California's sleeping giant, the San Andreas Fault, marks the slippery yet sticky boundary between two of Earth's tectonic plates. It is responsible for the biggest earthquakes in California, up to at least magnitude 8.1.

A moonquake is the lunar equivalent of an earthquake. They were first discovered by the Apollo astronauts. The largest moonquakes are much weaker than the largest earthquakes, though their shaking can last for up to an hour, due to fewer attenuating factors to dampen seismic vibrations.

Ninety percent of Earth's earthquakes, including the planet's most violent and dramatic seismic events, occur along the Ring of Fire, which includes the Pacific coasts of South America, North America and Kamchatka, and some islands in the western Pacific Ocean. The Ring of Fire is a direct result of plate tectonics: specifically the movement, collision and destruction of lithospheric plates under and around the Pacific Ocean. The collisions have created a nearly continuous series of subduction zones, where volcanoes are created and earthquakes occur.

The world's deadliest recorded earthquake occurred in 1556 in central China. It struck a region where most people lived in caves carved from soft rock. These dwellings collapsed during the earthquake, killing an estimated 830,000 people. Contemporary reports described leveled mountains, floods, fires that burned for days, and a drastically altered landscape. According to estimates, some counties lost about 60 percent of their population.

There are three main types of fault, all of which may cause an interplate earthquake: normal, reverse (thrust), and strike-slip.

The slip rate along the fault ranges from 20 to 35 mm (0.79 to 1.38 in)/yr. At this rate, Los Angeles and San Francisco will be neighbors in about 24 million years.

It is thought that more damage was done by the resulting fire after the 1906 San Francisco earthquake than by the earthquake itself.