A mechanism for sustained groundwater pressure changes induced by distant earthquakes
Journal of Geophysical Research B: Solid Earth
By: E. E. Brodsky, E. Roeloffs, D. Woodcock, I. Gall, and M. Manga
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Abstract
Large sustained well water level changes (>10 cm) in response to distant (more than hundreds of kilometers) earthquakes have proven enigmatic for over 30 years. Here we use high sampling rates at a well near Grants Pass, Oregon, to perform the first simultaneous analysis of both the dynamic response of water level and sustained changes, or steps. We observe a factor of 40 increase in the ratio of water level amplitude to seismic wave ground velocity during a sudden coseismic step. On the basis of this observation we propose a new model for coseismic pore pressure steps in which a temporary barrier deposited by groundwater flow is entrained and removed by the more rapid flow induced by the seismic waves. In hydrothermal areas, this mechanism could lead to 4 ?? 10-2 MPa pressure changes and triggered seismicity.
Suggested Citation
Brodsky, E.E., Roeloffs, E., Woodcock, D., Gall, I., Manga, M., 2003, A mechanism for sustained groundwater pressure changes induced by distant earthquakes: Journal of Geophysical Research B: Solid Earth, v. 108, no. 8.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | A mechanism for sustained groundwater pressure changes induced by distant earthquakes |
| Series title | Journal of Geophysical Research B: Solid Earth |
| Volume | 108 |
| Issue | 8 |
| Year Published | 2003 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Journal of Geophysical Research B: Solid Earth |