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At least 1,099 records · Page 61Linked to original sources
USGS2015

Using occupancy models to accommodate uncertainty in the interpretation of aerial photograph data: status of beaver in Central Oregon, USA

Beavers ( Castor canadensis ) influence habitat for many species and pose challenges in developed landscapes. They are increasingly viewed as a cost-efficient means of riparian habitat restoration and water storage. Still, information on their status is rare, particularly in western North America. We used aerial photography to evaluate changes in beaver occupancy between 1942–1968 and 2009 in upper portions of 2 large watersheds in Oregon, USA. We used multiple observers and occupancy modeling to account for bias related to photo quality, observers, and imperfect detection of beaver impoundments. Our analysis suggested a slightly higher rate of beaver occupancy in the upper Deschutes than the upper Klamath basin. We found weak evidence for beaver increases in the west and declines in eastern parts of the study area. Our study presents a method for dealing with observer variation in photo interpretation and provides the first assessment of the extent of beaver influence in 2 basins with major water-use challenges. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Oregon↗
USGS2010

Slow slip phenomena in Cascadia from 2007 and beyond: a review

Recent technological advances combined with more detailed analyses of seismologic and geodetic observations have fundamentally changed our understanding of the ways in which tectonic stresses arising from plate motions are accommodated by slip on faults. The traditional view that relative plate motions are accommodated by a simple cycle of stress accumulation and release on “locked” plate-boundary faults has been revolutionized by the serendipitous discovery and recognition of the significance of slow-slip phenomena, mostly in the deeper reaches of subduction zones. The Cascadia subduction zone, located in the Pacific Northwest of the conterminous United States and adjacent Canada, is an archetype of exploration and learning about slow-slip phenomena. These phenomena are manifest as geodetically observed aseismic transient deformations accompanied by a previously unrecognized class of seismic signals. Although secondary failure processes may be involved in generating the seismic signals, the primary origins of both aseismic and seismic phenomena appear to be episodic fault slip, probably facilitated by fluids, on a plate interface that is critically stressed or weakened. In Cascadia, this transient slip evolves more slowly and over more prolonged durations relative to the slip in earthquakes, and it occurs between the 30- and 40-km-depth contours of the plate interface where information was previously elusive. Although there is some underlying organization that relaxes nearly all the accrued plate-motion stresses along the entirety of Cascadia, we now infer that slow slip evolves in complex patterns indicative of propagating stress fronts. Our new understanding provides key constraints not only on the region where the slow slip originates, but also on the probable characteristics of future megathrust earthquakes in Cascadia. Herein, we review the most significant scientific issues and progress related to understanding slow-slip phenomena in Cascadia and highlight some of their societal implications. We provide a comprehensive review, from the big picture as inferred from studies of regional-scale monitoring data to the details revealed by innovative, focused experiments and new instrumentation. We focus on what has been learned largely since 2007, when several major investments in monitoring and temporary deployments dramatically increased the quality and quantity of available data.

Oregon↗
USGS2019

On the portability of ML-MC as a depth discriminant for small seismic events recorded at local distances

In this paper we show that M L -M C is a viable and regionally portable depth discriminant and therefore may contribute in nuclear test ban treaty verification. A recent study found that the difference between local magnitude (M L ) and coda duration magnitude (M C ) discriminates shallow seismic events (mining blasts, mining-induced earthquakes, and shallow tectonic earthquakes) from deeper tectonic earthquakes in the Utah region. The shallow seismic events had anomalously high M C values, with increasingly negative M L -M C values as depth decreased. Here we evaluate the performance of M L -M C as a depth discriminant in three new regions, finding that M L -M C increases between 0–9 km depth in all cases. Initially, we investigated M L -M C as a function of depth for naturally occurring earthquakes in the region around Yellowstone National Park, as recorded by the University of Utah Seismograph Stations. For 3,358 Yellowstone earthquakes with well-constrained depths, we found M L -M C increased 0.030 ± 0.007 magnitude units (m.u.) for each 1 km increase in depth up to 10 km depth. Next, we examined M L -M C values for anthropogenic seismicity in northern Oklahoma and southern Kansas, as recorded by the National Earthquake Information Center. For 1,628 events with well-constrained depths, we computed a slope for M L -M C of 0.022 ± 0.010 m.u./km. Finally, we analyzed M L -M C for 28,722 well-located earthquakes in Italy, as recorded by the National Institute of Geophysics and Volcanology, and found an M L -M C slope of 0.018 ± 0.001 m.u./km. In each case, the quoted error bounds represent 95% confidence regions which exclude zero, implying that the depth-dependence of M L -M C is statistically significant. We performed several robustness tests in which we varied the criterion used to define a well-constrained depth and the depth range used in the linear fit. In nearly all cases, we found a positive slope for M L -M C vs. depth at a confidence level above 95%.

Utah, Montana, Idaho, Wyoming, Kansas, Oklahoma↗
USGS2022

Adult white-tailed deer survival in hunted populations on public and private lands

Estimates of sex- and age-specific survival are important for guiding population management decisions for white-tailed deer ( Odocoileus virginianus ). However, differences in deer survival between public and private lands can exist and, if unaccounted for, may affect wildlife agencies' ability to effectively manage statewide and local deer populations. From 2014 to 2016, we radiocollared and monitored survival of 79 adult white-tailed deer (141 deer-years; 62 male, 79 female) on 2 public and 2 private properties in Alabama, USA. We assessed the effects of sex, age, and landownership type (i.e., public or private) on adult white-tailed deer harvest and survival patterns using an information-theoretic approach. Hunter harvest accounted for 77% of observed mortalities ( n = 23/30), but harvest and survival rates varied by sex and age. Harvest and survival were similar between public and private property despite more restrictive hunting regulations for antlered deer on public areas. Similar harvest rates were likely due to self-imposed, quality deer management (QDM) harvest strategies on private land that emulated the effects of a state-mandated antler point restriction (APR) on public land. Our findings indicate survival rates of adult white-tailed deer may be applicable across landownership types where state-mandated harvest regulations with respect to males are more restrictive on public than private property, due to the popularity of QDM by private-land deer hunters. However, where regulations are similar across landownership types (e.g., no state-mandated APR), differences in harvest and survival rates may exist.

Alabama↗
USGS2000

The bellerophont controversy revisited

An old controversy reestablished itself in the late 1970s and early 1980s that focused on the systematic placement of the enigmatic Bellerophontoidea (informally, "bellerophonts"), a group of planispirally coiled, wholly fossil molluscs. The controversy embraced three fundamental concepts that are based on different philosophical interpretations of shell form, muscle scar patterns, and other preserved shell features: 1) all bellerophonts were monoplacophorans; 2) all bellerophonts were gastropods; and 3) some bellerophonts were monoplacophorans and some were gastropods. A review of the main issues appearing in the literature since the early 1980s indicates that these three philosophical divisions still exist and, indeed, have become entrenched. An examination of the relevant anatomical and shell features of recent gastropods and monoplacophorans, and comparison with preserved features in enigmatic fossil forms, convinces us that the bellerophontoideans and the coiled and high-domed "monoplacophorans" (Cyclomya) were gastropods. Only the flattened, spoon-and cap-shaped monoplacophorans (Tergomya) were true monoplacophorans. We present a hypothetical scheme for the morphological diversification of gastropods from early monoplacophorans that could account for Cyclomya, Bellerophontoidea, Patellogastropoda, and Prosobranchia.

American Malacological Bulletin↗
USGS2020

The NASA hydrological forecast system for food and water security applications

Many regions in Africa and the Middle East are vulnerable to drought and to water and food insecurity, motivating agency efforts such as the U.S. Agency for International Development’s (USAID) Famine Early Warning System Network (FEWS NET) to provide early warning of drought events in the region. Each year these warnings guide life-saving assistance that reaches millions of people. A new NASA multi-model, remote sensing-based hydrological forecasting and analysis system, NHyFAS, has been developed to support such efforts by improving the FEWS NET’s current early warning capabilities. NHyFAS derives its skill from two sources: (i) accurate initial conditions, as produced by an offline land modeling system through the application and/or assimilation of various satellite data (precipitation, soil moisture, and terrestrial water storage); and (ii) meteorological forcing data during the forecast period as produced by a state-of-the-art ocean-land-atmosphere forecast system. The land modeling framework used is the Land Information System (LIS), which employs a suite of land surface models, allowing multi-model ensembles and multiple data assimilation strategies to better estimate land surface conditions. An evaluation of NHyFAS shows that its one-to-five month forecasts successfully capture known historic drought events. The system also benefits from strong collaboration with end-user partners in Africa and the Middle East, who provide insights on strategies to formulate and communicate early warning indicators to water and food security communities. The additional lead time provided by this system will increase the speed, accuracy and efficacy of humanitarian disaster relief, helping to save lives and livelihoods.

Bulletin of the American Meteorological Society↗
USGS2002

Displaced rocks, strong motion, and the mechanics of shallow faulting associated with the 1999 Hector Mine, California, earthquake

The paucity of strong-motion stations near the 1999 Hector Mine earthquake makes it impossible to make instrumental studies of key questions about near-fault strong-motion patterns associated with this event. However, observations of displaced rocks allow a qualitative investigation of these problems. By observing the slope of the desert surface and the frictional coefficient between these rocks and the desert surface, we estimate the minimum horizontal acceleration needed to displace the rocks. Combining this information with observations of how many rocks were displaced in different areas near the fault, we infer the level of shaking. Given current empirical shaking attenuation relationships, the number of rocks that moved is slightly lower than expected; this implies that slightly lower than expected shaking occurred during the Hector Mine earthquake. Perhaps more importantly, stretches of the fault with 4 m of total displacement at the surface displaced few nearby rocks on 15?? slopes, suggesting that the horizontal accelerations were below 0.2g within meters of the fault scarp. This low level of shaking suggests that the shallow parts of this rupture did not produce strong accelerations. Finally, we did not observe an increased incidence of displaced rocks along the fault zone itself. This suggests that, despite observations of fault-zone-trapped waves generated by aftershocks of the Hector Mine earthquake, such waves were not an important factor in controlling peak ground acceleration during the mainshock.

California↗
USGS2004

Hawaiian submarine manganese-iron oxide crusts - A dating tool?

Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from postdepositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest—i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae landslide southwest of Oahu has yielded samples with the greatest manganese-iron oxide crusts (9.5 mm thick) and therefore apparently represents the oldest submarine material yet found in the study area. The submarine volcanic field 100 km southwest of Oahu is apparently younger than the Waianae landslide.

Hawaii↗
USGS2002

Timing and magnitude of Broad-winged Hawk migration at Montclair Hawk Lookout, New Jersey, and Hawk Mountain Sanctuary, Pennsylvania

The Broad-winged Hawk ( Buteo platypterus ) breeds in eastern and central Canada and the United States, and winters in Central America and northern and central South America. Birders and ornithologists count migrating Broad-winged Hawks at dozens of traditional watch sites throughout the northeastern United States. We modeled counts of migrating Broad-winged Hawks from two raptor migration watch sites: Montclair Hawk Lookout, New Jersey, and Hawk Mountain Sanctuary, Pennsylvania, to determine whether annual abundance and trend estimates from individual sites within the mid-Atlantic states are representative of the region as a whole. We restricted ourselves to counts made between 10:00 and 16:00 EST during September to standardize count effort between sites. We created one model set for annual counts and another model set for daily counts. When modeling daily counts we incorporated weather and identity of individual observers. Akaike’s Information Criteria were used to select the best model from an initial set of competing models. Annual counts declined at both sites during 1979–1998. Broad-winged Hawk migration began, peaked, and ended later at Montclair than at Hawk Mountain, even though Hawk Mountain is 155 km west-southwest of Montclair. Mean annual counts of hawks at Montclair were more than twice those at Hawk Mountain, but were not correlated. Broad-winged Hawks counted at Montclair may not be the same birds as those counted at Hawk Mountain. Rather, the two sites may be monitoring different regional subpopulations. Broad-winged Hawks counted at the two sites may use different migration tactics, with those counted at Hawk Mountain being more likely to slope soar, and those at Montclair more likely to use thermal soaring. A system of multiple watch sites is needed to monitor various breeding populations of this widely dispersed migrant.

New Jersey, Pennsylvania↗
USGS1998

Winter habitat of Kirtland's warbler: an endangered nearctic/neotropical migrant

Habitats of Kirtland?s Warbler (Dendroica kirtlandii) on the wintering grounds in the Bahama Archipelago are presented based upon data from 29 specimens, two bandings, and 67 sightings of at least 61 individuals on 13 islands scattered through the region. Major emphasis is placed on a study site in central Eleuthera, with additional information on sites on Grand Turk, North Caicos, and Crooked Island. The warblers used upland habitats that have a low shrub/scrub component with a patchiness of small openings and openings within the vegetation at the ground level. Six broad habitats were identified as being used: Natural Shrub/Scrub, Secondary Shrub/Scrub, Low Coppice, Pineland Understory, Saline/Upland Ecotone, and Suburban; High Coppice is not used. The structure and floristic composition of the habitats are described. Observations (N=451) of a Kirtland?s Warbler male (uniquely color banded) and female over three months indicated the birds generally stayed on or near the ground, generally < 3 m (98% of observations), and used a territory of 8.3 ha. A crude estimate of potential winter habitat suggests that there is more than an adequate amount in the Bahama Archipelago for the currently small warbler population (733 singing males in 1997) and allows for a considerable population increase. No serious future threat to the amount of that habitat is foreseen.

The Wilson Bulletin↗
USGS2002

Test of a habitat suitability index for black bears in the southern Appalachians

We present a habitat suitability index (HSI) model for black bears (Ursus americanus) living in the southern Appalachians that was developed a priori from the literature, then tested using location and home range data collected in the Pisgah Bear Sanctuary, North Carolina, over a 12-year period. The HSI was developed and initially tested using habitat and bear data collected over 2 years in the sanctuary. We increased number of habitat sampling sites, included data collected in areas affected by timber harvest, used more recent Geographic Information System (GIS) technology to create a more accurate depiction of the HSI for the sanctuary, evaluated effects of input variability on HSI values, and duplicated the original tests using more data. We found that the HSI predicted habitat selection by bears on population and individual levels and the distribution of collared bears were positively correlated with HSI values. We found a stronger relationship between habitat selection by bears and a second-generation HSI. We evaluated our model with criteria suggested by Roloff and Kernohan (1999) for evaluating HSI model reliability and concluded that our model was reliable and robust. The model's strength is that it was developed as an a priori hypothesis directly modeling the relationship between critical resources and fitness of bears and tested with independent data. We present the HSI spatially as a continuous fitness surface where potential contribution of habitat to the fitness of a bear is depicted at each point in space.

Wildlife Society Bulletin↗
USGS2026

Growth and erosion of volcanic islands since 1963 analyzed by multi-sensor satellite data and historical records

Most volcanic activity is taking place in the oceans. Depending on water depth, eruption recurrence times and volumes, a new island can form. The power of erosional forces, the type of erupted material and the efficiency of secondary processes determine the island’s lifetime. Since the famous eruption of Surtsey (Iceland) in 1963, at least another 23 volcanic islands have appeared. Some islands remained intact for years or decades, whereas others disappeared within just weeks or months. In this study, we analyzed satellite data to determine growth and erosion rates of the volcanic edifices related to these 24 islands. We combined multi-sensor (optical, thermal, radar) satellite data time series with information from literature and the Global Volcanism Program database. We developed a comprehensive dataset, including 19 parameters, on the islands’ lifetime, shape, area, volume, eruption style and duration, environmental conditions, development of sedimentary deposits, and the geomorphic evolution of the island over time. Our dataset is available in a database format. This database allows us to test eight hypotheses about factors influencing the islands’ lifetime. Our results show that instead of one single critical factor, a combination of different factors influences the life history of volcanic islands. For instance, we show that larger islands do not necessarily live longer. The mechanical properties of the eruption products affect the island’s structural integrity. Irrespective of the material, a minimum initial area of around 50,000 m 2 seems to be a reasonable threshold to give the island a chance to exist longer.

Bulletin of Volcanology↗
USGS2026

The potential impact of three-dimensional distributed slip models derived from real-time GNSS data on the performance of the ShakeAlert earthquake early warning system for slab interface earthquakes

The ShakeAlert® earthquake early warning (EEW) system is designed to warn users of imminent strong ground motion with sufficient time to take protective actions. ShakeAlert currently uses three algorithms to characterize the earthquake source. One estimates the location and magnitude using the first few seconds of the P wave and, while fast, tends to underestimate magnitude for M w 7.0+ earthquakes. A second estimates the location, orientation, length, and corresponding magnitude of a line source using observed peak ground acceleration and contributes primarily to M w 5.5+ earthquakes. The third infers earthquake magnitude from peak ground displacement measured using Global Navigation Satellite System (GNSS) data and offers nonsaturating magnitudes for M w 7.0+ earthquakes. Other EEW algorithms exist that infer temporally evolving spatially variable slip on a 3D fault surface from real‐time GNSS data, information that might enable more accurate and timely alerts in the event of large‐magnitude subduction interface earthquakes. Here, we evaluate the potential contribution of one such algorithm, BEFORES ( Minson et al. , 2014 ), to improve ShakeAlert performance through a simulated real‐time implementation of Bayesian evidence‐based fault orientation and real‐time earthquake slip (BEFORES) and other ShakeAlert algorithms using data for eight M w 7.6+ earthquakes. The test results demonstrate that BEFORES can produce well‐constrained and accurate magnitude estimates as soon as or sooner than other EEW algorithms, in turn enabling it to increase the amount of warning time users receive in many cases. However, with a modified Mercalli intensity (MMI) threshold of 3.5, which is commonly used for issuing alerts, BEFORES would tend to alert large geographic regions that did not feel strong shaking (MMI 6+). This effect can be mitigated using a higher alert threshold of MMI 4.5 without negative impact on the amount of warning time obtainable with BEFORES.

Bulletin of the Seismological Society of America↗
USGS2024

Salmon data mobilization

Despite substantial research and conservation efforts, many salmon populations are in decline. Globally, salmon research is not delivering effective decision support products to help managers apply research insights as informed management actions. Data Mobilization (DM) is a key step towards building the wider evidence base required to deliver accountable, reliable, and usable scientific advice to managers. Best practices for DM are being adopted throughout the scientific community but have not permeated deeply into the culture of salmon research and conservation. To address this, we present a strategy for Salmon Data Mobilization (SDM). This strategy defines three spheres of agencies and practitioners that must interact to advance SDM: (1) authoritative bodies that can create policies to support SDM uptake; (2) agencies that can promote, fund, and implement those policies; and (3) the broad salmon community of practice that can support uptake of SDM within focused interest groups. We sketch a future for SDM and propose functional changes required to improve it throughout the community.

North Pacific Anadromous Fish Commission Bulletin↗
USGS2013

Data management challenges in species distribution modeling

An important component in the fields of ecology and conservation biology is understanding the environmental conditions and geographic areas that are suitable for a given species to inhabit. A common tool in determining such areas is species distribution modeling which uses computer algorithms to determine the spatial distribution of organisms. Most commonly the correlative relationships between the organism and environmental variables are the primary consideration. The data requirements for this type of modeling consist of known presence and possibly absence locations of the species as well as the values of environmental or climatic covariates thought to define the species habitat suitability at these locations. These covariate data are generally extracted from remotely sensed imagery, interpolated/gridded historical climate data, or downscaled climate model output. Traditionally, ecologists and biologists have constructed species distribution models using workflows and data that reside primarily on their local workstations or networks. This workflow is becoming challenging as scientists increasingly try to use these modeling techniques to inform management decisions under different climate change scenarios. This challenge stems from the fact that remote sensing products, gridded historical climate, and downscaled climate models are not only increasing in spatial and temporal resolution but proliferating as well. Any rigorous assessment of uncertainty requires a computationally intensive sensitivity analysis accounting for various sources of uncertainty. The scientists fitting these models generally do not have the background in computer science required to take advantage of recent advances in web-service based data acquisition, remote high-powered data processing, or scientific workflow systems. Ecologists in the field of modeling are in need of a tractable platform that abstracts the inherent computational complexity required to incorporate the burgeoning field of coupled climate and ecological response modeling. In this paper we describe the computational challenges in species distribution modeling and solutions using scientific workflow systems. We focus on the Software for Assisted Species Modeling (SAHM) a package within VisTrails, an open-source scientific workflow system.

Bulletin of the Technical Committee on Data Engine↗
USGS2023

The USGS 2023 Conterminous U.S. time‐independent earthquake rupture forecast

We present the 2023 U.S. Geological Survey time‐independent earthquake rupture forecast for the conterminous United States, which gives authoritative estimates of the magnitude, location, and time‐averaged frequency of potentially damaging earthquakes throughout the region. In addition to updating virtually all model components, a major focus has been to provide a better representation of epistemic uncertainties. For example, we have improved the representation of multifault ruptures, both in terms of allowing more and less fault connectivity than in the previous models, and in sweeping over a broader range of viable models. An unprecedented level of diagnostic information has been provided for assessing the model, and the development was overseen by a 19‐member participatory review panel. Although we believe the new model embodies significant improvements and represents the best available science, we also discuss potential model limitations, including the applicability of logic tree branch weights with respect different types of hazard and risk metrics. Future improvements are also discussed, with deformation model enhancements being particularly worthy of pursuit, as well as better representation of sampling errors in the gridded seismicity components. We also plan to add time‐dependent components, and assess implications with a wider range of hazard and risk metrics.

Bulletin of the Seismological Society of America↗
USGS2017

Reevaluation of thermal maturity and stages of petroleum formation of the Mississippian Barnett Shale, Fort Worth Basin, Texas

New data including measured reflectance (% R o ), programmed open-system pyrolysis data, and kerogen elemental analyses obtained on the Mississippian Barnett Shale in the Fort Worth Basin, Texas, indicate that secondary-gas generation starts at 1.5% R o and not at the previously prescribed 1.1% R o . Oil-cracking kinetic parameters derived from pyrolysis experiments in the presence and absence of water indicate that secondary-gas generation will not occur at a thermal maturity as low as 1.1% R o and requires a minimum thermal maturity of 1.5% R o . This difference is especially important in using the Barnett Shale as an analog for evaluating other possible shale-gas plays. The new reflectance measurements have a good relationship with hydrogen indices (HIs) and compare well with other published data sets. However, the relationship does not compare well with the previously published data used to prescribe 1.1% R o as the start of secondary-gas generation in the Barnett Shale. This discrepancy is attributed to differences in measured % R o values and not attributed to differences in the HI values. Lack of publicly available information on the previously reported % R o values makes it difficult to ascertain the reason for their lower values. These lower % R o values also have impact on the previously prescribed relationship for estimating % R o from the temperature at maximum yield by programmed open-system pyrolysis ( T max ). As a result, the new data do not agree with a previously described relationship, and the considerable scatter makes the new relationship unreliable. However, the relationship between the HI and % R o has less scatter, which indicates that HI offers a better proxy in calculating % R o than T max for the Barnett Shale. Comparison of various programmed open-system pyrolysis methods (i.e., Rock-Eval II, Rock-Eval 6, Source Rock Analyzer, and Hawk) indicates that variations in HI are within ±10% of one another. An HI of at least 44 mg/g total organic carbon is prescribed as a more certain limit for the start of secondary-gas generation and prospective in situ gas-shale accumulations.

Texas↗
USGS2021

Near-real-time volcanic cloud monitoring: Insights into global explosive volcanic eruptive activity through analysis of Volcanic Ash Advisories

Understanding the location, intensity, and likely duration of volcanic hazards is key to reducing risk from volcanic eruptions. Here, we use a novel near-real-time dataset comprising Volcanic Ash Advisories (VAAs) issued over 10 years to investigate global rates and durations of explosive volcanic activity. The VAAs were collected from the nine Volcanic Ash Advisory Centres (VAACs) worldwide. Information extracted allowed analysis of the frequency and type of explosive behaviour, including analysis of key eruption source parameters (ESPs) such as volcanic cloud height and duration. The results reflect changes in the VAA reporting process, data sources, and volcanic activity through time. The data show an increase in the number of VAAs issued since 2015 that cannot be directly correlated to an increase in volcanic activity. Instead, many represent increased observations, including improved capability to detect low- to mid-level volcanic clouds (FL101–FL200, 3–6 km asl), by higher temporal, spatial, and spectral resolution satellite sensors. Comparison of ESP data extracted from the VAAs with the Mastin et al. (J Volcanol Geotherm Res 186:10–21, 2009a ) database shows that traditional assumptions used in the classification of volcanoes could be much simplified for operational use. The analysis highlights the VAA data as an exceptional resource documenting global volcanic activity on timescales that complement more widely used eruption datasets.

Bulletin of Volcanology↗