EF2C. Stay Current—Why Do Volcanoes Erupt?

2024-04-18. Swift Quakes Caused by Stomping Feet, Not Booming Beat. By Carolyn Wilke, Eos/AGU. Excerpt: When 70,000 fans bounced up and down to Taylor Swift last year, the ground pulsed with them, making distinct spikes in seismic signals that many referred to as Swift quakes. Scientists have now analyzed the tremors to learn about their source. …Tepp jumped up and down next to the sensor and the speaker. “It gave a very nice harmonic signal,” she said, suggesting that the motion of jumping fans produced the curious seismic signals. The researchers published their findings in Seismological Research Letters. …The concert data also revealed that the most intense seismic signals came during Swift hits “Shake It Off,” “You Belong with Me,” and “Love Story.”… See article at https://eos.org/articles/swift-quakes-caused-by-stomping-feet-not-booming-beat.

2024-02-14. The United States Has an Updated Map of Earthquake Hazards. [https://eos.org/articles/the-united-states-has-an-updated-map-of-earthquake-hazards] By Caroline Hasler, Eos/AGU. Excerpt: Almost 15% of the U.S. population is “somewhat likely” to experience a damaging earthquake in the coming decades, according to the recently published U.S. National Seismic Hazard Model (NSHM). The model, created by scientists at the U.S. Geological Survey (USGS), synthesizes seismic and geological data to identify which regions of the country are at risk of strong shaking. …First, earthquakes induced by mining, wastewater injection, or other human activities were removed from the catalog; the hazard map depicts only natural hazards. Aftershocks were also removed because they occur as a result of a main shock and cause a particular hazard to be overrepresented. The researchers used the resulting data set to estimate the rate at which earthquakes occur across the United States. They calculated the strength of ground shaking for all earthquakes with magnitudes greater than 5.0, which are likely to cause damaging shaking.

2024-01-29. How Dangerous Is Mexico’s Popocatépetl? It Depends on Who You Ask. [https://eos.org/features/how-dangerous-is-mexicos-popocatepetl-it-depends-on-who-you-ask] By Katherine Kornei, Eos/AGU. Excerpt: The stratovolcano in central Mexico presents a rich case study of risk perception, science communication, and preparedness surrounding natural hazards. …Reports frequently use words and phrases such as “threatening” and “booming eruptions” to describe the active stratovolcano 70 kilometers southeast of Mexico’s capital. …A research team led by Ivan Sunyé Puchol recently estimated that the volcano has erupted explosively more than 25 times over the past 500,000 years. …Popocatépetl’s last explosive eruption of significant size occurred roughly 1,100 years ago. However, the volcano rumbled to life again in late 1994 with a series of small eruptions …that produced a 7-kilometer-high column of ash. …light brown ash has repeatedly dusted nearby towns like Tetela del Volcán and even more outlying cities like Puebla and Mexico City. Mudflows of pumice and ash known as lahars have coursed down the volcano’s nearly vertical slopes. Pyroclastic density currents, clouds of hot gas and volcanic debris that race downslope at hundreds of kilometers per hour, have also been reported at Popocatépetl. “Ash falls, lahars, and pyroclastic density currents are, in my opinion, the real hazards today,” said Sunyé Puchol….

2023-12-19. Icelandic Fissure Finally Erupts. [https://eos.org/articles/icelandic-fissure-finally-erupts] By Kimberly M. S. Cartier, , Eos/AGU/AGU. Excerpt: At 10:17 p.m. local time on 18 December, a magma fissure erupted on Iceland’s Reykjanes Peninsula between Sýlingarfell and Hagafell. An earthquake swarm north of Grindavík preceded the eruption by an hour. …The eruptive fissure is 4 kilometers long, and its southern tip is about 3 kilometers north of Grindavík, which was fully evacuated several weeks ago. …This is the fourth eruption of the Fagradalsfjall volcano complex in 3 years and is 3–4 times larger than previous ones, according to volcanologist Ármann Höskuldsson at the University of Iceland….

2023-08-28. A New, Underground Atlas of Subduction Zones. [https://eos.org/articles/a-new-underground-atlas-of-subduction-zones] By J. Besl, Eos/AGU. Excerpt: Subduction zones are complex. But mapping them is now as simple as cropping a family photo. That’s thanks to Submap, an online resource hosted by the University of Montpellier in France. The latest version was intentionally designed for a wide audience, suitable for students, teachers, and professional researchers. The fast, free service incorporates dozens of data sets and makes mapping available to anyone with an Internet connection….

2023-07-20. Warning signs detected hours ahead of big earthquakes. [https://www.science.org/content/article/warning-signs-detected-hours-ahead-big-earthquakes] By Paul Voosen, Science. Excerpt: Established earthquake warning systems provide at best just a minute or two of notice—and that’s only if the shaking doesn’t start under your feet. …Now, researchers say they have identified nearly imperceptible shifts along fault zones up to 2 hours before large earthquakes, according to a report today in Science. Although existing monitoring systems cannot yet pick up this signal in real time, the discovery points toward a future where residents could retreat to safe havens ahead of the most catastrophic quakes. …Bletery and Nocquet stacked the time series on top of each other. For the first 46 hours, they found the records to be basically featureless. But in the 2 hours before the earthquake, the duo found signs of increasing movement—as if the faults were starting to slip ahead of the main rupture, Bletery says….

2023-06-23. The Mysterious Case of Ireland’s Missing Earthquakes. [https://eos.org/articles/the-mysterious-case-of-irelands-missing-earthquakes] By Elise Cutts, Eos/AGU. Excerpt: Ireland and Britain should be, seismologically speaking, equally boring. The two islands lie thousands of kilometers from the nearest plate boundary and are not volcanic hot spots. But though the ground rarely rumbles in Ireland, neighboring Britain experiences plenty of weak and moderate earthquakes. The lithosphere—Earth’s outermost rocky veneer, which includes the crust and the solid upper mantle—is thicker and cooler beneath Ireland than it is beneath Britain, new research has suggested. Cool, thick lithosphere is mechanically stronger than warm, thin lithosphere, which could explain the Emerald Isle’s puzzling paucity of earthquakes. The new results, published in Geophysical Journal International, hinted that lithosphere thickness could underpin patterns in seismic activity in other places far from plate boundaries….

2023-06-09. Lava comes in two ‘flavors.’ Scientists may have finally figured out why. [https://www.science.org/content/article/lava-comes-two-flavors-scientists-may-have-finally-figured-out-why] By Maya Wei-Haas. Excerpt: …Jenny Suckale was rambling across an old Hawaiian lava flow when an abrupt change in the jet-black rocks caught her eye. On one side was the smooth, undulating lava type called pahoehoe (pronounced pah-hoy-hoy); on the other was the sharp, jagged kind known as aa (pronounced ah-ah). …What causes the dramatic transformation in texture, seen in lavas worldwide? …But no single factor has explained the shift. Now, by modeling the dynamics of lava flows, Suckale and her colleagues have offered up another explanation: The abrupt transition could be triggered by a chaotic churn within the flood of molten rock, the team reported last month in Geophysical Research Letters. …Understanding how pahoehoe morphs into aa is more than just scientific curiosity because the two lava types move at different speeds and pose distinct hazards….

2023-04-19. “It’s just mind boggling.” More than 19,000 undersea volcanoes discovered. [https://www.science.org/content/article/it-s-just-mind-boggling-more-19-000-undersea-volcanoes-discovered] By Paul Voosen, Science. Excerpt: …In 2005, the nuclear-powered USS San Francisco collided with an underwater volcano, or seamount, at top speed, killing a crew member and injuring most aboard. It happened again in 2021 when the USS Connecticut struck a seamount in the South China Sea, damaging its sonar array. With only one-quarter of the sea floor mapped with sonar, it is impossible to know how many seamounts exist. But radar satellites that measure ocean height can also find them, by looking for subtle signs of seawater mounding above a hidden seamount, tugged by its gravity. A 2011 census using the method found more than 24,000. High-resolution radar data have now added more than 19,000 new ones. The vast majority—more than 27,000—remain uncharted by sonar. “It’s just mind boggling,” says David Sandwell, a marine geophysicist at the Scripps Institution of Oceanography, who helped lead the work. Published this month in Earth and Space Science, the new seamount catalog is “a great step forward,” says Larry Mayer, director of the University of New Hampshire’s Center for Coastal and Ocean Mapping. Besides posing navigational hazards, the mountains harbor rare-earth minerals that make them commercial targets for deep-sea miners. Their size and distribution hold clues to plate tectonics and magmatism. They are crucial oases for marine life….

2023-02-17. Why Did a Turkish City Withstand the Quake When Others Crumbled? [https://www.nytimes.com/2023/02/17/world/middleeast/erzin-turkey-earthquake.html] By Cora Engelbrecht and Nimet Kirac, The New York Times. Excerpt: For miles around the small Turkish city of Erzin, the earth is shattered and buildings are razed, towns and cities turned into tombs of concrete by last week’s 7.8-magnitude earthquake. But Erzin still stands, an oasis of stability near the Mediterranean, where the question of why the city weathered the quake and a powerful aftershock — and so many others did not, leaving more than 40,000 dead in Turkey and Syria — is consuming the population. In Erzin, the mayor said, no one died and not a single building fell. …engineers and scientists credited …factors combining to save the city, like better construction that followed the latest seismic codes, and Erzin’s lucky location on very solid ground. …soft, water-laden sediments make cities and villages uniquely vulnerable to earthquakes,” …When one strikes… “this land, it moves like a wave.” …In contrast, Erzin stands higher above sea level, and is built on hard ground comprising “bedrock and coarser grains than sand,” said Tamer Duman, a geographer. …The hard soil acts as a shock absorber between structures and a quake’s waves, reducing buildings’ sway….

2022-07-27. Massive undersea eruption filled atmosphere with water. [https://www.science.org/content/article/massive-undersea-eruption-filled-atmosphere-water] By Nathaniel Scharping, Science Magazine. Excerpt: On 15 January, Tonga’s Hunga Tonga-Hunga Ha’apai volcano erupted under the sea, rocking the South Pacific nation and sending tsunamis racing around the world. The eruption was the most powerful ever recorded, causing an atmospheric shock wave that circled the globe four times, and sending a plume of debris more than 50 kilometers into the atmosphere. …The ash and gasses punching into the sky also shot billions of kilograms of water into the atmosphere, a new study concludes. That water will likely remain there for years, where it could eat away at the ozone layer and perhaps even warm Earth. …In all, the plume shot approximately 146 billion kilograms of water into Earth’s stratosphere, an arid layer of the atmosphere that begins several miles above sea level, the authors report this month in Geophysical Research Letters. …Other volcanoes have added measurable amounts of water vapor to Earth’s atmosphere, he says, but the scale this time was unprecedented. That’s likely because of the eruption’s magnitude and underwater location, he says. The water will probably remain in the stratosphere for half a decade or more, [study co-author and JPL atmospheric scientist Luis Millán] says. Big volcanic eruptions often cool the climate, because the sulfur dioxide they release forms compounds that reflect incoming sunlight. But with so much water vapor flung aloft, the Tonga eruption could have a different impact. Water absorbs incoming energy from the Sun, making it a potent greenhouse gas. And the sulfur dioxide will dissipate in just a few years whereas the water will likely stick around for at least 5 years—and potentially longer Millán thinks.…

2022-06-01. ‘Singing’ lava lakes could help predict when volcanoes will blow. By Zach Savitsky, Science Magazine. Excerpt: In 2007, lava began to pool inside one of the craters atop Hawaii’s Kilauea volcano, a gentle eruption that would culminate more than a decade later in a spectacular display of spewed ash and massive lava flows. Until that final outburst, the lava lake was a tourist spectacle, a calm surface that hid the churn of magma deeper within the volcano. Now, researchers have found a new way to identify key signs of Kilauea’s eruptive potential—by listening to vibrations from these lava lakes. Eventually, they hope to use these lava “songs” to forecast when a volcano will start and stop erupting…. [https://www.science.org/content/article/singing-lava-lakes-could-help-predict-when-volcanoes-will-blow

2022-04-22. Studying Volcanoes through Myths, Legends, & Other Unconventional Data. By Nancy Averett, Eos/AGU. Excerpt: Studying historic eruptions through a storytelling lens often improves our understanding of and ability to prepare for such events.… [https://eos.org/features/studying-volcanoes-through-myths-legends-other-unconventional-data]

2022-03-10. New insight into magma chambers could improve volcano models. By Colin Barras, Science Magazine. Excerpt: Researchers have discovered a simple and surprising control over the depth of a volcano’s magma chamber: how much water it contains. The finding is significant because water fuels the most devastating eruptions—from Vesuvius in 79 C.E. to Mount Pinatubo in 1991. The work could also help improve models that predict eruptions, which for years have been based on a volcano’s seismic rumblings and records of its past behavior. …Daniel Rasmussen …and his colleagues wanted to understand why magma chambers—slushy mixes of molten rock, solid crystals, and gases—lie anywhere between about 1 kilometer and 12 kilometers below the surface of “arc” volcanoes, a common kind of volcano that forms near the boundaries of tectonic plates. When plates of ocean crust slide into the mantle, the layer that makes up most of Earth’s interior, they drag water with them that gets locked away in minerals. This water then fuels the formation of magmas. As this magma rises through cracks and fissures, it is depressurized …much like the bubbles in a popped can of carbonated soda. But magma also gets stickier as it loses water, and …gradually becomes so thick it can rise no farther—at least until a physical disturbance such as an injection of extra magma drives an eruption. …A magma body with 1% water by weight would begin to lose water just 1 kilometer below the surface, …but for magma with 7% water by weight, loss would begin much deeper, at about 12 kilometers. This means, counterintuitively, that “wetter” magmas—even though they’re initially more fluid—thicken up and stall out at greater depths than “drier” ones. The researchers thought this could explain why magmas occur at different depths.… [https://www.science.org/content/article/new-insight-magma-chambers-could-improve-volcano-models]

2022-01-21. Radiometric Dating Sheds Light on Tectonic Debate. By Aaron Sidder, Eos/AGU. Excerpt: At the far edges of continents, where the continental shelf transitions into the deep ocean, continental and oceanic plates come face to face. At many of these margins, the denser oceanic plate is pushed below the continental plate in a process called subduction. However, in some cases, known as obduction, the oceanic plate ends up atop the more buoyant continental plate instead of diving below it. …The resulting ophiolites—slices of oceanic crust and mantle atop a continental plate—offer uncommon opportunities to view seafloor geology from the comfort of land. The Samail Ophiolite (Oman–United Arab Emirates), in the northeastern corner of the Arabian Peninsula, is frequently studied as a model of obduction because of its well-exposed and well-studied geology. …In a new study, Garber et al. sought to clarify the timing of the obduction episode in Oman. …Samarium-neodymium (Sm-Nd) and uranium-lead (U-Pbradiometric dating on the garnet, zircon, and rutile crystals in the rocks helped determine the age of the subduction event. …The results indicate that the episode occurred approximately 81–77 million years ago when the Arabian continental plate subducted to the northeast below the Samail Ophiolite.… [https://eos.org/research-spotlights/radiometric-dating-sheds-light-on-tectonic-debate]

2022-01-19. Here’s What Scientists Know About the Tonga Volcano Eruption. By Henry Fountain, The New York Times. Excerpt: The explosion probably won’t cool the planet as some previous eruptions have done, but it could affect weather in the short term.… [https://www.nytimes.com/2022/01/19/climate/scientists-tonga-volcano-eruption-effects.html]

2022-01-04. Sensing Iceland’s Most Active Volcano with a “Buried Hair”. By Sara Klaasen,  Sölvi Thrastarson,  Andreas Fichtner,  Yeşim Çubuk-Sabuncu and  Kristín Jónsdóttir, Eos/AGU. Excerpt: Distributed acoustic sensing offered researchers a means to measure ground deformation from atop ice-clad Grímsvötn volcano with unprecedented spatial and temporal resolutions.… [https://eos.org/science-updates/sensing-icelands-most-active-volcano-with-a-buried-hair]

2021-09-15. Forget oil or water. In Iceland, well diggers seek to tap a volcano’s magma. Source: By Paul Voosen, Science Magazine. Excerpt: KRAFLA VOLCANO IN ICELAND—After years of effort, volcanologists are ready to open a gateway to hell. From the rim of the Víti (“hell” in Icelandic) crater—a smaller crater within Krafla’s 10-kilometer caldera—Ottó Elíasson looks down on at a tranquil grassy field disturbed only by a spindly weather station. …The main attraction lies 2 kilometers below this spot on this volcanically hyperactive island, which is being split in two by the spreading Mid-Atlantic Ridge. In 2009, drillers trying to tap hot water for geothermal energy here accidentally pierced a hidden magma chamber. After an outpouring of steam and glass shards from quenched magma, the borehole created the hottest geothermal well ever measured—until the casing failed. Now, researchers are returning to penetrate the molten rock on purpose, using hardier equipment, to create the world’s only long-term magma observatory. …They could also shed light on how the continents formed and grew.… [https://www.science.org/content/article/forget-oil-or-water-iceland-well-diggers-seek-tap-volcano-s-magma] For GSS Energy Flow chapter 2.

2021-08-31. Anticipating Climate Impacts of Major Volcanic Eruptions. Source: By Simon A. Carn, Paul A. Newman, Valentina Aquila, Helge Gonnermann, and Josef Dufek, Eos/AGU. Excerpt: NASA’s rapid response plan for gathering atmospheric data amid major volcanic eruptions, paired with efforts to improve eruption simulations, will offer better views of these events’ global effects.… [https://eos.org/science-updates/anticipating-climate-impacts-of-major-volcanic-eruptions]. See also Making the Most of Volcanic Eruption Responses.

2021-08-06. Don’t Call It a Supervolcano. Source: By Mary Caperton Morton, Eos/AGU Excerpt: Yellowstone National Park, the world’s first and arguably most famous national park, is home to one of the planet’s largest and potentially most destructive volcanoes. The 50- by 70-kilometer Yellowstone caldera complex is so massive that it can really be appreciated only from the air. But although the caldera isn’t always visible on the ground, it’s certainly no secret: Copious thermal features like hot springs and geyser basins dot the landscape and have attracted people to the uniquely beautiful and ecologically rich area for at least 11,000 years. …Every season, recurring bouts of earthquake swarms trigger sensational stories that Yellowstone could be gearing up for another “big one.” But there’s no need to cancel your family vacation to see the park’s free-roaming bison and grizzly bears: The geologists who keep a very close eye on the Yellowstone caldera system say it’s not going to erupt again in our lifetimes. …The story of Yellowstone begins around 16.5 million years ago, when a plume of magma began fueling intense bouts of volcanism along the border of what is now Idaho, Nevada, and Oregon. This magma plume, like the one that formed the Hawaiian Islands, is stationary, but as the North American plate moves to the southwest over the hot spot, its surface expression migrates, creating a 750-kilometer-long trail of volcanism, including dozens of calderas, across southern Idaho and into northwest Wyoming…. [https://eos.org/features/dont-call-it-a-supervolcano]

2021-06-14. [https://eos.org/research-spotlights/magma-pockets-lie-stacked-beneath-juan-de-fuca-ridge] – Magma Pockets Lie Stacked Beneath Juan de Fuca Ridge. Source: By Sarah Stanley, Eos/AGU. Excerpt: Off the coast of the U.S. Pacific Northwest, at the Juan de Fuca Ridge, two tectonic plates are spreading apart at a speed of 56 kilometers per 1 million years. As they spread, periodic eruptions of molten rock give rise to new oceanic crust. Seismic images captured by Carbotte et al. now provide new insights into the dynamics of magma chambers that feed these eruptions. …Sites of fast and intermediate spreading are typically fed by a thin, narrow reservoir of molten magma—the axial melt lens—that extends along the ridge at an intermediate depth in the oceanic crust, but still well above the mantle. …some seafloor spreading sites around the world contain additional magma chambers beneath the axial melt lens. These additional chambers are stacked one above another in the “crystal mush zone,” an area of the actively forming oceanic crust that contains a low ratio of melted rock to crystallized rock. Beneath the Axial Seamount portion of the Juan de Fuca Ridge …a 2020 investigation showed evidence of stacked magma chambers in the crystal mush zone beneath the large magma reservoir that underlies this on-axis hot spot. …These findings…suggest that these stacked chambers are short-lived and may arise during periods when the crystal mush zone undergoes compaction and magma is replenished from the mantle below. The chambers do not cool and crystallize in place, but instead are tapped and contribute magma to eruptions and other crust-building processes…. 

2021-05-14. [https://eos.org/articles/high-school-junior-builds-cheap-earthquake-warning-device] – High School Junior Builds Cheap Earthquake Warning Device. Source: By Jack Lee, Eos/AGU. Excerpt: A Southern California high school junior has developed a low-cost seismometer using parts that total less than $100—a fraction of the cost of a scientific-grade system. …“It’s small and cheap and accessible,” said Vivien He, a student at Palos Verdes Peninsula High School in Rolling Hills Estates, Calif. In April, she presented her work at the 2021 Annual Meeting of the Seismological Society of America. …When an earthquake occurs, it generates compressional (P) waves and shear (S) waves, which emanate from the epicenter through Earth. Sensors that detect P waves can provide a warning before slower—but more destructive—S waves arrive. “Even with just a few seconds of warning, we can provide a useful alert to people: that they can do something…to protect themselves,” said Angie Chung, a seismologist at the Berkeley Seismological Laboratory in Berkeley, Calif. For instance, someone could duck under a table for protection from falling objects…. 

2021-02-25. Fleets of radar satellites are measuring movements on Earth like never before. By Julia Rosen, Science Magazine. Excerpt: East Africa …the geologically active region has also given birth to dozens of volcanoes. Few have been monitored for warnings of a potential eruption, and until recently, most were believed to be dormant. Then, Juliet Biggs decided to take a closer look—or rather, a farther look. Biggs, a geophysicist at the University of Bristol, uses a technique called interferometric synthetic aperture radar (InSAR) to detect tiny movements of Earth’s surface from space. In a series of studies, she and her co-authors analyzed satellite data on the East African volcanoes. According to their latest results, which were published last month, 14 have been imperceptibly growing or shrinking in the past 5 years—a clue that magma or water is moving underground and that the volcanoes are not completely asleep. …After data showed that the Corbetti volcano, which abuts the fast-growing city of Hawassa, Ethiopia, is inflating steadily at a rate of 6.6 centimeters per year, Biggs’s Ethiopian colleagues included it in the country’s geological hazard monitoring network. …Individual GPS stations can track surface movements of less than 1 millimeter, but InSAR can measure changes almost as subtle across a swath hundreds of kilometers wide. …With InSAR, scientists are tracking how ice streams flow, how faults slip in earthquakes, and how the ground moves as fluids are pumped in or out…. [https://www.sciencemag.org/news/2021/02/fleets-radar-satellites-are-measuring-movements-earth-never] See also A technique to track Earth’s subtle movements with orbiting radars is heating up, by Meagan Cantwell, Science Magazine, Mar 5, 2021.

GSS book cover for Energy Flow

Non-chronological resources

Earthquake Resources

Volcano Resources

Internal Earth Processes – 36 multimedia resources from Teachers’ Domain Earth and Space Science multimedia resources (movies and interactives).

Website discussing the origin of hot spot vulcanism.

Plate tectonic, continental drift animations from UC Berkeley Museum of Paleontology

Subduction in a Nutshell

USGS Hazards Gateway – about earthquakes, floods, hurricanes, landslides, tsunamis, and volcanoes.

USGS Volcano site 

Volcano Observatories