Scientists survey for changes in "tilt" of the ground
in the southern part of Long Valley caldera using the single-setup
leveling technique (also known as the dry-tilt method). Mammoth
Mountain, located on the southwestern rim of the caldera, rises about
1,000 meters above this part of the caldera floor in the distance.
This intermittent, labor-intensive method of measuring ground tilt is
no longer used at Long Valley. Today, an expanding network of tiltmeters,
dilatometers, and GPS receivers are being used to continuously record
ground deformation in the caldera.
Current
deformation data from these instruments can be viewed on the
USGS Long Valley caldera website.
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