Description: The Joint Task Force, Science Monitoring And Reliable Telecommunications (SMART) Subsea Cables is working to integrate environmental sensors (temperature, pressure, seismic acceleration) into submarine telecommunications cables. This will support climate and ocean observation, sea-level monitoring, observations of Earth structure, tsunami and earthquake early warning, and disaster risk reduction. Recent advances include regional SMART pilot systems that are the initial steps to trans-ocean and global implementation. Building on the OceanObs’19 conference and community white paper (https://doi.org/10.3389/ fmars.2019.00424), this paper presents an overview of the initiative and a description of ongoing projects including: InSea wet demonstration project off Sicily; Vanuatu and New Caledonia; Indonesia; CAM-2 ring system connecting the Portuguese mainland, Azores, and Madeira; New Zealand; and Antarctica. In addition to the diverse scientific and societal benefits, the telecommunications industry’s mission of societal connectivity will also benefit because environmental awareness improves both individual cable system integrity and the resilience of the overall global communications network. Keywords: telecommunication cables, SMART sensors, seafloor sensing, earthquake early warning, tsunami detection

Description: The Joint Task Force, Science Monitoring And Reliable Telecommunications (JTF SMART) Subsea Cables, is working to integrate environmental sensors for ocean bottom temperature, pressure, and seismic acceleration into submarine telecommunications cables. The purpose of SMART Cables is to support climate and ocean observation, sea level monitoring, observations of Earth structure, and tsunami and earthquake early warning and disaster risk reduction, including hazard quantification. Recent advances include regional SMART pilot systems that are the first steps to trans-ocean and global implementation. Examples of pilots include: InSEA wet demonstration project off Sicily at the European Multidisciplinary Seafloor and water column Observatory Western Ionian Facility; New Caledonia and Vanuatu; French Polynesia Natitua South system connecting Tahiti to Tubaui to the south; Indonesia starting with short pilot systems working toward systems for the Sumatra-Java megathrust zone; and the CAM-2 ring system connecting Lisbon, Azores, and Madeira. This paper describes observing system simulations for these and other regions. Funding reflects a blend of government, development bank, philanthropic foundation, and commercial contributions. In addition to notable scientific and societal benefits, the telecommunications enterprise’s mission of global connectivity will benefit directly, as environmental awareness improves both the integrity of individual cable systems as well as the resilience of the overall global communications network. SMART cables support the outcomes of a predicted, safe, and transparent ocean as envisioned by the UN Decade of Ocean Science for Sustainable Development and the Blue Economy. As a continuation of the OceanObs’19 conference and community white paper (Howe et al., 2019, doi: 10.3389/fmars.2019.00424), an overview of the SMART programme and a description of the status of ongoing projects are given.

Description: The recent proliferation of broadband ocean bottom seismometer (BBOBS) deployments has generated datasets from diverse marine environments, improving our understanding of tectonics and earthquake processes. In turn, the community of scientists using this data has expanded. This growth in BBOBS data collection is likely to persist with the arrival of new seismic seafloor technologies, and continued scientific interest in marine and amphibious targets. However, the noise inherent in OBS data poses a challenge that is markedly different from that of terrestrial data. As a step towards improved understanding of the sources of variability in this noise, we present a new compilation and analysis of BBOBS noise properties from 15 years of US-led seismic deployments. We find evidence for similarity of noise properties when grouped across a variety of parameters, with groupings by seismometer type and deployment water depth yielding the most significant and interpretable results. Instrument design, that is the entire deployed package, also plays an important role, although it strongly covaries with seismometer and water depth. We find that the presence of tilt noise is primarily dependent on the type of seismometer used (covariant with a particular subset of instrument design), that compliance noise follows anticipated relationships with water depth, and that shallow, oceanic shelf environments have systematically different microseism noise properties (which are, in turn, different from instruments deployed in shallow lake environments). We discuss implications for the viability of commonly used seismic analysis techniques, and future directions for improvements in the efficiency of analysis of BBOBS data.

Description: Recent research points to complex, multi-layered, transcrustal magmatic systems beneath volcanoes. But constraints on depths of magma storage in the mid-to-deep crust beneath volcanoes remain an enigmatic target. At volcanic arcs, magmatic processes at these depths are a critical link between the input from the slab and mantle wedge, the emplacement processes that build and alter arc crust, and the shallow crustal reservoirs that drive eruptions. Magmatic storage depths and pathways may be governed by a variety of properties, including volatile content, crustal stress regime, prexisting structures, and more. To better understand how these variables may impact arc volcano processes, we must employ techniques that allow us to characterize magma storage depths at volcanoes globally. Here, we investigate receiver functions as a technique to provide systematic, first-order constraints on magma storage depths in the mid-to-deep crust using data from the Alaska-Aleutian island arc as a case study. Receiver functions are sensitive to abrupt seismic velocity boundaries, and have detected low velocity zones in the crust interpreted as magmatic-mush systems at Akutan and Cleveland, two Alaska-Aleutian arc volcanoes. They do not rely on the presence of local seismicity, do not require a wide-aperature array to image the whole crust, and can be analyzed at volcanoes with relatively few (〈 4) local instruments. We present results of the application of this technique across the Alaska-Aleutian arc, and examine along-arc trends in receiver function properties.