Mapping of the East Pacific Rise between the equator and 40° S. shows the location and trend of nine active fracture zones and the probable location of a few more. An area of relatively shallow sea floor west of Easter Island marks a second active spreading center discovered by Herron (1972b). New data indicate that segments of several fracture zones exist on either side of the rise and can be correlated across that feature. New segments of the fossil Galapagos Rise have been identified, indicating that its southern part is significantly deeper than the northern segments. At 15° S., 120° W., the topographic configuration of the East Pacific Rise is markedly asymmetric: the western part is shallower than 2,000 fm (3,750 m) and occupies twice the area of that part to the east of the rise crest.