Stanford researchers have created the first global map of rare continental mantle earthquakes
Study finds deep earthquakes clustered beneath regions such as the Himalayas and the Bering Strait
New method distinguishes mantle quakes from crustal ones using seismic waveforms
Findings could improve understanding of how earthquakes originate deep within the Earth
Stanford researchers have produced the first global map of a rare type of earthquake that occurs not in the Earth’s crust but deep within the planet’s mantle, offering fresh insights into how earthquakes originate and how the Earth works beneath its surface.
According to a press release from Stanford University, the study, published on February 5, 2026 in the journal Science, shows that so-called continental mantle earthquakes occur worldwide but are regionally clustered, particularly beneath the Himalayas in southern Asia and the Bering Strait between Asia and North America. The findings mark the first time scientists have had a clear global picture of where and how often these deep earthquakes occur.
The research was led by Shiqi (Axel) Wang, a former PhD student at the Stanford Doerr School of Sustainability, working with geophysics professor Simon Klemperer. “Until this study, we haven’t had a clear global perspective on how many continental mantle earthquakes are really happening and where,” Wang said in the press release. “With this new dataset, we can start to probe at the various ways these rare mantle earthquakes initiate.”
Unlike most earthquakes, which originate in the Earth’s cold, brittle crust at depths of around 10 to 29 kilometres, mantle earthquakes occur far deeper, sometimes more than 80 km below the boundary between the crust and the mantle. This boundary, known as the Mohorovičić discontinuity or “Moho”, separates the crust from the warm, semi-solid mantle that makes up most of the planet’s interior.
For decades, scientists debated whether the mantle could host earthquakes at all. While deep earthquakes are well known in subduction zones, where oceanic plates sink beneath continental plates, evidence of similarly deep quakes beneath continents away from subduction zones was harder to confirm. Over the past decade, most researchers have accepted that such earthquakes do occur, but identifying them reliably has remained difficult.
To overcome this, Wang and Klemperer developed a method that compares two types of seismic waves: Sn waves, which travel through the top of the mantle, and Lg waves, which move easily through the crust. The relative strength of these waves allows scientists to determine whether an earthquake originated in the crust or the mantle. “Our approach is a complete game-changer,” Wang said, “because now you can actually identify a mantle earthquake purely based on the waveforms of earthquakes.”
Using this technique, the team analysed data from more than 46,000 earthquakes recorded since 1990, narrowing them down to 459 confirmed continental mantle earthquakes. The researchers say this figure is conservative and that many more such quakes may be detected as seismic monitoring expands, particularly in remote regions such as the Tibetan Plateau.
Although mantle earthquakes are too deep to cause serious shaking at the surface, the press release notes that studying them could improve understanding of earthquake mechanics more broadly. “Mantle earthquakes offer a novel way to explore earthquake origins and the internal structure of Earth beyond ordinary crustal earthquakes,” Klemperer said.
The Stanford team now plans to investigate whether these rare events are triggered by stress transferred from crustal earthquakes or by heat-driven processes within the mantle itself. Ultimately, they hope the new global map will help scientists better understand how the Earth’s crust and mantle function together as a single, interconnected system.