Continental Mantle Earthquakes: Causes and Geological Significance

Category: Physical Geography / Earthquakes

UPSC Notes

Continental mantle earthquakes are seismic events originating within the mantle beneath continental regions rather than exclusively within the Earth's crust. They challenge the traditional assumption that most continental earthquakes occur in the shallow, brittle crust.

The lithosphere consists of the crust and the rigid uppermost mantle. The boundary between the crust and mantle is known as the Mohorovičić discontinuity, or Moho.

Possible mechanisms

  • Concentrated stresses associated with continental collision.

  • Reactivation of deep-seated faults and structural weaknesses.

  • Variations in temperature, pressure, water content and rock strength.

  • Coupling between crustal deformation and mantle processes.

Key Pointers for UPSC

  • Earthquakes can occur in the crust and, under suitable conditions, in the mantle.

  • Earthquake depth provides clues about tectonic structures and lithospheric dynamics.

  • Deep earthquakes in subducting oceanic slabs are well documented; continental mantle earthquakes are a distinct and important research topic.

  • Mantle earthquakes are not evidence that the entire mantle behaves like brittle crust.

  • Seismic waves help scientists determine earthquake location, depth and the Earth's internal structure.