A New Perspective on the 9°50’N East Pacific Rise 2006 Eruption

Abstract:

Seismic data from ocean bottom seismometers at 9°50'N on the East Pacific Rise captured a seafloor eruption in January 2006 that was preceded by a prolonged buildup of seismicity. The seismicity buildup culminated in ~6 hours of most intense seismic activity interpreted as a period of dike propagation on January 22^nd 2006 (Tolstoy et. al., 2006). Approximately 3 hours after the start of this seismic crisis, impulsive, waterborne seismic signals emerged and then gradually petered out over the next two weeks. The characteristics of these signals are similar to those observed during the 2015 Axial Seamount eruption (Garcia et. al.; Wilcock et. al., this meeting) and are believed to be associated with cooling/degassing of seafloor lava. Locations of ~2000 of these events delineate the lava flow region mapped using digital seafloor imagery in 2006-2007(Soule et. al., 2007) which confirms the association between these events and eruptions/lava flow. The spatiotemporal evolution of these events sheds light on the lava flow dynamics during this eruption. Earthquakes located during the 6-hour period of most intense seismic signals concentrated around 9°50-9°51’N which may be the main region where magma intruded from the axial magma lenses. Throughout the deployment, minute-long tremor bursts were also observed. The event count of these tremor bursts peaked at ~20 hours after the period of most intense seismic signals before petering out over the next few weeks. These events may be associated with magma movement and refilling of axial and/or sub-axial magma lenses during the eruption.