Earthquakes on the USGS list
USGS lists the 1964 earthquake as M9.2 in southern Alaska, also called the Great Alaska Earthquake, the Prince William Sound Earthquake, and the Good Friday Earthquake. The table date is 1964-03-28 at 03:36 UTC, epicenter 60.91°N, 147.34°W. Other Aleutian events on the same list are below. The 1952 Kamchatka earthquake and the 1963 Kuril Islands earthquake continue the Pacific margin west of the date line, and they have their own page: Kamchatka and the Kurils.
| Earthquake | Mag | Time (UTC) | Epicenter |
|---|---|---|---|
| 1964 M9.2 Great Alaska earthquake | 9.2 | 1964-03-28 03:36 UTC | 60.91, -147.34 |
| 1965 M8.7 Rat Islands, Aleutians | 8.7 | 1965-02-04 05:01 UTC | 51.25, 178.72 |
| 1957 M8.6 Andreanof Islands, Aleutians | 8.6 | 1957-03-09 14:23 UTC | 51.5, -175.63 |
| 1946 M8.6 Unimak Island, Alaska | 8.6 | 1946-04-01 12:29 UTC | 53.49, -162.83 |
Why there are three rectangles
Longitude jumps at 180°. This site splits the Aleutians into an east-of-date-line box (longitude −180 to −165) and a west-of-date-line box (longitude 165 to 180), plus an Alaska / Gulf of Alaska box (latitude 54 to 72, longitude −170 to −130). Shishaldin falls in the Alaska box. A point on the Rat Islands side of the date line can fall in the western Aleutian box instead. The split is bookkeeping so the filter does not drop islands that cross 180°.
Tsunami context, not a warning
Several of these earthquakes are historically tied to ocean-wide tsunamis. This page does not issue a warning. Alert words — warning, advisory, watch, information statement — are defined by the National Weather Service and linked from the tsunami alerts guide. DART buoys on the live map are observations.