Dana Manalang

Axial Seamount, a hotspot volcano on the Juan de Fuca Ridge, has been monitored through three eruptions with vertical geodesy documenting cycles of inflation and deflation. However, vertical motions alone cannot fully discriminate between distributed volumetric inflation and fault-accommodated uplift. We present three years of horizontal acoustic ranging observations (2022-2025) across Axial caldera from seafloor transponders defining 1.8-, 1.6-, and 3.3-km baselines spanning the western and eastern sides of the caldera and its full width. We observe 30 cm of extension across the caldera that is asymmetric with 24 cm of extension on the eastern baseline. Modeling of horizontal and vertical geodetic observation demonstrates that the observed deformation is primarily from volumetric inflation rather than fault motion. The data is consistent with a deeper pressure source coincident with a stacked sill complex under the southern caldera and a smaller shallow source under the northeastern caldera where eruptions originate.

Recent changes in US oceanographic assets are impacting scientists' ability to access seafloor and sub‐seafloor materials and thus constraining progress on science critical for societal needs. Here we identify national infrastructure needs to address critical science questions. This commentary reports on community‐driven discussions that took place during the 3‐day FUTURE of US Seafloor Sampling Capabilities 2024 Workshop , which used an “all‐hands‐on‐deck” approach to assess seafloor and sub‐seafloor sampling requirements of a broad range of scientific objectives, focusing on capabilities that could be supported through the US Academic Research Fleet (US‐ARF) now or in the near future. Cross‐cutting issues identified included weight and size limitations in the over‐boarding capabilities of the US‐ARF, a need to access material at depths greater than ∼20 m below the seafloor, sampling capabilities at the full range of ocean depths, technologies required for precise navigation‐guided sampling and drilling, resources to capitalize on the research potential of returned materials, and workforce development.

Wireless power transfer in seawater removes the inherent risks and complexities of mating conductive surfaces in seawater. An effective underwater wireless power transfer system for subsea vehicles must maintain power transfer despite the potential for dynamic misalignment between the power transmission and receive elements and therefore requires an adaptive system. We describe the development and characterization of a subsea wireless power system, including a transmit-receive coil pair optimized for seawater performance. Built on the adaptive resonant wireless power transfer technology of WiBotic, Inc., the system automatically adjusts for misalignment and separation between the transmit and receive coils. We demonstrate that transmit-receive coil pairs can be effectively tuned to provide adaptive wireless power transfer in salt water, with no significant effects of increased pressure at depth. Furthermore, we describe the full system marinization of the wireless power system and its application to a system that uses a wave energy converter for subsea vehicle charging.

Current estimations of seabed methane release into the ocean (0.4–48 Tg yr⁻¹) are based on short‐term observations and implicitly assume that fluxes are constant over time. However, the intensity of gas seepage varies significantly throughout a seep lifetime. We used instruments operated by the Ocean Observatories Initiative's Regional Cabled Array to monitor variations of gas emissions over the entire Southern Hydrate Ridge summit. We show that bubble plumes emanate from distinct and persistent vents. Multiple plumes can occur within each vent and the location of their outlets may shift progressively. Active bubble plumes vary temporally in number and intensity, even within single vents. Gas emission fluctuations are partly periodic and linked to the local tide. However, short‐term variability and high ebullition events unrelated to tidal cycles are also commonly observed. Our data indicate that small‐scale processes beneath or at the sediment surface are responsible for the short‐term variability of the venting activity that is otherwise modulated by tides. Furthermore, a decrease of venting at one vent may coincide with an increase in plume activity at other vents. Our results depict a spatially and temporally dynamic seep environment, the variability of which cannot be fully characterized without systematic and comprehensive monitoring of the entire area. These results indicate that flux estimations may be largely overestimated or underestimated depending on the time, duration, and place of observation. Although sudden ebullition bursts are hardly predictable, we argue that tidal cycles must be taken into consideration when estimating gas fluxes.

Whether near shore or in the open ocean, stationary ocean observing systems lack the ability to respond spatially to transient and difficult-to-predict phenomena, such as mid-ocean ridge eruptions, instabilities in methane hydrate deposits, turbidite flows, sea–ice interactions, mass wasting events, or changes in coastal currents. Detecting and characterizing these types of events and the processes driving them requires mobile systems available at the time of the event onset. Ideally, mobile autonomous underwater vehicles (AUVs) would permanently be stationed in or near areas where events of interest are likely to occur. Traditionally, due to their dependence on batteries, AUV mission durations are often measured in hours and require costly on-water support vessels and human intervention, making it impractical to sustain a mobile observing presence. However, advances in cabled power/comms and renewable marine energy technologies present significant opportunities for developing persistent mobile subsea systems able to recharge their batteries from fixed underwater infrastructure. In addition to power, these “resident” AUVs will require navigation and data transmission support. Acoustic systems will play key roles as sensing systems, navigation, vehicle homing, data transfer, and advanced robotic operations. This talk will present an overview of the systems and concepts relevant to subsea mobile ocean observing systems along with example applications.

Persistent mobile ocean observation platforms, supported by arrays of subsea marine vehicle service stations, will enable direct study of oceanographic and geological processes that, due to their transient nature and spatiotemporal variability, are not well understood. These include, but are not limited to, ocean-seafloor interactions and crustal ecosystems, mid-ocean ridge volcanism, coastal circulation and shelf ecosystems, reef health, and arctic sea-ice interaction. Further, certain types of subsea events, such as erupting submarine volcanoes, instabilities in methane hydrate deposits, marine mass-wasting events, turbidite flows, the ecological impacts of major earthquakes, breaking internal waves, the fate of mid-water vortices, and episodes of anoxic upwelling, can be energetic, transient, and unpredictable, often having unverifiable consequences. These cannot be readily detected, characterized, or quantified owing to the difficulty of anticipating the onset of such phenomena. The intractability of launching major sea-going assets with short lead times to capture and document such evanescent system-level processes from beginning to end means that our understanding of these and related processes is not readily expandable with current oceanographic tools.Marine Vehicle Highways (MVHs) will change the way ocean science is conducted by making temporally and spatially distributed data sets more attainable and accessible, opening the door for broader participation in transformative ocean science.