The 2015 eruption on Axial Seamount
IPGP - Îlot Cuvier
Séminaires Géosciences Marines
University of Washington
In late 2014, a real-time cabled seafloor observatory was deployed on Axial Seamount in the NE Pacific Ocean, as part of the US National Science Foundation’s Ocean Observatories Initiative. The observatory, which spans the southern half of an elongated summit caldera, comprises a small seismic network, geodetic sensors and a collection of instruments to monitor two hydrothermal vent fields. On April 24, 2015, only five months after the seismic data streams first came on-line, the volcano erupted. In this talk I will review the geophysical observations of the eruption focusing on the seismic network. Well over 100,000 earthquakes were detected in the five months prior to the eruption. The majority of these define outward dipping fault planes along the east and west walls of the caldera that are interpreted as the ring fault. The earthquakes display a very strong tidal triggering signal. The seismic crisis comprised >9000 detected earthquakes and involved a dike intrusion along the east wall of the caldera and along the north rift. In the month following the eruption >35,000 acoustic signals were recorded from explosions on the seafloor at the sites of lava flows.