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| Titel |
Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data |
| VerfasserIn |
O. H. Lücke, I. G. Arroyo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 4 ; Nr. 6, no. 4 (2015-10-29), S.1169-1183 |
| Datensatznummer |
250115520
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| Publikation (Nr.) |
 copernicus.org/se-6-1169-2015.pdf |
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| Zusammenfassung |
| 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
interactions which originated the Cocos Ridge, a structure that converges
with the Caribbean Plate in southeastern Costa Rica. The complex structure
of the oceanic plate directly influences the dynamics and geometry of the
subduction zone along the Middle American Trench. In this paper an
integrated interpretation of the slab geometry in Costa Rica is presented
based on 3-D density modeling of combined satellite and
surface gravity data, constrained by available geophysical and geological
data and seismological information obtained from local networks. The results
show the continuation of steep subduction geometry from the Nicaraguan
margin into northwestern Costa Rica, followed by a moderate dipping slab
under the Central Cordillera toward the end of the Central American Volcanic
Arc. Contrary to commonly assumed, to the southeast end of the volcanic arc,
our preferred model shows a steep, coherent slab that extends up to the
landward projection of the Panama Fracture Zone. Overall, a gradual change
in the depth of the intraplate seismicity is observed, reaching 220 km in
the northwestern part, and becoming progressively shallower toward the
southeast, where it reaches a maximum depth of 75 km. The changes in the
terminal depth of the observed seismicity correlate with the increased
density in the modeled slab. The absence of intermediate depth
(> 75 km) intraplate seismicity in the southeastern section and the higher
densities for the subducted slab in this area, support a model in which
dehydration reactions in the subducted slab cease at a shallower depth,
originating an anhydrous and thus aseismic slab. |
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