Mw 9.3 Aleutian Islands, Alaska
updated 5 May 2022

On 11 June 1585 a great earthquake occurred at the (eastern) Aleutian Islands, Alaska. Based on tsunami records, both written (Japan) and from sand deposits (Hawaii) it may have had an estimated moment magnitude (Mw) of up to 9.3. Going by the Japanese tsunami record and the planetary geometry at the time, the earthquake probably occurred between 10 June 22:00 and 11 June 8:00 UTC.

On the 6th Earth was between Mars and Uranus and the Moon made critical geometry with both outer planets late on the 7th, early 8th (lunar peak at index 16). In addition, Venus aligned with the Sun and Jupiter late on the 10th while the Moon aligned with Jupiter at the same time, which caused a high lunar peak (index 15) at the time of the alignment. Going by the planetary geometry alone, the earthquake could have occurred one or two days later, but the Japanese tsunami record pointing at 11 June local time is key in the timing of the seismic event.

Mars-Earth-Uranus         1585-06-06, 15:52:35  340°55'57"
Venus-Sun-Jupiter         1585-06-10, 23:35:22   56°58'30"
Mercury-Sun-Saturn        1585-06-11, 13:49:57   17°17'41"
Sun-Mercury-Mars          1585-06-12, 22:49:30  202°01'12"

Moon-Earth-Saturn         1585-06-07, 16:53:19   22°32'13"
Moon-Earth-Jupiter        1585-06-10, 16:35:20   61°36'11"
Moon-Earth-Sun            1585-06-12, 17:17:48   87°08'36"
SSGI chart
SSGI COMMON graph of critical planetary (PG) and lunar (LG) geometry

SSGI chart
SSGI SUM graph of critical planetary (PG) geometry