In a trailblazing advancement for geophysics, researchers at Stanford University have unveiled the first comprehensive global map of continental mantle earthquakes—a class of seismic events originating not in the Earth’s crust but deep within its mantle. This groundbreaking work challenges long-standing assumptions about earthquake generation and offers fresh insights into the enigmatic dynamics at play beneath the planet’s surface. The mantle, a vast and complex layer sandwiched between the brittle Earth’s crust and its molten core, reveals itself as an unexpected theater for seismic activity, fundamentally altering how we understand the Earth’s internal processes.
Until now, earthquakes have predominantly been associated with movements and stress releases in the Earth’s crust, typically occurring at depths of about six to eighteen miles below the surface. The crust, being rigid and brittle, fractures and shifts, creating the ground shakes we commonly experience. However, Stanford’s latest research, published in the journal Science, demonstrates that seismic activity does, in fact, extend well beneath the crust into the mantle—a hot, dense, and semi-solid rock layer approximately 1,800 miles thick. These mantle earthquakes, though fewer and less understood, cluster in certain regions around the world, including notable clusters under the Himalayas and near the Bering Strait.
The boundary marking the crust-mantle transition is known as the Mohorovičić discontinuity, or simply “the Moho.” The discovery of mantle earthquakes below this boundary is significant, as it not only confirms that the mantle supports seismic ruptures despite its viscous nature but also opens avenues to study stress mechanics deep underground. Unlike the crust, the mantle’s higher temperature and plasticity had led many to question whether it could accumulate enough elastic strain to generate earthquakes. The new findings provide conclusive evidence that it can, albeit at substantially lower frequencies than crustal events—roughly one hundred times less frequent according to the Stanford team’s analysis.
This revelation was made possible through an innovative seismic wave analysis technique developed by lead author Shiqi (Axel) Wang and professor Simon Klemperer. Their method hinges on contrasting two types of seismic waves generated by earthquakes: Sn waves, which skim the uppermost mantle layer, or “the lid,” and Lg waves, which resonate strongly within the crust. Sn waves are a subtype of shear waves that travel efficiently across the rigid lid atop the mantle, while Lg waves bounce and scatter within the crust’s heterogeneous structure. By measuring the size ratio of Sn to Lg waves in recorded seismograms, the researchers were able to decisively pinpoint the earthquakes’ depths and differentiate mantle-origin quakes from the much more common crustal ones with impressive clarity.
An extensive review of seismic data from global monitoring stations yielded a conservative tally of 459 confirmed continental mantle earthquakes worldwide since 1990. This number underscores the rarity of these events but also highlights an extensive under-recognition due to limited seismic observation coverage, especially in remote regions such as the Tibetan Plateau. These deep earthquakes remain largely undetectable, or their signals mixed, in zones without dense seismic networks. The research underscores the urgent need to expand global seismological infrastructure to capture a fuller inventory of these elusive deep tremors, thereby enriching our understanding of mantle dynamics and their relationship to surface geology.
The ramifications of this discovery extend beyond pure academic interest, holding promise for enhancing earthquake risk assessments and seismic hazard models. Mantle earthquakes, though too deep to pose direct threats through surface shaking, may reflect deeper mantle processes influencing tectonic plate movements and stress propagation through the Earth’s lithosphere. Some mantle quakes appear to occur as aftershocks triggered by seismic waves from crustal earthquakes, suggesting a dynamic interplay and feedback mechanism between the Earth’s crust and upper mantle. Others may arise from convection currents and thermal stresses inherent to the mantle’s recycling of subducted crustal material, pointing to complex thermomechanical behavior previously inaccessible for study.
Understanding the origins and mechanics of mantle earthquakes offers a unique window into the elusive crust-mantle boundary, illuminating properties of the lithosphere and asthenosphere interface. Traditional seismic knowledge has largely relegated earthquake hazards to crustal fault systems; however, this new perspective necessitates reevaluating existing models of earthquake cycles to include mantle contributions. These insights may prompt the refinement of geodynamic simulations and hazard predictions, paving the way for improved preparedness in earthquake-prone regions influenced by deep mantle processes.
The Stanford team’s research not only shifts paradigms but also initiates a broader discourse on Earth’s internal systemic functions. The mantle, long regarded primarily as a driver of plate tectonics through its convective motions and magmatic influences, now emerges as a seismically active player with intricate linkages to surface tectonics. This holistic view envisions the Earth as an intricately interconnected system where seismicity spans multiple layers, each influencing the other in a complex feedback loop critical to geodynamics and crustal deformation.
Looking forward, Wang and Klemperer aim to dissect the specific triggers and characteristics of these mantle earthquakes in more detail. Their next steps involve exploring the various initiation mechanisms, which range from stress accumulations due to mantle convection and thermal anomalies to dynamic triggering by seismic waves propagating from crustal faults. Expanding sensor arrays and integrating seismic tomography with this new wave-ratio identification technique promises to deepen understanding of Earth’s deep interior structures and processes.
This research also underscores the potential for mantle earthquakes to act as natural probes, revealing properties of Earth’s interior inaccessible through direct observation. Such seismic events may be harnessed to refine seismic velocity models and elucidate the physical and chemical heterogeneity at the crust-mantle interface. By enhancing resolution beneath continents and isolating deeper seismic signals, scientists stand to gain unprecedented insight into the planet’s formative and ongoing tectonic mechanisms.
In sum, the discovery and mapping of continental mantle earthquakes stand as a pivotal milestone in Earth sciences. It accentuates the nuanced relationship between shallow and deep seismicity and redefines the boundaries for where and how earthquake-generating processes occur. This knowledge offers a richer, more integrated understanding of Earth’s seismic behavior, reinforcing the interconnectedness of its outermost layers and the profound forces shaping our ever-changing planet.
Subject of Research: Continental mantle earthquakes and their global distribution, mechanics, and implications for Earth sciences.
Article Title: Continental mantle earthquakes of the world
News Publication Date: February 5, 2026
Web References: http://dx.doi.org/10.1126/science.adz4367
References: Wang, S., Klemperer, S. (2026). Continental mantle earthquakes of the world. Science. DOI: 10.1126/science.adz4367
Image Credits: Axel Wang
Keywords: mantle earthquakes, continental earthquakes, seismic waves, crust-mantle boundary, Mohorovičić discontinuity, Moho, seismic tomography, shear waves, Sn waves, Lg waves, tectonic plate movement, earthquake mechanics
