Free Earth Vibration Studies
Mercer University Physics Department Student Special Project Possibility
|The following link provides: A good deal of recent work that has been done in this area.|
For several years Dr Peters has been looking at free earth vibrations that result when the earth experiences a rapid internal relaxation--rapid compared to its eigenmodes, the longest period of which is 54 minutes. It is postulated that internal relaxations of this type occur as the earth rotates under the influence of the12-hour periodic tidal force. Thus the measurements are correlated to the lunar synodic period.
The instrument with which this work is performed is a tiltmeter, whose displacement depends on the total mass configuration of the earth. As such, it responds to changes in direction of the earth's field g (local acceleration of gravity) as opposed to changes in the magnitude of g. Whereas the magnitude changes are very small and difficult to detect (and a source of recent activity by the geoscience community), this novel instrument readily detects many of the free earth eigenmodes on a monthly basis. Some of the records that have been studied by autocorrelation to remove high frequency noises suggest the possibility of earthquake prediction.
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