Geophysical Constraints on the Relationship Between Seamount Subduction, Slow Slip, and Tremor at the North Hikurangi Subduction Zone, New Zealand
Abstract
We use a prestack depth migration reflection image and magnetic anomaly data across the northern Hikurangi subduction zone, New Zealand, to constrain plate boundary structure and geometry of a subducting seamount in a region of shallow slow slip and recent International Ocean Discovery Program drilling. Our 3-D model reveals the subducting seamount as a SW-NE striking, lozenge-shaped ridge approximately 40 km long and 15 km wide, with relief up to 2.5 km. This seamount broadly correlates with a 20-km-wide gap separating two patches of large (>10 cm) slow slip and the locus of tectonic tremor associated with the September-October 2014 Gisborne slow slip event. Largest slow slip magnitudes occurred where the décollement is underlain by a 3.0-km-thick zone of highly reflective subducting sediments. Wave speeds within this zone are 7% lower than adjacent and overlying strata, supporting the view that high fluid pressures within subducting sediments may facilitate shallow slow slip along the north Hikurangi margin.
- Publication:
-
Geophysical Research Letters
- Pub Date:
- December 2018
- DOI:
- 10.1029/2018GL080259
- Bibcode:
- 2018GeoRL..4512804B
- Keywords:
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- Hikurangi margin;
- seamount;
- seismic reflection;
- subducting slab;
- fault slip behavior;
- slow slip