Reprocessing and synthetic seismic modeling of COCORP profiles across the eastern margin of the Rio Grande rift at Abo Pass, New Mexico, suggest that synthetic and antithetic Cenozoic normal faults sole into or are truncated by a northwest dipping listric master fault which bounds the eastern side of the basin and reaches a depth of at least 10 km beneath the southern Albuquerque basin. This fault appears to project toward the surface position of the Los Pinos Cenozoic normal fault, which lies basinward of and trends parallel to a mapped Laramide duplex thrust zone. The Los Pinos fault may sole into the older thrust, reactivating this preexisting compressional structure at depth. A lateral change in reflection amplitude and frequency is conspicuous across the eastern rift margin. Analysis demonstrates that source coupling is the main cause of a much deteriorated signal below the rift basin, although complex ray paths and attenuation by the graben fill may contribute.