Density Structure and Geometry of the Costa Rican Subduction Zone from 3D Gravity Modelling and Local Earthquake Data.

Lücke, O. H., Arroyo, Ivonne G. and Götze, Hans-Jürgen (2012) Density Structure and Geometry of the Costa Rican Subduction Zone from 3D Gravity Modelling and Local Earthquake Data. [Poster] In: The Lübeck Retreat, Collaborative Research SFB 574 Volatiles and Fluids in Subduction Zones: Climate Feedback and Trigger Mechanisms for Natural Disasters. , 23.-25.05.2012, Lübeck . The Lübeck Retreat: final colloquium of SFB 574; May 23-25, 2012: program & abstracts. ; p. 18 .

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The eastern part of the oceanic Cocos Plate presents a heterogeneous crustal structure due to
diverse origins and ages as well as plate-hot spot interaction. The complex structure of the oceanic
plate directly influences the dynamics and geometry of the subduction zone along the Middle
American Trench. In this work, an integrated interpretation of the slab geometry is presented based
on three-dimensional density modelling of satellite-derived gravity data constrained by seismological
information obtained by local networks. Results show the continuation of steep subduction from the
Nicaraguan margin into northwestern Costa Rica followed by a shallower slab under the Central
Cordillera toward the end of the Central American Volcanic Arc. To the southeast of the termination of
the volcanic arc, the slab appears to steepen and continue as a coherent structure until reaching the
landward projection of the Panama Fracture Zone. Overall a gradual change in the depth of intra-plate
seismicity is observed reaching 220 km for the northwestern part and becoming shallower toward the
southeast where it reaches a maximum depth of 70-75 km. The changes in the depth of the observed
seismicity correlate with changes in the density structure of the subducting slab and may indicate that
differences in the state of initial hydration of the oceanic lithosphere affect the depth reached by
dehydration reactions in the subduction zone.

Document Type: Conference or Workshop Item (Poster)
Keywords: Geodynamics
Research affiliation: OceanRep > SFB 574 > A5
OceanRep > SFB 574
OceanRep > SFB 574 > A2
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Kiel University
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Date Deposited: 21 Sep 2012 10:44
Last Modified: 21 Sep 2012 10:44

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