Moment magnitude scale (Kanamori; Hanks and Kanamori)
Magnitud de momento (Kanamori; Hanks y Kanamori)
- Date
- 1977-1979 · confidence high
- Place
- Pasadena, California, United States
- Credited to
- Hiroo Kanamori and Thomas Hanks
- Field
- Cosmos & Earth
What was discovered
Kanamori proposed measuring an earthquake's size by its seismic moment (rigidity times rupture area times slip), which does not saturate for the largest earthquakes as earlier scales do, and Hanks and Kanamori normalised it in 1979 as the Mw magnitude. It is the standard measure of large earthquakes.
The seismic moment concept was introduced by Keiiti Aki in 1966; Kanamori proposed using it as a scale in 1977 and Hanks and Kanamori normalised it in 1979.
What it led to
- the USGS standard magnitude since the 1990s
- physical comparison of earthquakes of all sizes