News- Stanford researchers created the first global map of continental mantle earthquakes, published on February 5, 2026 in Science.
About Continental Mantle Earthquakes
Continental mantle earthquakes are rare earthquakes that occur deep within the Earth’s mantle beneath continents.
Global Distribution:
- Although only 459 continental mantle earthquakes have been identified worldwide, they are regionally clustered.
- A high concentration is found beneath the Himalayas in southern Asia and the Bering Strait between Asia and North America.
Key Characteristics of Continental Mantle Earthquakes (CMEs)
- Origin: These earthquakes occur in the mantle, below the Mohorovičić discontinuity (Moho), which separates the crust from the mantle.
- Depth: They can occur more than 80 km below the Mohorovičić discontinuity (Moho), which separates the crust from the mantle.
- Identification: Scientists identify them by comparing Sn waves, which travel through the mantle, and Lg waves, which move through the crust.
- Impact: They are too deep to cause serious shaking at the surface.
Significance
- Crust–Mantle Coupling: They show that the crust and mantle behave as a coupled system in collision zones.
- Stress and Lithosphere Dynamics: They help scientists understand the strength and ductility of the continental lithosphere and show how stress extends below the Moho.
About Mohorovičić discontinuity (Moho)
- Mohorovičić discontinuity is the boundary between Earth’s crustand the underlying mantle
- It was identified in 1909 by the Croatian seismologist Andrija Mohorovičić.
- The Moho is defined by a sharp increase in the speed of P-waves (compressional waves), typically jumping from about 6.7–7.2 km/s in the lower crust to about 7.6–8.6 km/s in the upper mantle.
