Scientists have produced the first global map of a rare class of earthquakes that originate deep within the Earth’s mantle rather than in the crust. The study provides a clearer picture of where these continental mantle earthquakes occur and how they may begin. The strongest clusters were found beneath the Himalayas in southern Asia and the Bering Strait region between Asia and North America.
What the Study Found
The research identified 459 confirmed continental mantle earthquakes from more than 46,000 events recorded since 1990. These quakes occur far below the crust-mantle boundary, known as the Moho, sometimes more than 80 km beneath it. Most earthquakes begin in the brittle crust at shallow depths, but these rare events originate in the warmer mantle.
Why the Discovery Matters
For decades, scientists debated whether the mantle could host earthquakes at all. Deep earthquakes are well known in subduction zones, where one tectonic plate sinks beneath another. However, confirming similar events beneath continents has been difficult. The new global map offers the first broad evidence that such earthquakes are real, widespread and regionally concentrated.
How the Earthquakes Were Identified
Researchers used a seismic method that compares Sn waves and Lg waves. Sn waves travel through the upper mantle, while Lg waves move easily through the crust. Their relative strength helps determine whether an earthquake started in the crust or the mantle. This approach allowed scientists to classify deep events more reliably than before.
Exam Value and Future Research
Although these earthquakes are too deep to cause major surface damage, they are important for understanding earthquake mechanics and Earth’s internal structure. Future work will examine whether they are triggered by stress from crustal earthquakes or by heat-related processes within the mantle.
Last Modified: April 28, 2026