PDFFirst Paragraph
In 1972, at a location in the eastern equatorial Pacific ~ 200 miles northeast of the Galápagos Islands, a young graduate student researcher was using surplus US Navy sonobuoys to listen to the portion of the global mid-ocean ridge known as the Galápagos Spreading Center (GSC) (Figure 1). The global mid-ocean ridge is a giant volcanic seam where Earth’s lithospheric plates repeatedly rip apart and erupt lava to form new seafloor in a process known as seafloor spreading. Ken Macdonald was listening for the sounds of ripping and volcanic eruptions produced by seafloor spreading, and he was quite excited when he heard a swarm of such sounds (80 earthquakes per hour!) through his headphones. When he went out on the deck of the ship, he saw many dead fish floating on the sea surface, and quickly realized that these were benthic fish, which live near the seafloor at great depth. He logically concluded that the fish had been killed by the seafloor events producing the sounds detected by his sonobuoys, and he published a paper in 1974 to propose that the crest of the GSC near 86°W had experienced a volcanic eruption (Macdonald and Mudie, 1974).