MENLO PARK (KPIX 5) — It’s an old theory that scientists have been pondering for decades: Can heavy rainfall trigger earthquakes?
The answer is a resounding … maybe.
Professor Gillian Foulger, a well-respected geophysicist at Deerham University in England has recently published an article titled: California’s Rain May Shed New Light On Questions About What Causes Earthquakes.
Her team points to several events throughout history where heavy rains were followed by earthquake swarms. It happened in Mt. Hochstaufen in Germany in 2002 and in the Riemenstalden area of Switzerland in 2005.
Foulger says if rain percolates down far enough into a fault: The fault may become “unclamped”. The two sides are then free to slip past one another, causing an earthquake.
Art Mcgarr, a geophysicist at the USGS office in Menlo Park, knows Foulger and respects her work. But he’s been researching the field of induced earthquakes for years and says when you compare rain and earthquake data going back a hundred years, there’s nothing there.
McGarr said, “Nobody has yet uncovered any kind of relationship between the earthquake activity and rainfall cycles.”
Foulger also points to earthquakes believed to be triggered by man-made reservoirs.
After the 32-mile long Koyna Reservoir was built in India in the 1960s, scientists believe the weight of all that water triggered a 6.3 earthquake that killed more than 180 people.
In fact, Oroville Dam had a 5.8 earthquake seven years after it was built, and scientists are still debating about what caused it.
It begs the question, with Oroville Dam and Anderson Dam at full capacity, should we be worried about the weight of all that water?
McGarr said, “So it’s a very poorly understood topic. We know that some dams are effective at triggering earthquakes, but certainly not very many of them…Let’s just say of all the things that we should be worried about in our day to day life, I do not think rainfall-triggered earthquakes is one of those.”