Principal Investigator: Kirk McIntosh

Funded by: National Science Foundation

Data has been acquired to investigate the upper plate response to three different morphological segments of the Cocos plate that subduct beneath Costa Rica. The smooth, seamount-dominated, and Cocos Ridge segments of the Cocos plate were surveyed using a large marine airgun source, 20-30 ocean bottom instruments (seismometers and hydrophones), 30+ land instruments, and selected land shots to obtain wide aperture and near vertical seismic data along the three regional transects. The wide aperture data will be used to establish crustal structure/velocity models across the arc and forearc areas, which are poorly known at present. The resulting models can also be used to process (i.e., migrate) near-vertical data recorded by the ocean bottom and land instruments to image the plate boundary zone reflections landward into the zone of seismogenic subduction and seaward to tie with existing seismic reflection data. Along all three transects a primary goal is to construct accurate velocity models so that the images of the plate boundary zone produced in this project can be tied to relocated earthquake hypocenters. Integration of these two data sets could provide a missing link in understanding the transition from aseismic to seismogenic plate motion.