Mw 7.9 Nicobar Islands
updated 6 august 2021

On 31 December 1881 a major earthquake occurred at the Nicobar Islands. The seismic event occurred at 01:49 UTC and had an estimated moment magnitude (Mw) 7.9.

Two planetary alignments preceded the earthquake, most critical of which was Mercury-Earth-Mars less than a day earlier. Lunar geometry already peaked 13 on the 27th when Earth lined up with the Sun and Mars. On the 30th, just after the second alignment lunar geometry became very critical reaching 19 on the index into the 31st at the time of the earthquake. The strain at the fault must have been very high for the earthquake to occur so early in time of the critical geometry, which would have indicated a very critical time from 31 December to approximately 3 January 1882 in which seismic activity could have potentially reached magnitude 7.8 or larger. By comparison, the 2015 Nepal earthquake (Mw 7.8) occurred three days after Earth aligned with Mercury and Mars.

It should be noted that the geometry at the time of the earthquake was quite complex with Venus involved in three close alignments (less then 2°) with outer planets, most critical of which was Venus-Mercury-Neptune.

Sun-Earth-Mars           1881-12-27,  5:12:45   97°18'23"
Mercury-Earth-Mars       1881-12-30,  7:30:54   96°05'25"

Venus-Mercury-Saturn     1881-12-31,  0:00:00              1°16'40"
Venus-Mercury-Neptune    1881-12-31,  0:00:00              1°37'59"
Venus-Earth-Mars         1881-12-31,  0:00:00              1°55'30"
SSGI chart
SSGI depiction of planetary (PG) and lunar (LG) geometry


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