Mw 9.5 Bio-Bio, Chile
updated 28 August 2021

On 22 May 1960 a great earthquake occurred in Bio-Bio, Chile at a depth of 25 km. The seismic event occurred at 19:11:20 UTC and had an estimated moment magnitude (Mw) 9.5. It is the largest earthquake recorded since recording began in 1901.

Major seismic activity preceded the great earthquake, often referred to as the "Great Valdivia earthquake". Critical planetary and lunar geometry resulted in another great earthquake in the same region a day earlier, that was followed by several strong to major earthquakes. A major earthquake occurred again two weeks later in Aisen, Chile.

Mercury-Sun-Earth         1960-05-17, 15:04:11  237°15'07"
Venus-Sun-Neptune         1960-05-20, 12:29:24  218°27'30"
Mars-Mercury-Uranus       1960-05-21, 15:05:56  141°42'49"
Mercury-Sun-Jupiter       1960-05-22,  8:32:19  266°57'27"

Earth:   Moon-Jupiter     1960-05-17,  4:30:34   45°00'00"
Earth:   Moon-Mars        1960-05-17,  8:09:02   45°00'00"

Earth-Moon-Mars           1960-05-20, 22:49:12    7°53'36"
					
SSGI chart
SSGI depiction of planetary (PG) and lunar (LG) geometry