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Signals from the ionosphere could improve tsunami forecasts
Monday, December 12, 2022
Research from the University of Washington shows that signals from the upper atmosphere could improve tsunami forecasting and, someday, help track ash plumes and other impacts after a volcanic eruption.
A new study analyzed the Hunga Tonga-Hunga Ha'apai eruption in the South Pacific earlier this year. The Jan. 15, 2022, volcanic eruption was the largest to be recorded by modern equipment. Ash blanketed the region. A tsunami wave caused damage and killed at least three people on the island of Tonga. It also had unexpected distant effects.
No volcanic eruption in more than a century has produced a global-scale tsunami. The tsunami wave from the underwater eruption was first predicted as only a regional hazard. Instead, the wave reached as far as Peru, where two people drowned.
Results of the new study, published this fall in Geophysical Research Letters, uses evidence from the ionosphere to help explain why the tsunami wave grew larger and traveled faster than models predicted.
Satellite images show the cloud generated by the underwater eruption of the Hunga Tonga-Hunga Ha'apai volcano on Jan. 15, 2022.NASA
"This was the most powerful volcanic eruption since the 1883 eruption of Krakatau, and a lot of aspects of it were unexpected," said lead author Jessica Ghent, a UW doctoral student in Earth and space sciences. "We used a new monitoring technique to understand what happened here and learn how we could monitor future natural hazards."
She will present the work in a poster Wednesday, Dec. 14, at the American Geophysical Union annual meeting in Chicago and she will present the work at the meeting that afternoon.
Tsunamis are rare enough occurrences that forecast models, relying on a limited number of tide gauges and ocean sensors, are still being perfected. This study is part of an emerging area of research exploring the use of GPS signals traveling through the atmosphere to track events on the ground.
A big earthquake, or in this case a huge volcanic eruption, generates pressure waves in the atmosphere. As these pressure waves pass through the zone from about 50 to 400 miles altitude where electrons and ions float freely, known as the ionosphere, the particles are disturbed. GPS satellites beaming coordinates back down to Earth transmit a slightly altered radio signal that tracks the disturbance.
"Other groups have been looking at the ionosphere to monitor tsunamis. We are interested in applying it for volcanology," said co-author Brendan Crowell, a UW research scientist in Earth and space sciences. "This Tonga eruption kicked our research into overdrive. There was a big volcanic eruption and a tsunami -- normally you'd study one or the other."
For the new study, the researchers analyzed 818 ground stations in the Global Navigation Satellite System, the global network that include GPS and other satellites, around the South Pacific to measure the atmospheric disturbance in the hours following the eruption. Results support the hypothesis that the sonic boom generated by the volcanic explosion made the tsunami wave bigger and faster. The ocean wave got an extra push from the atmospheric pressure wave created by the eruption. This extra push wasn't included in the initial tsunami forecasts, researchers said, because volcano-triggered tsunamis are so rare.
"Tsunamis typically can travel in the open ocean at 220 meters per second, or 500 miles per hour. Based on our data, this tsunami wave was moving at 310 meters per second, or 700 miles per hour," Ghent said.
The authors were able to separate out different aspects of the eruption - the acoustic sound wave, the ocean wave and other types of pressure waves - and check their accuracy against ground-based observation stations.
"The separation of these signals, from the acoustic sound wave to the tsunami, was what we had set out to find," Ghent said. "From a hazards-monitoring perspective, it validates our hope for what we can use the ionosphere for. This unusual event gives us confidence that we might someday use the ionosphere to monitor hazards in real time."
While the Tonga eruption didn't eject much ash for the size of the event, Ghent and Crowell say the Global Navigation Satellite System signals could be used in other ways to accurately track volcanic ash plumes.
Looking upward to monitor volcanoes and tsunamis is appealing because ground-based monitoring has challenges in the Pacific Northwest and other areas. Sensors must be maintained and repaired, snow and ice can block signals or cause damage, accessing the monitoring stations may be difficult.
What's more, "the wild mountain goats can eat the cables of the ground instruments because the goats like salt," Ghent said.
"If you have a way to monitor an area without actually being there, you're really opening the door to being able to monitor it all year long and help keep people safe around the world."
This research was funded by NASA and the National Science Foundation.
For more information, contact Ghent at jghent@uw.edu and Crowell at crowellb@uw.edu.
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UW brings field geology to students with ‘Virtual Field Geology’
Friday, December 9, 2022
Graduate Student Max Needle and his advisor, Juliet Crider, are featured in UW news for their, creaton of computer-based field experiences. Read More -
Salt Spray May Stifle Lightning over the Sea
Tuesday, November 8, 2022
Most lightning occurs over land, but most precipitation occurs over the ocean, said Daniel Rosenfeld (Hebrew Univ), Robert Holzworth (ESS) and other coauthors, of a new study in Nature Communications (https://www.nature.com/articles/s41467-022-31714-5 ). For the past 20-some years, researchers have been batting about ideas on why. “I had many friendly arguments with my colleagues,” Rosenfeld said. Over land and sea, lightning forms from the collisions of ice particles and pellets in a cloud. The process starts with small water droplets being wafted high into a cloud, where it’s cold. Even when the temperature is below freezing, the droplets can stay liquid, becoming supercooled. But eventually, some droplets form ice crystals, and when other supercooled droplets ram into them, these droplets freeze fast. These pellets, called graupel, fall under their own weight. When graupel collides with small ice crystals, the collisions create electrical charges. The falling graupel tends to grab the negative charges, whereas rising ice crystals tend to stash positive ones. Eventually, the air between those separated charges breaks down, sending a bolt of lightning crashing through the cloud. But sea spray forms large salt particles—greater than 1 micrometer. Water gloms onto these aerosols, creating large raindrops. The falling rain starves oceanic clouds of the water needed to create zaps of lightning, researchers reported. WWLLN lightning data were used to make the case about lightning. Read More -
"Lifting the Fog" Webinar and Panel Q&A
Friday, November 4, 2022
The Seattle Times and the M.J. Murdock Charitable Trust sponsored a webinar and Q&A panel on the subject of preparedness for regional earthquake and tsunami hazards. Panelists included ESS Research Professor Paul Bodin, Seattle Times science reporter Sandi Doughton and Washington State emergency manager Elyssa Tappero The webinar recording is available online at https://murdocktrust.org/2022/09/webinar-lifting-the-fog-preparing-for-the-big-one/ Read More -
UW is No. 6 in the world, according to US News Best Global Universities
Thursday, October 27, 2022
The University of Washington rose from No. 7 to No. 6 on the U.S. News & World Report's Best Global Universities rankings, released on Tuesday. The UW maintained its No. 2 ranking among U.S. public institutions.
U.S. News also ranked several subjects, and the UW placed in the top 10 in 10 subject areas, including immunology (No. 4), molecular biology and genetics (No. 5), clinical medicine (No. 6), and geosciences (No 7.).
In another ranking out this week, Times Higher Education World University Rankings 2023 by Subject, six subject areas at the UW 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," UW 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 UW is No. 6 in the world, according to US News & World Report’s Best Global Universities ranking.Mark Stone/University of Washington
The U.S. News ranking methodology -- 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 UW 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 Times Higher Education World University Rankings by Subject rankings, UW's programs in these areas placed in the top 25:
- Computer Science: No. 15
- Life Sciences (includes agriculture and forestry, biological sciences, veterinary science and sport science): No. 16
- Clinical and Health (includes medicine, dentistry and other health subjects): No. 17
- Social Sciences (includes communication and media studies, politics and international studies -- including development studies, sociology and geography): No. 18
- Physical Sciences (includes mathematics and statistics, physics and astronomy, chemistry, geology, environmental sciences, and Earth and marine sciences): No. 19
- Education (includes education, teacher training, and academic studies in education): No. 23
The subject tables employ the same 13 performance indicators used in the overall World University Rankings 2023; however, the methodology is recalibrated for each subject, with the weightings changed to suit the individual fields.
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New ground as tech aims to help boost soil health | BBC
Monday, October 24, 2022
According to experts, more than half of the world's agricultural soil is degraded, devoid of healthy micro-organisms needed for plant growth. New tech might just be able to help freshen up the soil. David Montgomery, professor of Earth and space sciences at the UW, is quoted. Read More -
Washington prepares for flooding, landslides as rain returns | KING 5
Thursday, October 20, 2022
Much of Western Washington is looking forward to forecasted rains heading into the weekend, hopeful that it will give some relief from wildfire smoke. But the rain also marks the start of a season that carries potential flood and landslide hazards, which emergency managers are preparing for, especially in areas scarred by fires. David Montgomery, professor of Earth and space sciences at the UW, is quoted. Read More -
When the Big One Hits Portland, Cargo Bikers Will Save You | WIRED
Monday, September 26, 2022
Community groups in Portland, Seattle, and Tsukuba, Japan, are preparing for earthquakes by hosting bike races. Cyclists who participate solve a variety of challenges that might face communities days after a devastating earthquake, demonstrating the capabilities of cargo bikes in a disaster and familiarizing the cyclists with local emergency response patterns. Quoted is graduate student Elizabeth Davis, who participated in the Portland event and organizes similar efforts in Seattle. Read More -
Deepest scientific ocean drilling effort sheds light on Japan's next 'big one'
Thursday, September 22, 2022
Scientists who drilled deeper into an undersea earthquake fault than ever before have found that the tectonic stress in Japan's Nankai subduction zone is less than expected.
The results of the study led by the University of Washington and the University of Texas at Austin, published Sept. 5 in Geology, are a puzzle, since the fault produces a great earthquake almost every century and was thought to be building for another big one.
Although the Nankai fault has been stuck for decades, the findings reveal that it is not yet showing major signs of pent-up tectonic stress. Authors say the result doesn't alter the long-term outlook for the fault, which last ruptured in 1946, when it caused a tsunami that killed thousands, and is expected to do so again during the next 50 years.
The findings will help scientists home in on the link between tectonic forces and the earthquake cycle. This could potentially lead to better earthquake forecasts, both at Nankai and other megathrust faults, like the Cascadia subduction zone off the coast of Washington and Oregon.
The deep-sea scientific drilling vessel Chikyu, which in 2018 performed the deepest drilling of a subduction zone earthquake fault.Wikimedia/Gleam
Harold Tobin of the University Washington inspects drilling pipes. Researchers used similar equipment during a record-breaking attempt to drill Japan's Nankai fault in 2018.University of Washington
"Right now, we have no way of knowing if the big one for Cascadia -- a magnitude-9 scale earthquake and tsunami -- will happen this afternoon or 200 years from now," said lead author Harold Tobin, a UW professor of Earth and space sciences and co-chief scientist on the drilling expedition. "But I have some optimism that with more and more direct observations like this one from Japan we can start to recognize when something anomalous is occurring and that the risk of an earthquake is heightened in a way that could help people prepare.
“We learn how these faults work by studying them all over the world, and that knowledge will directly translate into insight into the Cascadia hazard as well."
Megathrust faults such as Nankai and Cascadia, and the tsunamis they generate, are among the most powerful and damaging on the globe. Scientists say they currently have no reliable way of knowing when and where the next big one will hit.
The hope is that by directly measuring the force felt between tectonic plates pushing on each other -- tectonic stress -- scientists can learn when a great earthquake is ready to happen.
"This is the heart of the subduction zone, right above where the fault is locked, where the expectation was that the system should be storing energy between earthquakes," said co-author Demian Saffer at University of Texas at Austin, who also co-led the scientific drilling expedition. "It changes the way we're thinking about stress in these systems."
The nature of tectonics means that the great earthquake faults are found in deep ocean, miles under the seafloor, making them incredibly challenging to measure directly. Tobin and Saffer's drilling expedition is the closest scientists have come.
Their record-breaking feat took place in 2018 aboard a Japanese scientific drilling ship, the Chikyu, which drilled almost 2 miles, or just over 3 kilometers, into the tectonic plate before the borehole got too unstable to continue -- 1 mile short of the fault.
Nevertheless, the researchers gathered invaluable data about subsurface conditions near the fault, including stress. To do that, they measured how much the borehole changed shape as the Earth squeezed it from the sides, then pumped water to see what it took to force its walls back out. That told them the direction and strength of horizontal stress felt by the plate pushing on the fault.
Contrary to predictions, the horizontal stress expected to have built up since the most recent great earthquake was close to zero, as if the system had already released its pent-up energy.
The researchers suggested several explanations: It could be that the fault simply needs less pent-up energy than thought to slip in a big earthquake, or that the stresses are lurking nearer to the fault than the drilling reached. Or it could be that the tectonic push will come suddenly in the coming years. Either way, the researchers said the drilling showed the need for further investigation and long-term monitoring of the fault.
"Findings like this can seem like they muddy the picture, because things aren’t as simple as our theory or models predicted they were," Tobin said. "But that just means we’re gaining more understanding of how the real world works, and the real world is messy and complicated."
The research was funded by the Integrated Ocean Drilling Program and the Japan Agency for Marine-Earth Science and Technology, or JAMSTEC. Other co-authors are Takehiro Hirose at JAMSTEC and David Castillo at Insight GeoMechanics in Australia.
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For more information, contact Tobin at htobin@uw.edu or Saffer at demian@ig.utexas.edu.
Adapted from an article by the University of Texas at Austin.
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Alaskan glaciers advance and retreat in satellite imagery | Eos
Thursday, September 15, 2022
Scientists tracked 19 maritime glaciers in Kenai Fjords National Park over several decades and found that tidewater glaciers tended to experience less ice loss than other types of glaciers. Taryn Black, a doctoral student in Earth and space sciences at UW, is quoted. Read More