The Los Angeles Basin has the reputation of being a dangerous place when it comes to earthquakes, but a new study suggests that reputation might be overstated.

Two scientists with the US Geological Survey looked at the region's biggest quakes between 1900 and 1935 and found that we humans might be more to blame than natural fault lines, reports the Los Angeles Times.

The reason? Oil production. In the Bulletin of the Seismological Society of America, researchers Susan Hough and Morgan Page show that big quakes of that era often occurred near oil wells not long after production started, reports Scientific American.

That includes the magnitude 6.4 Long Beach quake of 1933 that killed 120 people, though the study merely shows a link, not proof the drilling was to blame.

“It was kind of more of a Wild West industry back a hundred years ago, and the technology wasn’t as sophisticated,” says Hough. “People would just pump oil, and in some cases the ground would subside—fairly dramatically.” The scientists say their study shouldn't be used in the modern debate over fracking, which involves an entirely different process.

They also note that today's oil-drilling practices are safer, including the use of water to replace oil, and thus their results "do not necessarily imply a high likelihood of induced earthquakes at the present time," per NPR.

The LAT sees good and bad news: The study suggests the region isn't as prone to natural quakes as believed, but it also suggests that humans play a greater role in inducing them than thought.

(Are the Sierras overdue for a big one?)

This article originally appeared on Newser: Old California Earthquakes May Have Been Man-Made

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