The affiliation for fourth author Dr. César Renaro was incorrectly listed in the previous version of this article. Proper association with ICREA has now been added.
Overriding plate structure of the Nicaragua convergent margin: Relationship to the seismogenic zone of the 1992 tsunami earthquake
Article first published online: 3 SEP 2013
©2013. American Geophysical Union. All Rights Reserved.
Geochemistry, Geophysics, Geosystems
Volume 14, Issue 9, pages 3436–3461, September 2013
How to Cite
2013), Overriding plate structure of the Nicaragua convergent margin: Relationship to the seismogenic zone of the 1992 tsunami earthquake, Geochem. Geophys. Geosyst., 14, 3436–3461, doi:10.1002/ggge.20214., , , , , and (
- Issue published online: 24 OCT 2013
- Article first published online: 3 SEP 2013
- Accepted manuscript online: 29 JUN 2013 12:59AM EST
- Manuscript Revised: 25 JUN 2013
- Manuscript Accepted: 25 JUN 2013
- Manuscript Received: 15 APR 2013
- convergent margin;
- tsunami earthquake;
- wide-angle seismics;
- travel time tomography
 We present 2-D seismic velocity models and coincident multichannel seismic reflection images of the overriding plate and the inter-plate boundary of the Nicaragua convergent margin along two wide-angle seismic profiles parallel and normal to the trench acquired in the rupture area of the 1992 tsunami earthquake. The trench-perpendicular profile runs over a seamount subducting under the margin slope, at the location where seismological observations predict large coseismic slip. Along this profile, the igneous basement shows increasing velocity both with depth and away from the trench, reflecting a progressive decrease in upper-plate rock degree of fracturing. Upper mantle-like velocities are obtained at ∼10 km depth beneath the fore-arc Sandino basin, indicating a shallow mantle wedge. A mismatch of the inter-plate reflector in the velocity models and along coincident multichannel seismic profiles under the slope is best explained by ∼15% velocity anisotropy, probably caused by subvertical open fractures that may be related to fluid paths feeding known seafloor seepage sites. The presence of a shallow, partially serpentinized mantle wedge, and the fracture-related anisotropy are supported by gravity analysis of velocity-derived density models. The downdip limit of inter-plate seismicity occurs near the tip of the inferred mantle wedge, suggesting that seismicity could be controlled by the presence of serpentinite group minerals at the fault gouge. Near the trench, the inferred local increase of normal stress produced by the subducting seamount in the plate boundary may have made this fault segment unstable during earthquake rupture, which could explain its tsunamigenic character.