The state of stress in subducting slabs as revealed by earthquakes analysed by moment tensor inversion
Abstract
We have used a data set of earthquakes whose mechanisms have been studied, here or elsewhere, by moment tensor inversion, to confirm some earlier ideas concerning the state of stress in subducting slabs. The moment tensor method offers the advantages of speed and objectivity over earlier methods, usually based exclusively on first-motion data. Deep earthquakes (below 300-400 km) tend to have compression axes aligned with the dip of the subducting slab. The behavior of intermediate earthquakes (from 70 to 300 km) is less clear. There is some evidence for down-dip tension, but the alignment is not as obvious as it is in the case of the compression axes of deep events. Tonga shows a tendency toward down-dip compression at intermediate depths, but other deep-extending slabs, as well as shallow-extending slabs (slabs with maximum depths shallower than 300 km), seem to be closer to down-dip tension.
- Publication:
-
Earth and Planetary Science Letters
- Pub Date:
- July 1984
- DOI:
- 10.1016/0012-821X(84)90083-9
- Bibcode:
- 1984E&PSL..69..195V
- Keywords:
-
- Axial Stress;
- Compressing;
- Earthquakes;
- Seismology;
- Tension;
- Tensor Analysis