Scientists combing a “fairly dusty corner of cyberspace” found evidence suggesting a link between a number of damaging historical earthquakes in Southern California and local oil drilling, a U.S. Geological Survey geophysicist said Monday.
Specifically, state reports on California oil-drilling operations dating back to 1915 yielded data that pointed to oil production as a possible cause of the 1920 Inglewood quake, the 1929 Whittier shaker, the 1930 Santa Monica temblor and the 1933 Long Beach quake, according to the USGS.
The Long Beach temblor is considered the deadliest local quake in recorded history, killing at least 115 people and inflicting widespread damage.
The findings by USGS geophysicists Susan Hough and Morgan Page will be published Tuesday in the Bulletin of the Seismological Society of America.
Seismologists had heard rumors of a cause-and-effect relationship between early 20th century oil-drilling and earthquakes, Hough said, but “the impression was that there was no industry data to look at. But in poking around, I learned that there were state reports on California oil field operation that go back to the beginning of the oil boom.”
Hough said the reports — found “in a fairly dusty corner of cyberspace” — document “all sorts of stuff: production volume, drilling activity in each field, (and) notable activity in each field.”
Hough described the documents as a “treasure trove” of information and “the key” to establishing a possible link between oil drilling and the temblors.
Oil and gas production practices then were significantly different from Monday’s retrieval methods, according to the USGS.
In the early part of the last century, oil-drilling crews would remove oil and gases from the earth, but would not replace the fluids, said co- researcher Page. That practice changes the pressure at depth, she said.
“Basically, by removing the weight (of the fluids) without replacing it, that can unclamp the force that was keeping the fault locked,” according to Page. The result of an `unlocked fault could be an earthquake.
Hough said scientists cannot say with certainty that the earthquakes would not have occurred without the industrial activity, but the new data is suggestive that the quakes were the result of industrial activity.
According to the USGS, Los Angeles’ oil boom began in 1892 when oil was discovered near present-day Dodger Stadium. Oil fields in the Los Angeles Basin accounted for 20 percent of the world’s total production of crude oil by 1923, according to the agency.
“Despite this massive scale of production, it does not appear that induced earthquakes were common in the basin during the early 20th century,” according to the USGS.
–City News Service