We’re only a month into 2018, but natural disasters like earthquakes, tsunamis, and volcanoes have made a lot of headlines thus far. The past week alone has seen several seismic events: The Philippines’ Mount Mayon erupted last Monday, forcing the evacuation of more than 75,000 people. The day after, a 7.9-magnitude earthquake struck off the coast of Alaska, lighting up Pacific tsunami warning systems as far away as San Diego. That same day, a volcano erupted near a Japanese ski hill, killing one person and injuring many others. Two days later, a quake rattled Los Angeles, and another two struck in close proximity off the coast of Northern California.
These events, taken together, signal that Earth’s Ring of Fire is waking from its slumber, and that more, bigger catastrophes are on the way—that is, if the proliferation of alarmist headlines that have followed is to be believed.
“You get every Tom, Dick, and Harry writing down all sorts of crazy things about: ‘The big earthquake is coming,’” Stephen Malone, a seismologist with the Pacific Northwest Seismic Network and professor emeritus with the University of Washington told The Daily Beast. “Well, yes, it is coming, but not necessarily any sooner because of the recent earthquakes.”
Every great lie is built on a foundation of truth.c We also know that the Cascadia Subduction Zone will one day unzip, sending a megathrust earthquake and tsunami at breakneck speeds toward the Pacific Northwest. It’s true, too, that earthquakes in one place can trigger more far away, over thousands of miles. It may even be true that the worldwide coincidence of major quakes is more than coincidence, that there are global patterns that bring disaster into sync.
But the bigger truth is that scientists still don’t know enough about the fundamental physics of earthquakes to predict with precision and certainty when a seismic event will happen. Earthquakes aren’t entirely random, but for the purpose of day-to-day threat assessment, they may as well be.
And, it should be said, that the seismic events of the last few weeks are hardly anomalous. “If you go on the worldwide catalog of earthquakes at the USGS on the web, you will see that there’s earthquakes going on all over the world, all the time,” Malone said. “Any sort of random sequence of events will have times when things are clustered and times when they’re not.”
Earthquakes can trigger more earthquakes, but the known ways this happens are limited. Quakes occur in the places where tectonic plates move and grind against one another; when that pressure builds to a breaking point, the fault shifts and the ground shakes. But some of that stress can be moved to other parts of the fault, where it may push it past the breaking point again, setting off another earthquake. Normally, the subsequent quakes are smaller, and are called aftershocks. In the rarer cases where later tremors are stronger, the first becomes a foreshock.
Over longer distances, there’s evidence a big quake can set off smaller ones, although the mechanism isn’t well understood. It isn’t by directly impacting the stresses at the fault, so it must be an effect of the shockwaves coming through. Paul Bodin, a seismologist at the Pacific Northwest Seismic Network and the University of Washington, said he expects it works a bit like tapping a window that’s stuck with a hammer to jostle it open.
But even a very large quake on the other side of the planet is unlikely to set off the Big One close to home. “There’s little to no evidence for triggering of large earthquakes across vast tracts of land,” Bodin said.