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Global Lockdown Quieted Earth’s Seismic Noise by 50%

COVID-19 lockdowns led to a remarkable 50% global reduction in human-induced seismic noise, allowing scientists unprecedented views beneath Earth's surface.

By Medha deb

Created on Sep 27, 2025

COVID-19 lockdowns led to a remarkable 50% global reduction in human-induced seismic noise, allowing scientists unprecedented views beneath Earth's surface.

Global Lockdown: Earth’s Quietest Seismic Period on Record

The widespread COVID-19 lockdowns in early 2020 triggered a dramatic global slowdown of human activity. One remarkable result, confirmed by international seismic research, was a 50% reduction in human-generated seismic noise. This seismic quiet period—unprecedented in modern history—allowed scientists to listen to the natural vibrations of the Earth with unusual clarity and provided insight into the relationship between society and our planet’s solid crust.

Understanding Seismic Noise: What Is It?

Seismic noise refers to the constant background vibrations detected by seismometers. While these instruments are generally designed to capture natural events like earthquakes and volcanic eruptions, human activities—from traffic and urban construction to industrial processes—also generate low-frequency seismic waves. This cumulative “buzz” obscures weaker signals and complicates seismic monitoring, especially in bustling cities.

Natural sources: Earthquakes, volcanoes, ocean waves.
Human sources: Foot traffic, trains, vehicles, machinery, factories.

Historically, urban seismometers were overwhelmed by anthropogenic noise, making it difficult to detect smaller or more distant earthquakes and other subsurface processes.

Lockdown Measures: A Wave of Global Silence

In response to the COVID-19 pandemic, movement restrictions, business closures, and travel bans were implemented in countries around the world. According to research published in Science, seismic sensors recorded a 50% reduction in ambient seismic noise at hundreds of stations worldwide during the tightest lockdown periods.

Urban noise fell steeply as transportation, industry, and construction halted.
This period was quieter than Christmas, traditionally the least noisy time of year.
The “wave of quiet” was sequential: China first, then Italy, across Europe, eventually reaching the Americas.

Over 300 seismic stations contributed data, revealing that even sensors buried deep underground or located in remote regions detected this lull.

Key Findings from the Global Seismic Study

Seismic noise dropped by up to 50% globally, most dramatically in urban areas.
Noise levels reached historic lows, “the quietest period in decades” per data spanning 20 years.
Reduced human-induced vibrations exposed previously hidden or weak earthquake signals.
Lockdown signatures were confirmed at stations in Africa and sensors hundreds of meters underground.
Correlations found between seismic noise decreases and mobility datasets from mapping apps.

Where Was Quietest?

Region	Seismic Noise Change	Main Factors
Urban Centers	Up to 50% drop	Reduced traffic, factory shutdowns
Remote Sensors	Noticeable drop	Travel restrictions, economic slowdown
Certain Cities (Canada)	Little/no change	Variations in lockdown severity and sensor locations

Why Is Reduced Seismic Noise Important?

Seismologists generally strive for “quiet” conditions to pick up subtle tremors and faint signals from within the Earth. During lockdown:

Smaller earthquakes and mild tremors were detected more easily—events normally masked by urban buzz.
Scientists gained new insights into seismic hazards in cities and the probabilities of larger future earthquakes.
The quiet period functioned as a “natural experiment,” impossible to engineer under normal circumstances.
Improved noise tracking methods offer privacy-friendly monitoring of urban mobility trends.

Frederick Massin, a scientist cited in the collaboration, described the period as an “unprecedented opportunity” to study the Earth’s crust—never before had there been such a cessation of global activity.

Environmental and Societal Impacts of the Anthropause

The seismic quiet period is a facet of the broader “anthropause“—the term coined for the dramatic reduction in human activity during the pandemic. The lockdowns also led to reduced atmospheric emissions, decreased traffic, and lower noise pollution, with broad environmental effects:

Diminished pollution and clearer skies in many major cities
Potentially positive impacts on wildlife due to reduced disturbance
Enhanced ability to study natural Earth processes without anthropogenic interference

This global experiment illuminates how much influence our daily routines have on planetary systems that often go unnoticed.

Citizen Science and Collaboration

The research process during lockdown showcased the power of collaboration and citizen science. The Raspberry Shake network, consisting of independent seismic sensors installed by enthusiasts in homes and schools, contributed data alongside professional observatories.

The study led by geologist Thomas Lecocq involved 76 authors from 66 institutions across 27 countries. By pooling knowledge and datasets, the group mapped the spread and impact of the seismic quiet period worldwide.

Tracking Urban Mobility: Anonymous Insights from Seismic Data

With growing concerns over privacy, seismic monitoring offers a novel, anonymous method for tracking urban mobility. Unlike cell phone tracking or online analytics, seismic noise provides data on movement intensity without recording personal details.

Correlation found between seismic noise and mobility datasets from Google and Apple.
Potential for real-time monitoring of human activity in cities.
Seismic proxies could supplement or refine traditional mobility metrics.

Uncovering Concealed Earthquake Signals

One of the headline benefits of this unique period was the ability to detect hidden earthquake signals, especially during the day. Typically, city-based seismometers are compromised by local noise, but lockdowns rendered their daytime records clearer:

Previously hidden earthquakes and microseisms observed in urban areas.
Comparison of Canadian cities: Quieting seen in Montreal, Toronto, Vancouver; none detected in others due to local differences.

This clarity may improve seismic hazard assessments and allow for more detailed monitoring of both natural and human-induced changes beneath cities.

Limitations and Unique Regional Variations

Not all regions experienced the same drop in seismic noise. Factors influencing local outcomes included:

Severity and duration of lockdown measures
Proximity of sensors to highways, industrial centers, or essential services
Regional differences in behavioral response and economic structure

In Canada, for instance, only cities where both the lockdown was strict and the sensor location was suitable showed meaningful quieting. Other cities saw little change, highlighting the complexity of tracing human impact across diverse environments.

Broader Scientific and Societal Implications

The seismic lockdown underscores the profound, often underestimated influence of human behavior on Earth’s systems. It not only demonstrates how technology can harness global events for scientific advancement, but also raises awareness about the scale of our geophysical footprint.

Offers a template for future studies of urban seismic hazards and monitoring
Prompts reflection on how urban planning and population growth intersect with natural hazards
Highlights opportunities to develop privacy-safe environmental monitoring techniques

The ability to “listen” more closely to Earth may lead to new discoveries about earthquakes, volcanic activity, and other geodynamics.

Frequently Asked Questions (FAQs)

What is seismic noise?

Seismic noise consists of steady vibrations recorded by seismometers, typically comprising both natural events (earthquakes, waves) and human activity (vehicle movement, industry).

Why did seismic noise drop during lockdown?

Global lockdowns led to decreased travel, shuttered factories, and reduced construction, eliminating much of the anthropogenic “buzz” captured by seismic stations.

Did the reduction in seismic noise mean there were fewer earthquakes?

No. The frequency of earthquakes did not decline; rather, the background noise obscuring smaller events diminished, allowing more faint tremors to be detected.

Which areas saw the strongest quieting?

Urban centers benefited most, seeing up to a 50% drop in seismic noise, but noticeable effects appeared even in remote stations and sensors buried deep underground.

Will seismic noise levels remain lower post-pandemic?

As societies reopened, human seismic noise returned to prior levels. Only a sustained shift in behavior or activity could produce longer-term changes.

Does seismic data reveal mobility trends?

Yes. Researchers correlated decreases in seismic noise directly with mobility data, suggesting seismic monitoring could supplement insight into urban movement patterns.

Is seismic noise reduction beneficial for the environment?

Lower seismic noise allowed improved earthquake monitoring and contributed to a quieter urban and natural environment. However, broader environmental effects depend on multiple factors, including emission reductions and wildlife disturbance.

Can seismic noise tracking protect privacy?

Compared to phone tracking, seismic data reflects movement intensity without recording identities, offering a privacy-friendly alternative for mobility studies.

Conclusion: Lessons from a Quieter World

The COVID-19 lockdowns provided a rare global experiment in geophysical silence. By stripping away human-induced noise, scientists were able to tune in to Earth’s natural rhythms and uncover concealed earthquake signals. These insights extend beyond academic curiosity; they offer practical templates for future urban planning, environmental monitoring, and disaster preparedness, while reminding us of humanity’s profound impact on the environment—even when all we do is move through our cities.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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