Precise continuous monitoring of seismic velocity variations and their possible connection to solid Earth tides
Article first published online: 20 SEP 2012
Copyright 1977 by the American Geophysical Union.
Journal of Geophysical Research
Solid Earth and Planets
Volume 82, Issue 33, pages 5365–5373, 10 November 1977
How to Cite
1977), Precise continuous monitoring of seismic velocity variations and their possible connection to solid Earth tides, J. Geophys. Res., 82(33), 5365–5373, doi:10.1029/JB082i033p05365., , and (
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 28 JUN 1977
- Manuscript Received: 20 DEC 1976
Seismic velocities in the siting area of the Norwegian Seismic Array (Norsar) have been monitored over a time period of 1 week by using a hydroelectric power plant as a continuous wave generator. Propagational phase angle differences have been measured over travel distances ranging from 4.7 to 13.7 km, and group velocities of the order of 3.5 km/s are derived. This is close to the expected (phase) velocity for S waves, and the particle motions derived at a distance of 4.7 km also correspond well with those for S waves. The obtained precisions are 10−3 for a time period of about 2 hours and 10−4 when 1 week of data is used. The phase difference data exhibit a clear semidiurnal variation which probably corresponds to variations in the seismic velocities with peak to trough amplitudes around 10−3. There is some possibility that the observed variations could be caused by tidal effects. Observed spatial variations show that the influence of the local geology is significant.