Intermediate-depth earthquakes facilitated by eclogitization-related stresses
Geology
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Abstract
Eclogitization of the basaltic and gabbroic layer in the oceanic crust involves a volume reduction of 10%–15%. One consequence of the negative volume change is the formation of a paired stress field as a result of strain compatibility across the reaction front. Here we use waveform analysis of a tiny seismic cluster in the lower crust of the downgoing Pacific plate and reveal new evidence in favor of this mechanism: tensional earthquakes lying 1 km above compressional earthquakes, and earthquakes with highly similar waveforms lying on well-defined planes with complementary rupture areas. The tensional stress is interpreted to be caused by the dimensional mismatch between crust transformed to eclogite and underlying untransformed crust, and the earthquakes are probably facilitated by reactivation of fossil faults extant in the subducting plate. These observations provide seismic evidence for the role of volume change–related stresses and, possibly, fluid-related embrittlement as viable processes for nucleating earthquakes in downgoing oceanic lithosphere.
Suggested Citation
Nakajima, J., Uchida, N., Shiina, T., Hasegawa, A., Hacker, B.R., and Kirby, S.H., 2013, Intermediate-depth earthquakes facilitated by eclogitization-related stresses: Geology, v. 41, no. 6, p. 659-662, https://doi.org/10.1130/G33796.1.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Intermediate-depth earthquakes facilitated by eclogitization-related stresses |
| Series title | Geology |
| DOI | 10.1130/G33796.1 |
| Volume | 41 |
| Issue | 6 |
| Year Published | 2013 |
| Language | English |
| Publisher | Geological Society of America |
| Publisher location | Boulder, CO |
| Description | 4 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geology |
| First page | 659 |
| Last page | 662 |