"1" . "SDN:L05::155" . "SDN:L05::155" . . . "1" . "false" . "" . . . . "accepted"@en . . "SDN:L05::155" . . "seismic refraction systems"@en . "2007-11-20 09:34:40.0" . "2007-11-20 09:34:40.0" . . . . "A network of seismometers or geophones plus an energy source that determine geologic structure by detecting waves refracted by subsurface layers."@en . . .