Hydrothermal vent fluid temperature at Endeavour Segment, northeast Pacific Ocean
Date
2026
Authors
Hodge, Kimberly
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Abstract
Hydrothermal vent fluid temperatures at mid-ocean ridges are highly dynamic and are thought to reflect interactions between seismic activity, tidal forcing, and subsurface permeability structure. However, limited long-term observations make it difficult to resolve the mechanisms driving this variability. Here, we investigate temporal changes in vent fluid temperature at the Endeavour Segment of the Juan de Fuca Ridge, with a focus on the relative roles of earthquakes, tides, and permeability evolution. A ~ 6°C temperature perturbation on March 6th, 2024 is associated with a magnitude 3.6 earthquake, with a smaller precursor signal suggesting foreshock influence. The initial temperature decrease is interpreted to result from increased permeability, promoting fluid dispersion and potential seawater entrainment, while the subsequent recovery is consistent with permeability reduction through mineral precipitation and conduit insultation. In contrast, a gradual ~ 10°C temperature increase over a longer period corresponds to reduced seismicity, suggesting passive permeability decline and increased insulation of fluid pathways, potentially enhanced by anhydrite precipitation. Tidal signals are evident at daily and fortnightly timescales, although their mechanisms remain unclear and may reflect indirect influences such as tidally modulated bottom currents. Irregular temperature fluctuations show no consistent relationship with seismicity or tides, indicating the combined influence of multiple interacting processes within a heterogeneous crustal system. Analysis of mooring data provides no clear evidence for a corresponding plume response to the March 6th event, highlighting the limitations of temperature and conductivity measurements alone. We conclude that vent fluid temperature variability is strongly controlled by site-specific permeability dynamics influenced by both seismic and tidal processes, and emphasize the need for long-term, multidisciplinary observations, including water chemistry, to better constrain hydrothermal system behavior.
Supervisor: Casey Brant
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Keywords
oceanography, hydrothermal vents, earthquakes, Ocean Networks Canada