Northern EPR at 9.8°N Volcano — Undersea Features

A series of dives with the submersible Alvin in 1991 on the East Pacific Rise at about 9°50'N detected evidence for a very recent, possibly ongoing, eruption. Hot-vent animal communities documented during November-December 1989 had been buried by fresh basaltic lava flows, and the scorched soft tissues of partially buried biota had not yet attracted bottom scavengers. Fresh black smoker chimneys and new lava flows were present. This site is south of the Clipperton Fracture Zone at a depth of about 2,500 m, and about 1,000 km SW of Acapulco, México; the south end of the Lamont Seamount chain is about 10 km NW. This is also the location where lava flows previously estimated as being less than roughly 50 years old had been found. Later dating using very short half-life radionuclides from dredged samples confirmed the young age of the eruption and indicated that another eruptive event had taken place in late 1991 and early 1992. An eruption in 2005-2006 produced lava flows that entrapped previously emplaced seismometers.