SEARCH · Search USGS

Results for “Earth’s Future”

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

SourceResearch connectionFrom yearThrough year

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

At least 685 records · Page 38Linked to original sources

USGS2011

Volcanism on Io: New insights from global geologic mapping

We produced the first complete, 1:15 M-scale global geologic map of Jupiter’s moon Io, based on a set of monochrome and color Galileo – Voyager image mosaics produced at a spatial resolution of 1 km/pixel. The surface of Io was mapped into 19 units based on albedo, color and surface morphology, and is subdivided as follows: plains (65.8% of surface), lava flow fields (28.5%), mountains (3.2%), and patera floors (2.5%). Diffuse deposits (DD) that mantle the other units cover ∼18% of Io’s surface, and are distributed as follows: red (8.6% of surface), white (6.9%), yellow (2.1%), black (0.6%), and green (∼0.01%). Analyses of the geographical and areal distribution of these units yield a number of results, summarized below. (1) The distribution of plains units of different colors is generally geographically constrained: Red–brown plains occur >±30° latitude, and are thought to result from enhanced alteration of other units induced by radiation coming in from the poles. White plains (possibly dominated by SO 2 + contaminants) occur mostly in the equatorial antijovian region (±30°, 90–230°W), possibly indicative of a regional cold trap. Outliers of white, yellow, and red–brown plains in other regions may result from long-term accumulation of white, yellow, and red diffuse deposits, respectively. (2) Bright (possibly sulfur-rich) flow fields make up 30% more lava flow fields than dark (presumably silicate) flows (56.5% vs. 43.5%), and only 18% of bright flow fields occur within 10 km of dark flow fields. These results suggest that secondary sulfurous volcanism (where a bright-dark association is expected) could be responsible for only a fraction of Io’s recent bright flows, and that primary sulfur-rich effusions could be an important component of Io’s recent volcanism. An unusual concentration of bright flows at ∼45–75°N, ∼60–120°W could be indicative of more extensive primary sulfurous volcanism in the recent past. However, it remains unclear whether most bright flows are bright because they are sulfur flows, or because they are cold silicate flows covered in sulfur-rich particles from plume fallout. (3) We mapped 425 paterae (volcano-tectonic depressions), up from 417 previously identified by Radebaugh et al. (Radebaugh, J., Keszthelyi, L.P., McEwen, A.S., Turtle, E.P., Jaeger, W., Milazzo, M. [2001]. J. Geophys. Res. 106, 33005–33020). Although these features cover only 2.5% of Io’s surface, they correspond to 64% of all detected hot spots; 45% of all hot spots are associated with the freshest dark patera floors, reflecting the importance of active silicate volcanism to Io’s heat flow. (4) Mountains cover only ∼3% of the surface, although the transition from mountains to plains is gradational with the available imagery. 49% of all mountains are lineated and presumably layered, showing evidence of linear structures supportive of a tectonic origin. In contrast, only 6% of visible mountains are mottled (showing hummocks indicative of mass wasting) and 4% are tholi (domes or shields), consistent with a volcanic origin. (5) Initial analyses of the geographic distributions of map units show no significant longitudinal variation in the quantity of Io’s mountains or paterae, in contrast to earlier studies. This is because we use the area of mountain and patera materials as opposed to the number of structures, and our result suggests that the previously proposed anti-correlation of mountains and paterae (Schenk, P., Hargitai, H., Wilson, R., McEwen, A., Thomas, P. [2001]. J. Geophys. Res. 106, 33201–33222; Kirchoff, M.R., McKinnon, W.B., Schenk, P.M. [2011]. Earth Planet. Sci. Lett. 301, 22–30) is more complex than previously thought. There is also a slight decrease in surface area of lava flows toward the poles of Io, perhaps indicative of variations in volcanic activity. (6) The freshest bright and dark flows make up about 29% of all of Io’s flow fields, suggesting active emplacement is occurring in less than a third of Io’s visible lava fields. (7) About 47% of Io’s diffuse deposits (by area) are red, presumably deriving their color from condensed sulfur gas, and ∼38% are white, presumably dominated by condensed SO 2 . The much greater areal extent of gas-derived diffuse deposits (red + white, 85%) compared to presumably pyroclast-bearing diffuse deposits (dark (silicate tephra) + yellow (sulfur-rich tephra), 15%) indicates that there is effective separation between the transport of tephra and gas in many Ionian explosive eruptions. Future improvements in the geologic mapping of Io can be obtained via (a) investigating the relationships between different color/material units that are geographically and temporally associated, (b) better analysis of the temporal variations in the map units, and (c) additional high-resolution images (spatial resolutions ∼200 m/pixel or better). These improvements would be greatly facilitated by new data, which could be obtained by future missions.

Icarus↗

USGS1980

High throughput Landsat imagery film recorder

The Earth Resources Observation Systems (EROS) Data Center is responsible for processing, archiving, reproducing, and distributing satellite and aircraft remotely-sensed Earth imagery data in both film and digital format. Landsat Multispectral Scanner (MSS) and Return Beam Vidicon (RBV) sensor data alone represents a daily recording requirement of 23 billion pixels on 1000 feet of film. New satellites and sensors may double this amount of data within two years. To handle these requirements, the EROS Data Center installed an operational, multi-mode, programmable, high throughput, high resolution laser-beam film recording system directly on-line to the primary digital image processing computer. This system employs an Argon-Ion laser light source, electro-optic modulator, and rotating mirror to expose film in a flat-field line-scanned format at rates up to 400 lines per second. Laboratory-type requirements, such as a geometric fidelity of ± 0.05% and density repeatability within ± 0.05D, are maintained in a high-throughput production environment. To provide for future sensor formats, the scan rate, scanning spot size, film velocity, laser power, and number of overscans are firmware programmable for up to 16 on-line, auto-matically selectable configurations.

Conference Paper↗

USGS2007

Facing tomorrow’s challenges—U.S. Geological Survey science in the decade 2007–2017

Executive Summary In order for the U.S. Geological Survey (USGS) to respond to evolving national and global priorities, it must periodically reflect on, and optimize, its strategic directions. This report is the first comprehensive science strategy since the early 1990s to examine critically major USGS science goals and priorities. The development of this science strategy comes at a time of global trends and rapidly evolving societal needs that pose important natural-science challenges. The emergence of a global economy affects the demand for all resources. The last decade has witnessed the emergence of a new model for managing Federal lands—ecosystem-based management. The U.S. Climate Change Science Program predicts that the next few decades will see rapid changes in the Nation’s and the Earth’s environment. Finally, the natural environment continues to pose risks to society in the form of volcanoes, earthquakes, wildland fires, floods, droughts, invasive species, variable and changing climate, and natural and anthropogenic toxins, as well as animal-borne diseases that affect humans. The use of, and competition for, natural resources on the global scale, and natural threats to those resources, has the potential to impact the Nation’s ability to sustain its economy, national security, quality of life, and natural environment. Responding to these national priorities and global trends requires a science strategy that not only builds on existing USGS strengths and partnerships but also demands the innovation made possible by integrating the full breadth and depth of USGS capabilities. The USGS chooses to go forward in the science directions proposed here because the societal issues addressed by these science directions represent major challenges for the Nation’s future and for the stewards of Federal lands, both onshore and offshore. The six science directions proposed in this science strategy are summarized in the following paragraphs. The ecosystems strategy is listed first because it has a dual nature. It is itself an essential direction for the USGS to pursue to meet a pressing national and global need, but ecosystem-based approaches are also an underpinning of the other five directions, which all require ecosystem perspectives and tools for their execution. The remaining strategic directions are listed in alphabetical order.

Circular↗

USGS2023

Long-term trends in Arctic riverine chemistry signal multi-faceted northern change

Rivers integrate processes occurring throughout their watersheds and are therefore sentinels of change across broad spatial scales. River chemistry also regulates ecosystem function across Earth’s land–ocean continuum, exerting control from the micro- (for example, local food web) to the macro- (for example, global carbon cycle) scale. In the rapidly warming Arctic, a wide range of processes—from permafrost thaw to biological uptake and transformation—might reasonably alter river water chemistry. Here we use data from major rivers that collectively drain two-thirds of the Arctic Ocean watershed to assess widespread change in biogeochemical function within the pan-Arctic basin from 2003 to 2019. While the oceanward flux of alkalinity and associated ions increased markedly over this time frame, nitrate and other inorganic nutrient fluxes declined. Fluxes of dissolved organic carbon showed no overall trend. This divergence in response indicates the perturbation of multiple processes on land, with implications for biogeochemical cycling in the coastal ocean. We anticipate that these findings will facilitate refinement of conceptual and numerical models of current and future functioning of Arctic coastal ecosystems and spur research on scale-dependent change across the river-integrated Arctic domain.

Arctic↗

USGS2013

Baseline coastal oblique aerial photographs collected from Pensacola, Florida, to Breton Islands, Louisiana, February 7, 2012

The U.S. Geological Survey (USGS) conducts baseline and storm response photography missions to document and understand the changes in vulnerability of the Nation's coasts to extreme storms (Morgan, 2009). On February 7, 2012, the USGS conducted an oblique aerial photographic survey from Pensacola, Fla., to Breton Islands, La., aboard a Piper Navajo Chieftain at an altitude of 500 feet (ft) and approximately 1,000 ft offshore. This mission was flown to collect baseline data for assessing incremental changes since the last survey, and the data can be used in the assessment of future coastal change. The photographs provided here are Joint Photographic Experts Group (JPEG) images. The photograph locations are an estimate of the position of the aircraft and do not indicate the location of the feature in the images (see the Navigation Data page). These photos document the configuration of the barrier islands and other coastal features at the time of the survey. The header of each photo is populated with time of collection, Global Positioning System (GPS) latitude, GPS longitude, GPS position (latitude and longitude), keywords, credit, artist (photographer), caption, copyright, and contact information using EXIFtools (Subino and others, 2012). Photographs can be opened directly with any JPEG-compatible image viewer by clicking on a thumbnail on the contact sheet. Table 1 provides detailed information about the assigned location, name, data, and time the photograph was taken along with links to the photograph. In addition to the photographs, a Google Earth Keyhole Markup Language (KML) file is provided and can be used to view the images by clicking on the marker and then clicking on either the thumbnail or the link above the thumbnail. The KML files were created using the photographic navigation files (see the Photos and Maps page).

Alabama, Florida, Louisiana, Mississippi↗

USGS2021

Mineral deposits of the Mesoproterozoic Midcontinent Rift System in the Lake Superior region – Metallogeny of the prolifically mineralized Keweenawan LIP

The Keweenawan large igneous province (LIP) of the Midcontinent Rift System (MRS) of North America is perhaps the most prolifically and diversely mineralized LIP known on Earth (Nicholson et al., 1992). The MRS is an approximately 2,200 km curvilinear continental rift that stretches from Kansas northeast to the Lake Superior region where it turns southeast and extends through lower Michigan (Fig. 1). Rocks of the MRS host a varied suite of magmatic and hydrothermal mineral deposits in the Lake Superior region of the United States and Canada where rift rocks are exposed at or near the surface. Historically, hydrothermal deposits, such as Michigan’s native Cu deposits and the White Pine sediment-hosted stratiform Cu deposit, were major MRS metal producers. On-going exploration for and potential development of Cu-Ni sulfide deposits hosted by the Duluth Complex of Minnesota and the opening of the Eagle Ni mine in Michigan indicate an expanding interest in MRS magmatic deposits. Many of the MRS hydrothermal and magmatic mineral deposits are significant past, present, and likely future providers of critical minerals. We have placed these deposits into a space and time metallogenic framework (Woodruff et al., 2020a) that is summarized here.

Iowa, Kansas, Minnesota, Michigan, Nebraska, Ontar↗

USGS1999

Stress transfer by the 1988-1989 M=5.3 and 5.4 Lake Elsman foreshocks to the Loma Prieta fault: Unclamping at the site of peak mainshock slip

We study the stress transferred by the June 27, 1988, M = 5.3 and August 8, 1989, M = 5.4 Lake Elsman earthquakes, the largest events to strike within 15 km of the future Loma Prieta rupture zone during 74 years before the 1989 M = 6.9 Loma Prieta earthquake. We find that the first Lake Elsman event brought the rupture plane of the second event 0.3–1.6 bars (0.03–0.16 MPa) closer to Coulomb failure but that the Lake Elsman events did not bring the future Loma Prieta hypocentral zone closer to failure. Instead, the Lake Elsman earthquakes are calculated to have reduced the normal stress on (or “undamped”) the Loma Prieta rupture surface by 0.5–1.0 bar (0.05–0.10 MPa) at the site where the greatest slip subsequently occurred in the Loma Prieta earthquake. This association between the sites of peak unclamping and slip suggests that the Lake Elsman events did indeed influence the Loma Prieta rupture process. Unclamping the fault would have locally lowered the resistance to sliding. Such an effect could have been enhanced if the lowered normal stress permitted fluid infusion into the undamped part of the fault. Although less well recorded, the M L = 5.0 1964 and M L = 5.3 1967 Corralitos events struck within 10 km of the southwest end of the future Loma Prieta rupture. No similar relationship between the normal stress change and subsequent Loma Prieta slip is observed, although the high-slip patch southwest of the Loma Prieta epicenter corresponds roughly to the site of calculated Coulomb stress increase for a low coefficient of friction. The Lake Elsman-Loma Prieta result is similar to that for the 1987 M = 6.2 Elmore Ranch and M = 6.7 Superstition Hills earthquakes, suggesting that foreshocks might influence the distribution of mainshock slip rather than the site of mainshock nucleation.

Journal of Geophysical Research B: Solid Earth↗

USGS2017

A decade of insights into grassland ecosystem responses to global environmental change

Earth’s biodiversity and carbon uptake by plants, or primary productivity, are intricately interlinked, underlie many essential ecosystem processes, and depend on the interplay among environmental factors, many of which are being changed by human activities. While ecological theory generalizes across taxa and environments, most empirical tests of factors controlling diversity and productivity have been observational, single-site experiments, or meta-analyses, limiting our understanding of variation among site-level responses and tests of general mechanisms. A synthesis of results from ten years of a globally distributed, coordinated experiment, the Nutrient Network (NutNet), demonstrates that species diversity promotes ecosystem productivity and stability, and that nutrient supply and herbivory control diversity via changes in composition, including invasions of non-native species and extinction of native species. Distributed experimental networks are a powerful tool for tests and integration of multiple theories and for generating multivariate predictions about the effects of global changes on future ecosystems.

Nature Ecology & Evolution↗

USGS2015

Baseline coastal oblique aerial photographs collected from the Virginia/North Carolina border to Montauk Point, New York, October 5-6, 2014

Summary The U.S. Geological Survey (USGS) conducts baseline and storm response photography missions to document and understand the changes in vulnerability of the Nation's coasts to extreme storms (Morgan, 2009). On October 5-6, 2014, the USGS conducted an oblique aerial photographic survey from the Virginia/North Carolina border to Montauk Point, New York, aboard a Cessna 182 at an altitude of 500 feet (ft) and approximately 1,200 ft offshore. This mission was flown to collect baseline data to assess incremental changes since the last survey, flown in November 2012, and the data can be used in the assessment of future coastal change. The images provided in this report are Joint Photographic Experts Group (JPEG) images. ExifTool was used to add the following to the header of each photo: time of collection, Global Positioning System (GPS) latitude, GPS longitude, keywords, credit, artist (photographer), caption, copyright, and contact information. The photograph locations are an estimate of the position of the aircraft and do not indicate the location of any feature in the images (see the Navigation Data page). These photographs document the state of the barrier islands and other coastal features at the time of the survey. Pages containing thumbnail images of the photographs, referred to as contact sheets, were created in five-minute segments of flight time. These segments can be found on the Photos and Maps page. Photographs can be opened directly with any JPEG-compatible image viewer by clicking on a thumbnail on the contact sheet. In addition to the photographs, a Google Earth Keyhole Markup Language (KML) file is provided and can be used to view the images by clicking on the marker and then clicking on either the thumbnail or the link above the thumbnail. The KML files were created using the photographic navigation files.

New York, North Carolina, Virginia↗

USGS2011

Wind energy in the United States and materials required for the land-based wind turbine industry from 2010 through 2030

The generation of electricity in the United States from wind-powered turbines is increasing. An understanding of the sources and abundance of raw materials required by the wind turbine industry and the many uses for these materials is necessary to assess the effect of this industry's growth on future demand for selected raw materials relative to the historical demand for these materials. The U.S. Geological Survey developed estimates of future requirements for raw (and some recycled) materials based on the assumption that wind energy will supply 20 percent of the electricity consumed in the United States by 2030. Economic, environmental, political, and technological considerations and trends reported for 2009 were used as a baseline. Estimates for the quantity of materials in typical "current generation" and "next generation" wind turbines were developed. In addition, estimates for the annual and total material requirements were developed based on the growth necessary for wind energy when converted in a wind powerplant to generate 20 percent of the U.S. supply of electricity by 2030. The results of the study suggest that achieving the market goal of 20 percent by 2030 would require an average annual consumption of about 6.8 million metric tons of concrete, 1.5 million metric tons of steel, 310,000 metric tons of cast iron, 40,000 metric tons of copper, and 380 metric tons of the rare-earth element neodymium. With the exception of neodymium, these material requirements represent less than 3 percent of the U.S. apparent consumption for 2008. Recycled material could supply about 3 percent of the total steel required for wind turbine production from 2010 through 2030, 4 percent of the aluminum required, and 3 percent of the copper required. The data suggest that, with the possible exception of rare-earth elements, there should not be a shortage of the principal materials required for electricity generation from wind energy. There may, however, be selective manufacturing shortages if the total demand for raw materials from all markets is greater than the available supply of these materials or the capacity of industry to manufacture components. Changing economic conditions could also affect the development schedule of anticipated capacity.

Scientific Investigations Report↗

USGS2019

Extreme coastal water level in Washington state: Guidance to support sea level rise planning

This document provides guidelines for assessing exposure to future coastal flooding during extreme coastal water level events – whether these are due to tides, surge, wave run-up, or, more likely, a combination of the three. These guidelines provide information about the current and future magnitude of extreme coastal water levels across Washington State and the underlying processes that influence them. This information is intended to be combined with sea level projections to assess future exposure to coastal flooding along Washington’s coastline. Although the results of our analyses can be combined with any available sea level projections, this report is intended as a companion to the localized sea level rise projections (Miller et al., 2018) developed as part of the Washington Coastal Resilience Project. The Washington Coastal Resilience Project was a three-year effort to rapidly increase the state’s capacity to prepare for sea level rise. The project aimed to improve risk projections, provide better guidelines for land use planners and strengthen capital investment programs for coastal restoration and infrastructure. Partners in the Washington Coastal Resilience Project included Washington Sea Grant, Washington Department of Ecology, Island County, King County, NOAA Office for Coastal Management, Pacific Northwest National Laboratory, Padilla Bay National Estuary Research Reserve, The City of Tacoma, The Nature Conservancy, U.S. Geological Survey, University of Oregon, University of Washington Climate Impacts Group, University of Washington Department of Earth and Space Sciences, Washington Department of Fish and Wildlife and Western Washington University. The 2018 sea level projections are described in an accompanying technical report, along with a review of the science related to sea level rise (Miller et al., 2018). The report and all associated supporting information are available on the Washington Coastal Hazards Resilience Network website (http://www.wacoastalnetwork.com/).

Washington↗

USGS2002

Landscape ecology of plague in the American southwest, September 19-20, 2000, Fort Collins, Colorado

During September 19-20, 2000, a workshop titled "Landscape Ecology of Plague in the American Southwest" was held in Fort Collins, Colorado. The workshop was funded by the U.S. Geological Survey (USGS)-Earth Surface Processes Team and sponsored by the USGS National Wildlife Health Center. Forty scientists and natural resource managers and administrators representing 8 federal agencies, 4 state agencies, 6 universities, and other local agencies and nongovernment organizations met to discuss historical and current status of plague in the United States, current activities in plague surveillance, research, and management in wildlife, and research and information needs relative to plague control and management. Eleven individual presentations on plague history, status, and trends; diagnostic technologies; epizootiological studies and observations; and control and management strategies and studies, followed by a panel discussion on the impact of plague on wildlife and ecosystems, led the way to extensive group discussions on important plague-related questions, issues and problems. Workshop attendees participated in identifying important research and information needs relevant to control and management of plague in wildlife, and in the process, established new cooperative and collaborative partnerships and enhanced existing relationships upon which future research and information needs can be met. The proceedings from this workshop are intended to be used by the natural resource managers and researchers from the various participating agencies, research facilities, as well as other stakeholders to aid in the development of future research and information programs and funding initiatives related to both zoonotic and sylvatic plague.

American Southwest↗

USGS2016

The global Landsat archive: Status, consolidation, and direction

New and previously unimaginable Landsat applications have been fostered by a policy change in 2008 that made analysis-ready Landsat data free and open access. Since 1972, Landsat has been collecting images of the Earth, with the early years of the program constrained by onboard satellite and ground systems, as well as limitations across the range of required computing, networking, and storage capabilities. Rather than robust on-satellite storage for transmission via high bandwidth downlink to a centralized storage and distribution facility as with Landsat-8, a network of receiving stations, one operated by the U.S. government, the other operated by a community of International Cooperators (ICs), were utilized. ICs paid a fee for the right to receive and distribute Landsat data and over time, more Landsat data was held outside the archive of the United State Geological Survey (USGS) than was held inside, much of it unique. Recognizing the critical value of these data, the USGS began a Landsat Global Archive Consolidation (LGAC) initiative in 2010 to bring these data into a single, universally accessible, centralized global archive, housed at the Earth Resources Observation and Science (EROS) Center in Sioux Falls, South Dakota. The primary LGAC goals are to inventory the data held by ICs, acquire the data, and ingest and apply standard ground station processing to generate an L1T analysis-ready product. As of January 1, 2015 there were 5,532,454 images in the USGS archive. LGAC has contributed approximately 3.2 million of those images, more than doubling the original USGS archive holdings. Moreover, an additional 2.3 million images have been identified to date through the LGAC initiative and are in the process of being added to the archive. The impact of LGAC is significant and, in terms of images in the collection, analogous to that of having had two additional Landsat-5 missions. As a result of LGAC, there are regions of the globe that now have markedly improved Landsat data coverage, resulting in an enhanced capacity for mapping, monitoring change, and capturing historic conditions. Although future missions can be planned and implemented, the past cannot be revisited, underscoring the value and enhanced significance of historical Landsat data and the LGAC initiative. The aim of this paper is to report the current status of the global USGS Landsat archive, document the existing and anticipated contributions of LGAC to the archive, and characterize the current acquisitions of Landsat-7 and Landsat-8. Landsat-8 is adding data to the archive at an unprecedented rate as nearly all terrestrial images are now collected. We also offer key lessons learned so far from the LGAC initiative, plus insights regarding other critical elements of the Landsat program looking forward, such as acquisition, continuity, temporal revisit, and the importance of continuing to operationalize the Landsat program.

Remote Sensing of Environment↗

USGS2011

Towards sustainable groundwater use: Setting long-term goals, backcasting, and managing adaptively

The sustainability of crucial earth resources, such as groundwater, is a critical issue. We consider groundwater sustainability a value‐driven process of intra‐ and intergenerational equity that balances the environment, society, and economy. Synthesizing hydrogeological science and current sustainability concepts, we emphasize three sustainability approaches: setting multigenerational sustainability goals, backcasting, and managing adaptively. As most aquifer problems are long‐term problems, we propose that multigenerational goals (50 to 100 years) for water quantity and quality that acknowledge the connections between groundwater, surface water, and ecosystems be set for many aquifers. The goals should be set by a watershed‐ or aquifer‐based community in an inclusive and participatory manner. Policies for shorter time horizons should be developed by backcasting, and measures implemented through adaptive management to achieve the long‐term goals. Two case histories illustrate the importance and complexity of a multigenerational perspective and adaptive management. These approaches could transform aquifer depletion and contamination to more sustainable groundwater use, providing groundwater for current and future generations while protecting ecological integrity and resilience.

Ground Water↗

USGS2022

Deep-ocean polymetallic nodules and cobalt-rich ferromanganese crusts in the global ocean: New sources for critical metals

The transition from a global hydrocarbon economy to a green energy economy and the rapidly growing middle class in developing countries are driving the need for considerable new sources of critical materials. Deep-ocean minerals, namely cobalt-rich ferromanganese crusts and polymetallic nodules, are two such new resources generating interest. Polymetallic nodules are essentially two-dimensional mineral deposits sitting on abyssal plain sediments at about 3,500–6,000 m water depths. Metals of economic interest enriched in nodules include nickel, copper, manganese, cobalt and molybdenum. Cobalt-rich ferromanganese crusts are also two-dimensional deposits forming pavements on rock outcrops on seamounts and ridges at water depths of 400–7,000 m. Metals of economic interest for crusts include cobalt, manganese, nickel, molybdenum, tellurium, platinum, vanadium and rare earth elements. A conservative estimate is that 21.1 billion dry tons of polymetallic nodules exist in the Clarion-Clipperton Zone ( CCZ ) manganese nodule field, the largest in area and tonnage of the known global nodule fields. Based on that estimate, tonnages of many critical metals in the CCZ nodules are greater than those found in global terrestrial reserves. About 7.5 billion dry tons of cobalt-rich ferromanganese crusts are estimated to occur in the Pacific Ocean Prime Crust Zone, the area with the highest tonnage of critical-metal-rich crust deposits, with many elements contained therein estimated to be greater than those found in global terrestrial reserves. Deep-ocean mining has not yet been carried out in the Exclusive Economic Zone of any nation, nor in the Areas beyond national jurisdiction, although extensive mineral exploration and environmental studies are being conducted and exploitation regulations codified, indicating that mining activities will likely begin in the near future. If deep-ocean mining follows the evolution of offshore production of petroleum, we can expect that about 35–45 per cent of the demand for critical metals will come from deep-ocean mines by 2065.

Book chapter↗

USGS2012

Relative sea-level rise as indicated by gage data along the Mississippi and Alabama Gulf Coasts

Global warming, or the increasing of earth's temperatures, leads to rising sea level as polar ice caps and mountain glaciers melt and ocean water undergoes thermal expansion. Tidal records collected by the U.S. Army Corps of Engineers (COE), Mobile District, at Gulfport, Biloxi, and Pascagoula, Mississippi, and at Mobile, Alabama, indicate trends of water-surface elevations increasing with time (relative sea-level rise). The trends indicated by the COE data were compared to relative sea-level trends indicated by the National Ocean Survey gages in the Gulf of Mexico. The average global rate of sea level rise has been suggested to approach about 2 mm/yr (0.007 ft/yr). Some leading scientists have suggested rates of sea level rise that are greater than 2 mm/yr, when accounting for effects of greenhouse gas emissions. As the sea level rises and inundates the coastal plain, structures along the existing coast and structures located in the back bays of estuaries will be even more adversely affected by future flooding. Also, if the land surface adjacent to the water also sinks due to soil compaction and other geologic processes (collectively call subsidence), additional land will be inundated. Copyright ASCE 2004.

Conference Paper↗

USGS2001

Patterns and processes of wetland loss in coastal Louisiana are complex: A reply to Turner 2001. Estimating the indirect effects of hydrologic change on wetland loss: If the Earth is curved, then how would we know it?

The coastal wetlands of Louisiana comprise a vast expanse of marine to freshwater wetland plant communities interspersed w-ith shallow bays and bayous. These wetlands were built by processes associated with the present-day Mississippi and Atchatfalaya River deltas and older distributaries occupied by the river over the past 7,000 }rears. The high rates of wetland loss identified in this system during the 20th century have serious consequences for living resources (Boesch et al. 1994) and coastal residents, and they affect our ability to maintain navigation and flood control. The restoration and management response to this problem must be grounded in a sound understanding of the causative factors. The system has been highly altered by river levees, roads and railway embankments, impoundments, and canals of many dimensions dredged for a variety of purposes. These changes have been imposed on a landscape that is essentially the result of a delicate natural balance between wetland building processes and compaction, subsidence, and sea-level rise. Many now recognize that coastal wetlands can cope with relatively high rates of subsidence and sea-level rise, as long as the processes that ensure wetland sustainability through vertical accumulation of substrate remain unimpaired (Boesch et al. 2000). The challenge facing both the scientific community and coastal resource managers in Louisiana is to look to the future. We must use our understanding of the problem and how it evolved to develop a multi-use ecosystem management plan, and some efforts have been made by state and federal agencies towards this goal (LCWCRTF & WCRA 1998). The present discussions (Turner 1997, 2001; Day et al. 2000; Gosselink 2001) demonstrate the complexity of the issues faced in Louisiana. While such discourse is common in the scientific community where varied approaches and interpretations are a sign of vitality, it is helpful to be clear about the state of knowledge and what levels of uncertainty exist. We seek to clarify some of the issues that have been raised in the discussion, recognizing that our best-available science cannot yet resolve many of them as completely as all would like.

Louisiana↗

USGS2014

Crustal earthquake triggering by pre-historic great earthquakes on subduction zone thrusts

Triggering of earthquakes on upper plate faults during and shortly after recent great ( M> 8.0) subduction thrust earthquakes raises concerns about earthquake triggering following Cascadia subduction zone earthquakes. Of particular regard to Cascadia was the previously noted, but only qualitatively identified, clustering of M> ~6.5 crustal earthquakes in the Puget Sound region between about 1200–900 cal yr B.P. and the possibility that this was triggered by a great Cascadia thrust subduction thrust earthquake, and therefore portends future such clusters. We confirm quantitatively the extraordinary nature of the Puget Sound region crustal earthquake clustering between 1200–900 cal yr B.P., at least over the last 16,000. We conclude that this cluster was not triggered by the penultimate, and possibly full-margin, great Cascadia subduction thrust earthquake. However, we also show that the paleoseismic record for Cascadia is consistent with conclusions of our companion study of the global modern record outside Cascadia, that M> 8.6 subduction thrust events have a high probability of triggering at least one or more M> ~6.5 crustal earthquakes.

Cascadia;Puget Sound↗