

It also provides access to sites that have limited or risky access.��

“At the Whaleback anticline a lot of the interesting, curved rock geometry is exposed at a height of 30 feet, where you can’t walk without risking fatality,” Needle said.

The team recently demonstrated the virtual reality version of the Pennsylvania site. Although VR requires a special headset, the field of view is larger, and VR offers a sense of scale that’s helpful at sites like the 30-foot-tall Whaleback anticline. An interactive feature lets the user pick up a rock hammer and split open a 3D model of a rock.

Max Needle (far right) and Jacky Mooc (center in blue sweater) at the Geological Society of America’s annual meeting, in Denver in October. Two meeting attendees explore the Whaleback anticline geologic site by donning an Oculus Quest 2 headset. Photo: 91̽��

“As a teaching assistant, I’ve seen students confronted with challenges in the field that go beyond the academic aspect,” Needle said. “Or maybe someone can’t go into the field because they have bad asthma, or a particular field site can only be accessed with specialized climbing gear. We think a lot of people can benefit from these tools.”

Needle ran a short course at the Geological Society of America’s annual meeting in October showing other geologists how to use the 91̽��software to create other virtual field visits. This was the third such workshop he’s given, and the largest so far. All the software used for the 91̽��experiences are freely available.

Max Needle presents the Virtual Field Geology project at the Geological Society of America’s annual meeting in Denver in October. Photo: 91̽��

Projects are under way for sites in Pennsylvania, Vermont and California. Needle hopes that someday the software might be used to visit the bottom of the ocean or the surface of another planet.��

“I think this is a prototype of where the field of geology could be headed in the future,” Needle said.

The lead designers are , a recent 91̽��graduate in computer science and engineering who is now a software engineer at Lockheed Martin, and John Akers of the 91̽��Reality Lab. It was one of the first projects of the , which pairs 91̽��undergraduates with projects needing augmented-reality or virtual-reality programming. The effort and required tools for this work was funded by the National Science Foundation, 91̽��Research Royalty Fund, 91̽��Department of Earth and Space Sciences, 91̽��Student Technology Fund, and the Geological Society of America.

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For more information, contact Needle at mneedle@uw.edu, Crider at criderj@uw.edu and Condit at ccondit@uw.edu .��

91̽��is No. 6 in the world, according to US News Best Global Universities

Jackson Holtz — Wed, 26 Oct 2022 16:17:48 +0000

The 91̽��is No. 6 in the world, according to US News & World Report’s Best Global Universities ranking. Photo: Mark Stone/91̽��

The 91̽�� rose from No. 7 to No. 6 on the��, released on Tuesday. The 91̽��maintained its No. 2 ranking among U.S. public institutions.

U.S. News also ranked several subjects, and the 91̽��placed in the top 10 in 10 subject areas, including immunology (No. 4), molecular biology and genetics (No. 5) and clinical medicine (No. 6).

In another ranking out this week, Times Higher Education World University Rankings 2023 by Subject, six subject areas at the 91̽��placed in the top 25.

“As a global public research university, the UW’s mission is to create and accelerate change for the public good,” 91̽��President Ana Mari Cauce said. “I’m proud that these rankings reflect the outstanding and wide-ranging work of our faculty, staff and students to expand knowledge and discovery that is changing people’s lives for the better, particularly in the health sciences.”

The U.S. News ranking —�� based on Web of Science data and metrics provided by Clarivate Analytics InCites — weighs factors that measure a university’s global and regional research reputation and academic research performance. For the overall rankings, this includes bibliometric indicators such as publications, citations and international collaboration.

The overall Best Global Universities ranking, now in its ninth year, encompasses the top 2,000 institutions spread across 90 countries, according to U.S. News.��American universities make up eight of the top 10 spots.

Here are all the top 10 91̽��rankings in U.S. News’ subject rankings:

Immunology – No. 4
Molecular biology and genetics – No. 5
Clinical medicine – No. 6
Geosciences – No. 7
Infectious diseases – No. 7
Public, environmental and occupational health – No. 7
Social sciences and public health – No. 7
Biology and biochemistry – No. 8
Microbiology – No. 10

In the rankings, UW’s programs in these areas placed in the top 25:

: No. 15
(includes agriculture and forestry, biological sciences, veterinary science and sport science): No. 16
(includes medicine, dentistry and other health subjects): No. 17
(includes communication and media studies, politics and international studies — including development studies, sociology and geography): No. 18
(includes mathematics and statistics, physics and astronomy, chemistry, geology, environmental sciences, and Earth and marine sciences): No. 19
(includes education, teacher training, and academic studies in education): No. 23

The subject tables employ the same used in the overall��; however, the methodology is recalibrated for each subject, with the weightings changed to suit the individual fields.

Rankings: 91̽��among best in world for health and life sciences

Jackson Holtz — Thu, 16 Sep 2021 18:59:04 +0000

Life Sciences Building on the 91̽��campus Photo: Kevin Scott

The 91̽�� is among the best universities in the world for the studies of health and life sciences, according to the Times Higher Education World University Rankings by Subject 2022.

The rankings, released , looked at four overall disciplines: , , and .

In physical sciences, the 91̽��ranked No. 21 in the world, third among U.S. public institutions. Physical sciences includes mathematics and statistics; physics and astronomy; chemistry; and geology, environmental, earth and marine sciences.

The 91̽��was among 107 debut institutions this year on the life sciences list, coming in at No. 18, or third place among U.S. public universities. This topic includes agriculture and forestry; biological sciences; veterinary science; and sports science.

For the psychology ranking, the 91̽��placed among the top 10 U.S. public institutions, and No. 31 in the world. Psychology includes psychology; educational/sport/business/animal psychology; and clinical psychology.

And, finally, for the clinical & health rankings, the 91̽��placed No. 21, or third among U.S. public institutions. This discipline includes medicine and dentistry; and other health subjects.

The rankings included 1,523 universities from 98 countries and regions. The subject tables employ the same range of��used in the overall��, however, the overall methodology is recalibrated for each subject, with the weightings changed to suit the individual fields.

Most landslides in western Oregon triggered by heavy rainfall, not big earthquakes

Hannah Hickey — Wed, 16 Sep 2020 18:11:38 +0000

This view from Saddle Mountain, in the Oregon Coast Range just north of the study area, shows the bare hillsides that can give way during heavy rains. Photo:

Researchers at the 91̽��, Portland State University and the University of Oregon have shown that deep-seated landslides in the central Oregon Coast Range are triggered mostly by rainfall, not by large offshore earthquakes.

The open-access was published Sept. 16 in Science Advances.

“Geomorphologists have long understood the importance of rainfall in triggering landslides, and our study is simply driving home just how important it is,” said first author , who did the work as part of his doctorate at the UW. “Our results show that more frequent, localized landslide events triggered by rainfall are just as important to consider as less frequent but more far-reaching Cascadia Subduction Zone earthquakes.”

The Oregon Coast Range run from about Newport, Oregon, south to Port Orford. The low-lying mountain range is near the Cascadia Subduction Zone, an offshore fault that can trigger magnitude-9 earthquakes. Photo: LaHusen et al/Science Advances

Heavy rains are known to cause landslides that can be disruptive and deadly. A less frequent landslide trigger is a rupture on the geologic fault off the coast of Washington and Oregon that’s known as the Cascadia Subduction Zone — among a long list of concerns after a major earthquake. Landslide risks of all types increase if human development or wildfires remove trees, taking away the roots that stabilize the soil.

Recent research in Nepal and Japan, however, suggests that offshore earthquakes might not trigger as many landslides as previously believed. The new study finds a similar situation in the Pacific Northwest.

“We aren’t suggesting that the landscape had no response to these magnitude-9 earthquakes, but that the deeper-seated landslide deposits and scars out on the Oregon Coast Range hillslopes today were primarily triggered by precipitation events,” said senior author , a 91̽��associate professor of Earth and space sciences. “We conclude that past Cascadia Subduction Zone earthquakes triggered no more than a few hundred deep landslides during great earthquake events.”

The researchers used high-resolution aerial laser maps of the Oregon coast to look at 1,000 years of landslide activity. Landslides tended to happen in places with heavier rainfall, they found. But surprisingly, there was no detectable change in the number of deep landslides at the time of the large earthquake that shook the Pacific Northwest in 1700, or for two earlier offshore earthquakes that happened in roughly the years 1150 and 1470.

This Google Earth image shows a site about 5 miles south of Florence, on the central Oregon coast, that experienced a landslide in winter 2017. The new paper uses aerial imagery that penetrates through tree cover to study the occurrence of such slides over more than 1,000 years. Photo: Google Earth/Sean LaHusen

Duvall, LaHusen and co-author at Portland State University developed a method for dating landslides while studying the site of the deadly March 2014 mudslide in Oso, Washington. In that study, they used high-resolution images to view the surface roughness. Over time, soil settles and exposed rock erodes. The surface gets smoother, so surface roughness can be used to calculate a landslide’s age.

“The central Oregon Coast Range offered a massive, 10,000-square-kilometer natural laboratory to explore patterns in deep-seated landslide events through space and time,” LaHusen said. “It’s 50-million-year-old sandstone and siltstone that was deposited offshore, buried and compacted, and then uplifted to form the mountains we see today.”

Aerial with less than 3-foot resolution revealed 9,938 landslides inside the study area. Researchers narrowed those down to 2,676 landslides that have happened within the past 1,000 years, and then looked at the landslide frequency during that time.

Within the study zone, seen on the left, analyses of aerial lidar imagery revealed almost 10,000 landslides. On the subset at the right, landslides that have occurred in the past thousand years are shown in red. Photo: LaHusen et al/Science Advances

For the new study, they applied their method to a larger area in the central Oregon Coast Range. To study landslide activity related to the Cascadia Subduction Zone, the researchers needed an area near the Cascadia fault zone with a consistent rock type and publicly available lidar imagery.

Researchers caution that the study doesn’t apply to shallow landslides, which frequently occur during earthquakes but leave no long-term evidence and can’t be analyzed with this method, or to different soil types, and so doesn’t necessarily apply to other regions. The research also didn’t consider shallower earthquakes from surface faults.

But the paper does support recent findings in Asia suggesting that offshore earthquakes don’t trigger as many deep landslides as once believed, and that rainfall may be the bigger factor in shaping the landscape over longer timescales.

“These data strengthen the point that we don’t need big earthquakes to trigger large and devastating landslides in Washington and Oregon,” Duvall said. “Seasonal precipitation and large rain events are important to focus on in landslide preparedness planning.”

This research was funded by the National Science Foundation and the Geological Society of America. The team began the work as part of the 91̽��, which is studying magnitude-9 earthquakes from the fault that runs parallel to the Washington and Oregon coastlines. Slips along this fault can lead to a so-called “Big One,” which last struck the Pacific Northwest in 1700.

Other co-authors are , , and at the UW; and and at the University of Oregon. LaHusen is now working at the U.S. Geological Survey in Mountain View, California.

Co-authors Will Struble (left) and Alison Duvall dig into a landslide deposit near the community of Sitkum, Oregon, in search of wood that could be used for radiocarbon dating of the past slide. Photo: Sean LaHusen

For more information, contact LaHusen at seanlah@gmail.com or Duvall at aduvall@uw.edu.

Volcanic activity and changes in Earth’s mantle were key to rise of atmospheric oxygen

Hannah Hickey — Tue, 09 Jun 2020 15:43:20 +0000

Oxygen first accumulated in the Earth’s atmosphere about 2.4 billion years ago, during the Great Oxidation Event. A long-standing puzzle has been that geologic clues suggest early bacteria were photosynthesizing and pumping out oxygen hundreds of millions of years before then. Where was it all going?

Something was holding back oxygen’s rise. A new interpretation of rocks billions of years old finds volcanic gases are the likely culprits. The led by the 91̽�� was published in June in the open-access journal Nature Communications.

“This study revives a classic hypothesis for the evolution of atmospheric oxygen,” said lead author , a 91̽��postdoctoral researcher in Earth and space sciences. “The data demonstrates that an evolution of the mantle of the Earth could control an evolution of the atmosphere of the Earth, and possibly an evolution of life.”

These giant mounds of fossil stromatolites from about 2.5 billion years ago are located in South Africa. For scale, notice a person’s dangling legs at the top center. These layered minerals were deposited on an ancient coastline by communities of microbes, including photosynthetic bacteria that generated oxygen. The new study suggests that for millions of years the oxygen produced by these microbes reacted with volcanic gases before it began to accumulate in Earth’s atmosphere, about 2.4 billion years ago. Photo: David Catling/91̽��

Multicellular life needs a concentrated supply of oxygen, so the accumulation of oxygen is key to the evolution of oxygen-breathing life on Earth.

“If changes in the mantle controlled atmospheric oxygen, as this study suggests, the mantle might ultimately set a tempo of the evolution of life,” Kadoya said.

The new work builds on a 2019 that found the early Earth’s mantle was far less oxidized, or contained more substances that can react with oxygen, than the modern mantle. That study of ancient volcanic rocks, up to 3.55 billion years old, were collected from sites that included South Africa and Canada.

at Scripps Institution of Oceanography, at the University of Maryland, and at Arizona State University are among the authors of the 2019 study. They are also co-authors of the new paper, looking at how changes in the mantle influenced the volcanic gases that escaped to the surface.

The Archean Eon, when only microbial life was widespread on Earth, was more volcanically active than today. Volcanic eruptions are fed by magma – a mixture of molten and semi-molten rock – as well as gases that escape even when the volcano is not erupting.

Some of those gases react with oxygen, or oxidize, to form other compounds. This happens because oxygen tends to be hungry for electrons, so any atom with one or two loosely held electrons reacts with it. For instance, hydrogen released by a volcano combines with any free oxygen, removing that oxygen from the atmosphere.

An ancient komatiite lava from the Komati Valley in South Africa. Notice the tool on the right for scale. Co-authors used these types of lavas from more than 3 billion years ago to learn how the chemistry of the mantle has changed. Photo:

The chemical makeup of Earth’s mantle, or softer layer of rock below the Earth’s crust, ultimately controls the types of molten rock and gases coming from volcanoes. A less-oxidized early mantle would produce more of the gases like hydrogen that combine with free oxygen. The 2019 paper shows that the mantle became gradually more oxidized from 3.5 billion years ago to today.

The new study combines that data with evidence from ancient sedimentary rocks to show a tipping point sometime after 2.5 billion years ago, when oxygen produced by microbes overcame its loss to volcanic gases and began to accumulate in the atmosphere.

“Basically, the supply of oxidizable volcanic gases was capable of gobbling up photosynthetic oxygen for hundreds of millions of years after photosynthesis evolved,” said co-author , a 91̽��professor of Earth and space sciences. “But as the mantle itself became more oxidized, fewer oxidizable volcanic gases were released. Then oxygen flooded the air when there was no longer enough volcanic gas to mop it all up.”

This has implications for understanding the emergence of complex life on Earth and the possibility of life on other planets.

“The study indicates that we cannot exclude the mantle of a planet when considering the evolution of the surface and life of the planet,” Kadoya said.

This research was funded by the National Science Foundation.

For more information, contact Kadoya at skadoya@uw.edu or Catling at dcatling@uw.edu.