Mw 7.1 Aleppo, Syria
updated 2 September 2021

On 11 October 1138 a major earthquake occurred at Aleppo. The seismic event occurred in the afternoon and had an estimated moment magnitude (Mw) 7.1.

From 6 to 13 October 1138 five planetary alignments occurred, nearly all involving Venus, including alignments with Uranus and Neptune. The Moon also made critical geometry from the 6th to the 10th, including the very planets that were engaged in alignments. This resulted in high lunar peaks on 7-8 October and on 11 October reaching index 16 and 17 respectively. The earthquake occurred at the high lunar peak on the 11th, but was preceded by a foreshock on the 10th according to historical accounts. Based on the planetary and lunar geometry that preceded the earthquake from the 6th to the 10th, the magnitude may have been as high as 7.5 (± 0.1).

Mars-Venus-Uranus         1138-10-06,  7:46:14  227°55'48"
Sun-Venus-Uranus          1138-10-07, 11:25:01  227°52'14"
Venus-Sun-Mars            1138-10-09,  0:43:49   50°21'16"
Earth-Venus-Neptune       1138-10-10, 18:35:18  223°01'02"
Mercury-Sun-Jupiter       1138-10-13, 23:02:09  179°30'34"

Earth-Moon-Sun            1138-10-06, 23:42:53  211°51'53"
Earth-Moon-Venus          1138-10-07, 12:59:16  218°58'00"
Earth-Moon-Neptune        1138-10-07, 20:18:10  222°54'31"
Earth-Moon-Uranus         1138-10-08,  4:06:41  227°08'19"
Earth-Moon-Mercury        1138-10-08, 20:02:55  235°50'35"
Moon-Earth-Mars           1138-10-10, 12:12:54   78°12'20"

Earth:   Moon-Neptune     1138-10-11,  5:31:55   45°00'00"
Earth:   Moon-Venus       1138-10-11,  6:36:01   45°00'00"
Earth:   Moon-Saturn      1138-10-11,  8:14:55   45°00'00"
Earth:   Moon-Uranus      1138-10-11, 13:03:53   45°00'00"
					
SSGI chart
SSGI depiction of planetary (PG) and lunar (LG) geometry

SSGI chart
earthquake epicentre map