Size of great earthquakes of 1837–1974 inferred from tsunami data
Article first published online: 20 SEP 2012
Copyright 1979 by the American Geophysical Union.
Journal of Geophysical Research: Solid Earth (1978–2012)
Volume 84, Issue B4, pages 1561–1568, 10 April 1979
How to Cite
1979), Size of great earthquakes of 1837–1974 inferred from tsunami data, J. Geophys. Res., 84(B4), 1561–1568, doi:10.1029/JB084iB04p01561.(
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 12 OCT 1978
- Manuscript Received: 31 JUL 1978
A new magnitude scale Mt is defined by using the logarithm of the maximum amplitude of far-field tsunami waves measured by tide gauges or their substitutes. The Mt scale is experimentally adjusted to the Mw scale introduced by Kanamori (1977), so that the Mt scale measures the seismic moment of a tsunamigenic earthquake as well as the overall size of tsunami at the source. Mt and the conventional tsunami magnitude m are distinct scales. By using many amplitude data of tsunami waves now available the values of Mt are assigned to 65 tsunamigenic earthquakes that occurred in the Pacific area during the period from 1837 to 1974. The 1960 Chilean shock has the largest Mt, 9.4. The 1946 Aleutian (Mt = 9.3), the 1837 Chilean (Mt = 9¼), and the 1964 Alaskan (Mt = 9.1) events follow. Nine great events having Mt = 9 or over occurred during this period, and their occurrence is clustered in the years around 1840, 1870, and 1960. Of all the 65 events listed, at least six unusual earthquakes having tsunamis with an amplitude disproportionately large for their surface-wave magnitude Ms are identified from the Mt-Ms relation.