“Earth as a planet is gradually cooling. That transfer of heat from the deep earth to the surface is what gives rise to volcanoes and earthquakes"

Earthquakes, hurricanes and tornadoes - Oh my: Coming to terms with natural disasters - CUP Newswire

Earthquakes, generally speaking, are the side effects of the core of the planet cooling down.

“Earth as a planet is gradually cooling. That transfer of heat from the deep earth to the surface is what gives rise to volcanoes and earthquakes, and eventually, deep into the future, gradually the earth will cool to the point where all those [processes] cease,” says [Michael Bostock, a professor and earthquake seismologist at UBC]. “So Earth will eventually become a dead planet, but for the next few hundreds of millions, if not billions, of years there will continue to be earthquakes.”