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Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (Mw) that can exceed 9.0.[1][2] Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes.[3]
The thrust faults responsible for megathrust earthquakes often lie at the bottom of oceanic trenches; in such cases, the earthquakes can abruptly displace the sea floor over a large area. As a result, megathrust earthquakes often generate tsunamis that are considerably more destructive than the earthquakes themselves. Teletsunamis can cross ocean basins to devastate areas far from the original earthquake.
- ^ Meier, M.-A.; Ampuero, J. P.; Heaton, T. H. (22 September 2017). "The hidden simplicity of subduction megathrust earthquakes". Science. 357 (6357): 1277–1281. Bibcode:2017Sci...357.1277M. doi:10.1126/science.aan5643. PMID 28935803. S2CID 206660652.
- ^ "Questions and Answers on Megathrust Earthquakes". Natural Resources Canada. 19 October 2018. Retrieved 23 September 2020.
- ^ Johnston, Arch C.; Halchuk, Stephen (June–July 1993), "The seismicity data base for the Global Seismic Hazard Assessment Program", Annali di Geofisica, 36 (3–4): 133–151, pp. 140, 142 et seq.