New Mexico Geological Society Annual Spring Meeting — Abstracts

Seismic refraction and D.C. resistivity sounding surveys wer'e conducted in Mountainview, New Mexico to test the feasibility of using these methods for locating the water-table and possible variations in ground-water quality in this area. Mountainview, located along the Rio Grande River directly south of Albuquerque, has received much attention since 1961 when high concentrations of nitrate were reported contaminating domestic water supplies. The surveys were conducted on floodplain sediments of the Rio Grande River, which constitute the main aquifer for the region.

Two sites approximately 2.0 km apart were investigated with multiple lines run at each site. Each seismic refraction line consisted of a 12- geophone takeout with typical geophone separation of 3.0 m. Using the slope-intercept interpretation method, the seismic data consistently indicated a two-velocity profile: a low-velocity, surface layer (0.20 km/sec to 0.35 km/sec) of thickness between 3.0 to 5.0 meters overlaying a higher-velocity layer (1.5 km/sec to 1.6 km/sec) believed to be the water-saturated zone. The resistivity sounding lines used Schlumberger arrays with maximum AB/2 separation of 50.0 m. Interpretation of these data sets is still in progress, but preliminary findings do show a strong consistency between profiles taken at the same sites and a variation in profiles between the two sites. This variation may be an indication of a difference in water conductivity.