Reconnaissance seismic refraction-reflection surveys in northwestern New Mexico

Abstract A velocity model of the crust in northwestern New Mexico has been constructed from an interpretation of direct, refracted, and reflected seismic waves. The model suggests a sedimentary section about 3 km thick with an average P -wave velocity of 3.6 km/sec. The crystalline upper crust is 28 km thick and has a P -wave velocity of 6.1 km/sec. The lower crust below the Conrad discontinuity has an average P -wave velocity of about 7.0 km/sec and a thickness near 17 km. Some evidence suggests that velocity in both the upper and lower crust increases with depth. The P -wave velocity in the uppermost mantle is 7.95 ± 0.15 km/sec. The total crustal thickness near Farmington, New Mexico, is about 48 km (datum = 1.6 km above sea level), and there is evidence for crustal thinning to the southeast.