Geology topics

Research about Pacific Northwest

Source-linked reports with geographic coverage including Pacific Northwest.

At least 19 recordsLinked to original sources

USGS2026

Spatially concentrating logging could mitigate climate-magnified fragmentation risks to a globally endangered bird

1. Rising timber demand is transforming forest structure globally, profoundly affecting biodiversity and climate resilience. Logging-driven fragmentation is potentially a major driver of biodiversity loss in production landscapes, yet its interactions with escalating climate stressors remain poorly understood. 2. We combine two decades of Landsat-derived habitat metrics with 29,000 surveys of the marbled murrelet ( Brachyramphus marmoratus )—an iconic Pacific Northwest old-forest specialist seabird affecting management of >10 million hectares. Controlling for habitat amount and detection probability, increasing landscape-scale forest edge amount sharply reduces murrelet occupancy, with impacts worsening under unfavourable climate-driven ocean conditions. 3. Comparing alternative landscape-scale timber harvest strategies, spatially concentrated logging consistently supports higher murrelet populations than fragmented approaches producing equivalent wood volumes, with benefits amplified under adverse ocean conditions. However, historical harvesting policies in the Pacific Northwest have instead driven severe habitat fragmentation, which we show is eroding the value of core set-aside forests on federal and conservation lands and ultimately rendering murrelets more vulnerable to climate change. 4. Synthesis and applications : We map key opportunities to boost populations by reducing edginess around remaining nesting habitat and investigate these opportunities' spatial distribution across land ownership and timber productivity gradients. Concentrating logging could be critical for mitigating fragmentation and climate threats for murrelets and potentially other forest-dependent species amid rising timber demand.

California, Oregon, Washington↗

USGS2026

ENSO and PDO drive shoreline position anomalies in the U.S. Pacific Northwest

Sandy beaches act as buffers against various coastal hazards but are vulnerable to episodic (seasonal) and chronic (interannual) erosion. Understanding the variation of shoreline position, a key metric in coastal morphology, over a spectrum of time scales is therefore crucial in assessing hazard vulnerability. Long-standing research has investigated the role of El Niño-Southern Oscillation (ENSO), the dominant mode of climate variability in the Pacific Basin, in seasonal shoreline variability. Yet, ENSO’s chronic influence—and that of another Pacific climate mode, the Pacific Decadal Oscillation (PDO)—on shoreline anomalies remains poorly understood. Here, we examine the variability of sandy beaches in the US Pacific Northwest, a ∼750 km long coastal region on the US West Coast. We leverage 40 years (1984–2024) of shoreline data from publicly available Earth-observing (Landsat) satellite imagery at a high spatial resolution (>10,000 shore-normal transects at 50-m alongshore spacing) and employ Convergent Cross Mapping (CCM), a methodology for inferring causality in dynamical systems. We discover that strong El Niño years are signified by erosion (75.1% of transects), and strong La Niña years exhibit accretional behavior (73.4% of transects). Furthermore, we establish, for the first time, that both ENSO and PDO exert a statistically significant control on interannual shoreline variability, particularly on the alongshore component (in 95 and 100% of littoral cells, respectively), with water level fluctuations playing a critical role. This effort advances our understanding of the seasonal-to-interannual interactions between Pacific Basin climate variability and the PNW’s coastal morphodynamics, with implications for sediment management and coastal adaptation.

California, Oregon, Washington↗

USGS2025

Bayesian ETAS modeling for the Pacific Northwest: Uncovering effects of tectonic regimes, regional differences, and swarms on aftershock parameters

The Pacific Northwest (PNW) of North America has high seismic hazard due to numerous earthquake sources under populated areas. It hosts several tectonic regimes and subregional seismic zones that are hypothesized to have different patterns of earthquake and aftershock occurrence. It is also predisposed to earthquake swarms, which can complicate the statistical modeling of these patterns. We present the first statistical seismicity model of the PNW catalog using the epidemic‐type aftershock sequence (ETAS) framework. We develop a Bayesian inference procedure that provides a stable estimation of both ETAS parameters and their uncertainties for different sets of PNW earthquakes, even those with very sparse catalogs. The Bayesian approach allows us to investigate how parameter estimates change between the intraslab and crustal tectonic regimes, the northern and southern PNW, and when swarms are included and excluded from the catalog. We also utilize our Bayesian framework to calculate parameter estimates under different prior beliefs about PNW seismicity, as well as to propagate catalog measurement errors into ETAS parameter estimates. We discuss the implications of parameter differences across the region for aftershock forecasting for the PNW.

Pacific Northwest↗

USGS2025

Linking fire, food webs, and fish in stream ecosystems

As wildfire regimes shift, resource managers are concerned about potential threats to aquatic ecosystems and the species they support, especially fishes. However, predicting fish responses can be challenging because wildfires affect aquatic ecosystems via multiple pathways. Application of whole-ecosystem approaches, such as food web modeling, can act as heuristic tools that offer valuable insights that account for these different mechanisms. We applied a dynamic food web simulation model that mechanistically linked stream trophic dynamics to the myriad effects that wildfires can have on aquatic and riparian ecosystems at a local stream reach-scale. We simulated how wildfires of different severity may influence short- (months to years) and long-term (years to decades) periphyton, aquatic invertebrate, and fish biomass dynamics in forested headwater streams of the western Pacific Northwest (USA). In many cases, wildfire increased modeled periphyton, invertebrate, and fish biomass over both short- and long-time periods. However, modeled responses varied extensively in their direction (that is, positive or negative), magnitude, and duration depending on fire severity, time since fire, and trophic level. The shapes of these response trajectories were especially sensitive to predicted wildfire effects on water temperature, canopy cover, riparian shading, and instream turbidity. Model simulations suggest a single fire could result in a wide range of aquatic ecosystem responses, especially in watersheds with mixed burn severity. Our analysis highlights the utility of whole-ecosystem approaches, like food web modeling, as heuristic tools for improving our understanding of the mechanisms linking fire, food webs, and fish and for identifying contexts where fires could have deleterious impacts on fishes.

Oregon, Washington↗

USGS2023

Networks of tree-ring based streamflow reconstructions for the Pacific Northwest, U.S.A

Water resources in the Pacific Northwest (PNW) are characterized by significant interannual to interdecadal variation. Paleo-proxy reconstructions such as those derived from tree-rings provide longer-term context and supplement information on this expected range of variability, which can improve planning, management, and response related to extreme events and hydrologic change. However, existing paleo-proxy reconstructions have yet to address the potential for pronounced within- and among-basin variations in the PNW due to a lack of spatial coverage. Here we develop methodologically consistent reconstructions for 36 gages in the PNW, including the Columbia and Snake River drainages, as well as key coastal watersheds. These reconstructions extend back at least to the 1500s coefficient of efficiency. Reconstruction skill is relatively high (mean R 2 = 0.63), and snowpack- or winter precipitation-sensitive chronologies from high-elevation sites provide important contributions to reconstruction skill. At the whole-region scale, reconstructed variability indicates evidence for drier and wetter years, more persistent decadal variability, and correspondingly longer episodes of deficit and surplus compared to instrumental records. Within the region, this expanded range of extremes appears especially prevalent in the Snake River and southern PNW watersheds. Regionally, cumulative deficits in the early 1500s and mid 1600s rival those of the early 20 th century, though persistence and timing vary widely among basins. These reconstructions suggest that considering within-region variability will be key for water management and planning under climate change, and that sub-regional adaptation strategies are likely to be advantageous.

Pacific Northwest↗

USGS2022

Precision of headwater stream permanence estimates from a monthly water balance model in the Pacific Northwest, USA

Stream permanence classifications (i.e., perennial, intermittent, ephemeral) are a primary consideration to determine stream regulatory status in the United States (U.S.) and are an important indicator of environmental conditions and biodiversity. However, at present, no models or products adequately describe surface water presence for regulatory determinations. We modified the Thornthwaite monthly water balance model (MWBM) with a flow threshold parameter to estimate flow permanence and evaluated the model’s accuracy and precision for more than 1.3 million headwater stream reaches in the U.S. Pacific Northwest (PNW). Stream reaches were assigned to one of eight calibration groups by unsupervised classification based on sensitivity to MWBM parameters. Suitable MWBM parameter sets were identified by comparing modeled stream permanence estimates to surface water presence observations (SWPO). Parameter sets with accuracies > 65% were considered suitable. The MWBM estimated stream permanence with high precision at 40% of reaches, with poor precision at 20% of reaches, and no suitable parameter sets were identified for 40% of reaches. Results highlight the need for increased SWPO collection to improve calibration and assessment of stream permanence models. Additionally, implementation of the MWBM to estimate surface water presence indicates potential for process-based models to predict stream permanence with future development.

California, Idaho, Montana, Nevada, Oregon, Utah, ↗

USGS2022

Treading water: Conservation of headwater-stream associated amphibians in northwestern North America

Headwater streams of the Pacific Northwest of North America are home to 52 amphibian species, spanning a diversity of taxa and life histories. Headwater stream-associated amphibians occur both within coldwater-stream channels and throughout adjacent riparian habitat, reflective of the important role of old-growth forests in providing cool, moist microclimates for these sensitive species. Forests of the Pacific Northwest have undergone substantial change over the last century, due to a legacy of resource extraction and ever-evolving forest management practices, as well as climate change. These and other stressors have challenged the adaptive capacity of headwater stream-associated amphibians, as more than half of these species are considered to be of conservation concern at the state, provincial, or federal level in the U.S. and Canada. Here, we overview the primary threats to the persistence of this unique and imperiled taxonomic group and emphasize the urgent need for more research and conservation action to mitigate future decline.

Alaska, British Columbia, Idaho, Oregon, Washingto↗

USGS2021

LiDAR and paleoseismology solve earthquake mystery in the Pacific Northwest, USA

One of the largest historical earthquakes in the U.S. Pacific Northwest occurred on December 15, 1872 near the south end of Lake Chelan. Lack of recognized surface deformation suggested that the earthquake occurred on a blind, perhaps deep, fault. New LiDAR data revealed a NW-side-up scarp along the north side of Spencer Canyon near Entiat, Washington. Landslides triggered during the earthquake impounded small ponds in Spencer Canyon; the larger of the two landslides obliterated a portion of the scarp. Tree-ring counts show that the oldest trees on each landslide are 130 and 128 years old, and lend credence to the idea that the earthquake triggered the landslides. Trenches across the scarp exposed a NW-dipping thrust fault offsetting young soils and Mesozoic bedrock. Radiocarbon and tree ring data shows that the last fault movement was between 1856 and 1873 CE, and was most likely during the 1872 CE earthquake.

Idaho, Montana, Oregon, Washington↗

USGS2020

Climate-induced expansions of invasive species in the Pacific Northwest, North America: A synthesis of observations and projections

Climate change may facilitate the expansion of non-native invasive species (NIS) in aquatic and terrestrial systems. However, empirical evidence remains scarce and poorly synthesized at scales necessary for effective management. We conducted a literature synthesis to assess the state of research on the observed and predicted effects of climate change on a suite of 398 aquatic and terrestrial NIS now present in or a major threat to aquatic and terrestrial ecosystems of the Pacific Northwest (PNW), USA and British Columbia. Surprisingly, very few studies (n = 15) have investigated the observed effects of climate change on the distribution, abundance, spread, or impact of the focal NIS, with only five studies focusing on terrestrial (n = 2) or aquatic (n = 3) species within the PNW. Only 93 studies predicted the future dynamics of the focal NIS somewhere in their non-native range using climate model projections, yielding 117 species-specific predictions. However, only 30 of those studies generated predictions that overlapped with the PNW, and only six focused specifically on the expansion or abundance of NIS (n = 11 species) entirely within the region. Although our understanding of how climate change may interact with biological invasions is notably lacking, some evidence suggests that climate-induced NIS expansions are already underway in the PNW, particularly in aquatic ecosystems, and will be exacerbated by future changes in temperature and precipitation regimes. Better information is urgently needed for managers to implement strategic prevention, early detection, and proactive actions that ameliorate ecologically and economically devastating impacts of NIS.

Idaho, Montana, Nevada, Oregon, Utah, Washington, ↗

USGS2019

Development of two quantitative PCR assays for detection of several Cottus species from environmental DNA in Pacific coast watersheds of North America

We developed two quantitative PCR assays for use with environmental DNA (eDNA) to detect numerous species in the genus Cottus that are indigenous to the Pacific coast watersheds of North America. We conducted in vitro assay validations on ten Cottus species and 32 potentially co-occurring non- Cottus species. We demonstrate the efficacy of these assays by field testing eDNA samples collected from streams inhabited by Cottus . These assays will be particularly useful for detecting Cottus in habitats where one (or more) of several Cottus species could be present.

Pacific Northwest↗

USGS2019

Functional and geographic components of risk for climate sensitive vertebrates in the Pacific Northwest, USA

Rarity and life history traits inform multiple dimensions of intrinsic risk to climate and environmental change and can help systematically identify at-risk species. We quantified relative geographic rarity (area of occupancy), climate niche breadth, and life history traits for 114 freshwater fishes, amphibians, and reptiles in the U.S. Pacific Northwest. Our approach leveraged presence-only, publicly available data and traits-based inference to evaluate area of occupancy, climate sensitivity (i.e., climate niche breadth), and a Rarity and Climate Sensitivity (RCS) index of all species across multiple geographic extents, grain sizes, and data types. The RCS index was relatively stable across extents, grains, and data types, with climate sensitivity differentiating species with otherwise similar areas of occupancy. We also found that species with sensitivity-associated traits (e.g., long generation time, low fecundity) were not necessarily the same species identified as at-risk with geographical approaches (small range size, small climate niche breadth). Many multispecies assessments using coarse-scale data (e.g., entire range maps or convex-hull approaches) often focus on a single dimension of intrinsic risk; others rely on data-intensive models only applicable to a few well-studied species. What remains is a need for an approach that enables multispecies, multidimensional assessment efforts. This is particularly true at regional scales, where management needs require assessments that are intermediate to coarse- and fine-scale approaches. We demonstrate that by considering multiple dimensions of intrinsic risk to climate change (range size, climate sensitivity, and traits), site-specific locality data may offer a pathway for ensuring vulnerable, understudied species do not go overlooked in conservation.

Pacific Northwest↗

USGS2019

Pacific Northwest Aquatic Monitoring Partnership 2018 Annual Report

The Pacific Northwest Aquatic Monitoring Partnership (PNAMP) continued to promote the integration of monitoring resources and development of tools to support monitoring in 2018. Improved coordination and integration of goals, objectives, and activities among Pacific Northwest monitoring programs is essential to improving the quality and consistency of monitoring in the region.

Idaho, Oregon, Washington↗

USGS2018

Geoelectric hazard maps for the Pacific Northwest

Maps of extreme value, horizontal component geoelectric field amplitude are constructed for the Pacific Northwest United States (and parts of neighboring Canada). Multidecade long geoelectric field time series are calculated by convolving Earth surface impedance tensors from 71 discrete magnetotelluric survey sites across the region with historical 1‐min (2‐min Nyquist) geomagnetic variation time series obtained from two nearby observatories. After fitting statistical models to 1‐min geoelectric amplitudes realized during magnetic storms, extrapolations are made to estimate threshold amplitudes that are only exceeded, on average, once per century. One hundred‐year geoelectric exceedance amplitudes range from 0.06 V/km at a survey site in western Washington State to 9.47 V/km at a site in southeast British Columbia; 100‐year geoelectric exceedance amplitudes equal 7.10 V/km at a site north of Seattle and 2.28 V/km at a site north of Portland. Systematic and random errors are estimated to be less than 20%, much less than site‐to‐site differences in geoelectric amplitude that arise from site‐to‐site differences in surface impedance. Maps of 100‐year exceedance amplitudes are compared with the peak geoelectric amplitudes realized during the March 1989 magnetic superstorm; it is noted that some storms of relatively modest intensity can generate localized geoelectric fields of relatively high amplitude. The geography of geoelectric hazard across the Pacific Northwest is closely related to known geologic and tectonic structures.

Pacific Northwest↗

USGS2017

A systematic surveillance programme for infectious salmon anaemia virus supports its absence in the Pacific Northwest of the United States

In response to reported findings of infectious salmon anaemia virus (ISAV) in British Columbia (BC), Canada, in 2011, U.S. national, state and tribal fisheries managers and fish health specialists developed and implemented a collaborative ISAV surveillance plan for the Pacific Northwest region of the United States. Accordingly, over a 3-1/2-year period, 4,962 salmonids were sampled and successfully tested by real-time reverse-transcription PCR. The sample set included multiple tissues from free-ranging Pacific salmonids from coastal regions of Alaska and Washington and farmed Atlantic salmon ( Salmo salar L.) from Washington, all representing fish exposed to marine environments. The survey design targeted physiologically compromised or moribund animals more vulnerable to infection as well as species considered susceptible to ISAV. Samples were handled with a documented chain of custody and testing protocols, and criteria for interpretation of test results were defined in advance. All 4,962 completed tests were negative for ISAV RNA. Results of this surveillance effort provide sound evidence to support the absence of ISAV in represented populations of free-ranging and marine-farmed salmonids on the northwest coast of the United States.

Pacific Northwest↗

USGS2016

Reconstructions of Columbia River streamflow from tree-ring chronologies in the Pacific Northwest, USA

We developed Columbia River streamflow reconstructions using a network of existing, new, and updated tree-ring records sensitive to the main climatic factors governing discharge. Reconstruction quality is enhanced by incorporating tree-ring chronologies where high snowpack limits growth, which better represent the contribution of cool-season precipitation to flow than chronologies from trees positively sensitive to hydroclimate alone. The best performing reconstruction (back to 1609 CE) explains 59% of the historical variability and the longest reconstruction (back to 1502 CE) explains 52% of the variability. Droughts similar to the high-intensity, long-duration low flows observed during the 1920s and 1940s are rare, but occurred in the early 1500s and 1630s-1640s. The lowest Columbia flow events appear to be reflected in chronologies both positively and negatively related to streamflow, implying low snowpack and possibly low warm-season precipitation. High flows of magnitudes observed in the instrumental record appear to have been relatively common, and high flows from the 1680s to 1740s exceeded the magnitude and duration of observed wet periods in the late-19th and 20th Century. Comparisons between the Columbia River reconstructions and future projections of streamflow derived from global climate and hydrologic models show the potential for increased hydrologic variability, which could present challenges for managing water in the face of competing demands

Pacific Northwest↗

USGS2016

Linkages between unpaved forest roads and streambed sediment: why context matters in directing road restoration

Unpaved forest roads remain a pervasive disturbance on public lands and mitigating sediment from road networks remains a priority for management agencies. Restoring roaded landscapes is becoming increasingly important for many native coldwater fishes that disproportionately rely on public lands for persistence. However, effectively targeting restoration opportunities requires a comprehensive understanding of the effects of roads across different ecosystems. Here, we combine a review and a field study to evaluate the status of knowledge supporting the conceptual framework linking unpaved forest roads with streambed sediment. Through our review, we specifically focused on those studies linking measures of the density of forest roads or sediment delivery with empirical streambed sediment measures. Our field study provides an example of a targeted effort of linking spatially explicit estimates of sediment production with measures of streambed sediment. Surprisingly, our review uncovered few studies ( n  = 8) that empirically tested the conceptual framework linking unpaved forest roads and streambed sediment, and the results varied considerably. Field results generally supported the conceptual model that unpaved forest roads can control streambed sediment quality, but demonstrated high-spatial variability in the effects of forest roads on streambed sediment and the need to address hotspots of sediment sources. The importance of context in the effects of forest roads is apparent in both our review and field data, suggesting the need for in situ studies to avoid misdirected restoration actions.

Pacific Northwest↗

USGS2015

2014 Update of the Pacific Northwest portion of the U.S. National Seismic Hazard Maps

Several aspects of the earthquake characterization were changed for the Pacific Northwest portion of the 2014 update of the national seismic hazard maps, reflecting recent scientific findings. New logic trees were developed for the recurrence parameters of M8-9 earthquakes on the Cascadia subduction zone (CSZ) and for the eastern edge of their rupture zones. These logic trees reflect recent findings of additional M8 CSZ earthquakes using offshore deposits of turbidity flows and onshore tsunami deposits and subsidence. These M8 earthquakes each rupture a portion of the CSZ and occur in the time periods between M9 earthquakes that have an average recurrence interval of about 500 years. The maximum magnitude was increased for deep intraslab earthquakes. An areal source zone to account for the possibility of deep earthquakes under western Oregon was expanded. The western portion of the Tacoma fault was added to the hazard maps.

Earthquake Spectra↗

USGS2015

Collapse risk of buildings in the Pacific Northwest region due to subduction earthquakes

Subduction earthquakes similar to the 2011 Japan and 2010 Chile events will occur in the future in the Cascadia subduction zone in the Pacific Northwest. In this paper, nonlinear dynamic analyses are carried out on 24 buildings designed according to outdated and modern building codes for the cities of Seattle, Washington, and Portland, Oregon. The results indicate that the median collapse capacity of the ductile (post-1970) buildings is approximately 40% less when subjected to ground motions from subduction, as compared to crustal earthquakes. Buildings are more susceptible to earthquake-induced collapse when shaken by subduction records (as compared to crustal records of the same intensity) because the subduction motions tend to be longer in duration due to their larger magnitude and the greater source-to-site distance. As a result, subduction earthquakes are shown to contribute to the majority of the collapse risk of the buildings analyzed.

Pacific Northwest↗