Can heavy rainfall cause earthquakes? That’s the question three academics at the University of Durham in England are asking over at The Conversation. The Brits who posed the question don’t know the answer, but if we get hit with a rainquake soon you get the feeling there are going to be some genteel high-fives around the University of Durham campus.
From The Conversation:
“If there is an unusual surge of earthquakes in the near future – allowing time for the rain to percolate deep into faults – California may well become an interesting laboratory to study possible connections between weather and earthquakes.”
“An interesting laboratory” is such a pleasant way of saying “waves of destruction.” The Brits. They love their understatement. Still got it, old chaps.
Their theory: if wastewater disposal related to fracking causes some earthquakes, then maybe lots of rainwater seeping into the ground could, too. They go into more detail, which you’re welcome to explore, but that’s the gist.
Will our blessed rain be the death of us all?
Dr. Lucy Jones, one of L.A.’s top seismologists and the founder and director of the Dr. Lucy Jones Center for Science and Seismology, says that if the British theory held any water (my pun, not hers, and I completely stand by it) then it would have happened here already. There is no correlation between big rainfalls and notable earthquakes, she said, citing as just one example the megaflood of 1861-62.
Let’s science. If you increase or change the pressures underground, you increase the rate of earthquakes. This is what is happening in Oklahoma right now, where a large volume of wastewater from fracking is being pumped into the earth. The water, though, must reach the fracture systems and depths at which earthquakes occur. Significant earthquakes in California tend to start many kilometers deeper than our water table, which sits only a few hundred feet down. It would take a tremendous amount of water, such as a dam being built, to cause big changes in pressure in one area. This man-made effect is known as triggered or induced seismicity, which is something you’ll definitely want to keep in mind next time you build a dam. The 1975 Oroville Earthquake may have possibly been caused by the building of the Oroville Dam (below) in 1968.
“If someone went into the San Andreas Fault and started pumping fluids several kilometers down, then I think you could likely set off an earthquake,” Jones said. “But that’s not what rain does. The water table is rising, and you are slightly increasing the pore pressure (the pressure of groundwater held within rock). Evidence in California suggests that change is small enough to not be a factor.”
So there’s no way this could ever happen?
The studies cited by the Brits looked at swarms of small quakes in Europe that occurred after heavy rain. Theoretically, says Jones, rainfall could be a factor, there’s just no evidence it is in California. Jennifer Andrews, staff seismologist at Cal Tech’s Seismological Laboratory, agrees that it’s plausible, but there is no clear-cut correlation here. The Brits who posed the question admit “the effect is likely to be subtle and will require sophisticated computer modeling and statistical analysis.” Which is science for ¯\_(ツ)_/¯.
Why do we want to believe everything about earthquakes?
Because we yearn to think something causes earthquakes. Rain. Temperature. An angry vengeful smiting God. Anything. The human aversion to randomness—and our need to find patterns in everything and make sense of a world of madness—lies at the heart of wanting to believe that surface phenomenon (like mythical “earthquake weather”) causes cataclysmic events such as earthquakes. This leads to a vicinity bias.
“We experience the earthquake at the surface of the earth. So we think that what happens at the surface of the earth affects the earthquake. But it doesn’t,” Jones said.
When it comes to big ones, there is no pattern.
And as someone who reads to the end of earthquake articles, you know what that means…