Real aftershocks are possible after big earthquakes — but imagined ones can happen, too.
It’s a phenomenon called “phantom earthquakes,” Dr. Daniel Glaser of King’s College London wrote in The Guardian in 2016 after large tremblors struck in Italy.
“Aside from aftershocks, anyone caught up in the disaster may also experience the uncanny sensation of ‘phantom quakes,’ where it feels as if the earth is shaking when, in fact, it is perfectly still,” Glaser wrote. “This happens for the same reason as ‘sea legs’ — the swaying feeling you sometimes get when you walk on dry land after time on a boat.”
Imagined temblors might be understandable in California after a seismically eventful week: Back-to-back quakes hit Thursday and Friday, a 6.4 on the Fourth of July and a 7.1 the next day. Both struck in the Mojave Desert near Ridgecrest, but the shaking was felt as far away as Sacramento, Los Angeles and Las Vegas.
On Twitter, woozy Californians — still trying to regain their bearings — have already reported imagined aftershocks. Los Angeles Times writer Makeda Easter wrote that she apparently “woke up in the middle of the night and asked, ‘do you feel that?’ when nothing was actually shaking.
It probably didn’t help anyone’s nerves that Friday’s earthquake (which elicited a statewide chorus of “do you feel that?”) was definitely the real thing.
Some on Twitter offered helpful tips to ferret out real quakes.
“It’s completely normal,” one Twitter user wrote. “Trick is to leave a glass of water near you to distinguish between actual aftershocks and phantom quakes.”
It’s not the first time the phenomenon has been reported in California.
After the deadly Northridge earthquake in the Los Angeles area in 1994, Sue Manning wrote for the Associated Press of fighting “phantom quakes that you swear were the real thing.”
Experts say earthquakes are well known for causing mind games in people.
“The psychological impacts of earthquakes are fairly well-documented,” said Cornell University geology professor Larry Brown, according to Gothamist. “You’re walking and suddenly the ground you expect to be stable is no longer stable. It can be very disconcerting.”
Glaser explained in The Guardian that “normally, if you make an unpredictable movement, like stepping on something that’s lower than you think, your motor cortex quickly adapts as it knows what the real world is like. But experiencing an earthquake temporarily shakes these assumptions, so a misstep can possibly trigger a mini ‘earthquake’ that is all in your mind.”
But for some, it’s much worse than imagined shaking.
Doctors in Japan reported seeing an increasing number of patients with dizziness and anxiety from “earthquake sickness” after the 2011 quake that caused a meltdown at the Fukushima Daiichi nuclear power plant, according to The New York Times.
Dr. Munetaka Ushio of the University of Tokyo Hospital said “an estimated 30% of the population in quake-stricken areas have experienced this” and added that “even I have had it recently,” according to the Wall Street Journal. The newspaper reported that the Japanese term for the illness translates to “earthquake drunk” in English.
The unbalanced feeling earthquake sickness brings is usually temporary, lasting for hours or days. Ushio said it can be treated with motion sickness pills if it’s severe, the Journal reported.