Earth’s tectonic plates are in constant motion. Their movement is driven by heat within the Earth. This circular motion is called convection. Convection within the mantle drives the motion of the overlying plates.

The energy source for plate tectonics is Earth’s internal heat while the forces moving the plates are the “ridge push” and “slab pull” gravity forces. It was once thought that mantle convection could drive plate motions.

There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.

Convection, or the flow of mantle material transporting heat, drives plate tectonics. The deep mantle-derived buoyancy, together with plate cooling at the surface, creates negative buoyancy that together explain the observations along the East Pacific Rise and surrounding Pacific subduction zones.

Although natural earthquakes usually occur along fault lines, human-caused earthquakes can happen in areas unassociated with previous seismic activity. Scientists believe most human-induced earthquakes are the result of mining.

A nuclear explosion can cause an earthquake and even an aftershock sequence. However, earthquakes induced by explosions have been much smaller than the explosion, and the aftershock sequence produces fewer and smaller aftershocks than a similar size earthquake.

Small Mammals The red ruffed lemurs sounded an alarm call about 15 minutes before the quake and then again just after it occurred. The howler monkeys sounded an alarm call just after the earthquake. The black-and-rufous giant elephant shrew hid in his habitat and refused to come out for afternoon feeding.

Radon is useful as a potential earthquake predictor because it is radioactive and thus easily detected, and its short half-life (3.8 days) makes radon levels sensitive to short-term fluctuations. A 2009 review found 125 reports of changes in radon emissions prior to 86 earthquakes since 1966.

Research seismologists study the internal structure of the Earth and try to determine factors that contribute to or foretell an earthquake. They publish their findings in scientific journals or present them at academic forums—or do both.