Collaborative Research: Structure of the Nicaragua/Costa Rica Subduction Zone: A Framework for the Subduction Factory and Seismogenic Zone Initiatives

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99-05355 McIntoshRecommended Project is for a multichannel seismic (MCS) survey of the subducting ocean crust off the coasts of Nicaragua and Costa Rica in support of both SEIZE and Subduction Factory objectives in this Margins program study area. The primary objective is to characterize the changing structural nature of the subducting Cocos plate, and to try to relate these changes to known chemical segmentation of the volcanic arc, best shown by ratios such as Ba/La that reflect relative changes in material input into the subduction zone. The MCS survey will be supplemented by three wide-angle, ocean bottom hydrophone (OBH) refraction lines, two perpendicular and one parallel to the trench, as well as by Hydrosweep swath bathymmetry, gravity, and magnetics data. This proposed study is part of a larger, international effort, using the German research vessel R/V Sonne. The MCS and Hydrosweep surveys would be conducted aboard the R/V Maurice Ewing, using its 6 km-long streamer. The R/V Sonne will be used to supply, deploy and recover the OBH's, which will themselves be supplied by GEOMAR.***