Axial Seamount Continues to Reveal Its Secrets

RCA : Axial Seamount Continues to Reveal Its

Secrets Axial Seamount is the longest monitored mid-ocean ridge volcano, providing new insights into the relationships among magma supply, uplift-deflation behavior, and seismicity leading to and follow eruptions. Results are as summarized here from a new comprehensive publication by Chadwick et al., 2021. The magma supply rate changes significantly over periods of months to years. Since the 2015 eruption, the summit of the volcano has been slowly inflating at a decreasing rate. This slow rate is punctuated by eight discrete short-term deflation events occurring over 1-3 weeks, approximately every 4-6 months from August 2016 to May 2019. These events are co-registered with an abrupt decrease in seismic activity: seismic activity does not pick up until reinflation resumed. In contrast, the long-term monitoring indicates there was a significant increase in magma supply between 2011 and 2015, resulting in the two eruptions. Although the summit of the volcano has inflated 85%-90% of its pre 2015 eruption level, geodetic monitoring with coupled seismometers and cabled and uncabled pressure sensors suggests that the magma supply rate has been waning since the 2015, pushing the forecast for the next eruption out 4-9 years. Deformation and seismic activity are tightly coupled, showing an exponential increase in seismic activity per unit of uplift since the 2015 eruption. A significant conclusion from this study is that the transition from an exponential to linear increase in seismic activity to total uplift may indicate impending crustal failure between the shallow magma chamber and the seafloor. In concert, these results will lead to more refined forecasting of this highly

Chadwick, WW, Jr., Wilcock WSD, Nooner SL, Beeson JW, Sawyer AM, Lau, T-K ((2021). Geodetic Monitoring at Axial Seamount Since Its 2015 Eruption Reveals a Waning Magma Supply and Tightly Linked Rates of Deformation and Seismicity. Geochemistry, Geophysics, Geosystems, 23, e2021GC010153. https://doi.org/10.1029/2021GC010153