In the early morning of April 20, an earthquake, magnitude 2.9, occurred about 2 to 3 miles west of Little Thomas Mountain and the same distance south of Baldy Mountain.
The quake was at about 4:40 PDT. During the next 12 minutes, another four minor quakes were recorded. Their magnitudes ranged from .3 to 1.7. About an hour later, a .5 shake was recorded about 10 miles southeast of the original in the Santa Rosa Mountains area.
The initial report, minutes after the quake occurred, measured the tremblor at magnitude 3.3, but the current U.S. Geologoical Survey data indicates it was 2.9 magnitude.