Thanks to the extensive records of the United States Geological Service (USGS), it is quite easy to learn about the biggest earthquake ever recorded, which occurred near Santiago, Chile, in 1960. Known as the Great Chilean Earthquake, the quake measured an impressive 9.5 on the Richter scale. The death toll of the Great Chilean Earthquake is not known, but estimates go as high as 6,000, and the earthquake may have caused as much as 800 billion US Dollars in damage.

It is highly probable that some ancient earthquakes were of a higher magnitude, but because the Richter scale was not developed until the 1930s, it is difficult to quantitatively compare them. For example, the Lisbon Earthquake of 1755 was by all accounts quite severe, and it generated a massive tsunami which only magnified the death toll, and the Shaanxi Earthquake which occurred in China in the 1500s was the deadliest known to history, killing almost one million people. The Shaanxi Earthquake may also have been the biggest earthquake known to man, but there is simply no way to tell.

In terms of earthquakes which were studied, measured, and recorded on the Richter Scale, however, the Great Chilean Earthquake was far and away the biggest earthquake ever. Keeping in mind that the Richter Scale runs along an exponential progression, the next largest earthquake was a 1964 tremblor in Prince William Sound, Alaska, which measured 9.2. The 2004 Indian Ocean Earthquake is the next biggest earthquake ever recorded, clocking in at 9.1 on the Richter Scale and generating a formidable tsunami which damaged much of the coastline of Southeast Asia.

The risk of large earthquakes has become greatly increased since the Great Chilean Earthquake, thanks to increasing human population and the growth of megacities, and it wouldn't take the biggest earthquake ever recorded to create the most lethal earthquake ever recorded. Many huge cities happen to be located in seismically active areas, and an earthquake of major size in any of these regions could be devastating. Because earthquakes cannot be predicted or controlled, seismologists have warned communities, suggesting that they need to develop clear action plans for major quakes, as much of the damage and loss of life associated with earthquakes is caused by poor infrastructure.

Because an earthquake above the magnitude of 10.0 has never been recorded, researchers are not exactly sure what such an earthquake might feel like, although one may have occurred at some point in human history. The energy involved in a 10.0 would be equivalent to a teraton of TNT; a 12.0 would equal the daily amount of energy the Earth receives from the Sun, undoubtedly causing horrific loss of life and damage.