A new study from the USGS suggests that some early 20th century earthquakes in southern California might have been induced (man-made) by past practices that were used by the oil and gas industry.

In the new study, scientists evaluated the likely cause of several significant earthquakes within the Los Angeles Basin between 1900 and 1933, together with consideration of available oil industry records over this period.

They found that several damaging earthquakes, including a 1929 event near Whittier, California (estimated magnitude 5) and the 1933 Long Beach earthquake (magnitude 6.4) might have been induced by oil and/or gas production during the early decades of the Los Angeles-area oil boom. 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.

The study, “Potentially induced earthquakes during the early 20th century in the Los Angeles Basin,” was published Nov. 1 in the Bulletin of the Seismological Society of America.

More about the study can be found here.  The study does not seem to be on the USGS publications site yet, but you can pay for and download the study from BSSA here.