Mary Jane,
By the way, there is a really difficult ski run in the Colorado Mountains by the
same name, if you are a skier, try it sometime.
The "tremor" you are seeing is typical noise. This begins as traffic and
other useage of the area and surrounding areas is highest beginning
in mid-morning and usually lasting to evening. This has nothing to do
which recorded earthquakes or harmonic tremor, but is a daily phenomena
from cultural activity.
When there is an earthquake in the Mammoth Lakes region, try to
look at the seismograms. Even small earthquakes are quite clearly different
from noise. They have a sharp beginning and trail off to a line, and cannot
be mistaken once you have seen one or two.