USGS Science⌕ Search

SEARCH · USGS Science

Results for “Science Activities”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
USGS2009

Anatomy of the western Java plate interface from depth-migrated seismic images

Newly pre-stack depth-migrated seismic images resolve the structural details of the western Java forearc and plate interface. The structural segmentation of the forearc into discrete mechanical domains correlates with distinct deformation styles. Approximately 2/3 of the trench sediment fill is detached and incorporated into frontal prism imbricates, while the floor sequence is underthrust beneath the d??collement. Western Java, however, differs markedly from margins such as Nankai or Barbados, where a uniform, continuous d??collement reflector has been imaged. In our study area, the plate interface reveals a spatially irregular, nonlinear pattern characterized by the morphological relief of subducted seamounts and thicker than average patches of underthrust sediment. The underthrust sediment is associated with a low velocity zone as determined from wide-angle data. Active underplating is not resolved, but likely contributes to the uplift of the large bivergent wedge that constitutes the forearc high. Our profile is located 100 km west of the 2006 Java tsunami earthquake. The heterogeneous d??collement zone regulates the friction behavior of the shallow subduction environment where the earthquake occurred. The alternating pattern of enhanced frictional contact zones associated with oceanic basement relief and weak material patches of underthrust sediment influences seismic coupling and possibly contributed to the heterogeneous slip distribution. Our seismic images resolve a steeply dipping splay fault, which originates at the d??collement and terminates at the sea floor and which potentially contributes to tsunami generation during co-seismic activity. ?? 2009 Elsevier B.V.

Earth and Planetary Science Letters↗
USGS2016

Biogeochemical controls of uranium bioavailability from the dissolved phase in natural freshwaters

To gain insights into the risks associated with uranium (U) mining and processing, we investigated the biogeochemical controls of U bioavailability in the model freshwater species Lymnaea stagnalis (Gastropoda). Bioavailability of dissolved U(VI) was characterized in controlled laboratory experiments over a range of water hardness, pH, and in the presence of complexing ligands in the form of dissolved natural organic matter (DOM). Results show that dissolved U is bioavailable under all the geochemical conditions tested. Uranium uptake rates follow first order kinetics over a range encompassing most environmental concentrations. Uranium uptake rates in L. stagnalis ultimately demonstrate saturation uptake kinetics when exposure concentrations exceed 100 nM, suggesting uptake via a finite number of carriers or ion channels. The lack of a relationship between U uptake rate constants and Ca uptake rates suggest that U does not exclusively use Ca membrane transporters. In general, U bioavailability decreases with increasing pH, increasing Ca and Mg concentrations, and when DOM is present. Competing ions did not affect U uptake rates. Speciation modeling that includes formation constants for U ternary complexes reveals that the aqueous concentration of dicarbonato U species (UO 2 (CO 3 ) 2 –2 ) best predicts U bioavailability to L. stagnalis , challenging the free-ion activity model postulate.

Environmental Science & Technology↗
USGS2002

Determination of phosphate in natural waters by activation analysis of tungstophosphoric acid

Activation analysis may be used to determine quantitatively traces of phosphate in natural waters. Methods based on the reaction 31 P( n,γ ) 32 P are subject to interference by sulfur and chlorine which give rise to 32 P through n,p and n,α reactions. If the ratio of phosphorus to sulfur or chlorine is small, as it is in most natural waters, accurate analyses by these methods are difficult to achieve. In the activation analysis method, molybdate and tungstate ions are added to samples containing phosphate ion to form tungstomolybdophosphoric acid. The complex is extracted with 2,6-dimethyl-4-heptanone. After activation of an aliquot of the organic phase for 1 hour at a flux of 10 13 neutrons per cm 2 , per second, the gamma spectrum is essentially that of tungsten-187. The induced activity is proportional to the concentration of phosphate in the sample. A test of the method showed it to give accurate results at concentrations of 4 to at least 200 p.p.b. of phosphorus when an aliquot of 100 μl. was activated. By suitable reagent purification, counting for longer times, and activation of larger aliquots, the detection limit could be lowered several hundredfold.

Environmental Science & Technology↗
USGS2001

Steep-dip seismic imaging of the shallow San Andreas Fault near Parkfield

Seismic reflection and refraction images illuminate the San Andreas Fault to a depth of 1 kilometer. The prestack depth-migrated reflection image contains near-vertical reflections aligned with the active fault trace. The fault is vertical in the upper 0.5 kilometer, then dips about 70° to the southwest to at least 1 kilometer subsurface. This dip reconciles the difference between the computed locations of earthquakes and the surface fault trace. The seismic velocity cross section shows strong lateral variations. Relatively low velocity (10 to 30%), high electrical conductivity, and low density indicate a 1-kilometer-wide vertical wedge of porous sediment or fractured rock immediately southwest of the active fault trace.

California↗
USGS2015

Initiation of migration and movement rates of Atlantic salmon smolts in fresh water

Timing of ocean entry is critical for marine survival of both hatchery and wild Atlantic salmon ( Salmo salar ) smolts. Management practices and barriers to migration such as dams may constrain timing of smolt migrations resulting in suboptimal performance at saltwater entry. We modeled influences of stocking location, smolt development, and environmental conditions on ( i ) initiation of migration by hatchery-reared smolts and ( ii ) movement rate of hatchery- and wild-reared Atlantic salmon smolts in the Penobscot River, Maine, USA, from 2005 through 2014 using acoustic telemetry data. We also compared movement rates in free-flowing reaches with rates in reaches with hydropower dams and head ponds. We compared movement rates before and after (1) removal of two mainstem dams and (2) construction of new powerhouses. Initiation of movement by hatchery fish was influenced by smolt development, stocking location, and environmental conditions. Smolts with the greatest gill Na + , K + -ATPase (NKA) activity initiated migration 24 h sooner than fish with the lowest gill NKA activity. Fish with the greatest cumulative thermal experience initiated migration 5 days earlier than those with lowest cumulative thermal experience. Smolts released furthest from the ocean initiated migration earlier than those released downstream, but movement rate increased by fivefold closer to the ocean, indicating behavioral trade-offs between initiation and movement rate. Dams had a strong effect on movement rate. Movement rate increased from 2.8 to 5.4 km·h −1 in reaches where dams were removed, but decreased from 2.1 to 0.1 km·h −1 in reaches where new powerhouses were constructed. Movement rate varied throughout the migratory period and was inversely related to temperature. Fish moved slower at extreme high or low discharge. Responses in fish movement rates to dam removal indicate the potential scope of recovery for these activities.

Maine↗
USGS2002

Influence of hydrologic processes on reproduction of the introduced bivalve Potamocorbula amurensis in northern San Francisco Bay, California

Monthly censusing of reproductive condition of the Asian clam Potamocorbula amurensis at four sites in northern San Francisco Bay over a 9-yr period revealed year-to-year differences in local reproductive activity that are associated with patterns of hydrologic variability. Between 1989 and 1992, Northern California experienced a drought, whereas the period between 1993 and 1998 was marked by a mix of wet and dry years. We took advantage of the extreme year-to-year differences to examine reproductive responses to river inflow patterns. Populations of P. amurensis at the upstream sites in Suisun Bay and Carquinez Strait were more reproductively active during wet years than dry years. Conversely, at the downstream site in San Pablo Bay, the population was more reproductively active during dry years than wet years. We suggest that the different reproductive patterns observed reflect the clam's response to different sources of food. During wet years, organic matter from the rivers augments food supplies in Suisun Bay. During dry years, when inflow into the San Francisco Bay Estuary from the rivers is reduced, water transported from the adjacent ocean into the estuary as far as San Pablo Bay provides a supplemental food supply for the local production. The populations take advantage of these spatially distinct food supplies by initiating and maintaining local reproductive activity. We conclude that the ability of P. amurensis to consume and use various types of food to regulate its reproductive activity is part of the reason for its success as an invasive species.

California↗
USGS1979

Cholinesterase activity in Japanese quail dusted with carbaryl

Japanese quail (Coturnix coturnix japonica) were dusted with 5% carbaryl to determine if this topical treatment would alter plasma and brain cholinesterase activities. Within 6 hours after dusting, plasma cholinesterase activity was depressed compared with controls, the depression averaging 20% for females and 27% for males. By 24 hours the cholinesterase activity of females had returned to normal, but the cholinesterase activity of males remained depressed. Brain cholinesterase activity was not affected by the treatment, and there were no overt toxic signs.

Laboratory Animal Science↗
USGS1981

Water Resources Research October 1, 1979 - September 30, 1980: Summary statements of research activities by the Water Resources Division

Research in the WRD had its beginnings in the late 1950's when the "core research" line item was added to the Congressional budget. Since this time the Federal program has grown from a "basic sciences" program to one that includes a broad spectrum of basic and applied scientific investigations. Water resources research in WRD includes the study of water in all its phases and uses the basic sciences of mathematics, chemistry, physics, biology, geology and engineering to gain a fundamental understanding of the processes that affect the movement of water and its chemical constituents through hydrologic systems. The basic knowledge and methodologies derived from water resources research are applicable not only to the solution of current problems associated with the Nation's water resources, but also to anticipated hydrologic issues.

Report↗
USGS2006

Seasonal dynamics of microbial community composition and function in oak canopy and open grassland soils

Soil microbial communities are closely associated with aboveground plant communities, with multiple potential drivers of this relationship. Plants can affect available soil carbon, temperature, and water content, which each have the potential to affect microbial community composition and function. These same variables change seasonally, and thus plant control on microbial community composition may be modulated or overshadowed by annual climatic patterns. We examined microbial community composition, C cycling processes, and environmental data in California annual grassland soils from beneath oak canopies and in open grassland areas to distinguish factors controlling microbial community composition and function seasonally and in association with the two plant overstory communities. Every 3 months for up to 2 years, we monitored microbial community composition using phospholipid fatty acid (PLFA) analysis, microbial biomass, respiration rates, microbial enzyme activities, and the activity of microbial groups using isotope labeling of PLFA biomarkers (13C-PLFA) . Distinct microbial communities were associated with oak canopy soils and open grassland soils and microbial communities displayed seasonal patterns from year to year. The effects of plant species and seasonal climate on microbial community composition were similar in magnitude. In this Mediterranean ecosystem, plant control of microbial community composition was primarily due to effects on soil water content, whereas the changes in microbial community composition seasonally appeared to be due, in large part, to soil temperature. Available soil carbon was not a significant control on microbial community composition. Microbial community composition (PLFA) and 13C-PLFA ordination values were strongly related to intra-annual variability in soil enzyme activities and soil respiration, but microbial biomass was not. In this Mediterranean climate, soil microclimate appeared to be the master variable controlling microbial community composition and function. ?? 2006 Springer Science+Business Media, Inc.

Microbial Ecology↗
USGS2004

Fort Collins Science Center

The U.S. Geological Survey's Fort Collins Science Center (FORT) is one of 17 USGS biological science centers nationwide. FORT conducts research and develops technical applications to assist land managers in understanding and managing biological resources, habitats, and ecosystems. Although the majority of FORT's activities are conducted within the 15-state Central Region of the USGS, many FORT projects are national or international in scope. FORT serves all Department of the Interior land management bureaus and other natural resource agencies. In addition, FORT scientists partner with DOI and other federal entities such as CDC, DOE, EPA, NASA, NIH, and USDA to share expertise and resources. FORT also partners with several universities and works cooperatively with states and nongovernmental organizations. Products and services include reports and publications, predictive models and software, maps and GIS products, and other technical assistance in the form of meetings, workshops, training, field visits, and needs assessments.

Fact Sheet↗
USGS2013

Application of a hydrodynamic and sediment transport model for guidance of response efforts related to the Deepwater Horizon oil spill in the Northern Gulf of Mexico along the coast of Alabama and Florida

U.S. Geological Survey (USGS) scientists have provided a model-based assessment of transport and deposition of residual Deepwater Horizon oil along the shoreline within the northern Gulf of Mexico in the form of mixtures of sand and weathered oil, known as surface residual balls (SRBs). The results of this USGS research, in combination with results from other components of the overall study, will inform operational decisionmaking. The results will provide guidance for response activities and data collection needs during future oil spills. In May 2012 the U.S. Coast Guard, acting as the Deepwater Horizon Federal on-scene coordinator, chartered an operational science advisory team to provide a science-based review of data collected and to conduct additional directed studies and sampling. The goal was to characterize typical shoreline profiles and morphology in the northern Gulf of Mexico to identify likely sources of residual oil and to evaluate mechanisms whereby reoiling phenomena may be occurring (for example, burial and exhumation and alongshore transport). A steering committee cochaired by British Petroleum Corporation (BP) and the National Oceanic and Atmospheric Administration (NOAA) is overseeing the project and includes State on-scene coordinators from four States (Alabama, Florida, Louisiana, and Mississippi), trustees of the U.S. Department of the Interior (DOI), and representatives from the U.S. Coast Guard. This report presents the results of hydrodynamic and sediment transport models and developed techniques for analyzing potential SRB movement and burial and exhumation along the coastline of Alabama and Florida. Results from these modeling efforts are being used to explain the complexity of reoiling in the nearshore environment and to broaden consideration of the different scenarios and difficulties that are being faced in identifying and removing residual oil. For instance, modeling results suggest that larger SRBs are not, under the most commonly observed low-energy wave conditions, likely to move very far alongshore. This finding suggests that SRBs from one source location may not (outside of storm conditions) be redistributed to other up or down coast locations. This information can guide operational response decisions. In addition, because SRBs are less mobile compared with sand, they are likely to become buried and unburied under normal sand transport processes thereby lengthening the time SRBs may take to move onshore. The rate of onshore movement was not specifically addressed by this study, yet the results resolve the cross-shore domain and cross-shore variations in alongshore transport that are relevant to achieving the primary objectives. Furthermore, during infrequent events (for example, winter storms and severe meteorological events such as Hurricane Isaac of August 2012), energy is shown to be sufficient to move a greater range of SRB sizes and potentially expose and break up submerged oil mats. When SRBs do move alongshore, the models indicate that there are regions that are more conducive to accumulation of SRB material than others. Accumulation can occur where there are reversals and decelerations in alongshore currents and where forces created by shear stress drops below critical thresholds to maintain or initiate SRB movement. In addition, flow and SRB mobility patterns around inlets indicate patterns in hydrodynamic forces that influence redistribution of SRBs and the surface oil that mixed with sediment to form oil mats in the first place.

Alabama;Florida↗
USGS2020

Preliminary analyses of volcanic hazards at Kīlauea Volcano, Hawai‘i, 2017–2018

From 2017 to 2018, the U.S. Geological Survey (USGS) Hawaiian Volcano Observatory (HVO) responded to ongoing and changing eruptions at Kīlauea Volcano as part of its mission to monitor volcanic processes, issue warnings of dangerous activity, and assess volcanic hazards. To formalize short-term hazards assessments—and, in some cases, issue prognoses for future activity—and make results discoverable to both the public and the authorities, HVO released reports online. These reports were published rapidly, received peer review under the USGS’s Fundamental Science Practice guidelines, and were intended to address a focused question posed by one or more cooperating agencies—for this reason, they were called “cooperator reports.” This Open-File Report concatenates four such products issued in 2017 and 2018 into a single publication. These reports have been reformatted and lightly edited for clarity, but the content has not otherwise been changed from the versions first publicly released.

Hawaii↗
USGS2015

Flood Map for the Winooski River in Waterbury, Vermont, 2014

From August 28 to 29, 2011, Tropical Storm Irene delivered rainfall ranging from approximately 4 to more than 7 inches in the Winooski River Basin in Vermont. The rainfall resulted in severe flooding throughout the basin and significant damage along the Winooski River. In response to the flooding, the U.S. Geological Survey (USGS), in cooperation with the Federal Emergency Management Agency, conducted a new flood study to aid in flood recovery and restoration and to assist in flood forecasting. The study resulted in two sets of flood maps that depict the flooding for an 8.3-mile reach of the Winooski River from about 1,000 feet downstream of the Waterbury-Bolton, Vermont, town line upstream to about 2,000 feet upstream of the Waterbury-Middlesex, Vt., town line. The first set of maps consists of flood-recovery maps depicting the boundaries of floodwaters at the 10-, 4-, 2-, 1-, and 0.2-percent annual exceedance probability (AEP) discharges, the boundaries of the floodway, and the boundaries of floodwaters from Tropical Storm Irene as estimated by a hydraulic model. The second set of maps consists of flood-inundation maps depicting the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS Winooski River above Crossett Bk at Waterbury, VT (04288040) streamgage. The maps correspond to streamgage water levels ranging from 417.0 to 431.0 feet in 2-foot increments. The availability of these flood-inundation maps along with current stage from the USGS streamgage obtained from a USGS Web site will provide emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, as well as for post-flood recovery efforts. These flood inundation maps can be accessed through the USGS Flood Inundation Mapping Science Web site ( http://water.usgs.gov/osw/flood_inundation/ ). To generate the maps, flood profiles for the Winooski River were developed. The U.S. Army Corps of Engineers one-dimensional step-backwater Hydrologic Engineering Center River Analysis System model (HEC–RAS), was used to compute the water-surface profiles along the study reach. The simulated water-surface profiles were then combined with a geographic information system digital elevation model derived from light detection and ranging (lidar) data with a vertical accuracy that meets or exceeds vertical national map accuracy standards for 2-foot contour mapping to delineate the area flooded for each water-surface profile. High-water marks from Tropical Storm Irene were available for seven locations along the study reach. The highwater marks were used to estimate water-surface profiles and discharges resulting from Tropical Storm Irene throughout the study reach. From a comparison of the estimated water-surface profile for Tropical Storm Irene with the water-surface profiles for the 1- and 0.2-percent annual exceedance probability (AEP) floods, it was determined that the high-water elevations resulting from Tropical Storm Irene exceeded the estimated 1-percent AEP flood throughout the Winooski River study reach but did not exceed the estimated 0.2-percent AEP flood at any location within the study reach.

Vermont↗
USGS2016

The Land Processes Distributed Active Archive Center (LP DAAC)

The Land Processes Distributed Active Archive Center (LP DAAC) operates as a partnership with the U.S. Geological Survey and is 1 of 12 DAACs within the National Aeronautics and Space Administration (NASA) Earth Observing System Data and Information System (EOSDIS). The LP DAAC ingests, archives, processes, and distributes NASA Earth science remote sensing data. These data are provided to the public at no charge. Data distributed by the LP DAAC provide information about Earth’s surface from daily to yearly intervals and at 15 to 5,600 meter spatial resolution. Data provided by the LP DAAC can be used to study changes in agriculture, vegetation, ecosystems, elevation, and much more. The LP DAAC provides several ways to access, process, and interact with these data. In addition, the LP DAAC is actively archiving new datasets to provide users with a variety of data to study the Earth.

Fact Sheet↗
USGS2022

ECCOE Landsat Quarterly Calibration and Validation report—Quarter 2, 2022

Executive Summary The U.S. Geological Survey Earth Resources Observation and Science Calibration and Validation (Cal/Val) Center of Excellence (ECCOE) focuses on improving the accuracy, precision, calibration, and product quality of remote-sensing data, leveraging years of multiscale optical system geometric and radiometric calibration and characterization experience. The ECCOE Landsat Cal/Val Team continually monitors the geometric and radiometric performance of active Landsat missions and makes calibration adjustments, as needed, to maintain data quality at the highest level. This report provides observed geometric and radiometric analysis results for Landsats 7–8 for quarter 2 (April–June), 2022. All data used to compile the Cal/Val analysis results presented in this report are freely available from the U.S. Geological Survey EarthExplorer website: https://earthexplorer.usgs.gov . One specific activity that the ECCOE Landsat Cal/Val Team closely monitored was the lowering of the Landsat 7 orbit. On April 6, 2022, the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) sensor was placed into standby mode, and a series of spacecraft burns was completed throughout the month of April to lower the satellite’s orbit by 8 kilometers. Imaging resumed at the lower orbit of 697 kilometers on May 5, 2022, extending the science mission to allow for essential data to be acquired during the 2022 Northern Hemisphere fire and growing season. Additional information about the Landsat 7 orbit lowering is here: https://www.usgs.gov/centers/eros/news/landsat-7-lowered-standard-landsat-orbit#:~:text=The%20satellite's%20primary%20science%20mission%20has%20ended&text=On%20April%206%2C%202022%2C%20the,satellite's%20orbit%20by%208%20kilometers .

Open-File Report↗
USGS2023

ECCOE Landsat quarterly Calibration and Validation report—Quarter 3, 2022

Executive Summary The U.S. Geological Survey Earth Resources Observation and Science Calibration and Validation (Cal/Val) Center of Excellence (ECCOE) focuses on improving the accuracy, precision, calibration, and product quality of remote-sensing data, leveraging years of multiscale optical system geometric and radiometric calibration and characterization experience. The ECCOE Landsat Cal/Val Team continually monitors the geometric and radiometric performance of active Landsat missions and makes calibration adjustments, as needed, to maintain data quality at the highest level. This report provides observed geometric and radiometric analysis results for Landsats 7–8 for quarter 3 (July–September) of 2022. All data used to compile the Cal/Val analysis results presented in this report are freely available from the U.S. Geological Survey EarthExplorer website: https://earthexplorer.usgs.gov . One specific activity that the ECCOE Landsat Cal/Val Team closely monitored was the lowering of the Landsat 7 orbit. On April 6, 2022, the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) sensor was placed into standby mode, and a series of spacecraft burns was completed through the month of April to lower the satellite’s orbit by 8 kilometers. Imaging resumed at a lower orbit of 697 kilometers on May 5, 2022, extending the science mission to allow for essential data acquisition during the 2022 Northern Hemisphere fire and growing season. Additional information about the Landsat 7 orbit lowering is here: https://www.usgs.gov/centers/eros/news/landsat-7-lowered-standard-landsat-orbit#:~:text=The%20satellite's%20primary%20science%20mission%20has%20ended&text=On%20April%206%2C%202022%2C%20the,satellite's%20orbit%20by%208%20kilometers .

Open-File Report↗
USGS2023

ECCOE Landsat quarterly Calibration and Validation report—Quarter 4, 2022

Executive Summary The U.S. Geological Survey Earth Resources Observation and Science Calibration and Validation (Cal/Val) Center of Excellence (ECCOE) focuses on improving the accuracy, precision, calibration, and product quality of remote-sensing data, leveraging years of multiscale optical system geometric and radiometric calibration and characterization experience. The ECCOE Landsat Cal/Val Team continually monitors the geometric and radiometric performance of active Landsat missions and makes calibration adjustments, as needed, to maintain data quality at the highest level. This report provides observed geometric and radiometric analysis results for Landsats 7–8 for quarter 4 (October–December) of 2022. All data used to compile the Cal/Val analysis results presented in this report are freely available from the U.S. Geological Survey EarthExplorer website: https://earthexplorer.usgs.gov . One specific activity that the ECCOE Landsat Cal/Val Team closely monitored was the lowering of the Landsat 7 orbit. On April 6, 2022, the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) sensor was placed into standby mode, and a series of spacecraft burns was completed through the month of April to lower the satellite’s orbit by 8 kilometers. Imaging resumed at a lower orbit of 697 kilometers on May 5, 2022, extending the science mission. Additional information about the Landsat 7 orbit lowering is here: https://www.usgs.gov/centers/eros/news/landsat-7-lowered-standard-landsat-orbit#:~:text=The%20satellite's%20primary%20science%20mission%20has%20ended&text=On%20April%206%2C%202022%2C%20the,satellite's%20orbit%20by%208%20kilometers .

Open-File Report↗
USGS2022

Understanding and modeling tephra transport: Lessons learned from the 18 May 1980 eruption of Mount St. Helens

Discoveries made during the 18 May 1980 eruption of Mount St. Helens advanced our understanding of tephra transport and deposition in fundamental ways. The eruption enabled detailed, quantitative observations of downwind cloud movement and particle sedimentation, along with the dynamics of co-pyroclastic-density current (PDC) clouds lofted from ground-hugging currents. The deposit was mapped and sampled over more than 150,000 km 2 within days of the event and remains among the most thoroughly documented tephra deposits in the world. Abundant observations were made possible by the large size of the eruption, its occurrence in good weather during daylight hours, cloud movement over a large, populated continent, and the availability of images from recently deployed satellites. These observations underpinned new, quantitative models for the rise and growth of volcanic plumes, the importance of umbrella clouds in dispersing ash, and the roles of particle aggregation and gravitational instabilities in removing ash from the atmosphere. Exceptional detail in the eruption chronology and deposit characterization helped identify the eruptive phases contributing to deposition in different sectors of the distal deposit. The eruption was the first to significantly impact civil aviation, leading to the earliest documented case of in-flight engine damage. Continued eruptive activity in 1980 also motivated pioneering use of meteorological models to forecast ash-cloud movement. In this paper, we consider the most important discoveries and how they changed the science of tephra transport.

Washington↗