Northern EPR-Segment RO3

This second-order segment of the northern East Pacific Rise, also called Segment RO3, lies between the Orozco and Rivera transform faults, immediately north of the Orozco transform. This segment displays a broad, shallow profile that is the widest and shallowest of a 5,000-km-long area of the East Pacific Rise between 23°S and 23°N. The flat axial crest ranges from 3-4 to about 10 km wide, and is about 2,300-2,350 m deep; the axis morphology suggests a high magma supply rate. Magnetic paleointensity measurements on basaltic glasses dated several lava flows at about 2,000 +/- 1,000 years, suggesting a major volcanic episode that produced lava flows flooding much of the axial plateau and extended on to its flanks. Several other lava flows were dated at "contemporary" ages, perhaps less than 100 years.