An earthquake of the intensity R-F IV occurred in the vicinity of San Jose, California, at forty-seven minutes, twenty-eight seconds after eight o'clock on the morning of September 9, 1920 (Pacific standard time).
The maximum intensity, a vertical component of movement, and a roaring sound were found in a limited area that is traversed by the Penetencia fault, which is located about five miles east-northeast of San Jose.
In the vicinity of the San Andreas, Haywards, and most of the Calaveras fault the intensity was very low.
Physiographic evidence indicates that the fault has been active in relatively recent geological times.
The shock establishes the activity of a fault that is situated in close proximity to the closely settled alluvial area around San Jose.