Plate Tectonics Has a Surprise Silver Lining

By Robin George Andrews.

Without this restless geologic process, which triggers destructive earthquakes, Earth would not be habitable.

I IMAGINE THAT EXCEEDINGLY FEW people like to be unexpectedly jostled about by an earthquake. Whether you’re in an area known to be frequented by modestly powerful temblors, or whether you’re chilling out somewhere that isn’t especially prone to them—say, New York or New Jersey—it can be a disquieting experience. Earthquakes are also famously destructive: If they strike in just the right place, with sufficient shaking, they can ruin villages, towns, even cities and, should they trigger a tsunami, entire coastlines.

But Earth without earthquakes wouldn’t be, well, Earth. It wouldn’t be bursting with biology, nor would it have a clement atmosphere that supports a wealth of lifeforms. A lack of earthquakes would signify that the planet is geologically dead, or at the very least comatose—and things don’t end well for worlds whose innards are anything less than tumultuous.

Before I explain why, it’s important to note that quakes happen on other worlds. Wisely, scientists don’t call them earthquakes. Moonquakes happen, as do marsquakes; the former can cause the lunar surface to quiver for several minutes, while the latter are less dramatic, low-pitch grumbles. As these are the only two worlds (other than Earth) that have been studied with seismometers, we can only speculate about temblors on other planets and moons. But there are almost certainly quakes on hypervolcanic Venus too, as well as on the rime-covered surfaces of a multitude of icy moons, from Jupiter’s frigid Europa to Saturn’s frosted Enceladus.

All these celestial objects are geologically active to varying degrees—and, broadly speaking, that activity is driven by heat trapped within a world. That heat comes about in various ways.