Accession Number : AD0657935

Title :   OCEANIC ELECTRIC CURRENTS, GEOMAGNETIC VARIATIONS AND THE DEEP ELECTRICAL CONDUCTIVITY STRUCTURE OF THE OCEAN-CONTINENT TRANSITION OF CENTRAL CALIFORNIA,

Corporate Author : SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CALIF

Personal Author(s) : Filloux,Jean H.

Report Date : 30 JUN 1967

Pagination or Media Count : 186

Abstract : The variations of electromagnetic field components along a line across central California have been examined in the frequency range .125 to 4 cph by means of an array of stations extending from 320 km inland to 630 km offshore. The three components of the magnetic variations were recorded at six land positions. Simultaneously, records of the oceanic electric field in a direction approximately parallel to the coast were obtained at three stations located as far as 150 km offshore by using self-contained recorders installed on the sea floor. The cross-correlation of all field components leads to field relationships suggesting a large-scale, nearly two-dimensional structure of the electrical conductivity of the earth's crust and upper mantle in a region adjacent to the California coast. Estimates of the continental and oceanic conductivity distribution with depth were carried out by solving numerical models. The estimate of the offshore conductivity profile based on models of the coastal cross section are in excellent agreement with the independent magnetotelluric sounding. In the light of the present knowledge of the properties of rocks at high pressure and temperature, the high electrical conductivity of the oceanic basement favors a highly basaltic external mantle shell, extending to no less than 30 km below the Mohorovicic discontinuity. (Author)

Descriptors :   (*OCEAN CURRENTS, GEOMAGNETISM), (*GEOMAGNETISM, *ELECTRIC FIELDS), OCEANS, MAGNETOMETERS, NUMERICAL ANALYSIS, OCEAN BOTTOM, CONDUCTIVITY, DEPTH FINDING, ROCK, TEMPERATURE, PRESSURE, ELECTROMAGNETIC FIELDS, MAGNETIC PROPERTIES

Subject Categories : Physical and Dynamic Oceanography
      Geomagnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE