Collaborative Research: From Magma to Vents: Monitoring Hydrothermal Fluid Temperature and Upflow-zone Permeability in Relation to Magma Movement at Axial Seamount

University Of Washington, Seattle WA

Investigators

Abstract

Most of the volcanoes on Earth are located on the deep ocean floor and serve as heat reservoirs that boil sea water and give rise to hot springs on the seafloor. These deep-sea hot springs are the source of energy for many unique creatures on the seafloor far from any light. Knowledge of these deep-sea environments is still limited and there is much to be learned about how the hot springs change with time as a volcano’s heat reservoir grows and shrinks. This study will use specially designed gauges to measure the temperatures inside multiple hot springs located on an underwater volcano called Axial Seamount in the Northeast Pacific Ocean. Axial is one of the best studied volcanoes in the ocean. Using sensors that monitor the rise and fall of the seafloor on the volcano, scientists forecast that Axial will erupt in the next few years. By analyzing the temperature variations at Axial Volcano’s hot springs, this project will learn more about how the springs and their deep roots inside the volcano change during its buildup towards the next eruption. Magmatic activities along the mid-ocean ridge system related to seafloor spreading account for most of the earth’s volcanic output. The associated hydrothermal systems provide a key linkage between the lithosphere and the hydrosphere, transferring heat and nutrients that ultimately support the biosphere. Seafloor hydrothermal systems are primarily regulated by their subsurface heat supplies and hydrologic properties such as permeability that regulate crustal fluid flow. The considerable difficulties in establishing concurrent, long-term monitoring of those sub-seafloor properties within young oceanic crust in conjunction with surface venting have greatly limited our understanding of hydrothermal variability in relation to submarine magmatic processes. This project will fill this knowledge gap by 1) conducting long-term, high-resolution, time-series measurements of hydrothermal effluent temperature at multiple high-temperature, focused vent sites across the summit caldera of Axial Seamount, 2) using a one-dimensional, multi-layer poroelastic model to derive time-varying estimates of effective upflow-zone permeability from tidal modulation of vent-fluid temperature, and 3) interpreting observed temperature and permeability variations within a broader context constructed from the geodetic and seismic monitoring established at Axial as part of the Ocean Observatories Initiative’s Regional Cabled Array observatory along with other complementary geophysical observations such as state-of-the-art three-dimensional seismic imaging. The planned long-term monitoring of vent-fluid temperature and upflow-zone permeability across the summit-caldera of Axial Seamount will provide valuable insights into the variability of hydrothermal activity in relation to magma movement and associated changes in crustal permeability on a volcanically active spreading ridge segment. Additionally, should an eruption occur at Axial during the timeframe of this project, the proposed vent-fluid temperature measurements and analysis will provide a rare opportunity to investigate magma-hydrothermal interaction during the period of major magma movement immediately before and after the onset of an eruption. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.