Open AccessCollision versus sliver transport in the hanging wall at the Middle America subduction zone: Constraints from background seismicity in central Costa Rica
Author(s) -
Lewis Jonathan C.,
Boozer Adam C.,
López Allan,
Montero Walter
Publication year - 2008
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2007gc001711
Subject(s) - geology , seismology , ridge , subduction , trench , induced seismicity , focal mechanism , collision , collision zone , slip (aerodynamics) , tectonics , paleontology , computer security , computer science , chemistry , physics , organic chemistry , layer (electronics) , thermodynamics
Earthquake focal mechanism solutions for 135 small‐magnitude events are inverted for best fitting partial strain rate tensors that characterize contemporary strain in five areas that span the western margin of the Panama microplate in central Costa Rica. The results indicate the predominance of subhorizontal maximum stretching subparallel to the Middle America Trench (MAT) and provide constraints on the role of Cocos ridge collision at the MAT. The trajectory of maximum stretching changes ∼25°–45° over several tens of kilometers from the Central Costa Rica Deformed Belt (CCRDB) where it is nearly E–W to the area inboard of the Cocos ridge where it is NW–SE. This change suggests that background seismogenic deformation reflects the transition from the trailing edge of a fore‐arc sliver to an area of the upper plate affected by ridge collision. This diffuse deformation may be localized, in part, on conjugate strike‐slip faults of the CCRDB.