Mihaly Steven F.

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Mihaly
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Steven F.
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  • Article
    Bottom pressure signals at the TAG deep-sea hydrothermal field : evidence for short-period, flow-induced ground deformation
    (American Geophysical Union, 2009-10-01) Sohn, Robert A. ; Thomson, Richard E. ; Rabinovich, Alexander B. ; Mihaly, Steven F.
    Bottom pressure measurements acquired from the TAG hydrothermal field on the Mid-Atlantic Ridge (26°N) contain clusters of narrowband spectral peaks centered at periods from 22 to 53.2 minutes. The strongest signal at 53.2 min corresponds to 13 mm of water depth variation. Smaller, but statistically significant, signals were also observed at periods of 22, 26.5, 33.4, and 37.7 min (1–4 mm amplitude). These kinds of signals have not previously been observed in the ocean, and they appear to represent vertical motion of the seafloor in response to hydrothermal flow - similar in many ways to periodic terrestrial geysers. We demonstrate that displacements of 13 mm can be produced by relatively small flow-induced pressures (several kPa) if the source region is less than ∼100 m below the seafloor. We suggest that the periodic nature of the signals results from a non-linear relationship between fluid pore pressure and crustal permeability.
  • Article
    Integrating Multidisciplinary Observations in Vent Environments (IMOVE): decadal progress in deep-sea observatories at hydrothermal vents
    (Frontiers Media, 2022-05-13) Matabos, Marjolaine ; Barreyre, Thibaut ; Juniper, S. Kim ; Cannat, Mathilde ; Kelley, Deborah S. ; Alfaro-Lucas, Joan M. ; Chavagnac, Valerie ; Colaço, Ana ; Escartin, Javier E. ; Escobar Briones, Elva ; Fornari, Daniel J. ; Hasenclever, Jörg ; Huber, Julie A. ; Laës-Huon, Agathe ; Lantéri, Nadine ; Levin, Lisa A. ; Mihaly, Steven F. ; Mittelstaedt, Eric ; Pradillon, Florence ; Sarradin, Pierre-Marie ; Sarradin, Pierre-Marie ; Sarrazin, Jozée ; Tomasi, Beatrice ; Venkatesan, Ramasamy ; Vic, Clément
    The unique ecosystems and biodiversity associated with mid-ocean ridge (MOR) hydrothermal vent systems contrast sharply with surrounding deep-sea habitats, however both may be increasingly threatened by anthropogenic activity (e.g., mining activities at massive sulphide deposits). Climate change can alter the deep-sea through increased bottom temperatures, loss of oxygen, and modifications to deep water circulation. Despite the potential of these profound impacts, the mechanisms enabling these systems and their ecosystems to persist, function and respond to oceanic, crustal, and anthropogenic forces remain poorly understood. This is due primarily to technological challenges and difficulties in accessing, observing and monitoring the deep-sea. In this context, the development of deep-sea observatories in the 2000s focused on understanding the coupling between sub-surface flow and oceanic and crustal conditions, and how they influence biological processes. Deep-sea observatories provide long-term, multidisciplinary time-series data comprising repeated observations and sampling at temporal resolutions from seconds to decades, through a combination of cabled, wireless, remotely controlled, and autonomous measurement systems. The three existing vent observatories are located on the Juan de Fuca and Mid-Atlantic Ridges (Ocean Observing Initiative, Ocean Networks Canada and the European Multidisciplinary Seafloor and water column Observatory). These observatories promote stewardship by defining effective environmental monitoring including characterizing biological and environmental baseline states, discriminating changes from natural variations versus those from anthropogenic activities, and assessing degradation, resilience and recovery after disturbance. This highlights the potential of observatories as valuable tools for environmental impact assessment (EIA) in the context of climate change and other anthropogenic activities, primarily ocean mining. This paper provides a synthesis on scientific advancements enabled by the three observatories this last decade, and recommendations to support future studies through international collaboration and coordination. The proposed recommendations include: i) establishing common global scientific questions and identification of Essential Ocean Variables (EOVs) specific to MORs, ii) guidance towards the effective use of observatories to support and inform policies that can impact society, iii) strategies for observatory infrastructure development that will help standardize sensors, data formats and capabilities, and iv) future technology needs and common sampling approaches to answer today’s most urgent and timely questions.