LOS ANGELES — New research suggests oil drilling decades ago may have triggered earthquakes in the Los Angeles area, including the 1933 quake that killed more than 100 people.

If confirmed, it would be the first time oil operations have been linked to a deadly quake in the United States.

Scientists from the US Geological Survey combed through historical records and identified several quakes in the 1920s and 1930s that were potentially caused by industry activities, including the 1933 magnitude 6.4 jolt that struck the port city of Long Beach.

Until now, ‘‘we pretty much assumed that earthquakes in the LA area are natural and that induced earthquakes are either not happening or not significant,’’ said USGS seismologist Sue Hough, who led the study.

Drilling techniques have changed through the decades so the findings don’t necessarily point to a current risk. A separate study last year by a team at USGS and California Institute of Technology found no significant evidence of human-caused quakes in the LA region after 1935.

Southern California’s oil boom was sparked in 1892 when oil was discovered near what would become the site of Dodger Stadium, north of downtown LA. After tapping the wells dry, drillers headed to points south.

In the study, Hough and colleague Morgan Page found 13 cases of shaking that may have been caused by oil production ramping up.

Associated Press