Largest Earthquakes in the United States

This webpage is updated in January of each year to incorporate any relevant data from the previous year.

50 States

Maps of the Largest Earthquakes in the United States
 Location Date Time UTC Magnitude Damage
Photos
Isoseismal
Map
1. 1964 Great Alaska Earthquake 1964 03 28 03:36:14.0 UTC9.2 Damage photos available Isoseismal map available
2. Cascadia subduction zone 1700 01 26  UTC ˜9    
3. Rat Islands, Alaska 1965 02 04 05:01 UTC 8.7    
4. Andreanof Islands, Alaska 1957 03 09 14:22:31.9 UTC 8.6    
5. East of Shumagin Islands, Alaska 1938 11 10 20:18:41.2 UTC 8.2    
6. Unimak Islands, Alaska 1946 04 01 12:28 UTC 8.1    
7. Yakutat Bay, Alaska 1899 09 10 21:41 UTC 8.0   Isoseismal map available
8. Denali Fault, Alaska 2002 11 03 22:12 UTC 7.9    
9. Gulf of Alaska, Alaska 1987 11 30 19:23 UTC 7.9    
10. Andreanof Islands, Alaska 1986 05 07 22:47 UTC 7.9    
11. Near Cape Yakataga, Alaska 1899 09 04 00:22 UTC 7.9    
12. Ka'u District, Island of Hawaii 1868 04 03 02:25 UTC 7.9    
13. Fort Tejon, California 1857 01 09 16:24 UTC 7.9   Isoseismal map available
14. Rat Islands, Alaska 2003 11 17 06:43 UTC 7.8    
15. Andreanof Islands, Alaska 1996 06 10 04:03 UTC 7.8    
16. San Francisco, California 1906 04 18 13:12 UTC 7.8    
17. Imperial Valley, California 1892 02 24 07:20 UTC 7.8    
18. New Madrid, Missouri 1811 12 16 08:15 UTC 7.7   Isoseismal map available
19. New Madrid, Missouri 1812 02 07 09:45 UTC 7.7    
20. New Madrid, Missouri 1812 01 23 15:00 UTC 7.5    

48 States

Maps of the Largest Earthquakes in the United States
 LocationDate Time UTCMagnitude Damage
Photos
Isoseismal
Map
1. Cascadia subduction zone 1700 01 26  UTC ˜9    
2. Fort Tejon, California 1857 01 09 16:24 UTC 7.9   Isoseismal map available
3. San Francisco, California 1906 04 18 13:12 UTC 7.8 Damage photos available Isoseismal map available
4. Imperial Valley, California 1892 02 24 07:20 UTC 7.8    
5. New Madrid, Missouri 1811 12 16 08:15 UTC 7.7   Isoseismal map available
6. New Madrid, Missouri 1812 02 07 09:45 UTC 7.7    
7. New Madrid, Missouri 1812 01 23 15:00 UTC 7.5    
8. Owens Valley, California 1872 03 26 10:30 UTC 7.4   Isoseismal map available
9. Landers, California 1992 06 28 11:57 UTC 7.3    
10. Hebgen Lake, Montana 1959 08 18 06:37 UTC 7.3 Damage photos available Isoseismal map available
11. Kern County, California 1952 07 21 11:52 UTC 7.3   Isoseismal map available
12. West of Eureka, California 1922 01 31 13:17 UTC 7.3    
13. Charleston, South Carolina 1886 09 01 02:51 UTC 7.3    
14. California - Oregon Coast 1873 11 23 05:00 UTC 7.3    
15. N Cascades, Washington 1872 12 15 05:40 UTC 7.3    

Note: Widely differing magnitudes have been computed for some of these earthquakes; the values differ according to the methods and data used. For example, some sources list the magnitude of the 8.7 Rat Islands earthquake as low as 7.7. Similar variations exist for most events on this list, although generally not so large as for the example given.

In general, the magnitudes given in the list above have been determined from the seismic moment, when available. For very large earthquakes, the moment magnitude is considered to be a more accurate determination than the traditional amplitude magnitude computation procedures. Note that all of these values can be called "magnitudes on the Richter scale," regardless of the method used to compute them.

Revisions
The Andreanof Islands, Alaska earthquake of 1957 03 09, previously listed with a magnitude of 9.1, has had its magnitude reviewed, and it was updated to 8.6.

Revised March 04, 2010