Polarity reversal in the Solomon Islands arc
Abstract
McKenzie1 proposed that the direction of subduction beneath an island arc will reverse following arc-continent collision. Dewey and Bird2 suggested that such an arc polarity reversal occurred in northern New Guinea; Johnson and Molnar3, however, proposed two alternative models of plate convergence that could explain the observed seismicity. We present here a spatial seismicity study of the Solomon Islands region which has revealed the existence of two juxtaposed Wadati-Benioff (W-B) zones of opposite polarity. Shallow and intermediate foci define a north-east-dipping W-B zone associated with active subduction along the New Britain and San Cristobal trenches and a south-west-dipping W-B zone associated with the inactive North Solomon trench (NST). These data provide the first direct seismic evidence of a reversal in subduction polarity at an island arc.
- Publication:
-
Nature
- Pub Date:
- April 1985
- DOI:
- 10.1038/314428a0
- Bibcode:
- 1985Natur.314..428C