Hydrous minerals in the mantle wedge and the maximum depth of subduction thrust earthquakes
Article first published online: 7 DEC 2012
Copyright 1999 by the American Geophysical Union.
Geophysical Research Letters
Volume 26, Issue 16, pages 2517–2520, 15 August 1999
How to Cite
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 22 JUN 1999
- Manuscript Received: 23 FEB 1999
In many subduction zones the downdip limit of thrust earthquakes approximately coincides with the intersection of the subduction thrust with the forearc mantle. This limit may be explained by aseismic hydrous minerals present in the mantle wedge. During subduction, fluids released from the subducting slab infiltrate the overlying forearc mantle forming serpentine + brucite, especially in cool subduction zones. At the slab interface itself, talc-rich rocks form in the mantle by the addition of silica transported by rising fluids and by mechanical mixing of mantle and siliceous rocks. In the laboratory, serpentine generally exhibits stable-sliding aseismic behavior. The behavior of talc, a layered hydrous silicate, and brucite, a layered hydroxide, has not been investigated, but their structures also suggest weak stable-sliding behavior. We suggest all three layered hydrous minerals promote aseismic behavior and that their presence controls the downdip limit of thrust earthquakes in many subduction zones.