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At least 469 records · Page 26Linked to original sources
USGS1973

Pahoehoe flows from the 1969–1971 Mauna Ulu eruption, Kilauea Volcano, Hawaii

Note: This paper is dedicated to Aaron and Elizabeth Waters on the occasion of Dr. Waters' retirement. Three types of chemically similar pahoehoe flows were observed to form during the 1969–1971 Mauna Ulu eruption. (1) A cavernous type called shelly pahoehoe, characterized by fragile gas cavities, small tubes, and buckled fragments of surface crust, was deposited when gas-charged lava welled out of the source fissure with little or no accompanying fountaining. (2) A comparatively smooth-surfaced, dense type, characterized by surface channels and only a few large cavities, formed from voluminous flows of partly degassed fallout away from the foot of lava fountains more than 100 m high. (3) A relatively dense type, characterized by hummocky surfaces with abundant low tumuli and overlapping pahoehoe toes and lobes, formed when largely degassed lava issued from tubes after flowing underground for several kilometers or more. Shelly pahoehoe is rarely found in the geologic record, but the other two types occur commonly. These three types of pahoehoe, which are completely intergradational, can be related qualitatively to the relative gas content and mode of flowage of the lava. The present surface of Kilauea is underlain mostly by hummocky, tube-fed pahoehoe.

Hawai'i↗
USGS2014

Terrestrial reference standard sites for postlaunch sensor calibration

In an era when the number of Earth observation satellites is rapidly growing and measurements from satellite sensors are used to address increasingly urgent global issues, often through synergistic and operational combinations of data from multiple sources, it is imperative that scientists and decision-makers are able to rely on the accuracy of Earth observation data products. The characterization and calibration of these sensors, particularly their relative biases, are vital to the success of the developing integrated Global Earth Observation System of Systems (GEOSS) for coordinated and sustained observations of the Earth. This can only reliably be achieved in the postlaunch environment through the careful use of observations by multiple sensor systems over common, well-characterized terrestrial targets (i.e., on or near the Earth's surface). Through greater access to and understanding of these vital reference standard sites and their use, the validity and utility of information gained from Earth remote sensing will continue to improve. This paper provides a brief overview of the use of reference standard sites for postlaunch sensor radiometric calibration from historical, current, and future perspectives. Emphasis is placed on optical sensors operating in the visible, near-infrared, and shortwave infrared spectral regions.

Canadian Journal of Remote Sensing↗
USGS1975

The scientific referee

In the May 1973 issue of EOS, I criticized tendencies in earth science periodicals to discourage referee anonymity. I stressed that exposing referees to unnecessary personal and subjective influences tended to degrade standards of quality and promoted cliques, fragmentation, superspecialization, and proliferation of scientific literature. Generally speaking, division of opinion on this question, based on letters and personal contacts since 1973, has tended (with notable exceptions) to divide along two lines: the “wise old heads” favor anonymity, whereas many young idealists favor openness. Referees can help keep literature standards high (there is no evidence that they can or do thwart new ideas, determinedly pushed). but they can do little to stop literature proliferation, If individuals do scientific work, they may as well publish of not do it at all. The only real solutions to literature proliferation are fewer scientists or a drastic paper shortage, as experienced in Bulgaria.

IEEE Transactions on Professional Communication↗
USGS2003

Reclaiming agricultural drainage water with nanofiltration membranes: Imperial Valley, California, USA

We conducted pilot-scale field experiments using nanofiltration membranes to lower the salinity and remove Se, As and other toxic contaminants from saline agricultural wastewater in the Imperial Valley, California, USA. Farmlands in the desert climate (rainfall - 7.4 cm/a) of Imperial Valley cover -200,000 ha that are irrigated with water (-1.7 km 3 annually) imported from the Colorado River. The salinity (-850 mg/L) and concentration of Se (-2.5 μ g/L) in the Colorado River water are high and evapotranpiration further concentrates salts in irrigation drainage water, reaching salinities of 3,000-15,000 mg/L TDS and a median Se value of -30 μ g/L. Experiments were conducted with two commercially available nanofiltration membranes, using drainage water of varying composition, and with or without the addition of organic precipitation inhibitors. Results show that these membranes selectively remove more than 95% of Se, SO 4 , Mo, U and DOC, and -30% of As from this wastewater. Low percentages of Cl, NO 3 and HCO 3 , with enough cations to maintain electrical neutrality also were removed. The product water treated by these membranes comprised more than 90% of the wastewater tested. Results indicate that the treated product water from the Alamo River likely will have less than 0.2 μ g/L Se, salinity of 300-500 mg/L TDS and other chemical concentrations that meet the water quality criteria for irrigation and potable use. Because acceptability is a major issue for providing treated wastewater to urban centers, it may be prudent to use the reclaimed water for irrigation and creation of lower salinity wetlands near the Salton Sea; an equivalent volume of Colorado River water can then be diverted for the use of increasing populations of San Diego and other urban centers in southern California. Nanofiltration membranes yield greater reclaimed-water output and require lower pressure and less pretreatment, and therefore are generally more cost effective than traditional reverse osmosis membranes.

California↗
USGS2004

Comparison of natural resource issues on tropical pacific ranges

The natural resources issues on tropical Pacific ranges are compared. If active management plan is in place, FWS may exempt those spp. from critical Habitat Prevention and control or invasive species essential. Wetlands are low-hanging fruit for restoration, but birds present mgmt. challenge. Marine sites may offer less potential for precise mgmt. of natural resources than terrestrial sites such as, lack of knowledge, observational limits, ecosystem complexity, mobile biota. It has been suggested that the tremendus public interest in helping with conservation activities - volunteer opportunities may offset staffing shortfalls.

Conference Paper↗
USGS2019

Looking to the Future: Key points for sustainable management of Northern Great Plains grasslands

The grasslands of the northern Great Plains region of North America are considered endangered ecosystems and priority conservation areas yet have great ecological and economic importance. Grasslands in the northern Great Plains (referred to as NGP from this point) are no longer self-regulating adaptive systems. The challenges to these grasslands are widespread and serious (e.g., climate change, invasive species, fragmentation, altered disturbance regimes, and anthropogenic chemical loads). Because the challenges facing the region are dynamic, complex, and persistent, a paradigm shift in how we approach restoration and management of the grasslands in the northern Great Plains is imperative. The goal of this paper is to highlight 4 key points for land managers and restoration practitioners to consider when planning management or restoration actions. First, we discuss the appropriateness of using historical fidelity as a restoration or management target because of changing climate, widespread pervasiveness of invasive species, the high level of fragmentation, and altered disturbance regimes. Second, we highlight ecosystem resilience and long-term population persistence as alternative targets. Third, because the NGP is so heavily impacted with anthropogenic chemical loading, we discuss the risks of ecological traps and extinction debt. Finally, we highlight the importance of using adaptive management and having patience during restoration and management. Consideration of these 4 points will help management and restoration of grasslands move toward a more successful and sustainable future. Although we specifically focus on the northern Great Plains of North America, these same issues and considerations apply to grasslands globally as well as many other ecosystems.

Restoration Ecology↗
USGS1998

Suggestions for new and aspiring graduate students in wildlife science

The transition from an undergraduate to a graduate program can be a difficult experience for students. Many undergraduates are unfamiliar with the process of preparing for graduate school, especially the search for a graduate program. Once in graduate school, they may be unfamiliar with requirements (both written and unwritten) and expectations, and they may also lack the necessary knowledge or skills to complete a graduate program successfully. For students in wildlife science graduate programs, these problems can become major issues, especially for students with undergraduate degrees in fields other than wildlife science (e.g., biology programs). Although several authors have provided advice to graduate students (Stearns 1987, Hucy 1987, Witz 1994), their suggestions either did not provide sufficient information for undergraduate students, or did not apply to graduate students in wildlife science. We provide information for undergraduates and new graduate students in wildlife science that is often unavailable prior to and during the initial phases of a graduate program. Our objectives are: (1) to provide advice on how to prepare for graduate school; (2) to provide an approach to locating, evaluating, and selecting potential graduate schools and a graduate advisor; (3) to describe the fundamentals of graduate school; and (4) to familiarize students with available tools and techniques to enhance a graduate program. We hope that university professors will provide this paper to undergraduates to aid those interested in attending graduate school. In addition, graduate advisors may wish to provide this paper to new graduate students as they begin their programs.

Wildlife Society Bulletin↗
USGS1999

Water professionals and water policy in the Black Hills region

A case study approach based on examples from the Black Hills region is used to evaluate the role of water professionals in developing feasible and fair public policy involving water resources. Examples presented include a long-term hydrologic investigation in the Black Hills, a local wellhead protection program, issues being addressed by a local flood management commission, coordination of definitions of beneficial stream uses by two state agencies, water-quality problems related to rapid population increase in a rural area, and impacts of potential climate change on water resources. In some of these examples, the hydrologic work was separated from policy making to ensure neutrality. In other examples, involvement of the hydrologists and water resource engineers directly benefited policy development. Opportunities for increased effectiveness were observed in most of the examples.

South Dakota, Wyoming↗
USGS2009

HRSC: High resolution stereo camera

The High Resolution Stereo Camera (HRSC) on Mars Express has delivered a wealth of image data, amounting to over 2.5 TB from the start of the mapping phase in January 2004 to September 2008. In that time, more than a third of Mars was covered at a resolution of 10-20 m/pixel in stereo and colour. After five years in orbit, HRSC is still in excellent shape, and it could continue to operate for many more years. HRSC has proven its ability to close the gap between the low-resolution Viking image data and the high-resolution Mars Orbiter Camera images, leading to a global picture of the geological evolution of Mars that is now much clearer than ever before. Derived highest-resolution terrain model data have closed major gaps and provided an unprecedented insight into the shape of the surface, which is paramount not only for surface analysis and geological interpretation, but also for combination with and analysis of data from other instruments, as well as in planning for future missions. This chapter presents the scientific output from data analysis and highlevel data processing, complemented by a summary of how the experiment is conducted by the HRSC team members working in geoscience, atmospheric science, photogrammetry and spectrophotometry. Many of these contributions have been or will be published in peer-reviewed journals and special issues. They form a cross-section of the scientific output, either by summarising the new geoscientific picture of Mars provided by HRSC or by detailing some of the topics of data analysis concerning photogrammetry, cartography and spectral data analysis.

Conference Paper↗
USGS2007

USGS Tampa Bay Pilot Study

Many of the nation's estuaries have been environmentally stressed since the turn of the 20th century and will continue to be impacted in the future. Tampa Bay, one the Gulf of Mexico's largest estuaries, exemplifies the threats that our estuaries face (EPA Report 2001, Tampa Bay Estuary Program-Comprehensive Conservation and Management Plan (TBEP-CCMP)). More than 2 million people live in the Tampa Bay watershed, and the population constitutes to grow. Demand for freshwater resources, conversion of undeveloped areas to resident and industrial uses, increases in storm-water runoff, and increased air pollution from urban and industrial sources are some of the known human activities that impact Tampa Bay. Beginning on 2001, additional anthropogenic modifications began in Tampa Bat including construction of an underwater gas pipeline and a desalinization plant, expansion of existing ports, and increased freshwater withdrawal from three major tributaries to the bay. In January of 2001, the Tampa Bay Estuary Program (TBEP) and its partners identifies a critical need for participation from the U.S. Geological Survey (USGS) in providing multidisciplinary expertise and a regional-scale, integrated science approach to address complex scientific research issue and critical scientific information gaps that are necessary for continued restoration and preservation of Tampa Bay. Tampa Bay stakeholders identified several critical science gaps for which USGS expertise was needed (Yates et al. 2001). These critical science gaps fall under four topical categories (or system components): 1) water and sediment quality, 2) hydrodynamics, 3) geology and geomorphology, and 4) ecosystem structure and function. Scientists and resource managers participating in Tampa Bay studies recognize that it is no longer sufficient to simply examine each of these estuarine system components individually, Rather, the interrelation among system components must be understood to develop conceptual and predictive modeling tools for effective ecosystem adaptive management. As a multidisciplinary organization, the USGS possesses the capability of developing and coordinating an integrated science strategy for estuarine research founded on partnerships and collaborative efforts, multidisciplinary teams of scientists, and integrated field work, data analysis and interpretation, and product development. The primary role of the USGS in Tamps Bay research was defined with our partners based upon this capability to address estuarine issues using an integrated science approach with a regional perspective and within a national context to complement the numerous ongoing scien efforts by state and local agencies that address local issues within Tamp Bay. Six primary components of the USGS Tamp Bay Study address critical gaps within each of the the four estuarine system components and focus on: 1.) Examining how natural and man-made physical changes affect ecosystem health through mapping and modeling. 2.) Identifying sources and quality of groundwater, surface water, and sediment, 3.) Identifying sources and quality of groundwater, surface water, and sediment, 4.) Assessing the natural and man-made changes affecting wetland health and restoration, 5.) Identifying and measuring the impact of urbanization on seafloor habitats, Providing a web-based digital information management system of information for scientists and the public, including a system that supports the work of those officials who must make decisions that affect the state of the bay. The Tampa Bay Study is in its sixth year and will continue through September 2007. This paper presents a non-inclusive summary of key findings associated with the six primary project components listed above. Component 4 (above) is described in detail in the following chapter 13. More information on the Tampa Bay Study is available from our on-line digital information system for the Tampa Bay Study at http://gulfsci.usgs.gov.

Florida↗
USGS2019

Assessment of coal mine methane (CMM) and abandoned mine methane (AMM) resource potential of longwall mine panels: example from Northern Appalachian Basin, USA

"Coal mine methane (CMM) and abandoned mine methane (AMM), are by-products of underground coal mining. The quantity and the emission rate of CMM and AMM may vary depending on the type of mine, gas content of the mined coal seam, and gas sourced from strata and coal beds in overlying and underlying formations affected by mining. Therefore, if a mine has the potential of accumulating gas after being abandoned and sealed properly, methane may be produced and used as an energy source to serve to local communities around the mine. Producing AMM also prevents methane, which is a potent greenhouse gas, from leaking to the atmosphere through seals, shaft plugs or surface cracks. One of the technical barriers in front of investments to economical utilization of CMM and AMM is the difficulty to predict how much methane may be available in the gas emission zone (GEZ) as a resource during mining, and after the panels are sealed and the mine is abandoned. Another difficulty is to estimate how much of the potential methane resource can be produced, and its production feasibility with boreholes, such as gob gas ventholes (GGV) converted to capture AMM. In this study, a comparative assessment is presented to address the issues stated above. The assessment was conducted on two adjacent panels of a longwall mine that operated until 2016 in the Pennsylvania section of the Northern Appalachian Basin. The study is based on two approaches that might be used depending on the availability of data, extensive or minimal. The first approach uses an extensive geological data set, geostatistics, and measured shaft gas emission and GGV production values that were collected while the panel(s) were active to assess the AMM resource. The second approach uses a minimal amount of geologic data and its uncertainty as probabilistic distributions as well as predicted during-mining emissions using a publicly available software. Results showed that both approaches provide relatively comparable estimates of AMM resources and AMM recovery potential using wellbores. The differences in assessed quantities are mostly due to the characteristics of the two methods. In that regard, this paper can be considered as guidance to choose the assessment approach based on data availability. "

Northern Appalachian Basin↗
USGS2026

Determining Volcanic Risk in Auckland (DEVORA) Research Programme—A transdisciplinary approach to address the challenge of distributed volcanism in an urban environment

The Determining Volcanic Risk in Auckland (DEVORA) Research Programme was launched in 2008 to address the challenges associated with monogenetic volcanism in an urban setting and to enhance volcanic risk management in Tāmaki Makaurau Auckland in Aotearoa New Zealand. It is a multi-agency, increasingly transdisciplinary (defined here as research that transcends traditional disciplinary boundaries by integrating diverse types of knowledge, perspectives, and methods from academic and non-academic participants to create novel solutions to complex problems), and collaborative research program jointly led by Waipapa Taumata Rau University of Auckland and Earth Sciences New Zealand (ESNZ; formerly GNS Science), with core funding from Natural Hazards Commission Toka Tū Ake (NHC; formerly the Earthquake Commission, EQC) and Te Kaunihera o Tāmaki Makaurau Auckland Council (AC). The primary research focus of DEVORA is to investigate the geologic history, volcanic hazards, and risk posed by the basaltic intraplate Auckland Volcanic Field. Disruption from ash fall and gas from other Aotearoa New Zealand volcanoes is also considered. DEVORA’s work to explore exposure and vulnerability in Tāmaki Makaurau Auckland is also useful for assessing risks from other non-volcanic natural hazards, such as seismic and tsunami hazards. The greater Tāmaki Makaurau Auckland region has an ethnically and socio-economically diverse population of approximately 1.7 million, representing about one-third of the Aotearoa New Zealand population, and hosts critical infrastructure of national significance. The size and nature of the populace, consequential economic base, and important infrastructure within Tāmaki Makaurau Auckland mean that the effects of a volcanic eruption would be felt nationally, including through the disruption of air travel to Aotearoa New Zealand. The hazards from such an eruption could potentially affect hundreds of thousands of people, businesses, and lifelines (critical infrastructure). A considerable challenge for emergency and risk managers is the monogenetic nature of the volcanic field. It is not known where or when the next eruption will occur, how much warning we may get before an eruption, nor how an eruption and its effects might unfold. In this contribution, we highlight the concept and collaborative intent of the DEVORA Programme and show how it has evolved over the 16 years since its inception. We describe how DEVORA has unified more than 100 researchers (including more than 50 graduate students) and numerous stakeholders to address key issues facing Tāmaki Makaurau Auckland and describe how research findings are being implemented into policy and communicated to stakeholder agencies and the public. We also illustrate the broader influence of the DEVORA Programme and provide some learnings that might benefit others embarking on similar integrated projects, especially those focused on distributed volcanism in and near populated areas.

Auckland↗
USGS2004

USA: Glacier National Park, Biosphere Reserve and GLORIA Site

The National Park Service of the United States has 388 designated protected areas and parks that include historic and cultural sites as well as ‘natural resource’ parks set aside for their unique and outstanding natural features. Early efforts to create parks were focused on areas of beauty or unusual features but later efforts increasingly aimed to protect biodiversity and intact ecosystems. Protected areas in the National Park Service are found in nearly all the fifty states from Florida to Alaska, with examples of preserved natural environments ranging from coral reefs to the icy summit of Mt. McKinley in Alaska, at 6,187 m. Many of the larger parks have been designated as Biosphere Reserves under the United Nations Educational, Scientific and Cultural Organization (UNESCO) Man and the Biosphere Programme. The area now managed as Glacier National Park was first set aside as a Forest Reserve in 1897 and then designated as a national park in 1910, six years before a national park service was created to oversee the growing number of parks that the US Congress was establishing. Waterton National Park was created by Canada immediately north of the US–Canada border during the same period. In 1932, a joint lobbying effort by private citizens and groups convinced both the United States and Canada to establish the world’s first trans-boundary park to explicitly underscore and symbolize the neighbourly relationship between these two countries. This became the world’s first ‘peace’ park and was named Waterton–Glacier International Peace Park. The combined park is managed collaboratively on many issues but each national park is separately funded and operates under different national statutes and laws. It was, however, jointly named a Biosphere Reserve in 1976 and a World Heritage Site in 1995. There have been recent efforts to significantly increase the size of Waterton National Park by adding publicly owned forests on the western side of the continental divide in British Columbia, Canada. For the purposes of this chapter, I will emphasize the US portion of the Waterton-Glacier International Peace Park and refer to it as the Glacier Mountain Biosphere Reserve (MBR).

Montana↗
USGS1957

Preliminary survey of the saline-water resources of the United States

Basic hydrologic data available in the field offices of the U. S. Geological Survey and reports issued by the Survey furnish evidence that saline water (defined in this report as water containing more than 1,000 parts per million of dissolved solids) is available under diverse geologic and hydrologic conditions throughout the United States. The number of areas in which undeveloped supplies of fresh water are available has diminished considerably with the rapid growth of industries and population in the past decade. Many areas previously considered to have relatively unlimited water resources have reached the point at which water-supply shortages exist or are threatened.

Water Supply Paper↗
USGS2024

Mitigating disparate elevation differences between adjacent topobathymetric data models using binary code

Integrating coastal topographic and bathymetric data for creating regional seamless topobathymetric digital elevation models of the land/water interface presents a complex challenge due to the spatial and temporal gaps in data acquisitions. The Coastal National Elevation Database (CoNED) Applications Project develops topographic (land elevation) and bathymetric (water depth) regional scale digital elevation models by integrating multiple sourced disparate topographic and bathymetric data models. These integrated regional models are broadly used in coastal and climate science applications, such as sediment transport, storm impact, and sea-level rise modeling. However, CoNED’s current integration method does not address the occurrence of measurable vertical discrepancies between adjacent near-shore topographic and bathymetric data sources, which often create artificial barriers and sinks along their intersections. To tackle this issue, the CoNED project has developed an additional step in its integration process that collectively assesses the input data to define how to transition between these disparate datasets. This new step defines two zones: a micro blending zone for near-shore transitions and a macro blending zone for the transition between high-resolution (3 m or less) to moderate-resolution (between 3 m and 10 m) bathymetric datasets. These zones and input data sources are reduced to a multidimensional array of zeros and ones. This array is compiled into a 16-bit integer representing a vertical assessment for each pixel. This assessed value provides the means for dynamic pixel-level blending between disparate datasets by leveraging the 16-bit binary notation. Sample site RMSE assessments demonstrate improved accuracy, with values decreasing from 0.203–0.241 using the previous method to 0.126–0.147 using the new method. This paper introduces CoNED’s unique approach of using binary code to improve the integration of coastal topobathymetric data.

Remote Sensing↗
USGS1992

The supply and demand for pollution control: Evidence from wastewater treatment

This paper analyzes the determination of pollution control from wastewater treatment plants as an economic decision facing local or regional regulators. Pollution control is measured by plant design effluent concentration levels and is fully endogenous in a supply- and-demand model of treatment choice. On the supply side, plant costs are a function of the design treatment level of the plant, and on the demand side, treatment level is a function of both the costs of control and the regional or regulatory preferences for control. We find evidence that the economic model of effluent choice by local regulators has a good deal of explanatory power. We find evidence that wastewater treatment plant removal of biological oxygen demand (BOD) is sensitive to many local factors including the size of the treatment plant, the flow rate of the receiving water, the population density of the surrounding area, regional growth, state sensitivity to environmental issues, state income, and the extent to which the damages from pollution fall on other states. We find strong evidence that regulators are sensitive to capital costs in determining the design level of BOD effluent reduction at a plant. Thus, proposed reductions in federal subsidies for wastewater treatment plant construction are likely to have significant adverse effects on water quality.

Journal of Environmental Economics and Management↗
USGS2004

Standard penetration test-based probabilistic and deterministic assessment of seismic soil liquefaction potential

This paper presents'new correlations for assessment of the likelihood of initiation (or triggering) of soil liquefaction. These new correlations eliminate several sources of bias intrinsic to previous, similar correlations, and provide greatly reduced overall uncertainty and variance. Key elements in the development of these new correlations are (1) accumulation of a significantly expanded database of field performance case histories; (2) use of improved knowledge and understanding of factors affecting interpretation of standard penetration test data; (3) incorporation of improved understanding of factors affecting site-specific earthquake ground motions (including directivity effects, site-specific response, etc.); (4) use of improved methods for assessment of in situ cyclic shear stress ratio; (5) screening of field data case histories on a quality/uncertainty basis; and (6) use of high-order probabilistic tools (Bayesian updating). The resulting relationships not only provide greatly reduced uncertainty, they also help to resolve a number of corollary issues that have long been difficult and controversial including: (1) magnitude-correlated duration weighting factors, (2) adjustments for fines content, and (3) corrections for overburden stress. ?? ASCE.

Journal of Geotechnical and Geoenvironmental Engin↗
USGS2021

Expected warning times from the ShakeAlert earthquake early warning system for earthquakes in the Pacific Northwest

The ShakeAlert® earthquake early warning system has been live since October 2019 for the testing of public alerting to mobile devices in California and will soon begin testing this modality in Oregon and Washington. The Pacific Northwest presents new challenges and opportunities for ShakeAlert owing to the different types of earthquakes that occur in the Cascadia subduction zone. Many locations in the Pacific Northwest are expected to experience shaking from shallow crustal earthquakes (similar to those in California), earthquakes that occur deep within the subducted slab, and large megathrust earthquakes that occur primarily offshore. The different geometries and maximum magnitudes associated with these types of earthquakes lead to a range of warning times that are possible between when the initial ShakeAlert Message is issued and when a user experiences strong shaking. After an earthquake begins, the strategy of the ShakeAlert system for public alerting is to warn people who are located close enough to the fault that the system estimates they will experience at least weak to moderate shaking. By alerting the public at these low levels of expected shaking, it is possible to provide sufficient warning times for some users to take protective actions before strong shaking begins. In this study, we present an analysis of past ShakeAlert Messages as well as simulations of historical earthquakes and potential future Cascadia earthquakes to quantify the range of warning times that users who experience strong or worse shaking are likely to receive. Additional applications for ShakeAlert involve initiation of automatic protective actions prior to the onset of shaking, such as slowing trains, shutting water supplies, and opening firehouse doors, which are beyond the scope of this paper. Users in the Pacific Northwest should expect that the majority of alerts they receive will be from shallow crustal and intraslab earthquakes. In these cases, users will only have a few seconds of warning before strong shaking begins. This remains true even during infrequent, offshore great (magnitude ≥8) megathrust earthquakes, where warning times will generally range from seconds to tens of seconds, depending on the user’s location and the intensity of predicted shaking that a user chooses to be alerted for, with the longest warning times of 50–80 seconds possible only for users located at considerable distance from the epicenter. ShakeAlert thus requires short, readily understood alerts stating that earthquake shaking is imminent and suggesting protective actions users should take. Extensive education and outreach efforts that emphasize the need to take actions quickly will be required for ShakeAlert to successfully reduce injuries and losses.

California, Oregon, Washington↗