As of 2015, the largest recorded earthquake in world history occurred in 1960 in Valdivia, Chile, measuring 9.5 on the Richter scale; the second largest occurred in 1964 in Alaska, measuring 9.2 on the Richter scale; and the third largest occurred in 2004 off the west coast of northern Sumatra, measuring 9.1 on the Richter scale. The fourth largest was the 2011 earthquake off the coast of Honshu, Japan, which measured 9.0 on the Richter scale.
The 1556 earthquake in Shaanxi, China, which measured 8.0 on the Richter scale, is considered the most deadly earthquake in world history. Felt in 97 countries, it devastated an area of 520 square miles, causing deep crevices and landslides, and killed an estimated 830,000 people, which was over 60 percent of the area's population. The second deadliest earthquake in history was the 2004 earthquake and subsequent tsunami in Indonesia that killed an estimated 228,000 people.
The Richter scale is a base-10 logarithmic scale, which means that for each additional point on the scale, the amount of energy released increases by a factor of 10. The scale is not a measure of destruction, as that depends on many factors, such as the depth of the earthquake and the terrain.