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At least 1,099 records · Page 61Linked to original sources
USGS2004

Uranium mill tailings: Nuclear waste and natural laboratory for geochemical and radioecological investigations

Uranium mill tailings (UMT) are a high volume, low specific activity radioactive waste typically disposed in surface impoundments. This review focuses on research on UMT and related earth materials during the past decade relevant to the assessment of: (1) mineral hosts of radionuclides; (2) the use of soil analogs in predicting long-term fate of radionuclides; (3) microbial and diagenetic processes that may alter radionuclide mobility in the surficial environment; (4) waste-management technologies to limit radionuclide migration; and (5) the impact of UMT on biota.

Journal of Environmental Radioactivity↗
USGS2021

Acoustic tag retention and tagging mortality of juvenile cisco Coregonus artedi

Release of hatchery-reared juvenile cisco ( Coregonus artedi ) is an important tool for recovering Great Lakes populations, but post-release survival is unknown. Telemetry using small acoustic tags provides opportunities to assess the efficacy of hatchery-reared fish releases. However, better understanding of the tolerance of juvenile cisco to acoustic tags is needed. Juvenile cisco mortality and tag retention as a function of tag size:body size (Relative Tag Weight, RTW) was observed for 30 d post tag implantation in the laboratory. Tag loss and mortality increased with RTW. A single mortality occurred for RTW ≤ 3% and tag retention and survival was <50% for RTW > 7.0%. Logistic regression predicted >95% survival and tag retention to 30 d for RTW < 2.5%, with full survival of study fish for RTW of ≤2%. Sedation and surgery times did not affect survival of tagged fish, but results of anesthesia-only and sham surgeries highlight the need to minimize handling effects for effective acoustic telemetry studies. Our findings clarify thresholds of RTW and indicate that juvenile cisco can receive acoustic tag implants. Observing these limitations can improve the effectiveness of acoustic telemetry to assess success of cultured juvenile fish releases for conservation or restoration of native forage fish populations. Evaluation of the effects of acoustic tags over longer time periods and under environmental conditions, like those at release sites, are needed to further validate this technology.

Journal of Great Lakes Research↗
USGS2021

Enhancing Great Lakes coastal ecosystems research by initiating engagement between scientists and decision-makers

A disconnect between scientific research and environmental management communities can be a detriment to both. In the case of Great Lakes coastal ecosystems, which are inherently complex and subject to uncertain effects of future climatic, environmental, and anthropogenic drivers, greater collaboration could be beneficial to their sustainability. We capture the challenges and opportunities identified by a scientist/decision-maker co-production workshop focused on the future environmental quality of Great Lakes coastal wetlands. We explain our path through the stakeholder workshop process, our challenges in translating meeting outcomes into actionable items, and lessons learned to bridge gaps between scientists and decision-makers. Additionally, we determine topics and directions identified by decision-makers that can be modeled with existing technologies and others that require further research. These topics may be incorporated into future research efforts and could serve as a shortlist of research priorities that were identified by decision-makers working with coastal wetland issues. Based on lessons learned during and after the workshop, we provide suggestions for bridging the gap between researchers and decision-makers, including sustained engagement between these groups and improved interaction through the beginning, duration, and end of research and/or management efforts.

Great Lakes↗
USGS2024

Predicting Lake Huron Dreissena spp. spatial distribution patterns from environmental characteristics

Invasive dreissenid mussels ( Dreissena polymorpha and Dreissena rostriformis bugensis ) have altered Great Lakes ecosystems through a multitude of effects on benthic habitats, food web structure, and nutrient cycling. This study explores whether spatially continuous geographic data of environmental factors can be utilized to predict Dreissena spp. spatial distributions on a lake-wide scale. Categorical variables were also assessed for significant relationships with Dreissena spp. biomass. Point observations from the 2017 Lake Huron benthic survey under the Cooperative Science and Monitoring Initiative (CSMI) were utilized for in situ measurements of dreissenid presence and biomass at 119 sites across Lake Huron. Basin, bathymetric zone, and tributary influence were found to have statistically significant relationships to dreissenid biomass. A boosted regression tree (BRT) model (ROC score 0.707) was developed to spatially predict dreissenid presence probability across Lake Huron from six environmental explanatory variables: April, May, and October chlorophyll, June dissolved organic carbon, January bottom temperature, and May bottom temperature. The importance of food availability and bottom temperature illuminated relationships between dreissenid mussels and periods of benthic-pelagic mixing in the spring and fall seasons. Future models could be improved through advancements in survey technology for improved geographic characterization of mussel habitat characteristics and environmental constraints.

Lake Huron↗
USGS2025

Visioning and conceptual framework for coordinating Great Lakes connecting waters research and monitoring

The Laurentian Great Lakes are connected via naturally occurring straits and rivers: St. Marys River, Straits of Mackinac, St. Clair-Detroit River System, Niagara River, and the St. Lawrence River. Despite the historical ecological and economic importance of these waters, international agreements (e.g., Great Lakes Water Quality Agreement) only recently explicitly named the Great Lakes Connecting Waters (GLCWs), requiring governments to address the challenges of adequate restoration and protection from historical use and degradation. Standardized research and monitoring activities are needed; however, there is no established mechanism for coordination across the GLCWs. A three-day summit in 2023 convened experts to form the initial framework for a GLCWs Collaborative to increase standardizations and knowledge transfer. Participants drafted a governance structure and priorities following the principles of collective impact but allowed for place-based specificity for local connecting water organizations. Priorities and suggestions for success included: 1) co-development of the collaborative with all rights holders, stakeholders, and surrounding communities; 2) investment in research and technology specific to GLCWs; 3) investment in information transfer and training; 4) increased communication; and 5) better integration into existing Great Lakes research, monitoring, and funding programs. Expanding participation in all local GLCWs organizations with principles of inclusivity was identified as a larger collaborative goal. Next steps in the development of a GLCWs Collaborative include increased communication and formation of working groups and obtaining funding for a dedicated organization to begin supporting activities (communication, facilitation, logistics). By using a deliberate process for establishment, the potentially slower time frame for establishment may result in increased participation and success.

Laurentian Great Lakes↗
USGS2025

Real-time oil spill concentration assessment through fluorescence imaging and deep learning

Oil spills may pose severe ecological and socioeconomic threats, necessitating rapid and accurate environmental assessment. Traditional assessment methods used to determine the extent of a spill including gas chromatography-mass spectrometry, satellite imaging, and visual surveys, are often time-consuming, expensive, and limited by weather conditions or sampling constraints. Furthermore, these methods frequently struggle to provide real-time data crucial for prompt decision-making during spill emergencies. This study addresses these limitations by combining fluorescence imaging, deep learning, a mobile application, and a data management system for automated and real-time oil spill assessment. Our approach leverages a convolutional neural network architecture for feature extraction coupled with a custom regression model, trained and evaluated on a self-curated comprehensive dataset of 1,530 fluorescence images from two distinct oil types, a napthalenic crude oil and an aromatic-napthalenic crude oil, at concentrations ranging from 0 to 500 mg/L. The proposed approach demonstrates superior performance compared to both traditional machine learning models and more complex deep learning architectures, achieving an R² score of 0.9958 and RMSE of 9.28. The application enables rapid, cost-effective field measurements with robust data tracking and analysis capabilities. This research advances oil spill monitoring technology with a scalable solution that balances accuracy, speed, and accessibility for real-time environmental assessment and emergency response.

Journal of Hazardous Materials↗
USGS2005

Short human occupations in the Middle Palaeolithic level i of the Abric Romani rock-shelter (Capellades, Barcelona, Spain)

This paper presents a multidisciplinary study on the size of the occupied surfaces, provisioning strategies and behaviour planning at the Romani rock-shelter, using the Middle Palaeolithic record of the level i. This level is dated around 46.000 BP through U/Th ages. A behavioural interpretation is proposed, which emphasises the activities and the systemic value of the archaeological artefacts and structures. Occupation patterns are identified on the basis of the accumulations formed by human activities. These archaeological accumulations, consisting of artefacts and hearths, are easily defined visually as spatial units. The relationships between these accumulations, established by means of refitted remains, indicate that differences can be established between: 1) small and medium-sized occupation surfaces; 2) restricted and diversified provisioning strategies. This variability suggests that different modes of occupation are represented in the same archaeological level. The human activities reveal the generalization of fire technology. In almost all sizes of the occupation surfaces, the exploitation of vegetal resources near the Abric Romani marks the threshold of the restricted provisioning strategy. Limited use and fragmented knapping activities are recorded in the lithic assemblage. Faunal remains show differential transport. The exploitation of lithic, faunal and vegetal resources characterizes the diversified provisioning strategy. The small occupation surfaces and restricted provisioning strategies suggest short settlements in the Abric Romani. This shorter occupation model complements the longer diversified provisioning strategy recorded in both small and medium-sized occupied surfaces. The selection of precise elements for transport and the possible deferred consumption in the diversified provision strategy suggest an individual supply. In this respect, Neanderthal occupations in the Romani rock-shelter show a direct relation to: 1) hunting strategic resources; 2) high, linear mobility.

Journal of Human Evolution↗
USGS2014

Placing prairie pothole wetlands along spatial and temporal continua to improve integration of wetland function in ecological investigations

We evaluated the efficacy of using chemical characteristics to rank wetland relation to surface and groundwater along a hydrologic continuum ranging from groundwater recharge to groundwater discharge. We used 27 years (1974–2002) of water chemistry data from 15 prairie pothole wetlands and known hydrologic connections of these wetlands to groundwater to evaluate spatial and temporal patterns in chemical characteristics that correspond to the unique ecosystem functions each wetland performed. Due to the mineral content and the low permeability rate of glacial till and soils, salinity of wetland waters increased along a continuum of wetland relation to groundwater recharge, flow-through or discharge. Mean inter-annual specific conductance (a proxy for salinity) increased along this continuum from wetlands that recharge groundwater being fresh to wetlands that receive groundwater discharge being the most saline, and wetlands that both recharge and discharge to groundwater (i.e., groundwater flow-through wetlands) being of intermediate salinity. The primary axis from a principal component analysis revealed that specific conductance (and major ions affecting conductance) explained 71% of the variation in wetland chemistry over the 27 years of this investigation. We found that long-term averages from this axis were useful to identify a wetland’s long-term relation to surface and groundwater. Yearly or seasonal measurements of specific conductance can be less definitive because of highly dynamic inter- and intra-annual climate cycles that affect water volumes and the interaction of groundwater and geologic materials, and thereby influence the chemical composition of wetland waters. The influence of wetland relation to surface and groundwater on water chemistry has application in many scientific disciplines and is especially needed to improve ecological understanding in wetland investigations. We suggest ways that monitoring in situ wetland conditions could be linked with evolving remote sensing technology to improve our ability to better inform decisions affecting wetland sustainability and provide periodic inventories of wetland ecosystem services to document temporal trends in wetland function and how they respond to contemporary land-use change.

North Dakota↗
USGS2015

A comparison of thermal infrared to fiber-optic distributed temperature sensing for evaluation of groundwater discharge to surface water

Groundwater has a predictable thermal signature that can be used to locate discrete zones of discharge to surface water. As climate warms, surface water with strong groundwater influence will provide habitat stability and refuge for thermally stressed aquatic species, and is therefore critical to locate and protect. Alternatively, these discrete seepage locations may serve as potential point sources of contaminants from polluted aquifers. This study compares two increasingly common heat tracing methods to locate discrete groundwater discharge: direct-contact measurements made with fiber-optic distributed temperature sensing (FO-DTS) and remote sensing measurements collected with thermal infrared (TIR) cameras. FO-DTS is used to make high spatial resolution (typically m) thermal measurements through time within the water column using temperature-sensitive cables. The spatialtemporal data can be analyzed with statistical measures to reveal zones of groundwater influence, however, the personnel requirements, time to install, and time to georeference the cables can be burdensome, and the control units need constant calibration. In contrast, TIR data collection, either from handheld, airborne, or satellite platforms, can quickly capture point-in-time evaluations of groundwater seepage zones across large scales. However the remote nature of TIR measurements means they can be adversely influenced by a number of environmental and physical factors, and the measurements are limited to the surface skin temperature of water features. We present case studies from a range of lentic to lotic aquatic systems to identify capabilities and limitations of both technologies and highlight situations in which one or the other might be a better instrument choice for locating groundwater discharge. FO-DTS performs well in all systems across seasons, but data collection was limited spatially by practical considerations of cable installation. TIR is found to consistently locate groundwater seepage zones above and along the streambank, but submerged seepage zones are only well identified in shallow systems (e.g. <0.5 m depth) with moderate flow. Winter data collection, when groundwater is relatively warm and buoyant, increases the water surface expression of discharge zones in shallow systems.

Massachusetts, Michigan, Montana, New York, Pennsy↗
USGS2023

Learning from arid and urban aquatic ecosystems to inform more sustainable and resilient futures

The hydrology and aquatic ecology of arid environments has long been understudied relative to temperate regions. Yet spatially and temporally intermittent and ephemeral waters characterized by flashy hydrographs typify arid regions that comprise a substantial proportion of the Earth. Additionally, drought, intense storms, and human modification of landscapes increasingly affect many temperate regions, resulting in hydrologic regimes more similar to aridlands. Here we review the contributions of Dr. Nancy Grimm to aridland hydrology and ecology, and applications of these insights to urban ecosystems and resilience of social-ecological-technological systems. Grimm catalyzed study of nitrogen cycling in streams and characterized feedbacks between surface water-groundwater exchange, nitrogen transformations, and aquatic biota. In aridlands, outcomes of these interactions depend on short- and long-term variation in the hydrologic regime. Grimm and colleagues applied hydrological and biogeochemical insights gained from study of aridland streams to urban ecosystems, integrating engineering, social and behavioral sciences, and geography. These studies evolved from characterizing the spatial heterogeneity of urban systems (i.e., watersheds, novel aquatic systems) and its influence on nutrient dynamics to an approach that evaluated human decision-making as a driver of disturbance regimes and changes in ecosystem function. Finally, Grimm and colleagues have applied principles of urban ecology to look toward the future of cities, considering scenarios of sustainable and resilient futures. We identify cross-cutting themes and approaches that have motivated discoveries across Grimm’s multi-decadal career, including spatial and temporal heterogeneity, hydrologic connectivity and regime, disturbance, systems thinking, and resilience. Finally, we emphasize Grimm’s broad contributions to science via support of long-term research, dedication to mentoring, and extensive collaborations that facilitated transdisciplinary research.

Journal of Hydrology↗
USGS2024

Groundwater-Surface water interactions research: Past trends and future directions

Interactions between groundwater and surface water sustain groundwater-dependent ecosystems and regulate river temperature and biogeochemical cycles, amongst many other processes. These interactions occur in freshwater environments including rivers, springs, lakes, and wetlands, and in coastal environments via tidal pumping, submarine groundwater discharge, and seawater intrusion. Here, we explore groundwater-surface water interactions research using bibliometric analyses of titles, abstracts, and keywords from 20,275 journal papers published between 1970 and 2023 extracted from Scopus. Analyses show that research into groundwater-surface water interactions is highly multi-disciplinary, with growing contributions from the social and biological sciences. The number of groundwater-surface water interactions papers is rapidly increasing with over 1200 papers published per year since 2020. Drawing on our data-driven approach and expert knowledge, we synthesise current research trends and identify critical future research directions. Despite the thousands of papers on groundwater-surface water interactions, important processes are still difficult to quantify or predict at meaningful spatial scales to inform water-resources management. We see benefits in future groundwater-surface water interactions research focusing on: (1) using new technologies including internet-of-things-based sensors, uncrewed vehicles, and remote-sensing approaches for data collection to inform groundwater-surface water interactions at large scales, (2) seeking approaches to upscale site-specific findings to better inform management, and (3) continuing the movement towards multi-disciplinary investigations to better inform the understanding of groundwater-surface water interactions and processes that will enable better management outcomes.

Journal of Hydrology↗
USGS2006

North Kona slump: Submarine flank failure during the early(?) tholeiitic shield stage of Hualalai Volcano

The North Kona slump is an elliptical region, about 20 by 60 km (1000-km 2 area), of multiple, geometrically intricate benches and scarps, mostly at water depths of 2000–4500 m, on the west flank of Hualalai Volcano. Two dives up steep scarps in the slump area were made in September 2001, using the ROV Kaiko of the Japan Marine Science and Technology Center (JAMSTEC), as part of a collaborative Japan–USA project to improve understanding of the submarine flanks of Hawaiian volcanoes. Both dives, at water depths of 2700–4000 m, encountered pillow lavas draping the scarp-and-bench slopes. Intact to only slightly broken pillow lobes and cylinders that are downward elongate dominate on the steepest mid-sections of scarps, while more equant and spherical pillow shapes are common near the tops and bases of scarps and locally protrude through cover of muddy sediment on bench flats. Notably absent are subaerially erupted Hualalai lava flows, interbedded hyaloclastite pillow breccia, and/or coastal sandy sediment that might have accumulated downslope from an active coastline. The general structure of the North Kona flank is interpreted as an intricate assemblage of downdropped lenticular blocks, bounded by steeply dipping normal faults. The undisturbed pillow-lava drape indicates that slumping occurred during shield-stage tholeiitic volcanism. All analyzed samples of the pillow-lava drape are tholeiite, similar to published analyses from the submarine northwest rift zone of Hualālai. Relatively low sulfur (330–600 ppm) and water (0.18–0.47 wt.%) contents of glass rinds suggest that the eruptive sources were in shallow water, perhaps 500–1000-m depth. In contrast, saturation pressures calculated from carbon dioxide concentrations (100–190 ppm) indicate deeper equilibration, at or near sample sites at water depths of − 3900 to − 2800 m. Either vents close to the sample sites erupted mixtures of undegassed and degassed magmas, or volatiles were resorbed from vesicles during flowage downslope after eruption in shallow water. The glass volatile compositions suggest that the tholeiitic lavas that drape the slump blocks were erupted either (1) early during shield-stage tholeiitic volcanism prior to emergence of a large subaerial edifice, or alternatively (2) from submarine radial vents during subaerial shield-building. Because no radial vents have been documented on land or underwater for the unbuttressed flanks of any Hawaii volcano, alternative (1) is favored. In comparison to other well-documented Hawaiian slumps and landslides, North Kona structures suggest a more incipient slump event, with smaller down-slope motions and lateral displacements.

Hawaii↗
USGS2006

Submarine geology of Hana Ridge and Haleakala Volcano's northeast flank, Maui

We present a morphostructural analysis of the submarine portions of Haleakala Volcano and environs, based upon a 4-year program of geophysical surveys and submersible explorations of the underwater flanks of Hawaiian volcanoes that was conducted by numerous academic and governmental research organizations in Japan and the U.S. and funded primarily by the Japan Agency for Marine–Earth Science and Technology. A resulting reconnaissance geologic map features the 135-km-long Hana Ridge, the 3000 km 2 Hana slump on the volcano's northeast flank, and island-surrounding terraces that are the submerged parts of volcanic shields. Hana Ridge below 2000 m water depth exhibits the lobate morphology typical of the subaqueously erupted parts of Hawaiian rift zones, with some important distinctions: namely, subparallel crestlines, which we propose result from the down-rift migration of offsets in the dike intrusion zone, and an amphitheater at its distal toe, where a submarine landslide has embayed the ridge tip. Deformation of Haleakala's northeast flank is limited to that part identified as the Hana slump, which lies downslope from the volcano's submerged shield, indicating that flank mobility is also limited in plan, inconsistent with hypothesized volcanic spreading driven by rift-zone dilation. The leading edge of the slump has transverse basins and ridges that resemble the thrust ramps of accretionary prisms, and we present a model to describe the slump's development that emphasizes the role of coastally generated fragmental basalt on gravitational instability of Haleakala's northeast flank and that may be broadly applicable to other ocean-island slumps.

Hawai'i↗
USGS2006

The changing shapes of active volcanoes: History, evolution, and future challenges for volcano geodesy

At the very heart of volcanology lies the search for the 'plumbing systems' that form the inner workings of Earth’s active volcanoes. By their very nature, however, the magmatic reservoirs and conduits that underlie these active volcanic systems are elusive; mostly they are observable only through circumstantial evidence, using indirect, and often ambiguous, surficial measurements. Of course, we can infer much about these systems from geologic investigation of materials brought to the surface by eruptions and of the exposed roots of ancient volcanoes. But how can we study the magmatic processes that are occurring beneath Earth’s active volcanoes? What are the geometry, scale, physical, and chemical characteristics of magma reservoirs? Can we infer the dynamics of magma transport? Can we use this information to better forecast the future behavior of volcanoes? These questions comprise some of the most fundamental, recurring themes of modern research in volcanology. The field of volcano geodesy is uniquely situated to provide critical observational constraints on these problems. For the past decade, armed with a new array of technological innovations, equipped with powerful computers, and prepared with new analytical tools, volcano geodesists have been poised to make significant advances in our fundamental understanding of the behavior of active volcanic systems. The purpose of this volume is to highlight some of these recent advances, particularly in the collection and interpretation of geodetic data from actively deforming volcanoes. The 18 papers that follow report on new geodetic data that offer valuable insights into eruptive activity and magma transport; they present new models and modeling strategies that have the potential to greatly increase understanding of magmatic, hydrothermal, and volcano-tectonic processes; and they describe innovative techniques for collecting geodetic measurements from remote, poorly accessible, or hazardous volcanoes. To provide a proper context for these studies, we offer a short review of the evolution of volcano geodesy, as well as a case study that highlights recent advances in the field by comparing the geodetic response to recent eruptive episodes at Mount St. Helens. Finally, we point out a few areas that continue to challenge the volcano geodesy community, some of which are addressed by the papers that follow and which undoubtedly will be the focus of future research for years to come.

Journal of Volcanology and Geothermal Research↗
USGS2013

Merapi 2010 eruption—Chronology and extrusion rates monitored with satellite radar and used in eruption forecasting

Despite dense cloud cover, satellite-borne commercial Synthetic Aperture Radar (SAR) enabled frequent monitoring of Merapi volcano's 2010 eruption. Near-real-time interpretation of images derived from the amplitude of the SAR signals and timely delivery of these interpretations to those responsible for warnings, allowed satellite remote sensing for the first time to play an equal role with in situ seismic, geodetic and gas monitoring in guiding life-saving decisions during a major volcanic crisis. Our remotely sensed data provide an observational chronology for the main phase of the 2010 eruption, which lasted 12 days (26 October–7 November, 2010). Unlike the prolonged low-rate and relatively low explosivity dome-forming and collapse eruptions of recent decades at Merapi, the eruption began with an explosive eruption that produced a new summit crater on 26 October and was accompanied by an ash column and pyroclastic flows that extended 8 km down the flanks. This initial explosive event was followed by smaller explosive eruptions on 29 October–1 November, then by a period of rapid dome growth on 1–4 November, which produced a summit lava dome with a volume of ~ 5 × 10 6 m 3 . A paroxysmal VEI 4 magmatic eruption (with ash column to 17 km altitude) destroyed this dome, greatly enlarged the new summit crater and produced extensive pyroclastic flows (to ~ 16 km radial distance in the Gendol drainage) and surges during the night of 4–5 November. The paroxysmal eruption was followed by a period of jetting of gas and tephra and by a second short period (12 h) of rapid dome growth on 6 November. The eruption ended with low-level ash and steam emissions that buried the 6 November dome with tephra and continued at low levels until seismicity decreased to background levels by about 23 November. Our near-real-time commercial SAR documented the explosive events on 26 October and 4–5 November and high rates of dome growth (> 25 m 3 s − 1 ). An event tree analysis for the previous 2006 Merapi eruption indicated that for lava dome extrusion rates > 1.2 m 3 s − 1 , the probability of a large (1872-scale) eruption was ~ 10%. Consequently, the order-of-magnitude greater rates in 2010, along with the explosive start of the eruption on 26 October, the large volume of lava accumulating at the summit by 4 November, and the rapid and large increases in seismic energy release, deformation and gas emissions were the basis for warnings of an unusually large eruption by the Indonesian Geological Agency's Center for Volcanology and Geologic Hazard Mitigation (CVGHM) and their Volcano Research and Technology Development Center (BPPTK) in Yogyakarta — warnings that saved thousands of lives.

Merapi Volcano↗
USGS2013

Applying UV cameras for SO 2 detection to distant or optically thick volcanic plumes

Ultraviolet (UV) camera systems represent an exciting new technology for measuring two dimensional sulfur dioxide (SO 2 ) distributions in volcanic plumes. The high frame rate of the cameras allows the retrieval of SO 2 emission rates at time scales of 1 Hz or higher, thus allowing the investigation of high-frequency signals and making integrated and comparative studies with other high-data-rate volcano monitoring techniques possible. One drawback of the technique, however, is the limited spectral information recorded by the imaging systems. Here, a framework for simulating the sensitivity of UV cameras to various SO 2 distributions is introduced. Both the wavelength-dependent transmittance of the optical imaging system and the radiative transfer in the atmosphere are modeled. The framework is then applied to study the behavior of different optical setups and used to simulate the response of these instruments to volcanic plumes containing varying SO 2 and aerosol abundances located at various distances from the sensor. Results show that UV radiative transfer in and around distant and/or optically thick plumes typically leads to a lower sensitivity to SO 2 than expected when assuming a standard Beer–Lambert absorption model. Furthermore, camera response is often non-linear in SO 2 and dependent on distance to the plume and plume aerosol optical thickness and single scatter albedo. The model results are compared with camera measurements made at Kilauea Volcano (Hawaii) and a method for integrating moderate resolution differential optical absorption spectroscopy data with UV imagery to retrieve improved SO 2 column densities is discussed.

Journal of Volcanology and Geothermal Research↗
USGS2015

Intercomparison of SO 2 camera systems for imaging volcanic gas plumes

SO 2 camera systems are increasingly being used to image volcanic gas plumes. The ability to derive SO 2 emission rates directly from the acquired imagery at high time resolution allows volcanic process studies that incorporate other high time-resolution datasets. Though the general principles behind the SO 2 camera have remained the same for a number of years, recent advances in CCD technology and an improved understanding of the physics behind the measurements have driven a continuous evolution of the camera systems. Here we present an intercomparison of seven different SO 2 cameras. In the first part of the experiment, the various technical designs are compared and the advantages and drawbacks of individual design options are considered. Though the ideal design was found to be dependent on the specific application, a number of general recommendations are made. Next, a time series of images recorded by all instruments at Stromboli Volcano (Italy) is compared. All instruments were easily able to capture SO 2 clouds emitted from the summit vents. Quantitative comparison of the SO 2 load in an individual cloud yielded an intra-instrument precision of about 12%. From the imagery, emission rates were then derived according to each group's standard retrieval process. A daily average SO 2 emission rate of 61 &plusmn; 10 t/d was calculated. Due to differences in spatial integration methods and plume velocity determination, the time-dependent progression of SO 2 emissions varied significantly among the individual systems. However, integration over distinct degassing events yielded comparable SO 2 masses. Based on the intercomparison data, we find an approximate 1-sigma precision of 20% for the emission rates derived from the various SO 2 cameras. Though it may still be improved in the future, this is currently within the typical accuracy of the measurement and is considered sufficient for most applications.

Journal of Volcanology and Geothermal Research↗
USGS2021

Evaluating the state-of-the-art in remote volcanic eruption characterization Part II: Ulawun volcano, Papua New Guinea

Retrospective eruption characterization is valuable for advancing our understanding of volcanic systems and evaluating our observational capabilities, especially with remote technologies (defined here as a space-borne system or non-local, ground-based instrumentation which include regional and remote infrasound sensors). In June 2019, the open-system Ulawun volcano, Papua New Guinea, produced a VEI 4 eruption. We combined data from satellites (including Sentinel-2, TROPOMI, MODIS, Himawari-8), the International Monitoring System infrasound network, and GLD360 globally detected lightning with information from the local authorities and social media to characterize the pre-, syn - and post-eruptive behaviour. The Rabaul Volcano Observatory recorded ~24 h of seismicity and detected SO 2 emissions ~16 h before the visually-documented start of the Plinian phase on 26 June at 04:20 UTC. Infrasound and SO 2 detections suggest the eruption started during the night on 24 June 2019 at 10:39 UTC ~38 h before ash detections with a gas-dominated jetting phase. Local reports and infrasound detections show that the second phase of the eruption started on 25 June 19:28 UTC with ~6 h of jetting. The first detected lightning occurred on 26 June 00:14 UTC, and ash emissions were first detected by Himawari-8 at 01:00 UTC. Post-eruptive satellite imagery indicates new flow deposits to the south and north of the edifice and ash fall to the west and southwest. In particular, regional infrasound data provided novel insight into eruption onset and syn -eruptive changes in intensity. We conclude that, while remote observations are sufficient for detection and tracking of syn-eruptive changes, key challenges in data latency, acquisition, and synthesis must be addressed to improve future near-real-time characterization of eruptions at minimally-monitored or unmonitored volcanoes.

Bismark volcanic arc, New Britain Island, Ulawun v↗