The TICOSECT program aimed to investigate the crustal structure of the active continental margin of Costa Rica and to understand the geodynamic processes within the subduction system. With the help of a comprehensive wide-angle seismic data set, composed of an onshore/offshore experiment as well as refraction measurements on land in northern Costa Rica, the lithospheric structure from the Middle America Trench (MAT) to the Caribbean lowland was surveyed seismically.Here we provide seismic refraction data from an onshore/offshore seismic profile shot with the US American research vessel RV Mauris Ewing in spring of 1995 offshore of the Osa peninsula during the cruise EW9502. Data are reduced with 6 km/s and origin of the time series is at -2 sec. Note: the profile has been shot twice with a different shot interval at 25 s (p301) and 60 s (p302). Additional data from US partners can be found at http://www-udc.ig.utexas.edu/sdc/cruise.php?cruiseIn=ew9502.

Supplement to: Martinez-Loriente, Sara; Sallarès, Valenti; Ranero, César R; Ruh, Jonas B; Barckhausen, Udo; Grevemeyer, Ingo; Bangs, N L (2019): Influence of Incoming Plate Relief on Overriding Plate Deformation and Earthquake Nucleation: Cocos Ridge Subduction (Costa Rica). Tectonics, 38(12), 4360-4377