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At least 703 records · Page 39Linked to original sources

USGS2014

Termini of calving glaciers as self-organized critical systems

Over the next century, one of the largest contributions to sea level rise will come from ice sheets and glaciers calving ice into the ocean 1 . Factors controlling the rapid and nonlinear variations in calving fluxes are poorly understood, and therefore difficult to include in prognostic climate-forced land-ice models. Here we analyse globally distributed calving data sets from Svalbard, Alaska (USA), Greenland and Antarctica in combination with simulations from a first-principles, particle-based numerical calving model to investigate the size and inter-event time of calving events. We find that calving events triggered by the brittle fracture of glacier ice are governed by the same power-law distributions as avalanches in the canonical Abelian sandpile model 2 . This similarity suggests that calving termini behave as self-organized critical systems that readily flip between states of sub-critical advance and super-critical retreat in response to changes in climate and geometric conditions. Observations of sudden ice-shelf collapse and tidewater glacier retreat in response to gradual warming of their environment 3 are consistent with a system fluctuating around its critical point in response to changing external forcing. We propose that self-organized criticality provides a yet unexplored framework for investigations into calving and projections of sea level rise.

Nature Geoscience↗

USGS2010

Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate boundary zone

Tectonic reconstructions of the Caribbean Plate are severely hampered by a paucity of geochronologic and exhumation constraints from anastomosed basement blocks along its southern margin. New U/Pb, 40 Ar/ 39 Ar, apatite fission track, and apatite (U-Th)/He data constrain quantitative thermal and exhumation histories, which have been used to propose a model for the tectonic evolution of the emergent parts of the Bonaire Block and the southern Caribbean Plate boundary zone. An east facing arc system intruded through an oceanic plateau during ~90 to ~87 Ma and crops out on Aruba. Subsequent structural displacements resulted in >80°C of cooling on Aruba during 70–60 Ma. In contrast, exhumation of the island arc sequence exposed on Bonaire occurred at 85–80 Ma and 55–45 Ma. Santonian exhumation on Bonaire occurred immediately subsequent to burial metamorphism and may have been driven by the collision of a west facing island arc with the Caribbean Plate. Island arc rocks intruded oceanic plateau rocks on Gran Roque at ~65 Ma and exhumed rapidly at 55–45 Ma. We attribute Maastrichtian-Danian exhumation on Aruba and early Eocene exhumation on Bonaire and Gran Roque to sequential diachronous accretion of their basement units to the South American Plate. Widespread unconformities indicate late Eocene subaerial exposure. Late Oligocene–early Miocene dextral transtension within the Bonaire Block drove subsidence and burial of crystalline basement rocks of the Leeward Antilles to ≤1 km. Late Miocene–recent transpression caused inversion and ≤1 km of exhumation, possibly as a result of the northward escape of the Maracaibo Block.

Tectonics↗

USGS2011

Natural radium and radon tracers to quantify water exchange and movement in reservoirs

Radon and radium isotopes are routinely used to quantify exchange rates between different hydrologic reservoirs. Since their recognition as oceanic tracers in the 1960s, both radon and radium have been used to examine processes such as air-sea exchange, deep oceanic mixing, benthic inputs, and many others. Recently, the application of radon-222 and the radium-quartet (223,224,226,228Ra) as coastal tracers has seen a revelation with the growing interest in coastal groundwater dynamics. The enrichment of these isotopes in benthic fluids including groundwater makes both radium and radon ideal tracers of coastal benthic processes (e.g. submarine groundwater discharge). In this chapter we review traditional and recent advances in the application of radon and radium isotopes to understand mixing and exchange between various hydrologic reservoirs, specifically: (1) atmosphere and ocean, (2) deep and shallow oceanic water masses, (3) coastal groundwater/benthic pore waters and surface ocean, and (4) aquifer-lakes. While the isotopes themselves and their distribution in the environment provide qualitative information about the exchange processes, it is mixing/exchange and transport models for these isotopes that provide specific quantitative information about these processes. Brief introductions of these models and mixing parameters are provided for both historical and more recent studies.

Book chapter↗

USGS1974

Tectonic evolution of the southern Gulf of Mexico

A detailed magnetic survey in the southern Gulf of Mexico shows subdued irregular magnetic anomalies that are similar in wave length to those attributed to sea-floor spreading on present-day oceanic rises. The small amplitude of these anomalies, about 75γ, would be compatible with an oceanic basalt source at a depth of 10 km, and previous seismic refraction studies in this area have shown that layer 2 of the oceanic crust (presumed to be basalt) does indeed lie at approximately that depth. Palynomorphs in Deep Sea Drilling Project samples of cap-rock material from the Sigsbee Knolls have shown the associated salt to be Jurassic. A crustal model, based on seismic refraction evidence and on new gravity data, suggests that, whereas the salt-dome belt of the southern gulf is underlain by a thick layer with a density of 2.2 g per cm 3 (presumed to be halite rock), adjacent deeper areas of the basin seem to lack this low density layer. In northeastern Mexico, Triassic red beds fill grabens that are correlative with the Newark Group of the Atlantic Coast and suggest that the Gulf of Mexico originated at the time of the initial rifting of the North Atlantic. When the gulf was about half-opened during the Jurassic, oceanic circulation was restricted; and thick deep-basin evaporite deposits, analogous to those found in the Mediterranean Sea by the Deep Sea Drilling Project, were laid down. Further opening established normal salinity and led to the development of salt-free areas of oceanic crust that separated the Sigsbee Escarpment (together with adjacent ridges of offshore Mexico) from the Sigsbee Knolls and salt domes of Cuba. The subsequent structural evolution of the Gulf of Mexico basin is believed to have been mainly a result of interaction between it and tectonic plates of the Pacific area. After opening of the gulf, subduction began along the Cuban arc, where Atlantic rifting had created a nearly uninterrupted tract of oceanic crust extending from the Pacific between Yucatán and Colombia. Then, folding and gravity sliding associated with Laramide deformation on the west side of the gulf led to salt anticlines that underlie the ridges offshore from Mexico. Except for continued diapirism and subsidence associated with sediment loading, present tectonic activity is confined to the southwestern corner of the gulf, where volcanism and intermediate-focus earthquakes are a distant manifestation of subduction along the Middle America Trench on the Pacific side of Mexico.

Gulf of Mexico↗

USGS2016

Predictive mapping of seabirds, pinnipeds and cetaceans off the Pacific Coast of Washington

About this report This report supports Washington-led marine spatial planning and responsible stewardship of natural and cultural resources by the Olympic Coast National Marine Sanctuary. Washington state agencies and the sanctuary continually seek the best available science to improve management of marine uses and stewardship of resources (Etheridge et al., 2010; Washington Department of Fish and Wildlife, 2015a). This report and associated data provide new, state- and sanctuary-requested information on seabird, pinniped, and cetacean distributions. Through spatial planning, information on species distributions can help to identify high-value conservation areas, minimize adverse effects of ocean uses and mitigate impacts of coastal hazards. Correspondingly, the Washington Department of Fish and Wildlife has already begun to use the maps of predicted relative density presented in this report to identify ecologically important areas off the Pacific Coast of Washington and apply this information to plan for offshore renewable energy development. This is the culmination of three years of work to compile information on seabirds, pinnipeds, and cetaceans, and advance a modeling framework that can integrate data sets and develop accurate predictions of relative density for important species off the Pacific Coast of Washington. Previous reports, which evaluated existing datasets of at-sea observations (Menza et al., 2014; Kracker and Menza, 2015) and presented superseded versions of seabird models (Menza et al., 2015), provided base information for this report. In addition to the maps in this published report, all new seabird, pinniped and cetacean predictions will be made publicly available as digital geospatial data through the National Centers for Environmental Information. This research supports the National Oceanic and Atmospheric Administration (NOAA) Coastal Zone Management Program, a voluntary partnership between the federal government and U.S. coastal and Great Lakes states and territories authorized by the Coastal Zone Management Act (CZMA) of 1972 to address national coastal issues. The act provides the basis for protecting, restoring, and responsibly developing our nation’s diverse coastal communities and resources. To meet the goals of the CZMA, the national program takes a comprehensive approach to coastal resource management – balancing the often competing and occasionally conflicting demands of coastal resource use, economic development, and conservation. A wide range of issues are addressed through the program, including coastal development, water quality, public access, habitat protection, energy facility siting, ocean governance and planning, coastal hazards, and climate change. Accurate maps of seabird and marine mammal distributions are an important tool for making informed management decisions that affect all of these issues.

Washington↗

USGS2016

Intertidal salt marshes as an important source of inorganic carbon to the coastal ocean

Dynamic tidal export of dissolved inorganic carbon (DIC) to the coastal ocean from highly productive intertidal marshes and its effects on seawater carbonate chemistry are thoroughly evaluated. The study uses a comprehensive approach by combining tidal water sampling of CO 2 parameters across seasons, continuous in situ measurements of biogeochemically-relevant parameters and water fluxes, with high-resolution modeling in an intertidal salt marsh of the U.S. northeast region. Salt marshes can acidify and alkalize tidal water by injecting CO 2 (DIC) and total alkalinity (TA). DIC and TA generation may also be decoupled due to differential effects of marsh aerobic and anaerobic respiration on DIC and TA. As marsh DIC is added to tidal water, the buffering capacity first decreases to a minimum and then increases quickly. Large additions of marsh DIC can result in higher buffering capacity in ebbing tide than incoming tide. Alkalization of tidal water, which mostly occurs in the summer due to anaerobic respiration, can further modify buffering capacity. Marsh exports of DIC and alkalinity may have complex implications for the future, more acidified ocean. Marsh DIC export exhibits high variability over tidal and seasonal cycles, which is modulated by both marsh DIC generation and by water fluxes. The marsh DIC export of 414 g C m −2 yr −1 , based on high-resolution measurements and modeling, is more than twice the previous estimates. It is a major term in the marsh carbon budget and translates to one of the largest carbon fluxes along the U.S. East Coast.

Massachusetts↗

USGS2025

Surface-wave relocation and characterization of the October 2023 tsunamigenic seismic unrest near Sofugan volcano, Izu Islands, Japan

A moderate-magnitude earthquake swarm occurred in the remote Izu Islands region of Japan between October 1 and 8, 2023. The swarm included 151 shallow earthquakes cataloged by the U.S. Geological Survey, which notably included a roughly 2.5-hr episode of 15 successive magnitude (M) < 5.5 earthquakes. Origin times were coincident with regionally recorded tsunami waves, but tsunamigenesis for moderate-magnitude earthquakes is uncommon, indicating that volcanic activity generated the ocean displacements. Leveraging a surface-wave relative relocation approach, we estimate precise epicentroid locations for the remote swarm. Final epicentroids and caldera analogs indicate a three-stage model to explain swarm activity: (a) caldera pressurization due to magma intrusion, (b) depressurization via dike propagation away from the caldera, and (c) eruption corresponding with caldera reactivation either by collapse or additional intrusion.

Sofugan volcano, Izu Islands↗

USGS2014

Remediation scenarios for attenuating peak flows and reducing sediment transport in Fountain Creek, Colorado, 2013

The U.S. Geological Survey (USGS) in cooperation with the Fountain Creek Watershed, Flood Control and Greenway District assessed remediation scenarios to attenuate peak flows and reduce sediment loads in the Fountain Creek watershed. To evaluate these strategies, the U.S. Army Corps of Engineers Hydrologic Engineering Center (HEC) hydrologic and hydraulic models were employed. The U.S. Army Corps of Engineers modeling system HEC-HMS (Hydrologic Modeling System) version 3.5 was used to simulate runoff in the Fountain Creek watershed, Colorado, associated with storms of varying magnitude and duration. Rain-gage precipitation data and radar-based precipitation data from the April 28–30, 1999, and September 14–15, 2011, storm events were used in the calibration process for the HEC-HMS model. The curve number and lag time for each subwatershed and Manning's roughness coefficients for each channel reach were adjusted within an acceptable range so that the simulated and measured streamflow hydrographs for each of the 12 USGS streamgages approximated each other. The U.S. Army Corps of Engineers modeling system HEC-RAS (River Analysis System) versions 4.1 and 4.2 were used to simulate streamflow and sediment transport, respectively, for the Fountain Creek watershed generated by a particular storm event. Data from 15 USGS streamgages were used for model calibration and 7 of those USGS streamgages were used for model validation. The calibration process consisted of comparing the simulated water-surface elevations and the cross-section-averaged velocities from the model with those surveyed in the field at the cross section at the corresponding 15 and 7 streamgages, respectively. The final Manning’s roughness coefficients were adjusted between –30 and 30 percent at the 15 calibration streamgages from the original left, right, and channel-averaged Manning's roughness coefficients upon completion of calibration. The U.S. Army Corps of Engineers modeling system HEC-RAS version 4.2 was used to simulate streamflow and sediment transport for the Fountain Creek watershed generated by a design-storm event. The Laursen-Copeland sediment-transport function was used in conjunction with the Exner 5 sorting method and the Ruby fall-velocity method to predict sediment transport. Six USGS streamgages equipped with suspended-sediment samplers were used to develop sediment-flow rating curves for the sediment-transport-model calibration. The critical Shields number in the Laursen-Copeland sediment-transport function and the volume of sediment available at a given cross section were adjusted during the HEC-RAS sediment-model calibration process. HEC-RAS model simulations used to evaluate the 14 remediation scenarios were based on unsteady-state streamflows associated with a 24-hour, 1-percent annual exceedance probability (100-year) National Oceanic and Atmospheric Administration Type II precipitation event. Scenario 0 represents the baseline or current conditions in the watershed and was used to compare the remaining 13 scenarios. Scenarios 1–8 and 12 rely on side-detention facilities to reduce peak flows and sediment transport. Scenario 9 has a diversion channel, and scenario 10 has a reservoir. Scenarios 11 and 13 incorporate channel armoring and channel widening, respectively. Scenarios 8 and 10, the scenario with the most side-detention facilities, and the scenario with the reservoir, respectively, were the most effective at reducing sediment transport and peak flow at the Pueblo, Colorado, streamgage. Scenarios 8 and 10 altered the peak flow by –58.9 and –56.4 percent, respectively. In turn, scenarios 8 and 10 altered the sediment transport by –17.7 and –62.1 percent, respectively.

Colorado↗

USGS2013

Annual modulation of non-volcanic tremor in northern Cascadia

Two catalogs of episodic tremor events in northern Cascadia, one from 2006 to 2012 and the other from 1997 to 2011, reveal two systematic patterns of tremor occurrence in southern Vancouver Island: (1) most individual events tend to occur in the third quarter of the year; (2) the number of events in prolonged episodes (i.e., episodic tremor and slip events), which generally propagate to Vancouver Island from elsewhere along the Cascadia subduction zone, is inversely correlated with the amount of precipitation that occurred in the preceding 2 months. We rationalize these patterns as the product of hydrologic loading of the crust of southern Vancouver Island and the surrounding continental region, superimposed with annual variations from oceanic tidal loading. Loading of the Vancouver Island crust in the winter (when the land surface receives ample precipitation) and unloading in the summer tends to inhibit and enhance downdip shear stress, respectively. Quantitatively, for an annually variable surface load, the predicted stress perturbation depends on mantle viscoelastic rheology. A mechanical model of downdip shear stress on the transition zone beneath Vancouver Island—driven predominantly by the annual hydrologic cycle—is consistent with the 1997–2012 tremor observations, with peak-to-peak downdip shear stress of about 0.4 kPa. This seasonal dependence of tremor occurrence appears to be restricted to southern Vancouver Island because of its unique situation as an elongated narrow-width land mass surrounded by ocean, which permits seasonal perturbations in shear stress at depth.

Journal of Geophysical Research B: Solid Earth↗

USGS2018

Hawai‘i and U.S.-Affiliated Pacific Islands

The U.S. Pacific Islands are culturally and environmentally diverse, treasured by the 1.9 million people who call them home. Pacific islands are particularly vulnerable to climate change impacts due to their exposure and isolation, small size, low elevation (in the case of atolls), and concentration of infrastructure and economy along the coasts. A prevalent cause of year-to-year changes in climate patterns around the globe and in the Pacific Islands region is the El Niño –Southern Oscillation (ENSO). The El Niño and La Niña phases of ENSO can dramatically affect precipitation, air and ocean temperature, sea surface height, storminess, wave size, and trade winds. It is unknown exactly how the timing and intensity of ENSO will continue to change in the coming decades, but recent climate model results suggest a doubling in frequency of both El Niño and La Niña extremes in this century as compared to the 20th century under scenarios with more warming, including the higher scenario (RCP8.5). On islands, all natural sources of freshwater come from rainfall received within their limited land areas. Severe droughts are common, making water shortage one of the most important climate-related risks in the region. As temperature continues to rise and cloud cover decreases in some areas, evaporation is expected to increase, causing both reduced water supply and higher water demand. Streamflow in Hawai‘i has declined over approximately the past 100 years, consistent with observed decreases in rainfall. The impacts of sea level rise in the Pacific include coastal erosion, episodic flooding, permanent inundation, heightened exposure to marine hazards, and saltwater intrusion to surface water and groundwater systems. Sea level rise will disproportionately affect the tropical Pacific and potentially exceed the global average. Invasive species , landscape change, habitat alteration, and reduced resilience have resulted in extinctions and diminished ecosystem function. Inundation of atolls in the coming decades is projected to impact existing on-island ecosystems. Wildlife that relies on coastal habitats will likely also be severely impacted. In Hawaiʻi, coral reefs contribute an estimated $477 million to the local economy every year. Under projected warming of approximately 0.5°F per decade, all nearshore coral reefs in the Hawai‘i and Pacific Islands region will experience annual bleaching before 2050. An ecosystem -based approach to international management of open ocean fisheries in the Pacific that incorporates climate-informed catch limits is expected to produce more realistic future harvest levels and enhance ecosystem resilience. Indigenous communities of the Pacific derive their sense of identity from the islands. Emerging issues for Indigenous communities of the Pacific include the resilience of marine-managed areas and climate-induced human migration from their traditional lands. The rich body of traditional knowledge is place-based and localized and is useful in adaptation planning because it builds on intergenerational sharing of observations. Documenting the kinds of governance structures or decision-making hierarchies created for management of these lands and waters is also important as a learning tool that can be shared with other island communities. Across the region, groups are coming together to minimize damage and disruption from coastal flooding and inundation as well as other climate-related impacts. Social cohesion is already strong in many communities, making it possible to work together to take action. Early intervention can lower economic, environmental, social, and cultural costs and reduce or prevent conflict and displacement from ancestral land and resources.

Report↗

USGS2000

Growth response of a deep-water ferromanganese crust to evolution of the Neogene Indian Ocean

A deep-water ferromanganese crust from a Central Indian Ocean seamount dated previously by 10Be and 230Th(excess) was studied for compositional and textural variations that occurred throughout its growth history. The 10Be/9Be dated interval (upper 32 mm) yields an uniform growth rate of 2.8 ?? 0.1 mm/Ma [Frank, M., O'Nions, R.K., 1998. Sources of Pb for Indian Ocean ferromanganese crusts: a record of Himalayan erosion. Earth Planet. Sci. Lett., 158, pp. 121-130.] which gives an extrapolated age of ~ 26 Ma for the base of the crust at 72 mm and is comparable to the maximum age derived from the Co-model based growth rate estimates. This study shows that Fe-Mn oxyhydroxide precipitation did not occur from the time of emplacement of the seamount during the Eocene (~ 53 Ma) until the late Oligocene (~ 26 Ma). This paucity probably was the result of a nearly overlapping palaeo-CCD and palaeo-depth of crust formation, increased early Eocene productivity, instability and reworking of the surface rocks on the flanks of the seamount, and lack of oxic deep-water in the nascent Indian Ocean. Crust accretion began (older zone) with the formation of isolated cusps of Fe-Mn oxide during a time of high detritus influx, probably due to the early-Miocene intense erosion associated with maximum exhumation of the Himalayas (op. cit.). This cuspate textured zone extends from 72 mm to 42 mm representing the early-Miocene period. Intense polar cooling and increased mixing of deep and intermediate waters at the close of the Oligocene might have led to the increased oxygenation of the bottom-water in the basin. A considerable expansion in the vertical distance between the seafloor depth and the CCD during the early Miocene in addition to the influx of oxygenated bottom-water likely initiated Fe-Mn crust formation. Pillar structure characterises the younger zone, which extends from 40 mm to the surface of the crust, i.e., ~ 15 Ma to Present. This zone is characterised by > 25% higher content of oxide-bound elements than in the older zone, possibly corresponding to further increased oxygenation of bottom-waters, increased stability of the seamount slope, and gradually reduced input of continental detritus from the erosion of the Himalayas. Middle Miocene Antarctic glaciation, which peaked ~ 12-13 Ma ago, increased the oxic bottom-water influx to the basin resulting in accretion of the crust with low detritus. Therefore, the younger crust started to accrete in response to a shift in bottom-water circulation towards the contemporary pattern, which produced a uniform growth rate and pillar structure up to the present. (C) 2000 Published by Elsevier Science B.V.

Marine Geology↗

USGS2011

The geochemistry and petrogenesis of the Paleoproterozoic Green Mountain arc: A composite(?), bimodal, oceanic, fringing arc

The inferred subduction affinity of the ∼1780-Ma Green Mountain arc, a dominantly bimodal igneous terrane (together with immature marine and volcaniclastic sedimentary rocks) accreted to the southern margin of the Wyoming province, is integral to arc-accretion models of the Paleoproterozoic growth of southern Laurentia. Conversely, the dominantly bimodal nature of many putative arc-related igneous suites throughout southern Laurentia, including the Green Mountain arc, has also been used to support models of growth by extension of pre-existing crust. We report new geochemical and isotopic data from ∼1780-Ma gabbroic and granodioritic to tonalitic rocks of the Big Creek Gneiss, interpreted as consanguineous with previously studied metavolcanic rocks of the Green Mountain Formation. The ∼1780-Ma Big Creek Gneiss mafic rocks show clear geochemical signatures of a subduction origin and provide no supporting evidence for extensional tectonism. The ∼1780-Ma Big Creek Gneiss felsic rocks are attributed to partial melting of mafic and/or mixed lower-crustal material. The bimodal nature of the suite results from the combination of arc basalts and felsic crustal melts. The lack of andesite is consistent with the observed tholeiitic differentiation trend of the mafic magmas. The lower ɛ Nd (1780 Ma) values for the felsic rocks vs. the mafic rocks suggest that the unexposed lower crust of the arc may be older than the arc and that Trans-Hudson- or Penokean-aged rocks possibly form the substratum of the arc. Our results reinforce previous interpretations that arc-related magmatism played a key role in the Paleoproterozoic crustal growth of southern Laurentia, but also support the possibility of unexposed older crust as basement to the arcs.

Wyoming, Colorado↗

USGS2008

Factors influencing densities of non-indigenous species in the ballast water of ships arriving at ports in Puget Sound, Washington, United States

Oceanographic characteristics and the presence of international shipping in Puget Sound, Washington, USA contribute to its vulnerability to non-indigenous species (NIS) invasions. To evaluate NIS arriving in ballast water, zooplankton was sampled in 380 ballast tanks of ships after they entered Puget Sound. Taxa were classified into a higher risk group of coastal organisms (including known NIS), and a lower risk group of largely oceanic species. Most ships reported conducting mid-ocean ballast water exchange (BWE). However, despite state regulations requiring BWE, and apparent compliance by ship operators, most sampled tanks from both transpacific and coastal routes had coastal zooplankton densities exceeding internationally proposed discharge standards. BWE efficiency models and controlled before-and-after BWE experiments indicate that BWE consistently removes most coastal zooplankton. However, this study found that although the empty-refill method of BWE significantly reduced coastal plankton compared with un-exchanged tanks, the flow-through method did not, and in either case remaining coastal plankton densities presented appreciable risks of introducing NIS. Densities of high risk taxa were consistently and significantly higher from US domestic trips dominated by tank ships carrying ballast water from California, and lower in samples from trans-Pacific trips dominated by container ships and bulk carriers with ballast from Asia. These findings are probably a result of the dense and diverse NIS assemblages present in California and other US west coast estuaries and the comparatively short transit times between them and Puget Sound. While it appears that BWE can effectively replace NIS with less risky ocean species, new reporting, verification, and operational procedures may be necessary to enhance BWE efficacy. In the long-term, the introduction of ballast water treatment technologies may be required to significantly reduce the discharge of risky organisms from commercial ships if BWE practices do not become more effective. Copyright ?? 2008 John Wiley & Sons, Ltd.

Aquatic Conservation: Marine and Freshwater Ecosys↗

USGS2018

Hydrogeology of, simulation of groundwater flow in, and potential effects of sea-level rise on the Kirkwood-Cohansey aquifer system in the vicinity of Edwin B. Forsythe National Wildlife Refuge, New Jersey

The Edwin B. Forsythe National Wildlife Refuge encompasses more than 47,000 acres of New Jersey coastal habitats, including salt marshes, freshwater wetlands, tidal wetlands, barrier beaches, woodlands, and swamps. The refuge is along the Atlantic Flyway and provides breeding habitat for fish, migratory birds, and other wildlife species. The refuge area may be threatened by global climate change, including sea-level rise (SLR). The Kirkwood-Cohansey aquifer system underlies the Edwin B. Forsythe National Wildlife Refuge. Groundwater is an important source of freshwater flow into the refuge, but information about the interaction of surface water and groundwater in the refuge area and the potential effects of SLR on the underlying aquifer system is limited. The U.S. Geological Survey (USGS), in cooperation with the U.S. Fish and Wildlife Service (USFWS), conducted a hydrologic assessment of the refuge in New Jersey and developed a groundwater flow model to improve understanding of the geohydrology of the refuge area and to serve as a tool to evaluate changes in groundwater-level altitudes that may result from a rise in sea level. Groundwater flow simulations completed for this study include a calibrated baseline simulation that represents 2005–15 hydraulic conditions and three SLR scenarios―20, 40, and 60 centimeters (cm) (0.656, 1.312, and 1.968 feet, respectively). Results of the three SLR simulations indicate that the water table in the unconfined Kirkwood-Cohansey aquifer system in the refuge area will rise, resulting in increased discharge of fresh groundwater to freshwater wetlands and streams. As sea level rises, simulated groundwater discharge to the salt marsh, bay, and ocean is projected to decrease. Flow from the salt marsh, bay, and ocean to the overlying surface water is projected to increase as sea level rises. The simulated movement of the freshwater-seawater interface as sea level rises depends on the hydraulic-head gradient. In the center of the Forsythe model area, topographic relief is 23 feet (ft) and the hydraulic-head gradient is 0.0033. In the center of the Forsythe model area, the simulated interface moved inland about 600 ft and downward about 15 ft from the baseline simulation to scenario 3 as a result of a SLR of 60 cm. In the southern part of the Forsythe model area, the topography is flatter (relief of 8 ft) and the hydraulic-head gradient is smaller (0.001). In the southern part of the Forsythe model study area, the simulated interface in this area is projected to move inland about 200 ft from the baseline simulation to scenario 3 and does not move downward.

New Jersey↗

USGS2021

Preconditioning by sediment accumulation can produce powerful turbidity currents without major external triggers

Turbidity currents dominate sediment transfer into the deep ocean, and can damage critical seabed infrastructure. It is commonly inferred that powerful turbidity currents are triggered by major external events, such as storms, river floods, or earthquakes. However, basic models for turbidity current triggering remain poorly tested, with few studies accurately recording precise flow timing. Here, we analyse the most detailed series of measurements yet made of powerful (up to 7.2 m s −1 ) turbidity currents, within Monterey Canyon, offshore California. During 18-months of instrument deployment, fourteen turbidity currents were directly monitored. No consistent triggering mechanism was observed, though flows did cluster around enhanced seasonal sediment supply. We compare turbidity current timing at Monterey Canyon (a sandy canyon-head fed by longshore drift) to the only other systems where numerous (>10-100) flows have been measured precisely via direct monitoring; the Squamish Delta (a sandy fjord-head delta), and the Congo Canyon (connected to the mud-dominated mouth of the Congo River). A common seasonal pattern emerges, leading to a new model for preconditioning and triggering of turbidity currents initiating through slope failure in areas of sediment accumulation, such as canyon heads or river mouths. In this model, rapid or sustained sediment supply alone can produce elevated pore pressures, which may persist, thereby predisposing slopes to fail. Once preconditioned, a range of minor external perturbations, such as moderate storm-waves, result in local pore pressure variation, and thus become effective triggers. Major external triggers are therefore not always a prerequisite for triggering of powerful turbidity currents.

Earth and Planetary Science Letters↗

USGS2026

Advances in volcano monitoring driven by the first decade of Sentinel-1 observations

Sentinel-1 has transformed how satellite radar data (SAR and InSAR) are used in volcanology. The systematic, long-term archive and open-access policy means that volcano observatories and research organisations have invested in integrating Sentinel-1 datasets into their monitoring systems. We identify 233 high priority volcanoes and estimate that Sentinel-1 data has been used in peer-reviewed publications for 90 of them. We examine a global archive of 3.3 million automatically processed Sentinel-1 interferograms of volcanoes and use machine learning methods to identify eruptions and periods of unrest. We then review the ways in which InSAR data are being used in different contexts. At frequently erupting basaltic systems in Iceland, Hawaiʻi, the Galápagos , and Piton de la Fournaise, InSAR has become an effective monitoring tool and is integrated with other datasets and models to forecast magma pathways. For large explosive eruptions, deformation measurements often remain challenging, but SAR backscatter is increasingly used to map damaging flows and measure the changing shape of ocean islands. Sentinel-1's long archive provides critical baseline measurements that are vital for measuring slow deformation, capturing new periods of unrest and providing fresh insights into subsurface dynamics. Understanding the drivers of deformation remains challenging and typically relies on integration with external datasets. Future European Space Agency missions have the potential to improve both resolution and coverage providing an even richer dataset to further enhance global volcano monitoring

Erta Ale volcano↗

USGS2023

A global ecological signal of extinction risk in marine ray-finned fishes (class Actinopterygii)

Many marine fish species are experiencing population declines, but their extinction risk profiles are largely understudied in comparison to their terrestrial vertebrate counterparts. Selective extinction of marine fish species may result in rapid alteration of the structure and function of ocean ecosystems. In this study, we compiled an ecological trait dataset for 8,185 species of marine ray-finned fishes (class Actinopterygii) from FishBase and used phylogenetic generalized linear models to examine which ecological traits are associated with increased extinction risk, based on the International Union for the Conservation of Nature Red List. We also assessed which threat types may be driving these species toward greater extinction risk and whether threatened species face a greater average number of threat types than non-threatened species. We found that larger body size and/or fishes with life histories involving movement between marine, brackish, and freshwater environments are associated with elevated extinction risk. Commercial harvesting threatens the greatest number of species, followed by pollution, development, and then climate change. We also found that threatened species, on average, face a significantly greater number of threat types than non-threatened species. These results can be used by resource managers to help address the heightened extinction risk patterns we found.

Cambridge Prisms: Extinction↗

USGS2020

Water tracks enhance water flow above permafrost in upland Arctic Alaska hillslopes

Upland permafrost regions occupy approximately one third of the Arctic landscape. In upland regions, hydrologic fluxes are influenced by water tracks, curvilinear features on hillslopes that preferentially fill with and route water in response to snowmelt and rainfall when the soil above continuous permafrost thaws in the summer. As continued warming of the Arctic may alter hydrologic cycling leading to increased frequency of extreme hydrologic events like drought and flooding as well as modification of biogeochemical cycling, it is imperative to untangle the interplay between precipitation, runoff, and subsurface flow as water is routed from upland Arctic regions to the Arctic Ocean. This study quantifies how ground surface temperatures affect groundwater discharge from hillslopes with water tracks in the upland Arctic by employing a three-dimensional, physically based subsurface flow model with variable saturation and freeze and thaw capabilities that is calibrated to field measurements from the Upper Kuparuk River watershed on the North Slope of Alaska, USA. Model analysis indicates that higher ground surface temperatures along water track hillslopes promote increases in groundwater discharge where water tracks act as conduits for large recharge events and continue to discharge groundwater into the autumn after the adjacent hillslope has frozen. Simulating the conditions that distinguish water tracks from their hillslope watersheds changes subsurface water storage and ground thermal responses but does not alter the total magnitude of groundwater discharge outside of parameter uncertainty. These findings suggest that water tracks play a complex and critical role in hydrologic cycles of the upland Arctic.

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