UPPER-MANTLE VELOCITY STRUCTURE OF THE GREAT-BASIN

Teleseismic P‐wave travel‐times measured in the eastern Great Basin show ∼1 sec variations in travel‐time residuals. Inversion of these data images an alternating sequence of high‐ and low‐velocity upper‐mantle bodies trending NE across the eastern margin of the Great Basin. Low‐velocity mantle lies beneath the volcanic trends of the eastern Snake River Plain and the St. George volcanic field. These two low‐velocity trends are separated by high‐velocity mantle extending from northern Utah to SW Wyoming. Combining these results with seismic data from the western Great Basin reveals a continuation of these upper‐mantle trends across the Great Basin. Copyright 1990 by the American Geophysical Union.