Integrating Science Needs with Advanced Seafloor Sensor Engineering to Provide Early Warning of Geohazards: Visioning Workshop and Roadmap for the Future

The workshop was funded by the National Science Foundation (NSF), OCE Division of Ocean Sciences (Award # 1817257). This report summarizes the key findings, outcomes, and recommendations of the workshop and serves as a draft of the comprehensive roadmap

Geochemical observations on Hydrate Ridge, Cascadia Margin during R/V BROWN-ROPOS cruise : August 1998

A massive release of methane on the Cascadia Hydrate Ridge was documented during a ROPOS program in August 1998, consistent with previously reported observations in 1996. An extensive survey of the seafloor revealed that the seeps lie within a narrow band trending 109 degrees. This feature parallels larger mounds imaged by Seabeam as well as larger structures of the accretionary prism such as the Daisy bank. The area of intense bubbling is characterized by extensive bacterial mats. Large clam fields were observed ten's of meters away from the gas seeps. A third province with carbonate blocks but no clams or bacterial mats was mapped approximately 200 meters away from the seeps. To constrain fluid flow through the sediments, we deployed 8 osomotic flow meters. The areas of gas discharge are discrete and highly focussed within conduits with an approximate cross-sectional area of 5 cm2. We estimate the gas flow rate to be on the order of 5 liters/minute. While the subsurface plumbing is unknown, the high flow rate of the sampled gas seep suggests a very short transit time from the gas source (presumably the base of the BSR at 70 mbsf) to the sea floor. The Rn/CH4 ratio in gas samples collected from the gas vents is very high, approximately 50 dpm/liter (stp) CH4. Using these values, we estimate that the time required for the fluids to transit 70 m is approximately 1 hour. To further constrain the nature of the discharging fluids, we will analyze samples for their elemental and isotopic composition. Methane hydrate should be stable at the temperature and pressure conditions at the seafloor on Hydrate Ridge. Indeed, solid hydrate was observed to form within the gas samplers as well as on the camera itself, supporting the conclusion that methane is rapidly transported to the seafloor from beneath the BSR within discrete conduits, most likely separated from significant amounts of pore water. When discharged at the seafloor, some of the methane precipitate as hydrate and some continues to rise within the water column. Bubbles were observed with the ROV up to 50 meters above the seafloor. This methane generates a plume in the water column, which was first documented during the 1996 GEOMAR survey. The most pronounced methane plumes observed during 1998 occur nearest to the active discharge sites, where methane concentrations up to 800 nmol/l were recorded

Managing toxicities associated with immune checkpoint inhibitors: consensus recommendations from the Society for Immunotherapy of Cancer (SITC) Toxicity Management Working Group.

Cancer immunotherapy has transformed the treatment of cancer. However, increasing use of immune-based therapies, including the widely used class of agents known as immune checkpoint inhibitors, has exposed a discrete group of immune-related adverse events (irAEs). Many of these are driven by the same immunologic mechanisms responsible for the drugs\u27 therapeutic effects, namely blockade of inhibitory mechanisms that suppress the immune system and protect body tissues from an unconstrained acute or chronic immune response. Skin, gut, endocrine, lung and musculoskeletal irAEs are relatively common, whereas cardiovascular, hematologic, renal, neurologic and ophthalmologic irAEs occur much less frequently. The majority of irAEs are mild to moderate in severity; however, serious and occasionally life-threatening irAEs are reported in the literature, and treatment-related deaths occur in up to 2% of patients, varying by ICI. Immunotherapy-related irAEs typically have a delayed onset and prolonged duration compared to adverse events from chemotherapy, and effective management depends on early recognition and prompt intervention with immune suppression and/or immunomodulatory strategies. There is an urgent need for multidisciplinary guidance reflecting broad-based perspectives on how to recognize, report and manage organ-specific toxicities until evidence-based data are available to inform clinical decision-making. The Society for Immunotherapy of Cancer (SITC) established a multidisciplinary Toxicity Management Working Group, which met for a full-day workshop to develop recommendations to standardize management of irAEs. Here we present their consensus recommendations on managing toxicities associated with immune checkpoint inhibitor therapy

Geochemical observations on Hydrate Ridge, Cascadia Margin : July 1999

Geophysical and biogeochemical processes associated with fluid venting from active and passive continental margins will receive significant scientific and economic attention into the next century and are of major societal relevance. An important unknown among these interrelated processes is the role played by methane gas hydrates, at and below the seafloor, and their impact on the oceans and atmosphere. Research scientists from institutions in the USA, Germany and Canada have developed a research project dedicated to a long-term study of continental margin gas hydrates on the Cascadia Accretionary Prism, under the acronym "TECFLUX". It is conceived as multi-stage research effort with the eventual goal of measuring the energy and chemical fluxes associated with this system, determining its temporal variability in response to tectonic and oceanographic forcing, and evaluating its impact on marine biogeochemical cycles

The Cascadia Initiative : a sea change In seismological studies of subduction zones

Author Posting. © The Oceanography Society, 2014. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 27, no. 2 (2014): 138-150, doi:10.5670/oceanog.2014.49.Increasing public awareness that the Cascadia subduction zone in the Pacific Northwest is capable of great earthquakes (magnitude 9 and greater) motivates the Cascadia Initiative, an ambitious onshore/offshore seismic and geodetic experiment that takes advantage of an amphibious array to study questions ranging from megathrust earthquakes, to volcanic arc structure, to the formation, deformation and hydration of the Juan De Fuca and Gorda Plates. Here, we provide an overview of the Cascadia Initiative, including its primary science objectives, its experimental design and implementation, and a preview of how the resulting data are being used by a diverse and growing scientific community. The Cascadia Initiative also exemplifies how new technology and community-based experiments are opening up frontiers for marine science. The new technology—shielded ocean bottom seismometers—is allowing more routine investigation of the source zone of megathrust earthquakes, which almost exclusively lies offshore and in shallow water. The Cascadia Initiative offers opportunities and accompanying challenges to a rapidly expanding community of those who use ocean bottom seismic data.The Cascadia Initiative is supported by the National Science Foundation; the CIET is supported under grants OCE- 1139701, OCE-1238023, OCE‐1342503, OCE-1407821, and OCE-1427663 to the University of Oregon

Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere?

There is growing concern about the transfer of methane originating from water bodies to the atmosphere. Methane from sediments can reach the atmosphere directly via bubbles or indirectly via vertical turbulent transport. This work quantifies methane gas bubble dissolution using a combination of bubble modeling and acoustic observations of rising bubbles to determine what fraction of the methane transported by bubbles will reach the atmosphere. The bubble model predicts the evolving bubble size, gas composition, and rise distance and is suitable for almost all aquatic environments. The model was validated using methane and argon bubble dissolution measurements obtained from the literature for deep, oxic, saline water with excellent results. Methane bubbles from within the hydrate stability zone (typically below ∼500 m water depth in the ocean) are believed to form an outer hydrate rim. To explain the subsequent slow dissolution, a model calibration was performed using bubble dissolution data from the literature measured within the hydrate stability zone. The calibrated model explains the impressively tall flares (>1300 m) observed in the hydrate stability zone of the Black Sea. This study suggests that only a small amount of methane reaches the surface at active seep sites in the Black Sea, and this only from very shallow water areas (<100 m). Clearly, the Black Sea and the ocean are rather effective barriers against the transfer of bubble methane to the atmosphere, although substantial amounts of methane may reach the surface in shallow lakes and reservoirs

Investigation of the role of gas hydrates in continental slope stability west of Fiordland, New Zealand

Sediment weakening due to increased local pore fluid pressure is interpreted to be the cause of a submarine landslide that has been seismically imaged off the southwest coast of New Zealand. Data show a distinct and continuous bottom‐simulating reflection (BSR)—a seismic phenomena indicative of the presence of marine gas hydrate—below the continental shelf from water depths of c. 2400 m to c. 750 m, where it intersects the seafloor. Excess pore fluid pressure (EPP) generated in a free gas zone below the base of gas hydrate stability is interpreted as being a major factor in the slope's destabilisation. Representative sediment strength characteristics have been applied to limit‐equilibrium methods of slope stability analysis with respect to the Mohr‐Coulomb failure criterion to develop an understanding of the feature's sensitivity to EPP. EPP has been modelled with representative material properties (internal angle of friction, bulk soil unit weight and cohesion) to show the considerable effect it has on stability. The best estimate of average EPP being solely responsible for failure is 1700 kPa, assuming a perfectly elastic body above a pre‐defined failure surface in a static environment

Hydrate Ridge—A Gas Hydrate System in a Subduction Zone Setting

Hydrate Ridge is a 6–10 km wide, 22 km long N–S striking thrust ridge within the Cascadia accretionary prism offshore of Oregon in the NE Pacific Ocean. Over the past four decades it has been a primary focus site for studies of gas hydrate/free gas systems within a convergent margin setting. A local peak called the North Hydrate Ridge (NHR), located at a depth of 590 m, hosts the first documented cold seep system driven by convergent margin processes and supports chemosynthetic communities sustained by the anaerobic oxidation of methane. A southern peak at 780 m depth, known as the South Hydrate Ridge (SHR), is actively venting gas around an area of seafloor bacterial mats and a 40 m high carbonate chimney within a long-lived vent system separate from NHR. Bottom simulating reflections (BSRs) observed in seismic profiles indicate these vents are part of a broad gas hydrate province that extends across all of Hydrate Ridge. Hydrate Ridge has been the focus of extensive geophysical surveys, water column acoustic and sampling surveys, high-resolution seafloor mapping using remotely operated, autonomous and deep-towed vehicles, seafloor fluid flow monitoring, and a site for the Ocean Observatories Initiative (OOI). All of these are in support or complementing Ocean Drilling Program (ODP) drilling efforts during Legs 146 and 204 to quantify and characterize the gas hydrate/free gas system. Hydrate concentrations are up to 45% of pore space (30% of total volume), but typically 2–20%, and are strongly coupled with the structure and stratigraphy within the thrust ridge

NORTH-SOUTH VARIABILITY IN THE HISTORY OF DEFORMATION AND FLUID VENTING ACROSS HYDRATE RIDGE, CASCADIA MARGIN

ABSTRACT Hydrate Ridge is an accretionary thrust ridge located on the lower slope of the central Cascadia convergent margin. Structural mapping using 2-D and 3-D multichannel seismic reflection profiles and gridded bathymetry coupled with deep towed sidescan sonar data and ODP drilling biostratigraphy, suggest that seafloor fluid venting patterns are likely controlled by the seaward vergent structural style at the older (&gt;1.6-1.7 Ma) crest of northern Hydrate Ridge (NHR) and by the dominantly landward vergent structural style at the younger (1.7 Ma to recent) crest of southern Hydrate Ridge (SHR). North-south structural variability across Hydrate Ridge is manifested on the seafloor as aerially extensive authigenic carbonate crusts on NHR and a minor focused occurrence of authigenic carbonate on SHR. The older stratigraphy exposed at the seafloor at NHR has likely been subjected to a longer history of sediment compaction, dewatering, and deformation than the younger slope basin strata preserved at SHR, suggesting the extent of carbonates at NHR may result from a more intense history of fluid flow through a more uplifted, lithified, and fractured NHR sequence. Furthermore, instead of abundant fault and fracture conduits as at NHR, recent work at SHR shows that the major seafloor fluid venting site there is fed by fluid flow through a volcanic ash bearing turbidite sequence. These observations suggest, stratigraphic conduits for fluid flow may be important in less uplifted, landward vergent dominated portions of Hydrate Ridge. In addition, the variability in structural style observed at Hydrate Ridge may have implications for the distributions and concentrations of fluids and gas hydrates in other accretionary settings and play a role in the susceptibility of accretionary ridges to slope failure