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At least 1,189 records · Page 66Linked to original sources
USGS2019

Seismic design and hazard maps: Before and after

The 1994 Northridge earthquake generated world-record ground motions. At the time, the horizontal peak ground acceleration of 1.8 g measured by a seismometer in Tarzana was the largest ever. The same is true of the peak ground velocity of 148 cm/s measured in Granada Hills. Both measurements were within approximately 15 km of the source of the earthquake; they were also near most of the damage described in other articles of this series. Consequently, the near-source design forces from the seismic zone maps in the Uniform Building Code (UBC) were increased. From the 1994 to 1997 editions, acceleration- and velocity-related near-source factors were introduced. The factors increased the design forces in Zone 4, already the highest seismic zone, by a multiplier as large as 2.0. More enduringly, generational changes were made to the seismic design maps in the NEHRP Recommended Seismic Provisions for New Buildings and Other Structures . The NEHRP maps were – and continue to be – adopted into the International Building Code (IBC), which supplanted the UBC and other model building codes. As described below, the changes to the NEHRP maps took advantage of another post-Northridge change: the modern generation of U.S. Geological Survey (USGS) National Seismic Hazard Maps.

Structure↗
USGS2020

Planners tool up for the next big one

Data, modeling, risk analysis, and hazard scenario resources can help put earthquake mitigation efforts on firmer ground. Article discusses general earthquake information and findings of the HayWired scenario for a planner audience.

Planning↗
USGS2000

Compilation principles and the main units of the legend of the geodynamic map of North and Central Asia, Russian Southern Far East, Korea and Japan

A map at 1:5,000,000, covering the territories of Eastern and Southern Siberia, Mongolia, Northeast China and the southern part of the Russian Far East, Korea and Japan, is being compiled within the scope of the International Scientific Project on Tectonics, Geodynamics and Metallogeny. The principles and content of terrane analysis serving as a basis for the map are discussed in the article and definitions are given for key concepts: craton, terrane, accretion, amalgamation, dispersion, etc. The content of the terranes of different types shown on the map, overlapping and "suturing" together their formations, which are classified on the basis of the actualism principle, is set forth. The possibility of discriminating terranes in the Early Precambrian basement of cratons is discussed.

Siberia↗
USGS2020

Why are so many structures burning in California?

California has earned a reputation for wildfires that inflict serious damage on human infrastructure, dating back to images of Richard Nixon hosing down the roof of his house in the 1961 Bel-Air fire, and of the famous “fireproof” home of grocery store entrepreneur Fred Roberts burning to the ground in 1982. In recent years, this notoriety has been transformed into public alarm, reflected in the apocalyptic headlines of recent newspaper articles suggesting the “end of California” (New York Times, 30 October 2019) and that “California is becoming unlivable” (The Atlantic, 30 October 2019). Now the phrase “the new normal” has worked its way into the lexicon, sustained by record-breaking struc- ture loss numbers in 2017 and 2018 despite significantly lower structure losses in 2019. It remains to be seen whether or not those two recent years were back-to-back one-in-a-hundred-year events, or if the trend has crossed some kind of tipping point, but data do show a longterm trend of significant increase in structures lost to wildfires since the beginning of the 20th century (Fig. 1). What was an average of ~500 homes lost per year in Southern California from about 1950–2000 (CalFire 2000) has recently climbed to ~2700 structures per year statewide from 2000–2018 (Syphard and Keeley 2019). California is not alone in the U.S., or in the world, in suffering increasing impacts from wildfires (e.g., Blanchi et al. 2012, Haynes 2015, Viegas 2018). Impacts so far in the current Australian bushfire season have been recordbreaking, with several thousand structures lost, more than 25 fatalities, and unthinkable losses to wildlife. The question that follows, then, is why?

California↗
USGS2019

Fire, forests and city water supply

Forest landscapes generate 57 percent of runoff worldwide and supply water to more than 4 billion people (Millennium Ecosystem Assessment, 2005). As the world population continues to increase, there is a strong need to understand how forest processes link together in a cascade to provide people with water services like hydropower, aquaculture, drinking water and flood protection (Carvalho-Santos, Honrado and Hein, 2014). Wildfire is a major disturbance affecting forested watersheds and the water they provide (Box 1) (Paton et al., 2015). Several regions have experienced shifts in wildfires from natural ignition sources (primarily lightning) to ignitions dominated by human activities, especially in areas where populations are increasing (Moritz et al., 2014; Balch et al., 2017). Occasional wildfire is essential for the health and functioning of fire-adapted ecosystems through its effects on nutrient cycling, plant diversity and succession, and pest regulation (Pausas and Keeley, 2019). It also reduces the risk of subsequent wildfires until a forest has accumulated sufficient fuels and conditions are conducive for another fire. Extreme and hazardous wildfires, on the other hand, can cause erosion, gullying, soil loss and flooding – and, in severe cases, even debris flows and flash floods – by removing the protective functions of forests on hillsides (Ebel and Moody, 2017). Extreme wildfires have become more common after decades of fire suppression, allowing forests to become much denser with vegetation and causing more fuels to build up over time. Combined with increasing summer drought, this can have impacts on water yield and the ability of upstream forests to deliver high-quality water because forest vegetation uses less water immediately after fire and, in environments influenced by snow, more snow can accumulate in forest clearings (Kinoshita and Hogue, 2015; Hallema et al., 2019). Therefore, accounting for wildfire impacts on forests in water planning has become a priority for the nexus of fire, water and society or, in other words, the connection between fire risk and water security (Figure 1) (Martin, 2016). In this article, we discuss managed forest landscapes as nature-based solutions for water and explore how fire affects the provision of water-related services.

Unasylva↗
USGS2020

Forward-looking dryland restoration in an age of change

Drought, wildfires, and invasive species are among the many challenges practitioners face in achieving restoration goals in drylands. In this article, we highlight relevant restoration research and programs that pursue actionable information and resource management goals for the Intermountain West. In the context of international restoration targets recently set, we speak to dryland restoration challenges and opportunities related to climate change, social perceptions of drylands, and species selection strategies aimed at restoring healthy native plant communities.

Native Plants Journal↗
USGS2021

Putting people first: Using social science to reduce risk

Wildland-urban interface residents, who occupy the areas where wildlands meet and mix with human development, are both contributors to and recipients of the disastrous effects of wildland fires. They contribute through fire starts, flammable homes, unmitigated properties, opposition to mitigation on nearby public lands, and land use planning efforts. We argue that successful, sustainable wildland fire solutions are only possible if the WUI residents are engaged. In this article, we describe an evidence-based quantitative social science model to illustrate how to put people at the center of wildland fire solutions. Our hope is to spur greater use of social science in evidence-based wildland fire programs.

Wildfire Magazine↗
USGS2021

Foreword to this special issue on climate change and the critical zone geophysics

Welcome to this special issue on the use of geophysics in climate change and critical zone (CZ) research. The importance of these research areas cannot be overstated, and yet when we were selecting contributions for this special issue, we wrestled with the fundamental question: are climate change and the critical zone two separate research areas, or one? In other words, would there be a clear distinction between critical-zone focused articles and those addressing climate change, or would there be significant overlap making that distinction irrelevant. As we worked through the excellent submissions, it became more and more clear that any geophysical study addressing one of these elements would almost certainly be impacted in some way by the other.

FastTIMES↗
USGS1977

Land use and land cover changes: A framework for monitoring

Information on the rate and kind of change in the use of land resources is essential to-the proper planning, management, and regulation of the use of such resources. Starting in 1975, the U.S. Geological Survey has been engaged in mapping and inventory of land use and land cover at a scale of 1:250000 with plans to change to new 1:100000 base maps as they become available. Such scales are-appropriate for acquiring benchmark or baseline data on land use and land cover on a nationwide basis with a reasonable degree of standardization and accuracy, within a practical time frame of 6 to 7 years, and at a reasonable level of detail in categorization. Changes in land use and land cover occur at highly variable rates from place to place. Thus variations, in the intervals between updates of land use and land cover data should be carefully evaluated in order to provide an appropriate frame of reference for the systematic updating of such data. A methodological framework is needed for monitoring changes in land use and land cover that will be timely, relatively inexpensive, and appropriate for widely varying needs at national, interstate-regional, state, multicounty, county, and city levels. In this article a partial framework for monitoring land use and land cover changes is provided with opportunity to extend its use to greater levels of detail in categorization and shorter intervals of frequency when needed for selected areas.

Journal of Research of the U.S. Geological Survey↗
USGS2017

USGS revision of global iron ore production data—Clarification of the reporting of iron ore production in China and application of a uniform comparison methodology (2000-2015)

Iron ore is the source of primary iron for the world’s iron and steel industries. Its production can be reported as crude ore, usable ore or iron content of ore. Historically, the U.S. Geological Survey (USGS) used reported crude ore production from China in tabulations of world iron ore production while other countries have typically reported their production in terms of usable iron ore. When China’s crude ore production was tabulated with usable ore production from other countries, world iron ore production totals have been overestimated by 10 percent to a high of 32 percent (Figs. 1, 2). The significant increase in iron ore production in China from 2000 through 2015 amplified the overestimation resulting from tabulating inconsistent forms of the material. Sources of data for usable iron ore production in China, beginning in 2000, have become available. This article documents the revision of world iron ore production totals and augments historical China iron ore production figures to show both crude and usable ore values.

Mining Engineering↗
USGS2026

Helping California get ready for when the mud hits the fan

With frequent wildfires, powerful rainstorms, steep terrain, and dense population, California is particularly vulnerable to postfire hazards like flooding and debris flow. Major postfire flooding and debris-flow events can be more costly than the fire itself, causing dozens of fatalities and widespread damage (Chawner, 1934; Lancaster et al., 2021). Smaller events occur nearly every year in California and can locally damage structures and roads, affect water quality and storage, and result in injury or loss of life (e.g., Dow et al., 2024; Rodriguez, 2025; Swanson et al., 2024; Figure 1). To mitigate these threats, the U.S. Geological Survey (USGS) has developed tools to assist local, state, and federal agencies in rapidly assessing postfire debris-flow risk across California’s diverse geology and geography. This article summarizes that effort and describes ongoing work by the USGS and partners to advance these methods and help California better prepare for future wildfires.

Caliornia↗
USGS2026

USGS 2025 critical minerals review

The United States Geological Survey (USGS) provides scientific information for the Department of Interior and the nation, consistent with its original mission expressed in the Organic Act of 1879 (43 U.S.C. 31): “the classification of the public lands and examination of the geological structure, mineral resources, and products within and outside the national domain.” Legislation such as the Energy Act of 2020 and the 2022 Infrastructure Investment and Jobs Act (43 USC 31l) and recent executive actions (Executive Orders 14154 , 14153, 14241 Secretary’s Orders 3417, 3418, 3422, 3436) underscore the importance of mineral resources and focus USGS activities on mapping and assessing mineral resources, with a particular focus on those presently identified as critical, both in ground and above ground in mine wastes. This article reviews selected activities and accomplishments by the USGS Mineral Resources Program related to critical minerals in 2025. Highlights include a new List of Critical Minerals, a first-ever national mine waste inventory, international minerals partnerships, mineral resource assessment advancements, and national data collection activities and outcomes of the Earth Mapping Resources Initiative (Earth MRI). The selected contributions are not comprehensive but are intended to demonstrate USGS leadership in critical mineral mapping and assessment, the importance of domestic and global partnerships, and the breadth of research activities that are responsive to national needs and priorities.

Mining Engineering↗
USGS2026

Connecting the dots: Using multiple datasets to monitor the brown bear population in Katmai National Park and Preserve

Monitoring wide-ranging wildlife populations is challenging. Surveys are time consuming, expensive, and observation conditions need to be just right. But confidently assessing the number of animals, and if their numbers are increasing or decreasing is important for park management and ecological understanding. This article describes survey methods and how they can be combined for the most accurate estimates.

Alaska↗
USGS2006

Abundance: Population size and density estimation

Estimates of population size (total number of individuals) or density (number of individuals per unit area) are some of the most basic requirements for wildlife research and management. This article provides a brief overview of approaches for wildlife population estimation. These include habitat-based approaches such as quadrat, line intercept, distance, and repeated count methods, as well as animal-based approaches such as capture–recapture and harvest methods. In contrast to methods that only index changes in these parameters, estimates of size or density must account for the probability that an individual will be included in the sample used for estimation. The essential differences in the approaches are in how the samples are obtained and how the sampling probabilities are estimated.

Book chapter↗
USGS2013

Abundance: Population size and density estimation

Estimates of population size (total number of individuals) or density (number of individuals per unit area) are some of the most basic requirements for wildlife research and management. This article provides a brief overview of approaches for wildlife population estimation. These include habitat‐based approaches such as quadrat, line intercept, distance, and repeated count methods, as well as animal‐based approaches such as capture–recapture and harvest methods. In contrast to methods that only index changes in these parameters, estimates of size or density must account for the probability that an individual will be included in the sample used for estimation. The essential differences in the approaches are in how the samples are obtained and how the sampling probabilities are estimated.

Book chapter↗
USGS2015

Pre-fieldwork surveys

In sea-level studies, initial surveys at the office or library can increase a project’s likelihood of success. Pre-fieldwork surveys should begin with a thorough review of prior research literature that appraises available data, identifies data gaps, and places the project objectives into a broader scientific context. Whereas peer reviewed journal articles may contain a wealth of research findings, often the most useful maps, historical documents, images, and other data critical for sea-level research are discovered by searching government files, libraries, museums, unpublished reports, or, increasingly, online digital data collections.

Book chapter↗
USGS2017

Volcanic unrest and hazard communication in Long Valley Volcanic Region, California

The onset of volcanic unrest in Long Valley Caldera, California, in 1980 and the subsequent fluctuations in unrest levels through May 2016 illustrate: (1) the evolving relations between scientists monitoring the unrest and studying the underlying tectonic/magmatic processes and their implications for geologic hazards, and (2) the challenges in communicating the significance of the hazards to the public and civil authorities in a mountain resort setting. Circumstances special to this case include (1) the sensitivity of an isolated resort area to media hype of potential high-impact volcanic and earthquake hazards and its impact on potential recreational visitors and the local economy, (2) a small permanent population (~8000), which facilitates face-to-face communication between scientists monitoring the hazard, civil authorities, and the public, and (3) the relatively frequent turnover of people in positions of civil authority, which requires a continuing education effort on the nature of caldera unrest and related hazards. Because of delays associated with communication protocols between the State and Federal governments during the onset of unrest, local civil authorities and the public first learned that the U.S. Geological Survey was about to release a notice of potential volcanic hazards associated with earthquake activity and 25-cm uplift of the resurgent dome in the center of the caldera through an article in the Los Angeles Times published in May 1982. The immediate reaction was outrage and denial. Gradual acceptance that the hazard was real required over a decade of frequent meetings between scientists and civil authorities together with public presentations underscored by frequently felt earthquakes and the onset of magmatic CO 2 emissions in 1990 following a 11-month long earthquake swarm beneath Mammoth Mountain on the southwest rim of the caldera. Four fatalities, one on 24 May 1998 and three on 6 April 2006, underscored the hazard posed by the CO 2 emissions. Initial response plans developed by county and state agencies in response to the volcanic unrest began with “The Mono County Volcano Contingency Plan” and “Plan Caldera” by the California Office of Emergency Services in 1982–84. They subsequently became integrated in the regularly updated County Emergency Operation Plan. The alert level system employed by the USGS also evolved from the three-level “Notice-Watch-Warning” system of the early 1980s through a five level color-code to the current “Normal-Advisory-Watch-Warning” ground-based system in conjunction with the international 4-level aviation color-code for volcanic ash hazards. Field trips led by the scientists proved to be a particularly effective means of acquainting local residents and officials with the geologically active environment in which they reside. Relative caldera quiescence from 2000 through 2011 required continued efforts to remind an evolving population that the hazards posed by the 1980–2000 unrest persisted. Renewed uplift of the resurgent dome from 2011 to 2014 was accompanied by an increase in low-level earthquake activity in the caldera and beneath Mammoth Mountain and continues through May 2016. As unrest levels continue to wax and wane, so will the communication challenges.

Book chapter↗
USGS2015

The role of floodplain restoration in mitigating flood risk, Lower Missouri River, USA

Recent extreme floods on the Lower Missouri River have reinvigorated public policy debate about the potential role of floodplain restoration in decreasing costs of floods and possibly increasing other ecosystem service benefits. The first step to addressing the benefits of floodplain restoration is to understand the interactions of flow, floodplain morphology, and land cover that together determine the biophysical capacity of the floodplain. In this article we address interactions between ecological restoration of floodplains and flood-risk reduction at 3 scales. At the scale of the Lower Missouri River corridor (1300 km) floodplain elevation datasets and flow models provide first-order calculations of the potential for Missouri River floodplains to store floods of varying magnitude and duration. At this same scale assessment of floodplain sand deposition from the 2011 Missouri River flood indicates the magnitude of flood damage that could potentially be limited by floodplain restoration. At the segment scale (85 km), 1-dimensional hydraulic modeling predicts substantial stage reductions with increasing area of floodplain restoration; mean stage reductions range from 0.12 to 0.66 m. This analysis also indicates that channel widening may contribute substantially to stage reductions as part of a comprehensive strategy to restore floodplain and channel habitats. Unsteady 1-dimensional flow modeling of restoration scenarios at this scale indicates that attenuation of peak discharges of an observed hydrograph from May 2007, of similar magnitude to a 10 % annual exceedance probability flood, would be minimal, ranging from 0.04 % (with 16 % floodplain restoration) to 0.13 % (with 100 % restoration). At the reach scale (15–20 km) 2-dimensional hydraulic models of alternative levee setbacks and floodplain roughness indicate complex processes and patterns of flooding including substantial variation in stage reductions across floodplains depending on topographic complexity and hydraulic roughness. Detailed flow patterns captured in the 2-dimensional model indicate that most floodplain storage occurs on the rising limb of the flood as water flows into floodplain bottoms from downstream; at a later time during the rising limb this pattern is reversed and the entire bottom conveys discharge down the valley. These results indicate that flood-risk reduction by attenuation is likely to be small on a large river like the Missouri and design strategies to optimize attenuation and ecological restoration should focus on frequent floods (20–50 % annual exceedance probability). Local stage reductions are a more certain benefit of floodplain restoration but local effects are highly dependent on magnitude of flood discharge and how floodplain vegetation communities contribute to hydraulic roughness. The most certain flood risk reduction benefit of floodplain restoration is avoidance of flood damages to crops and infrastructure.

Iowa, Kansas, Minnesota, Missouri, Nebraska, South↗