Northern California was rocked by a 4.5 magnitude earthquake on Monday followed by several aftershocks. According to U.S. Geological Survey (USGS) geologist Keith Knudsen in the Los Angeles Times, the earthquake was centered 3 miles from the Concord fault and 9 miles underneath the surface. Shortly after the quake, ABC7 Meteorologist Drew Tuma tweeted,
This is a good time for your friendly Meteorologist to remind you that we can not forecast #earthquakes and there is no such thing as #earthquake weather. Keep calm and carry on
The San Francisco area meteorologist is apparently responding to a long-standing myth that a certain type of weather is a predictor of earthquakes. Let’s explore this myth.
I have lived in parts of the country that don’t experience very many earthquakes. On occasion, I have heard talk of “earthquake weather” but never paid much attention to it. Professor Tom Gill is a geology professor at University of Texas- El Paso. He told me in a private message, “Growing up in the San Francisco Bay Area in the 1970s, the “conventional wisdom” seemed to be that warm, still, clear, somewhat humid weather-a combination that is rare there- was earthquake weather.” Gill recalls local meteorologists even then trying to dispel the myth but based on Tuma’s need to tweet the message, it has obviously persisted.
As a meteorologist, I know that weather certainly has its own myths. For example, people say things like “tornadoes cannott hit cities” or “lightning never strikes twice.” People even think the heat of the day, so-called “heat lightning,” illuminates the sky on warm days. People can be emotional about things they believe so I am not surprised when Gill said about Tuma’s tweet, “Of course, no correlation at all but this meteorologist is getting roasted….Says a lot.”
The U.S. Geological Survey is the government agency that deals with all things geology and earthquakes. The USGS even has a website dedicated to the myth of earthquake weather. The website says:
In the 4th Century B.C., Aristotle proposed that earthquakes were caused by winds trapped in subterranean caves. Small tremors were thought to have been caused by air pushing on the cavern roofs, and large ones by the air breaking the surface. This theory lead to a belief in earthquake weather, that because a large amount of air was trapped underground, the weather would be hot and calm before an earthquake. A later theory stated that earthquakes occurred in calm, cloudy conditions, and were usually preceded by strong winds, fireballs, and meteors.
The website goes on to make the point that statistically there are an equal distribution of earthquakes in hot, cold, rainy, and other types of weather. They also acknowledge that significant changes in pressure associated with storms like typhoons or hurricanes have been known to trigger fault slips (slow earthquakes) but according to the website, “the numbers are small and are not statistically significant.” A 2004 study in the journal Risk Analysis explored beliefs and perceptions held by college students in Southern California about earthquakes. It cited a 1991 study finding that almost 26% of residents in Los Angeles County believed in “earthquake weather.”
Ironically, it is Earth Science Week, so I hope you found this discussion helpful and appropriate.