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Changes in magnetic and telluric fields in a seismically active region of Eeastern Canada: Preliminary results of earthquake prediction studies
- Source :
- Tectonophysics; January 1976, Vol. 34 Issue: 3 p219-230, 12p
- Publication Year :
- 1976
-
Abstract
- A project for detecting time-dependent electrical resistivity changes in crustal rocks by measuring short-period variations of the magnetic and telluric fields has been in operation since October, 1974 in a seismically active region northeast of Quebec City, Canada. Significant changes in amplitude and direction of telluric fields have been observed for variations ranging from 5 to 120 min. A change with a duration of a year or so seems to be a predominant feature. Superposed on it, a more rapid change with a duration of a few months is seen in late spring and early summer. Although the observed changes show a history similar to a premonitory change as expected from a model of dilatancy with fluid diffusion, they are unlikely to have any bearing on a dilatancy process in the crust since no earthquakes of magnitude greater than 3 associated with the changes have taken place in the survey area. It is pointed out, however, that the magnetotelluric method provides a useful means of detecting changes in electrical resistivity in the shallow crust. Thus the possibility exists of detecting resistivity changes associated with shallow earthquakes.
Details
- Language :
- English
- ISSN :
- 00401951
- Volume :
- 34
- Issue :
- 3
- Database :
- Supplemental Index
- Journal :
- Tectonophysics
- Publication Type :
- Periodical
- Accession number :
- ejs44796549
- Full Text :
- https://doi.org/10.1016/0040-1951(76)90097-4