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At least 577 records · Page 32Linked to original sources
USGS2021

Global cropland-extent product at 30-m resolution (GCEP30) derived from Landsat satellite time-series data for the year 2015 using multiple machine-learning algorithms on Google Earth Engine cloud

Executive Summary Global food and water security analysis and management require precise and accurate global cropland-extent maps. Existing maps have limitations, in that they are (1) mapped using coarse-resolution remote-sensing data, resulting in the lack of precise mapping location of croplands and their accuracies; (2) derived by collecting and collating national statistical data that are often subjective, leading to substantial uncertainties in cropland-area estimates, as well as their locations; and (3) extracted from one or more classes of a land use–land cover product in which cropland classes are not the focus of mapping, leading to their mixing with other classes and creating significant errors of omission and commission. These limitations can be overcome by producing high-resolution cropland-extent maps using satellite-sensor data, such as Landsat 30-m resolution or higher. The most fundamental cropland product is the high-resolution cropland-extent map because all higher level cropland products, such as crop-watering method (that is, whether crops are irrigated or rainfed), crop types, cropping intensities, cropland fallows, crop productivity, and crop-water productivity, are dependent on a precise and accurate cropland-extent product. Given these realities, the overarching goal of this study was to produce a Landsat satellite-derived global cropland-extent product at 30-m resolution. The work, which involved a paradigm shift in how global cropland-extent maps are produced, involved the following five key steps: (1) petabyte-scale computing that involved multiyear, 8- to 16-day, time-series Landsat 30-m resolution data for the global land surface; (2) composition of analysis-ready data (ARD) cubes; (3) creation of a large global-reference data hub for machine learning; (4) use of multiple machine-learning algorithms (MLAs) by writing software and computing in the cloud; and (5) Google Earth Engine (GEE) cloud computing. The five key steps involved nine distinct phases. First, the world was segmented into 74 agroecological zones (AEZs). Second, Landsat 8- to 16-day data were used to time-composite 10-band (blue, green, red, near-infrared, short-wave infrared band 1, short-wave infrared band 2, thermal infrared, enhanced vegetation index, normalized difference water index, and normalized difference vegetation index) Landsat 30-m resolution data cubes for every 2- to 4-month time period during 3- to 4-year periods (stated as nominal-year 2015 or, simply, 2015), along with two additional 30-m resolution bands (Shuttle Radar Topography Mission elevation, and slope) in each of the 74 AEZs. Third, more than 100,000 reference-training data samples were collected using ground data (some of which were collected using a mobile application), as well as submeter- to 5-m-resolution, very high-resolution imagery sourced from other reliable sources. Fourth, reference-training data were used to create a knowledge base for separating cropland from noncropland. Fifth, MLAs such as the pixel-based supervised random forest and support-vector machines were written on the GEE using Python and JavaScript. Sixth, object-based recursive hierarchical segmentation algorithm was used, in addition to MLAs, to overcome uncertainties. Seventh, MLAs used the knowledge base to classify and separate cropland from noncropland. Eighth, accuracy assessment was conducted by generating error matrices for each of the 74 AEZs using 19,171 independent validation-data samples. Ninth, cropland areas were computed for all countries of the world and compared with United Nation’s (UN’s) Food and Agricultural Organization (FAO) and other national statistics. The outcome was a Landsat-derived global cropland-extent product at 30-m resolution (GCEP30), which has an overall accuracy of 91.7 percent. For the cropland class, producer’s accuracy was 83.4 percent, and user’s accuracy was 78.3 percent. GCEP30 calculated (using direct pixel count) the global net-cropland area (GNCA) for the year 2015 as 1.873 billion hectares (~12.6 percent of the Earth’s terrestrial area). The continental cropland distribution as a percentage of GNCA was Asia, 33 percent; Europe, 25.5 percent; Africa, 16.7 percent; North America, 14.4 percent; South America, 8.1 percent; and Australia and Oceania, 2.4 percent. The worldwide cropland areas in GCEP30 for 2015 were higher by 236 to 299 million hectares (Mha) compared to national statistics reported elsewhere for the same year (for example, in Food and Agriculture Organization’s corporate statistical database [FAOSTAT] and in the monthly irrigated and rainfed crop areas [MIRCA] database). The global cropland area reported for 2015 increased by 344 Mha (22.5 percent), compared to the year 2000. During the same period (2000–2015), the world’s population increased by 20 percent. Whereas some of these areal increases are real increases in cropland areas, others are due to the types of data, methods, and approaches used. Using the highest known resolution (compared to previous coarse-resolution global products) enabled this study to capture fragmented croplands. Coarse-resolution data compute areas on the basis of subpixels, which, for a large proportion of certain land use–land cover classes, will show only a certain percentage of the total pixel area as actual area. Subpixel areas can lead to substantial uncertainties in area computation, as determining the exact fraction of cropland areas within a coarse-resolution pixel is resource intensive and subject to errors. Other innovations in GCEP30 include reference-data hubs, machine learning, and cloud computing. Cropland areas in 214 countries, territories, departments, and regions were calculated for the year 2015 using GCEP30, on the basis of UN’s global administrative unit layers (GAUL) boundaries. The 10 leading countries in terms of cropland area (as a percentage of the GNCA) were India (9.6 percent), United States (8.95 percent), China (8.82 percent), Russia (8.32 percent), Brazil (3.42 percent), Ukraine (2.32 percent), Canada (2.29 percent), Argentina (2.05 percent), Indonesia (2 percent), and Nigeria (1.91 percent). Together, these 10 countries occupy 50 percent of the global cropland, and they have 52 percent of the global population. Their combined cropland area increased by 2 percent between 2000 and 2015, compared to the substantial increase in population of 517 million (15.5 percent). Together, India, United States, China, and Russia encompass 36 percent of the total area. In the United States and Canada, from 2000 to 2015, cropland decreased by about 2 percent, whereas their populations increased by 14 and 13 percent, respectively. The additional food requirements in these 10 countries, which are caused by increased populations, as well as increasing nutritional demands, are met by production increases in existing cropland or through virtual food trade, or both. More than 18 countries, territories, departments, or regions had 60 percent or more of their geographic area as cropland: Republic of Moldova, San Marino, and Hungary had more than 80 percent of the country’s area as cropland; Denmark, Ukraine, Ireland, and Bangladesh, 70 to 80 percent; and Uruguay, Netherlands, United Kingdom, Spain, Lithuania, Poland, Gaza Strip, Czechia, Italy, India, and Azerbaijan, 60 to 70 percent. Europe and South Asia can be considered agricultural capitals of the world, on the basis of their percentages of geographic area as cropland. United States, China, and Russia, which all have high cropland areas, are ranked second, third, and fourth in the world; India is ranked first. However, the amount of cropland as a percentage of the country’s geographic area is relatively very low for United States (18.3 percent), China (17.7 percent), and Russia (9.5 percent), whereas it is 60.5 percent for India. Most African and South American countries, territories, departments, or regions have less than 15 percent of their geographic area as cropland. China and India together house 36 percent of the world’s population; however, between 2000 and 2015, the amount of China’s cropland area fell by 18.9 percent, owing to urban expansion and the abandonment of farmlands caused by demographic changes (that is, the movement of population from villages to cities). In contrast, China’s population grew by 10 percent. The amount of India’s cropland increased by 8.5 percent, whereas its population grew by 20 percent. This study showed that, out of the 10 leading cropland countries, Ukraine, Nigeria, Russia, and Indonesia showed an 18 to 31 percent increase in cropland areas, on the basis of GCEP30 by the year 2015, compared to 2000. Nigeria’s cropland area increased by 25 percent, and its population increased by 31 percent in the same period. In these countries, food security is maintained by cropland expansion, productivity increases, and virtual food trade. Nevertheless, this trend of increasing net-cropland area and productivity will likely become difficult to maintain, owing to diminishing arable lands and plateauing of 50 years of continual yield increases, requiring policymakers to explore novel and data-supported approaches to solving future food security issues. The GCEP30 product, which can be browsed at full resolution at www.croplands.org , has been released for public download and use through U.S. Geological Survey (USGS)–National Aeronautics and Space Administration (NASA) Land Processes Distributed Active Archive Center (see https://lpdaac.usgs.gov/news/release-of-gfsad-30-meter-cropland-extent-products/ ).

Professional Paper↗
USGS1992

The Landers earthquake; preliminary instrumental results

Early on the morning of June 28, 1992, millions of people in southern California were awakened by the largest earthquake to occur in the western United States in the past 40 yrs. At 4:58 a.m PDT (local time), faulting associated with the magnitude 7.3 earthquake broke through to earth's surface near the town of Landers, California. the surface rupture then propagated 70km (45 mi) to the north and northwest along a band of faults passing through the middle of the Mojave Desert. Fortunately, the strongest shaking occurred in uninhabited regions of the Mojave Desert. Still one child was killed in Yucca Valley, and about 400 people were injured in the surrounding area. the desert communities of Landers, Yucca Valley, and Joshua Tree in San Bernardino Country suffered considerable damage to buildings and roads. Damage to water and power lines caused problems in many areas.

California↗
USGS1890

Volume XIII: The tertiary insects of North America

That creatures so minute and fragile as insects, creatures which can so feebly withstand the changing seasons as to live, so to speak, but a moment, are to be found fossil, engraved, as it were, upon the rocks or embedded in their hard mass, will never cease to be a surprise to those unfamiliar with the fact. "So fragile," says Quinet, "so easy to crush, you would readily believe the insect one of the latest beings produced by nature, one of those which has least resisted the action of time; that its type, its genera, its forms, must have been ground to powder a thousand times, annihilated by the revolutions of the globe, and perpetually thrown into the crucible. For where is its defense? Of what value its antennae, its shield, its wings of gauze, against the commotions and the tempests which change the surface of the earth? When the mountains themselves are overthrown and the seas uplifted, when the giants of structure, the mighty quadrupeds, change form and habit under the pressure of circumstances, will the insect withstand them? Is it it which will display most character in nature? Yes! The universe flings itself against a gnat. Where will it find refuge? In its very diminutiveness, its nothingness." The pages and plates of the present volume bear testimony to the fact that our tertiary strata have preserved remnants of an ancient host, so varied in structure, so closely also resembling their brethren of to-day, that nearly or quite every prevalent family-group in the entire range of the insect-world has already been demonstrated to have then existed. While often fragmentary and crushed, sometimes beyond recognition, a not insignificant number are sufficiently preserved for us to repopulate the past; sometimes, too, are they preserved in such a wonderful manner that in tiny creatures with a spread of wings scarcely more than a couple of millimeters one may count under the microscope the hairs fringing the wings. In attempting thus to restore the past world of our insects, two or three general features have been forced upon my attention, which may well be mentioned here. One of them is the rernarkable fact that in hardly a single instance has the same species been found at two distinct localities. These localities, it is true, are in some instances separated by hundreds or even thousands of miles, and analogy with the present distribution of insects would lead us to expect more or less profound changes in passing from one to another. But at other times the distance is not great, or at any rate not great enough to make this a satisfactory reason. It is more probable that the beds in which they occur are not altogether synchronous; and we are led to believe that in the separation of horizons insects will give more precise and definite distinctions than may be gained by the study of the plant remains of the same beds. The data at our disposal are not yet sufficiently varied to enable us to speak with any confidence, but when the other groups of Florissant insects, not considered in the present volume, are worked out, and the new material that is at hand from the other principal localities have been fairly studied, it may be found that we are armed with a new weapon of attack in solving the immediate succession of the Tertiary series of the West in their finer subdivisions. Another point to which attention may be drawn is the very considerable number and quite extraordinary proportion of species which so far are represented by a single specimen. Leaving out of consideration certain marvelously prevalent forms in the beds of Florissant, such as certain Formicidae, Alydina, etc., one working these beds, from which many thousands of insects have already been taken, may confidently expect that every third or fourth specimen will prove something new. A quite similar statement can be made of all, or all but one, of the other localities where insects have been found in our Tertiary deposits: it surely indicates that with all the rich results of the explorations so far undertaken we are only upon the threshold of our possible knowledge. We find a richness of fauna far exceeding anything before supposed possible. The interest of the Tertiary fauna is further enhanced by the discovery that no inconsiderable proportion of the species in this fauna must be referred to genera not now extant. Granted that our knowledge of the subtropical forms of this continent (with which as a whole at least our Florissant fauna seems to be akin) is much too meager to be of great service; granted also that in many cases we are forced to establish new genera upon what would be regarded among recent animals as too slender grounds : it is nevertheless true that an unexpectedly large number of forms can not be forced into modern genera already established; in many cases, throughout whole groups, kindred differences from modern types are found which indicate considerable changes of structure in the intervening epochs along parallel lines. In illustration of this we would call special attention to the differences observed in the genera of plant-lice, and, in several places among other Hemiptera as well as among the Coleoptera, to the decided differences in the relative length of various members of the body. My own belief, which springs from the comparisons instituted in the study of this fauna, is that a much larger proportion of genera should really have been founded, and that, for every type which may turn up in Central American explorations of the near future identical with those now established upon the fossils alone, it will be necessary to separate from the familiar surroundings in which I have placed it some other of the insects from the same beds. It should be stated that the larger part of the plates in this volume were engraved before the insects were studied, except in a cursory manner to separate the species; the insects are therefore not always properly grouped, and the legends upon the plates are in part inaccurate. In the enumeration of the specimens at the end of the specific descriptions the numbers of the obverse and reverse of the same specimen are always connected by "and" without any intervening comma, and this typographical method is employed only for expressing this relation. In the study of these extinct insects much assistance has been received from friends, to whom my cordial thanks are due; for valuable suggestions from the late Dr. J. L. LeConte, from Baron R. von Osten Sacken, Edward Burgess, Esq., and Drs. G. H. Horn and H. A. Hagen; for the open collections of the late G. D. Smith, Esq., and of Messrs. E. P. Austin and Samuel Henshaw; and for important aid in obtaining typical series of modern insects in various groups by Messrs. E. P. Austin, P. R. Uhler, E. P. Van Duzee, Edward Burgess, Dr. A. Forel, and most especially Mr. Samuel Henshaw.

British Columbia, Colorado, Ontario, Utah, Wyoming↗
USGS1998

North American landscape characterization project: The production of a continental scale three-decade Landsat data set

The North American Landscape Characterization (NALC) project is a component of the National Aeronautics and Space Administration (NASA) Landsat Pathfinder program. Pathfinder projects are focused on the investigation of global change utilizing current remote sensing technologies. The NALC project is a cooperative effort between the U. S. Environmental Protection Agency (EPA), the U.S. Geological Survey (USGS), and NASA to make Landsat data available to the widest possible user community for scientific research and general public interest. The NALC project is principally funded by the EPA Office of Research and Development and the USGS's Earth Resources Observation Systems (EROS) Data Center (EDC). The objectives of the NALC project are to produce standardized remote sensing data sets, develop standardized analysis methods, and derive standardized land cover change products for a large portion of the North American continent (the conterminous United States and Mexico) (Lunetta and Sturdevant, 1993). The standard product is the NALC “triplicate”;, consisting of co‐registered Landsat multispectral scanner data for the years 1973, 1986, and 1991 (plus or minus one year), plus co‐registered 3 arcsecond digital terrain elevation data. Processing began with the 1986 scene, which was precision corrected (with full terrain correction) to a 60 meter Universal Transverse Mercator base. Automated cross‐correlation procedures were used to co‐register the 1970's and 1990's data to the 1980's base, and independent verifications of registration quality were performed on all triplicate components. The pertinent metadata were compiled in a relational database, which includes WRS2 path/rows, scene ID's, image dates, solar azimuth and elevation, verification RMSE's, and the number of verification control points. NALC triplicate data sets are being used for a number of applications, including the analysis of urbanization patterns, dynamics of climatic fluctuations, deforestation studies, and vegetation classification and mapping. These data are being distributed through the Earth Observing System Data and Information System (EOSDIS) Information Management System (IMS) at a cost of $15(U.S.) for each triplicate.

Geocarto International↗
USGS2006

Natural history collections: A scientific treasure trove

Natural history collections play an indispensable and often overlooked role in the conservation and management of our Nation’s flora and fauna. Scientific specimens housed in museum collections not only open an important window into the current and past diversity of life on Earth, but also play a vital role in fueling cutting-edge scientific research in many disciplines. The U.S. Geological Survey (USGS) Fort Collins Science Center (FORT) curates a collection of vertebrates from the Intermountain and Southwestern United States that is used by researchers from around the globe. As one of the largest Federal natural history collections in the western United States, the USGS specimen holdings offer unique opportunities to study the fauna of this incredibly diverse and unique region.

Fact Sheet↗
USGS1998

Catalog of the historically active volcanoes of Alaska

Alaska hosts within its borders over 80 major volcanic centers that have erupted during Holocene time (< 10,000 years). At least 29 of these volcanic centers (table 1) had historical eruptions and 12 additional volcanic centers may have had historical eruptions. Historical in Alaska generally means the period since 1760 when explorers, travelers, and inhabitants kept written records. These 41 volcanic centers have been the source for >265 eruptions reported from Alaska volcanoes. With the exception of Wrangell volcano, all the centers are in, or near, the Aleutian volcanic arc, which extends 2500 km from Hayes volcano 145 km west of Anchorage in the Alaska-Aleutian Range to Buldir Island in the western Aleutian Islands (fig. 1). The volcanic arc, a subduction-related feature associated with underthrusting of the Pacific plate beneath the North American plate is divided between oceanic island arc and continental margin segments, the boundary occurring at about 165° W longitude (fig. 1). An additional 7 volcanic centers in the Aleutian arc (table 2; fig. 1 A) have active fumarole fields but no reported historical eruptions. This report discusses the location, physiography and structure, eruptive history, and geology of those volcanoes in Alaska that have experienced one or more eruptions that have been recorded in the written history (i.e., in historical time). It is part of the group of catalogs entitled Catalogue of Active Volcanoes of the World published beginning in 1951 under the auspices of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI). A knowledge of the information contained in such catalogs aids in understanding the type and scale of activity that might be expected during a particular eruption, the hazards the eruption may pose, and even the prediction of eruptions. The catalog will thus be of value not only to the inhabitants of Alaska but to government agencies concerned with emergency response, air traffic operations, and weather, as well as to industry and scientists. The combination of the hazard posed by volcanic ash to jet aircraft and the heavy use of international air routes located parallel to, and on either side of, the Aleutian volcanic arc means that even remote volcanoes in Alaska now pose significant hazards to life and property. Although this report is concerned with historical eruptions from Alaskan volcanoes, other volcanoes in Alaska have erupted in the past 10,000 years and might therefore be expected to erupt again. Several Holocene volcanic centers in the Aleutian arc have no reported historical activity. Elsewhere in Alaska the Bering Sea basalt fields cover large areas of the Yukon Delta, Seward Peninsula, and several of the islands of the Bering Sea. Holocene centers also occur in the Wrangell Mountains and in isolated occurrences in the interior and southeastern Alaska. Eruptions from these centers have occurred within the past several hundred years but none were transcribed in the written record. Moodie and others (1992), however, report oral traditions among the Northern Athapaskan Indians of the southwestern Yukon Territory that may record the second and younger deposition of the White River Ash circa A.D. 720. This lobe of the White River Ash was deposited during the paroxysmal eruption of Churchill volcano in the Wrangell Mountains of eastcentral Alaska (McGimsey and others, 1992; Richter and others, 1995).

Alaska↗
USGS2007

Mineral resource of the month: industrial sand and gravel

With many diverse uses, industrial sand and gravel, also known as silica sand, is one of the most important nonmetallic minerals in the world. Industrial sand and gravel is a mining industry term used for sands that have a very high percentage of silicon dioxide, or greater than 95 percent quartz. Deposits of industrial sand and gravel can be found virtually everywhere on Earth, but are less widespread than deposits of common construction sand and gravel. Industrial sand and gravel is distinctive in grain size, hardness, inertness and resistance to high temperature and chemical action. Beverage containers, fiberglass insulation, fiber-optic cables and light bulbs are just some of today’s many products produced from industrial sand and gravel.

Geotimes↗
USGS2018

Euler-vector clustering of GPS velocities defines microplate geometry in southwest Japan

I have used Euler-vector clustering to assign 469 GEONET stations in southwest Japan to k clusters ( k = 2, 3,..., 9) so that, for any k , the velocities of stations within each cluster are most consistent with rigid-block motion on a sphere. That is, I attempt to explain the raw (i.e., uncorrected for strain accumulation), 1996–2006 velocities of those 469 Global Positioning System stations by rigid motion of k clusters on the surface of a spherical Earth. Because block geometry is maintained as strain accumulates, Euler-vector clustering may better approximate the block geometry than the values of the associated Euler vectors. The microplate solution for each k is constructed by merging contiguous clusters that have closely similar Euler vectors. The best solution consists of three microplates arranged along the Nankaido Trough-Ryukyu Trench between the Amurian and Philippine Sea Plates. One of these microplates, the South Kyushu Microplate (an extension of the Ryukyu forearc into the southeast corner of Kyushu), had previously been identified from paleomagnetic rotations. Relative to ITRF2000 the three microplates rotate at different rates about neighboring poles located close to the northwest corner of Shikoku. The microplate model is identical to that proposed in the block model of Wallace et al. (2009, https://doi.org/10.1130/G2522A.1) except in southernmost Kyushu. On Shikoku and Honshu, but not Kyushu, the microplate model is consistent with that proposed in the block models of Nishimura and Hashimoto (2006, https://doi.org/10.1016/j.tecto.2006.04.017) and Loveless and Meade (2010, https://doi.org/10.1029/2008JB006248) without the low-slip-rate boundaries proposed in the latter.

southwest Japan↗
USGS2010

The sedimentology and dynamics of crater-affiliated wind streaks in western Arabia Terra, Mars and Patagonia, Argentina

Wind streaks comprise recent aeolian deposits that have been extensively documented on Venus, Earth and Mars. Martian wind streaks are among the most abundant surface features on the planet and commonly extend from the downwind margins of impact craters. Previous studies of wind streaks emerging from crater interior deposits suggested that the mode of emplacement was primarily related to the deposition of silt-sized particles as these settled from plumes. We have performed geologic investigations of two wind streaks clusters; one situated in western Arabia Terra, a region in the northern hemisphere of Mars, and another in an analogous terrestrial site located in southern Patagonia, Argentina, where occurrences of wind streaks emanate from playas within maar craters. In both these regions we have identified bedforms in sedimentary deposits on crater floors, along wind-facing interior crater margins, and along wind streaks. These observations indicate that these deposits contain sand-sized particles and that sediment migration has occurred via saltation from crater interior deposits to wind streaks. In Arabia Terra and in Patagonia wind streaks initiate from crater floors that contain lithic and evaporitic sedimentary deposits, suggesting that the composition of wind streak source materials has played an important role in development. Spatial and topographic analyses suggest that regional clustering of wind streaks in the studied regions directly correlates to the areal density of craters with interior deposits, the degree of proximity of these deposits, and the craters' rim-to-floor depths. In addition, some (but not all) wind streaks within the studied clusters have propagated at comparable yearly (Earth years) rates. Extensive saltation is inferred to have been involved in its propagation based on the studied terrestrial wind streak that shows ripples and dunes on its surface and the Martian counterpart changes orientation toward the downslope direction where it extends into an impact crater. ?? 2009 Elsevier B.V.

Geomorphology↗
USGS1998

Evolution of cutoffs across meander necks in Powder River, Montana, USA

Over a period of several decades, gullies have been observed in various stages of forming, growing and completing the cutoff of meander necks in Powder River. During one episode of overbank flow, water flowing over the down-stream bank of the neck forms a headctu. The headcut migrates up-valley, forming a gully in its wake, until it has traversed the entire neck, cutting off the meander. The river then follows the course of the gully, which is subsequently enlarged as the river develops its new channel. The complete process usually requires several episodes of high water: in only one of the five cases described herein was a meander cutoff initiated and completed during a single large flood.

Earth Surface Processes and Landforms↗
USGS2017

Influence of pore pressure change on coseismic volumetric strain

Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

Earth and Planetary Science Letters↗
USGS1997

Debris-flow mobilization from landslides

Field observations, laboratory experiments, and theoretical analyses indicate that landslides mobilize to form debris flows by three processes: ( a ) widespread Coulomb failure within a sloping soil, rock, or sediment mass, ( b ) partial or complete liquefaction of the mass by high pore-fluid pressures, and ( c ) conversion of landslide translational energy to internal vibrational energy (i.e. granular temperature). These processes can operate independently, but in many circumstances they appear to operate simultaneously and synergistically. Early work on debris-flow mobilization described a similar interplay of processes but relied on mechanical models in which debris behavior was assumed to be fixed and governed by a Bingham or Bagnold rheology. In contrast, this review emphasizes models in which debris behavior evolves in response to changing pore pressures and granular temperatures. One-dimensional infinite-slope models provide insight by quantifying how pore pressures and granular temperatures can influence the transition from Coulomb failure to liquefaction. Analyses of multidimensional experiments reveal complications ignored in one-dimensional models and demonstrate that debris-flow mobilization may occur by at least two distinct modes in the field.

Annual Review of Earth and Planetary Sciences↗
USGS2005

Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index Composites

The Advanced Very High Resolution Radiometer (AVHRR) is a broad-band scanner with four to six bands, depending on the model. The AVHRR senses in the visible, near-, middle-, and thermal- infrared portions of the electromagnetic spectrum. This sensor is carried on a series of National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES), beginning with the Television InfraRed Observation Satellite (TIROS-N) in 1978. Since 1989, the United States Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) has been mapping the vegetation condition of the United States and Alaska using satellite information from the AVHRR sensor. The vegetation condition composites, more commonly called greenness maps, are produced every week using the latest information on the growth and condition of the vegetation. One of the most important aspects of USGS greenness mapping is the historical archive of information dating back to 1989. This historical stretch of information has allowed the USGS to determine a 'normal' vegetation condition. As a result, it is possible to compare the current week's vegetation condition with normal vegetation conditions. An above normal condition could indicate wetter or warmer than normal conditions, while a below normal condition could indicate colder or dryer than normal conditions. The interpretation of departure from normal will depend on the season and geography of a region.

Fact Sheet↗
USGS2024

Assessing influence from wastewater treatment facilities on Glorieta Creek and the Pecos River within Pecos National Historical Park, New Mexico, February–October 2022

The Pecos National Historical Park protects 2.9 miles of the Pecos River and part of Glorieta Creek within the park boundaries. Updated water-quality data can assist resource managers in determining if effluent from two nearby wastewater treatment plants (WWTPs) is affecting the quality of the water in the Pecos River and Glorieta Creek within the park. Water samples were collected four times in 2022 at two WWTP outfalls, two locations on Glorieta Creek, and two locations on the Pecos River. Water quality parameters (dissolved oxygen, water temperature, pH, turbidity, specific conductance) were measured in the field, and samples were collected and analyzed for major ions, trace elements, rare earth elements, nutrients, bacteria, and per- and polyfluoroalkyl substances (PFAS). Specific conductance values in all samples collected from Glorieta Creek exceeded the New Mexico Surface Water Quality Standard (NMWQS) of 300 microsiemens per centimeter at 25 degrees Celsius. Concentrations of dissolved oxygen in three samples collected from Glorieta Creek and one sample for the Pecos WWTP did not meet the standard for high-quality cold-water use. Concentrations of Escherichia coli in samples from the Pecos WWTP exceeded the NMWQS of 235 colony-forming units per 100 milliliters during every sampling event. Concentrations of E. coli in samples collected from two sites on Glorieta Creek in August exceeded the NMWQS. The chemical signature of water from Glorieta Creek indicated groundwater and (or) septic system contributions. Water samples collected from the Pecos River all had similar chemical signatures of calcium-bicarbonate type. Although concentrations of several trace elements were higher in samples from Glorieta Creek than in samples from the Pecos River, no concentrations exceeded the drinking-water standards. No concentrations exceeded aquatic life standards except for copper concentrations in two samples from the downstream location on Glorieta Creek. The trace element signature and the gadolinium anomalies in the WWTP samples indicate anthropogenic contributions. Eleven of the 28 PFAS compounds analyzed were detected in samples during this study, with the treated wastewater effluent samples having the highest total PFAS concentrations. The total PFAS concentrations in samples from Glorieta Creek decreased by an order of magnitude as the creek flowed downstream. At the downstream site on the Pecos River, there was only one sample that had a detection of PFAS.

New Mexico↗
USGS2000

Milestones in Antarctic Ice Sheet history: Preliminary results from Leg 188 drilling in Prydz Bay Antarctica

The Antarctic Ice Sheet is one of the great features of our planet. It plays a pivotal role in global atmospheric circulation and the sea-ice zone around it produces cold waters that control much of the ocean’s deep circulation. The Antarctic Ice Sheet is also the largest store of fresh water on earth and controls short-term sea level changes. The history of the Antarctic Ice Sheet has been pieced together from various sources. For the late Quaternary, ice cores contain a detailed record of accumulation, air temperature and atmospheric composition. For the Cenozoic, information has come from distal marine oxygen isotope records, records of detrital output from the continent and fragmentary outcrops in ice-free areas on the continent. These records have been augmented by drilling on the Antarctic continental margin to try and recover direct evidence of glacial ice and to investigatethe transition from pre-glacial to the full polar glacial conditions that we see today.

JOIDES Journal↗
USGS1988

The formation and failure of natural dams

Of the numerous kinds of dams that form by natural processes, dams formed from landslides, glacial ice, and late-neoglacial moraines present the greatest threat to people and property. Landslide dams form in a wide range of physiographic settings. The most common types of mass movements that form landslide dams are rock and debris avalanches; rock and soil slumps and slides; and mud, debris, and earth flows. The most common initiation mechanisms for dam-forming landslides are excessive rainfall and snowmelt and earthquakes. Landslide dams can be classified into six categories based on their relation with the valley floor. Type I dams (11% of 184 landslide dams from around the world that we were able to classify) do not reach from one valley side to the other. Type II dams (44%) span the entire valley floor, in some cases depositing material high on opposite valley sides. Type III dams (41%) move considerable distances both upstream and downstream from the landslide failure. Type IV dams (<1%) are rare and involve the contemporaneous failure of material from both sides of a valley. Type V dams (<1%) also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river. Type VI dams (3%) involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side. Many landslide dams fail shortly after formation. In our sample of 73 documented landslide-dam failures, 27% of the landslide dams failed less than 1 day after formation, and about 50% failed within 10 days. Over-topping is by far the most common cause of failure. The timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry; material characteristics of the blockage; rate of inflow to the impoundment; size and depth of the impoundment; bedrock control of flow; and engineering controls such as artificial spill-ways, diversions, tunnels, and planned breaching by blasting or conventional excavation. Glacial-ice dams can produce at least nine kinds of ice-dammed lakes. The most dangerous are lakes formed in main valleys dammed by tributary glaciers. Failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam. Cold polar-ice dams generally drain supraglacially or marginally by downmelting of an outlet channel. Warmer, temperate-ice dams tend to fail by sudden englacial or subglacial breaching and drainage. Late-neoglacial moraine-dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries. These late-neoglacial dams pose hazards because (1) they are sufficiently young that vegetation has not stabilized their slopes, (2) many dam faces are steeper than the angle of repose, (3) these dams and lakes are immediately downslope from steep crevassed glaciers and near-vertical rock slopes, and (4) downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks. The most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls, rockfalls, or snow or rock avalanches. Melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms. Natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam. Although data are few, for the same potential energy at the dam site, ownstream flood peaks from the failure of glacier-ice dams are smaller than those from landslide, moraine, and structed earth-fill and rock-fill dam failures. Moraine-dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 10 11 -10 12 joules. Differences in flood peaks natural-dam failures appear to be controlled by dam characteristics and failure mechanisms.

Geological Society of America Bulletin↗
USGS2022

gTOOLS, an open-source MATLAB program for processing high precision, relative gravity data for time-lapse gravity monitoring

gTOOLS is an open-source software for the processing of relative gravity data. gTOOLS is available in MATLAB and as a compiled executable to be run under the free MATLAB Runtime Compiler. The software has been designed for time-lapse (temporal) gravity monitoring. Although programmed to read the Scintrex CG-5 and CG-6 gravimeters output data files, it can be easily modified to read data files from other gravimeters. The software binds together single-task processing modules within a very simple user interface that is based on one text file. Gravity processing involves three modules: (a) gravimeter calibration; (b) automatic processing of gravity data to find adjusted gravity differences; and (c) post processing of results. Each module is optional and runs independently from the others. Data processing includes (a) averaging out the measurements noise, and correction for solid Earth tides, and ocean loading, and residual instrumental drift, and (b) calculate the residual instrumental drift and gravity differences between the base station and monitoring sites, and their uncertainties, by a weighted least square analysis of the gravity data. The software allows the automatic processing of a gravity campaign spanning multiple days in a single run. The software is tested on gravity data from 2015 eruption at Cotopaxi volcano, Ecuador.

Computers & Geosciences↗
USGS2017

Sources and dispersal of land-based runoff from small Hawaiian drainages to a coral reef: Insights from geochemical signatures

Land-based sediment and contaminant runoff is a major threat to coral reefs, and runoff reduction efforts would benefit from knowledge of specific runoff sources. Geochemical signatures of small drainage basins were determined in the fine fraction of soil and sediment, then used in the nearshore region of a coral reef-fringed urban embayment on southeast Oahu, Hawaii, to describe sources and dispersal of land-based runoff. The sedimentary rare earth element ratio (La/Yb)N showed a clear distinction between the two main rock types in the overall contributing area, tholeiitic and alkalic olivine basalt. Based on this geochemical signature it was apparent that the majority of terrigenous sediment on the reef flat originated from geologically old tholeiitic drainages. Sediment from one of five tholeiitic drainages had a distinct geochemical signature, and sediment with this signature was dispersed on the reef flat 2 km west and 150 m offshore of the contributing basin. Sediment and the anthropogenic metals Cd, Pb, and Zn were entrained in runoff from the most heavily urbanized region of the watershed. Although anthropogenic Cd and Zn had localized distributions close to shore, anthropogenic Pb was found associated with fine sediment on the westernmost part of the reef flat and 400 m offshore, illustrating how trade-wind-driven sediment transport can increase the scale of runoff impacts to nearshore communities. Our findings show that sediment geochemical signatures can provide insights about the source and dispersal of land-based runoff in shallow coastal environments. The application of such knowledge to watershed management and habitat remediation efforts can aid in the protection and restoration of runoff-impacted coastal ecosystems worldwide.

Hawaii↗