As part of the International ELAS (Electrical Studies of the Asthenosphere) Project (Eos, July 31, 1979, p. 551), which has been designated as a “key project” by the International Council of Scientific Unions (ICSU) Interunion Commission on the Lithosphere, large land and sea electromagnetic arrays have been deployed by workers from Canada, the United States, Mexico, and other countries during the summer and early fall of 1985. Soviet workers are expected to participate in the data analysis. This array, known as Project EMSLAB (for “electromagnetic study of the lithosphere and asthenosphere beneath (the Juan de Fuca Plate and adjacent continents)”), will use geomagnetic variation and magnetotelluric techniques to study the electrical conductivity of the crust, lithosphere, and asthenosphere in and above the actively subducting Juan de Fuca Plate. The area to be studied includes the region from the Juan de Fuca Ridge to the North American continent, across the Cascade Range of southern Canada, Washington and Oregon states, and into the Basin and Range Province of the western United States. Complementing the magnetic variometer array will be a profile of magnetotelluric and short-period magnetic variation sites along a swath through central Oregon.