Anatomy of a “zombie” volcano: investigating the cause of unrest inside Uturuncu

University of Oxford

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Gravimeter and GPS station with Cerro Uturuncu in the background. Photo credit Duncan Muir, Cardiff University.

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Credit: Duncan Muir, Cardiff University.

Images available via the link in the notes section

Scientists from China, the UK and the USA have collaborated to analyse the inner workings of Bolivia’s “zombie” volcano, Uturuncu. By combining seismology, physics models and analysis of rock composition, researchers identify the causes of Uturuncu’s unrest, alleviating fears of an imminent eruption. The findings have been published today (28 April) in the journal PNAS.

Deep in the Central Andes lies Uturuncu, Bolivia’s “zombie” volcano -so called because despite being technically dead (last erupting 250 thousand years ago), it still shows signs of unrest, including earthquakes and plumes of gases. This unrest manifests itself in a “sombrero” pattern of deformation, with the land in the centre of the volcanic system rising up, and surrounding areas sinking down.

For the local population, it is vitally important to assess the potential start and severity of an eruption from Uturuncu, which could cause widespread damage and threat to life. However, up to now there was no explanation for the continued volcanic unrest. Scientists believed that the key to understanding this was to visualise the way that magma and gases move around underneath the volcano.

This new study, which drew upon expertise from University of Science and Technology of China, the University of Oxford and Cornell University, used signals detected from more than 1,700 earthquake events to perform high-resolution imaging of the plumbing system in the shallow crust beneath Uturuncu. According to the findings, the “zombie”-like unrest of Uturuncu is due to the movement of liquid and gas beneath the crater, with a low likelihood of an imminent eruption.

Volcanic plumbing systems are a complex mixture of fluids and gases in magmatic reservoirs and hydrothermal systems. Previous studies have shown that Uturuncu sits above the world’s largest known magma body in the Earth’s crust, the Altiplano-Puna Volcanic Complex, and that an active hydrothermal system connects this body and the surface. But it was unknown how fluids may be moving through this underground system.

The research team made use of seismic tomography, a way of imaging the interior of the volcano, similar to methods used in medical imaging of the human body.  Seismic waves travel at different speeds through different materials, thereby providing high-resolution insights into the inner workings of Uturuncu in three dimensions. They combined this with analysis of the physical properties of the system, including rock composition, to better understand the subterranean volcanic system. This detailed analysis picked out possible upward migration pathways of geothermally heated fluids and showed how liquids and gases accumulate in reservoirs directly below the volcano’s crater. The research team believe that this is the most likely cause for the deformation in the centre of the volcanic system, and that the risk of a real eruption is low.

Co-author Professor Mike Kendall (Department of Earth Sciences, University of Oxford) said: “I am very pleased to be involved in this truly international collaboration. Our results show how linked geophysical and geological methods can be used to better understand volcanoes, and the hazards and potential resources they present.”

Co-author Professor Haijiang Zhang (School of Earth and Space Sciences, University of Science and Technology of China) said: “Understanding the anatomy of the Uturuncu volcanic system was only possible thanks to the expertise within the research team. This enabled us to combine various advanced geophysical imaging tools with modelling of the rock properties and their interactions with fluids.”

Co-author Professor Matthew Pritchard (Cornell University) added: "The methods in this paper could be applied to the more than 1400 potentially active volcanoes and to the dozens of volcanoes like Uturuncu that aren't considered active but that show signs of life — other potential zombie volcanoes." 

The research team hope that similar studies using the joint analysis of seismological and petrological properties can be used to view the anatomy of other volcanic systems in the future.

Notes to editors:

For media enquiries and interview requests, contact communications@earth.ox.ac.uk

The paper ‘Anatomy of magmatic hydrothermal system beneath Uturuncu volcano, Bolivia, by joint seismological and petrophysical analysis’ will be published in PNAS at 20:00 BST / 15:00 ET Monday 28 April, DOI 10.1073/pnas.2420996122

A pre-embargo copy of the paper can be viewed on the PNAS tipsheet on EurekAlert.

Images relating to the study which can be used in articles can be found at https://drive.google.com/drive/folders/1TXieDDIKOsfEp8imld9qpZRCtrYJ-p85?usp=sharing  These images are for editorial purposes relating to this press release ONLY and MUST be credited (see file name). They MUST NOT be sold on to third parties.

Cerro Uturuncu, one of many volcanoes on the Bolivian Altiplano that lie above the Altiplano-Puna Magma Body. Photo credit Jon Blundy, University of Oxford.

Cerro Uturuncu, right, and Cerro San Antonio, left, volcanoes above the small town of Quetena Chico on the Bolivian Altiplano. Photo Credit: Jon Blundy, University of Oxford.

About the University of Oxford

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Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2420996122 

Article Title

Anatomy of the magmatic hydrothermal system beneath Uturuncu volcano, Bolivia, by joint seismological and petrophysical analysis

Article Publication Date

28-Apr-2025

 

Flood risk increasing in Pacific Northwest

Virginia Tech

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This map (left image) indicates the sites of the 24 estuaries along the coast in the Cascadia subduction zone where Tina Dura and her team took geological core samples. The photo on the right is of Brandon Hatcher and Tina Dura with a core sample.

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Credit: Image and photo courtesy of Tina Dura.

The next great earthquake isn't the only threat to the Pacific Northwest.

A powerful earthquake, combined with rising sea levels, could significantly increase flood risks in the Pacific Northwest, impacting thousands of residents and properties in northern California, Oregon, and Washington, according to new Virginia Tech research.

A study published this week in the Proceedings of the National Academy of Sciences found that a major earthquake could cause coastal land to sink up to 6.5 feet, expanding the federally designated 1 percent coastal floodplain, an area with a 1-in-100 chance of flooding each year, by 35 to 116 square miles.

“The expansion of the coastal floodplain following a Cascadia subduction zone earthquake has not been previously quantified, and the impacts to land use could significantly increase the timeline to recovery,” said researcher Tina Dura, lead author of the study and assistant professor of geosciences in the College of Science.

The research shows the most severe effects would hit southern Washington, northern Oregon, and northern California, densely populated areas in the region.

Dura’s team generated tens of thousands of earthquake models to estimate the potential range of earthquake-driven subsidence — sinking land — that can be expected from the next large Cascadia earthquake. Then, using geospatial analysis, the team quantified the earthquake-driven expansion of the 1 percent floodplain at 24 estuaries and communities along the Cascadia subduction zone. Because the timing of the next large earthquake is uncertain, the team modeled the impacts of an earthquake striking today or in 2100, when climate-driven sea-level rise will further amplify the impacts of earthquake-driven subsidence.   

The study estimates that following an earthquake today, an additional 14,350 residents, 22,500 structures, and 777 miles of roadway would fall within the post-earthquake floodplain, more than doubling flood exposure. Potential flooding would affect five airports; 18 critical facilities, including public schools, hospitals, police stations, and fire stations; eight wastewater treatment plants; one electric substation; and 57 potential contaminant sources, including animal feeding operations, gas stations, and solid waste facilities. 

By 2100, the Intergovernmental Panel on Climate Change (IPCC) localized relative sea-level rise projections show that sea levels along the Cascadia subduction zone could be up to 3 feet higher than today. This climate-driven sea-level rise will amplify the impacts of future earthquake-driven subsidence, more than tripling the flood exposure of residents, structures, and roads.

“Today, and more so in 2100 as background sea levels rise, the immediate effect of earthquake-driven subsidence will be a delay in response and recovery from the earthquake due to compromised assets. Long-term effects could render many coastal communities uninhabitable,” said Dura, an affiliate with the Global Change Center.

Current low-lying land developed for cattle grazing and farming through diking and draining will experience heavy economic loss as increased tidal inundation will cause over salinization of soils and render them unusable. Additional impacts include erosion of natural systems, particularly coastal estuaries, intertidal wetlands and protective dunes and beaches. These act as buffers against storm surges and help to dissipate wave energy to prevent sediment erosion and protect property damage. According to Dura, the loss of these ecosystems may not be recoverable, and inland movement may be constrained by topography and human development.

“The loss of intertidal wetlands directly impacts ecosystem services such as water filtration, habitat for fisheries and shorebirds, and carbon storage capacity,” said Dura, an affiliate with the Fralin Life Sciences Institute. “Intertidal wetlands function as natural carbon sinks, and their erosion or conversion to tidal flats significantly reduces their ability to sequester carbon.”

The Cascadia subduction zone is one of many regions in the “Ring of Fire,” where the Pacific Plate meets another tectonic plate, causing the strongest earthquakes in the world and the majority of volcanic eruptions. However, a great earthquake — those with a seismic magnitude over 8.0 — has not occurred along the Cascadia subduction zone since Jan. 26, 1700, making coastal geologic records of past earthquakes and associated subsidence critical for understanding this hazard. 

Dura and her team are documenting geologic evidence of past earthquake-driven subsidence as the Paleoseismology Working Group Lead within the Cascadia Region Earthquake Science Center (CRESCENT), a center at the University of Oregon funded by the National Science Foundation that is providing a collaborative framework to tackle multidisciplinary scientific and societal challenges at the Cascadia subduction zone.

Their research of geologic evidence from the last six to seven thousand years indicates that 11 great earthquakes have happened approximately every 200 to 800 years in the Pacific Northwest. The last earthquake in the region resulted in between 1.5 to 6.5 feet of land along the coastline immediately sinking.

“Cascadia is a unique place. It’s not super heavily populated, but most estuaries have a community in them, and they’re all right in the zone of subsidence,” said Dura. “This is honestly where I think the subsidence could have bigger impacts than it has during other recent large earthquakes around the world.”

Global relevance

Subduction zones, which can also be found off the coasts of Alaska, Russia, Japan, Indonesia, New Zealand, and South America, are all similar in that one tectonic plate slides beneath another. Along portions of these subduction zones, there is an initial uplift in the top plate. Pressure between the two plates gradually builds over centuries. The resultant earthquake is created when the plate above become unstuck. Offshore, the plate rises, forcing an upward water surge that leads to a tsunami. Onshore, the plate subsides, immediately dropping the coastline up to 6.5 feet.  

The earthquake shaking begins the process. For a magnitude 9 earthquake or over, that takes about four to six minutes. While the shaking is occurring the land is dropping, and, depending on tidal conditions, low-lying areas may experience immediate flooding. Within 15 to 20 minutes the tsunami hits with further flooding. The entire process takes no longer than 30 minutes, and multiple tsunami waves may occur over one to two hours. However, the sinking of the land will persist for decades to centuries after the earthquake.

According to Dura, the 1960 Chile earthquake submerged a pine forest and farms, converting them to tidal marshes, and it flooded coastal towns, forcing residents to abandon their homes; the 1964 Alaska earthquake forced the relocation of communities and airstrips to higher ground; the 2004 Sumatra-Andaman earthquake destroyed waterfront aquaculture and caused coastal erosion; and the 2011 earthquake in Japan caused erosion, disrupted ports, and contributed to a nuclear disaster.

“Given the global prevalence of subduction zones, these insights hold relevance beyond Cascadia, informing hazard assessments and mitigation strategies for tectonically active regions worldwide,” Dura said.

Other Virginia Tech affiliates who contributed to the paper:

• Robert Weiss, professor of geosciences 
• Mike Willis, associate professor of geosciences
• David Bruce, postdoctoral fellow in geosciences
• William Chilton Ph.D. '23, now in private industry
• Jessica DePaolis, postdoctoral fellow in geosciences
• Mike Priddy, a former Ph.D. student in geosciences for this research

These images show the areas where the current flood plain is (figure on the left) and the expansion of the floodplain in 2100 (figure on the right) due to sea-level rise and an earthquake with either low, medium, or high levels of subsidence, or sinking land.

Credit

Images courtesy of Tina Dura.

Journal

Proceedings of the National Academy of Sciences

Article Publication Date

28-Apr-2025

Should Africa be worried about earthquakes?

Abubakar Said Saad and Hannah Heckelsmüller

DW

April 19, 2025

Myanmar's deadly earthquake has raised alarms beyond Southeast Asia. In Africa, fault lines stretching across the continent pose serious risks, yet preparedness remains low.

Morocco's 2023 earthquake disaster killed nearly 3,000 people

Image: FADEL SENNA/AFP


The recent earthquake in Myanmar has drawn fresh attention to global preparedness for natural disasters, including on the African continent.

African experts are concerned about seismic threats and limited local capacity to respond. For Gladys Karegi Kianji, a seismologist at the University of Nairobi, Kenya, who has studied African earthquakes for 15 years, this is far from a new worry.

"I don't hire an apartment in a tall building beyond the first floor in Nairobi,” Kianji said.

Is Africa at risk of earthquakes?

Earthquakes have struck the continent before. Thousands were killed in Morocco's 2023 disaster, while Ethiopia's 2005 quake resulted in the displacement of about 6,500 people.

Folarin Kolawole, a structural geologist at Columbia University, US, says assessing a region's earthquake risk involves looking at historic earthquakes in the region and identifying fault lines, which are fractures between rocks.

Africa, he says, lies on a complex geological structure that makes it vulnerable to seismic activity.

At the core of this risk is the East African Rift System, where the African Plate is slowly splitting into the Nubian and Somali Plates. As these plates drift apart more, Kolawole says it leads to earthquakes in countries like Ethiopia, Kenya, Uganda, Tanzania, and Mozambique.
Where are Africa's earthquake zones?

Africa has several active seismic zones.

In 2016, a group of geologists created the Seismotectonic Map of Africa, highlighting regions based on historical quakes and geological activity.


Kolawole identifies the East African Rift covering Malawi, Tanzania, Ethiopia and Madagascar as the most earthquake prone part of Africa.

These countries lie along a 3,000-kilometer (1,864-mile) fault stretching from Ethiopia to Mozambique and frequently experience tremors, some causing significant damage.

And while West Africa is often seen as tectonically stable, he points to Ghana's past earthquakes and recent tremors in Nigeria as signs of potential for a large magnitude earthquake to occur.

Lake Kivu: A volatile mix of geology and gas

Lake Kivu, between Rwanda and the Democratic Republic of Congo, is one of Africa's deepest lakes.

What makes it dangerous, Kolawole explained, is the large amount of dissolved carbon dioxide and methane, the latter being highly flammable.

In the event of a strong earthquake, these gases could be released in a rare "limnic eruption", potentially suffocating thousands.

In 1986, a similar event at Lake Nyos in Cameroon killed over 1,700 people when a gas cloud silently swept across nearby villages.

To mitigate this risk, the Rwandan government launched the KivuWatt Gas Methane Power Plant in 2016 to extract methane from the lake for electricity production.

Lake Kivu is one of Africa's deepest lakes and a risk-site for limnic eruptions

Image: Creative Commons/Sascha Grabow

Despite active fault lines, rising seismic activity, and initiatives like this methane extraction facility, Africa remains overall ill-prepared.

"[Governments] don't recognize the importance of putting a network that is going to feed them with the information to actually do the seismic hazard warning. Definitely nothing like that exists,” said Kianji.

She added that governments are often reactive rather than proactive in disaster risk reduction.

What's needed, she said, is greater awareness, seismic monitoring systems, better policies and urban planning, and economic investment.

Kolawole added that "conflict and unrest in some of the African countries such as Congo” hinders preparedness efforts.

"We cannot stop earthquakes from happening,” Kolawole said. "The best we can do is to prepare for it and monitor.”

Fewer than a third of African countries have implemented multi-hazard early warning systems.

The recent earthquake in Myanmar and Thailand has drawn fresh attention to global preparedness

Image: STR/AFP

Africa can learn from global examples including Myanmar's recent quake.

That includes better building standards and investment in understanding the geological activity in the region.

"I think there was a lapse in the administration in terms of the building and construction,” said Kianji of the Myanmar quakes.

"If a lot of [scientific] research was put in, some of those very active zones they may have been able to warn people to be able to evacuate.”

Edited by: Matthew Ward Agius

Abubakar Said Saad Sa’id Sa’ad is Nigerian writer and multimedia journalist currently based in Germany.@saidsaadwrites

Lake deposits reveal directional shaking during devastating 1976 Guatemala earthquake

Seismological Society of America

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Lake sediment core showing the background sedimentation in the lake (laminations) and the disruption generated by a turbidite (light gray layer with no internal structure). 

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Credit: Jonathan Obrist-Farner

Sediment cores drawn from four lakes in Guatemala record the distinct direction that ground shaking traveled during a 1976 magnitude 7.5 earthquake that devastated the country, according to researchers at the Seismological Society of America’s Annual Meeting.

The earthquake, which killed more than 23,000 people and left about 1.5 million people homeless, took place along the Motagua Fault, at the boundary between the North American and Caribbean tectonic plate boundary.

Severe ground shaking from the 1976 earthquake caused landslides and sediment-laden turbidity currents that can be seen clearly in cores taken from the lakebeds. Normally, researchers might expect that this shaking would produce the thinnest sediment deposits in lakes furthest away from an earthquake, since seismic waves weaken as they travel away from an earthquake epicenter.

But in the Guatemalan lakes, the cores with the thickest sediment traces of the earthquake occur at the end of the fault rupture, said Jonathan Obrist-Farner, a geologist at Missouri University of Science and Technology. “What we see is lakes that are actually the closest to the epicenter but just away from the rupture path have very thin deposits.”

Jeremy Maurer, a geophysicist also at Missouri University, suggested that the unusual pattern had in this case recorded the directivity of the 1976 shaking.

It’s not unusual for scientists to find evidence of past earthquakes in lake sediment cores, Maurer added, noting examples from New Zealand to Turkey that offer a glimpse at how far away a particular earthquake could have an impact.

“What hasn’t been done as much is looking at where these lakes are located in relationship to the fault,” said Maurer. “Are they off-axis or on-axis? Does the direction of the rupture have an effect on sediment deposits?”

When the U.S. Geological Survey collected field data after the 1976 earthquake, “they found, for example, adobe houses that were 10 kilometers south of the main rupture path that were still standing, yet those that were actually on the fault trace and towards the propagation direction all collapsed,” said Maurer. “I think there’s a lot of evidence that points to the directivity of the rupture and now we’re just looking at it sedimentologically from the lakes.”

The researchers began recovering and analyzing cores from the lakes in 2022. “We thought it would be a very interesting opportunity to not just look at the 1976 earthquake, but actually learn a little bit more about the paleoseismic history of the plate boundary, which we know very little of,” said Obrist-Farner, who is originally from Guatemala.

Although there was a brief rush of seismologists to the region after the 1976 earthquake, the impacts of a 36-year civil war and sparse instrumentation have left the plate boundary poorly monitored. Paleoseismic data like the lake records are important for building a more complete picture of the country’s seismic risk.

Last year Obrist-Farner’s team retrieved their largest cores yet from the lakes, with lengths of sediment that may represent up to four thousand years of lake history. Their initial analysis shows evidence of the 1816 earthquake of at least magnitude 7.5 that is known mostly from historical documents.

Native American names extend the earthquake history of northeastern North America

Seismological Society of America

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In 1638, an earthquake in what is now New Hampshire had Plymouth, Massachusetts colonists stumbling from the strong shaking and water sloshing out of the pots used by Native Americans to cook a midday meal along the St. Lawrence River, according to contemporaneous reports.

When Roger Williams, founder of the Rhode Island colony, talked with local Native Americans, he reported that the younger tribe members were surprised by the earthquake. But older tribe members said they had felt similar shaking four times in the past 80 years.

In his talk at the Seismological Society of America’s Annual Meeting, Boston College seismologist John Ebel urged his colleagues to collect more information about past earthquakes in eastern North American from Native American stories and languages.

Although it might not feel like earthquake country to a Californian, for example, northeastern North America experiences regular seismic activity and has hosted large earthquakes in the past. Written records of these earthquakes include the past 400 years, but Ebel said extending this record further into the past with the help of Native American knowledge can help scientists better understand earthquake hazard in the area.

Sometimes the clues to past seismic activity are in Native American place names, Ebel said. There’s Moodus, Connecticut, for instance. Moodus comes from an Algonquin dialect and means “place of noises.” For hundreds of years, people have heard “booms”—as if echoing in an underground cavern—in the area. Ebel said the Moodus noises are similar those he heard as a graduate student camping in the Mojave Desert following a magnitude 5.1 earthquake.

“The Moodus noises sounded like distant thunder of a boom coming up from the ground, very similar to what I heard from the California aftershocks several years before,” said Ebel, who noted that modern seismic instruments have recorded earthquake swarms in Moodus. “So the ‘place of noises’ means that they were hearing earthquakes long before Europeans came to that locality.”

Then there’s the regular small earthquake activity in the northwest suburbs of Boston, where Ebel and his colleagues have been monitoring since the mid-1970s. “I was going through books one day looking for information on historical earthquakes there, and I come across this WPA guide from the 1930s, and it's talking about Route 2, which runs right through that area, and it goes right near a hill called Mount Nashoba,” he recalled.

The guide included “a little translation that said Nashoba is from an Indian word that means ‘hill that shakes.’ So now I've got all of these little earthquakes, and right in the center of it is a place with an ancient name that means hill that shakes,” Ebel said.

Researching which tribes in the region have a word for earthquake could be useful, “because that would suggest that earthquakes were a rather repetitive thing,” he noted. His early searches indicate that the Seneca, Cayuga, Natick and Mi’kmaq tribes all have a word for earthquake.

Ebel said interdisciplinary research with ethnologists with more detailed knowledge about Native American languages and narratives could be very helpful to seismologists looking to extend the northeastern North America earthquake record into pre-colonial times. “If there are legends that preserve information about probable earthquakes, for instance, it might be possible to define some sort of estimate of [shaking] intensity from the descriptions in the stories,” he suggested.

How wide are faults?

Seismological Society of America

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At the Seismological Society of America’s Annual Meeting, researchers posed a seemingly simple question: how wide are faults?

Using data compiled from single earthquakes across the world, Christie Rowe of the Nevada Seismological Laboratory at the University of Nevada, Reno and Alex Hatem of the U.S. Geological Survey sought a more comprehensive answer, one that considers both surface and deep traces of seismic rupture and creep.

By compiling observations of recent earthquakes, Rowe and Hatem conclude that from Turkey to California, it’s not just a single strand of a fault but quite often a branching network of fault strands involved in an earthquake, making the fault zone hundreds of meters wide.

“So that suggests that significant parts of the broad array of fractures that develops over many earthquakes can be activated in a single earthquake,” said Rowe, who noted that this width sometimes roughly corresponds to the width of Alquist-Priolo zones established for safe building in California.

“We want to know how this might change things like the shaking patterns that you would expect, or how much radiated energy you get from an earthquake,” Rowe explained. “Because it’s not the same if you have slip distributed on many strands as when it is all on one strand of the fault.”

At the same time, the researchers found that the width of creep zones at these earthquakes are much narrower, both near the surface and 10-25 kilometers deep in the earth. The creep zones, between 2 and 10 meters wide, “may be the most localized behavior a fault does,” Rowe said.

The study emphasizes the importance of thinking of faults in a more three-dimensional manner, said Rowe.

“As a geologist, it's always kind of been a cognitive disconnect for me when I talk to earthquake modelers who have these two-dimensional features that they model earthquakes on,” she said. “Because the sheer resistance, the strength or the friction, comes from a volume of rock that's deforming during an earthquake or in between earthquakes. So the size of that volume controls the strength of the fault in some really tangible ways.”

The researchers used a variety of data in their study, including rupture maps, creeping zone width from surveys of slowly shifting monuments along faults and satellite observations, the locations of earthquake aftershocks, low velocity damage zone widths, and the zones delineated by certain types of rock such as pseudotachylyte, ultramylonite and mylonite that are a signature of creep and deformation.

The findings also have implications for how scientists study past earthquakes to calculate earthquake recurrence intervals on faults, Rowe noted.

Slip rates and recurrence intervals can be constrained using localized measurements, but it can be difficult to disentangle the slip that occurred during an earthquake and aseismic slip that occurred after the event. The 2014 Napa, California earthquake is a good example of this phenomenon, said Rowe, noting that almost half of the slip measured after that event occurred slowly after the earthquake.

But if the Napa earthquake occurred thousands of years ago and researchers came across its traces in the rock record, “you would just see a bigger earthquake. You might lump all of that slip as a single event,” Rowe said.

Creep isn’t always accounted for in calculating recurrence intervals, “so finding out that creep zones are quite narrow means that we should be aware that we could be convolving creep with seismic slip when we look at those paleoseismic records,” she added.