A magnitude 9.0 earthquake, classified as a "great" event, releases enormous energy equivalent to about 100 million grains of sand (roughly 572 pounds) in a common analogy for seismic power. Each full magnitude increase multiplies energy release by about 31.6 times, making a 9.0 roughly 1,000 times more powerful than a 7.0 and over 30 times stronger than an 8.0.
Effects
It causes serious damage and loss of life across areas hundreds of kilometers wide, often lasting 5 minutes or longer, collapsing most masonry buildings, destroying bridges, and hurling objects through the air. Historical examples include the 2011 Japan quake and the record 9.5 in Chile in 1960, both megathrust events along subduction zones.
Rarity
Such quakes occur rarely, with only about 1-2 per year globally at magnitude 8.0+, and none exceed 9.5 on record.
