Geophysical Service

Geophysical Service Inc.
Founded1930
HeadquartersDallas, Texas, U.S.
Websitewww.geophysicalservice.com

Geophysical Service Inc. (often abbreviated GSI) was a Texas-based company founded by John Clarence Karcher and Eugene McDermott in 1930, for the purpose of using refraction and reflection seismology to explore for petroleum deposits.