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Oil Drilling Likely Triggered Some of SoCal's Early 20th-Century Earthquakes

Scientists have linked oil and gas exploration to several L.A.-area quakes, including one that led to the passage of earthquake-resistant building codes.

A school lies damaged after the 1933 Long Beach earthquake. (W.L. Huber/USGS)

The Los Angeles Basin was (and still is) an incredibly productive oil source. By 1930, it’s thought about 25 percent of the world’s crude originated from the region.

And all that harvesting of oil and natural gas might’ve literally had consequences at the deepest level: Several earthquakes that struck the region in the ‘20s and ‘30s look to have been caused by rampant drilling, according to a new study from U.S. Geological Survey scientists.

The researchers link oil and gas production to earthquakes in 1933 in Long Beach, 1920 in Inglewood, and 1923 and 1929 near Whittier, just east of L.A. The Long Beach quake, though moderate in power, killed 115 people and destroyed structures (many built on landfill) over a vast area. Several schools and three square blocks of Compton basically crumbled; California responded to the disaster by enacting some of its first regulations for earthquake-resistant construction.

The problem is that drillers were using techniques that left the land sunken and unstable, writes the USGS:

During the early decades of the oil boom, withdrawal of oil was not balanced by injection of fluids, in some cases leading to dramatic ground subsidence, and potentially perturbing the sub-surface stress field on nearby faults.…

“It has been widely assumed that induced earthquakes do not contribute significantly to hazard in regions west of the Rocky Mountains, but our research suggests that damaging induced earthquakes might have occurred in the past,” said Susan Hough, USGS seismologist. “Our study further suggests that the rate of natural tectonic earthquakes in the Los Angeles basin for this time period might have been lower than previously estimated.”

The good news is SoCal's oil and gas industry no longer uses these antiquated processes. The bad is there’s ever-growing evidence humans are inducing earthquakes in places like Arkansas and Oklahoma, where the USGS says quake rates have “increased sharply in recent years.”

Another school that was totaled in the 1933 Long Beach quake. (USGS)

About the Author

  • John Metcalfe
    John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.