 Refraction seismography surveys started in 1930, augemented in 1948 with reflection seismography, which led to the discovery of the southern extent of the atoll with the Ezequiel Ordonez No.1 well in 1952 and additional discoveries through 1968.Marine seismic and magnetometer surveys starting in 1957 showed the extent of the atoll offshore and led to the first offshore well, Isla de Lobos No.