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The Landslide Handbook - A Guide to Understanding Landslides

This handbook is intended to be a resource for people affected by landslides to acquire further knowledge, especially about the conditions that are unique to their neighborhoods and communities. Considerable literature and research are available concerning landslides, but unfortunately little of it is synthesized and integrated to address the geographically unique geologic and climatic conditions around the globe. Landslides occur throughout the world, under all climatic conditions and terrains, cost billions in monetary losses, and are responsible for thousands of deaths and injuries each year. Often, they cause long-term economic disruption, population displacement, and negative effects on the natural environment. Outdated land-use policies may not always reflect the best planning for use of land that is vulnerable to landslides. The reasons for poor or nonexistent land-use policies that minimize the perceived or actual danger and damage potential from geologic hazards are many and encompass the political, cultural, and financial complexities and intricacies of communities. Landslides often are characterized as local problems, but their effects and costs frequently cross local jurisdictions and may become State or Provincial or national problems. Growing populations may be limited in their geographic expansion, except to occupy unstable, steep, or remote areas. Often, stabilizing landslide-scarred areas is too costly, and some inhabitants have no other places to relocate. Fortunately, simple, 'low-tech' precautions and actions can be adopted to at least ensure an individual's immediate safety, and this handbook gives a brief overview of many of these options. We strongly suggest that, where possible, the assistance of professional engineers/geologists or those experienced in the successful mitigation of unstable slopes be consulted before actions are taken. This handbook helps homeowners, community and emergency managers, and decisionmakers to take the positive step of encouraging awareness of available options and recourse in regard to landslide hazard. We provide a list of references, available in print or on the World Wide Web (Internet), that can be used for further knowledge about landslides. We recommend this handbook to managers and decisionmakers in communities in the hope that the information will be disseminated by such officials to other members of those communities. In response to the differing levels of literacy around the globe, we have emphasized visual information through the use of photographs and graphics. We plan to translate the handbook into additional languages as funding permits to further facilitate its use. We welcome comments and critiques and have provided our contact information and the names and addresses of our respective agencies.

Circular

Processes controlling the chemistry of two snowmelt‐dominated streams in the Rocky Mountains

Time‐intensive discharge and chemical data for two alpine streams in the Loch Vale watershed, Colorado, were used to identify sources of runoff, flow paths, and important biogeochemical processes during the 1992 snowmelt runoff season. In spite of the paucity of soil cover the chemical composition of the streams is regulated much as in typical forested watersheds. Soils and other shallow groundwater matrices such as boulder fields appear to be more important in controlling surface‐water chemistry than their abundance would indicate. The chemical composition of the major source waters (usually thought of as end‐members whose chemical composition is relatively constant over time) changes at the same time that their mixing ratio in streams changes, confounding use of end‐member mixing models to describe stream‐water chemistry. Changes in the chemical composition of these source waters are caused by the ionic pulse of solutes from the snowpack and the small size of the shallow groundwater reservoir compared to the volume of snowmelt passing through it. The brief hydrologic residence time in the shallow groundwater indicates that concentrations of most dissolved constituents of stream water were controlled by fast geochemical processes that occurred on timescales of hours to days, rather than slower processes such as weathering of primary minerals. Differences in the timing of snowmelt‐related processes between different areas of the watershed also affect the stream‐water chemical composition. Cirque lakes affect discharge and chemical composition of one of the streams; seasonal control on stream‐water NO 3 and SiO 2 concentrations by diatom uptake in the lakes was inferred. Elution of acidic waters from the snowpack, along with dilution of base cations originating in shallow groundwater, caused episodes of decreased acid‐neutralizing capacity in the streams, but the streams did not become acidic.

Colorado

Selected micrometeorological and soil-moisture data at Amargosa Desert Research Site in Nye County near Beatty, Nevada, 1998-2000

Selected micrometeorological and soil-moisture data were collected at the Amargosa Desert Research Site adjacent to a low-level radioactive waste and hazardous chemical waste facility near Beatty, Nev., 1998-2000. Data were collected in support of ongoing research studies to improve the understanding of hydrologic and contaminant-transport processes in arid environments. Micrometeorological data include precipitation, air temperature, solar radiation, net radiation, relative humidity, ambient vapor pressure, wind speed and direction, barometric pressure, soil temperature, and soil-heat flux. All micrometeorological data were collected using a 10-second sampling interval by data loggers that output daily mean, maximum, and minimum values, and hourly mean values. For precipitation, data output consisted of daily, hourly, and 5-minute totals. Soil-moisture data included periodic measurements of soil-water content at nine neutron-probe access tubes with measurable depths ranging from 5.25 to 29.75 meters. The computer data files included in this report contain the complete micrometeorological and soil-moisture data sets. The computer data consists of seven files with about 14 megabytes of information. The seven files are in tabular format: (1) one file lists daily mean, maximum, and minimum micrometeorological data and daily total precipitation; (2) three files list hourly mean micrometeorological data and hourly precipitation for each year (1998-2000); (3) one file lists 5-minute precipitation data; (4) one file lists mean soil-water content by date and depth at four experimental sites; and (5) one file lists soil-water content by date and depth for each neutron-probe access tube. This report highlights selected data contained in the computer data files using figures, tables, and brief discussions. Instrumentation used for data collection also is described. Water-content profiles are shown to demonstrate variability of water content with depth. Time-series data are plotted to illustrate temporal variations in micrometeorological and soil-water content data. Substantial precipitation at the end of an El Ni?o cycle in early 1998 resulted in measurable water penetration to a depth of 1.25 meters at one of the four experimental soil-monitoring sites.

Nevada

Physical property changes in hydrate-bearing sediment due to depressurization and subsequent repressurization

Physical property measurements of sediment cores containing natural gas hydrate are typically performed on material exposed, at least briefly, to non-in situ conditions during recovery. To examine the effects of a brief excursion from the gas-hydrate stability field, as can occur when pressure cores are transferred to pressurized storage vessels, we measured physical properties on laboratory-formed sand packs containing methane hydrate and methane pore gas. After depressurizing samples to atmospheric pressure, we repressurized them into the methane-hydrate stability field and remeasured their physical properties. Thermal conductivity, shear strength, acoustic compressional and shear wave amplitudes, and speeds of the original and depressurized/repressurized samples are compared. X– ray computed tomography images track how the gas-hydrate distribution changes in the hydrate-cemented sands owing to the depressurizaton/repressurization process. Because depressurization-induced property changes can be substantial and are not easily predicted, particularly in water-saturated, hydrate-bearing sediment, maintaining pressure and temperature conditions throughout the core recovery and measurement process is critical for using laboratory measurements to estimate in situ properties.

Journal of Geophysical Research B: Solid Earth

Selected micrometeorological, soil-moisture, and evapotranspiration data at Amargosa Desert Research Site in Nye County near Beatty, Nevada, 2001-05

Selected micrometeorological and soil-moisture data were collected at the Amargosa Desert Research Site adjacent to a low-level radio-active waste and hazardous chemical waste facility near Beatty, Nevada, 2001-05. Evapotranspiration data were collected from February 2002 through the end of December 2005. Data were col-lected in support of ongoing research to improve the understanding of hydrologic and contaminant-transport processes in arid environments. Micrometeorological data include solar radiation, net radiation, air temperature, relative humidity, saturated and ambient vapor pressure, wind speed and direction, barometric pressure, precipitation, near-surface soil temperature, soil-heat flux and soil-water content. All micrometeorological data were collected using a 10-second sampling interval by data loggers that output daily and hourly mean values. Daily maximum and minimum values are based on hourly mean values. Precipitation data output includes daily and hourly totals. Selected soil-moisture profiles at depth include periodic measurements of soil volumetric water-content measurements at nine neutron-probe access tubes to depths ranging from 5.25 to 29.25 meters. Evapotranspiration data include measurement of daily evapotranspiration and 15-minute fluxes of the four principal energy budget components of latent-heat flux, sensible-heat flux, soil-heat flux, and net radiation. Other data collected and used in equations to determine evapotranspiration include temperature and water content of soil, temperature and vapor pressure of air, and covariance values. Evapotranspiration and flux estimates during 15-minute intervals were calculated at a 0.1-second execution interval using the eddy covariance method. Data files included in this report contain the complete micrometeorological, soil-moisture, and evapotranspiration field data sets. These data files are presented in tabular Excel spreadsheet format. This report highlights selected data contained in the computer generated data files using figures, tables, and brief discussions. Instrumentation used for data collection also is described. Water-content profiles are shown to demonstrate variability of water content with depth. Time-series data are plotted to illustrate temporal variations in micrometeorological, soil-water content, and evapotranspiration data.

Nevada

Lower Eastern Shore Tributary summary: A summary of trends in tidal water quality and associated factors, 1985-2023

The Lower Eastern Shore Tributary Summary outlines change over time according to a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period 1985 – 2023, and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring (March-May) and summer (July-September) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO4), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in an Appendix B. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as winddriven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submersed aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the Lower Eastern Shore. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who use tidal water quality to inform management decisions, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. The Tributary Summary documents are sources of readily available background for change over time in tidal water quality observed with monitoring data. They help answer questions related to water quality, show how landscape factors drive water-quality changes over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Maryland, Virginia

Paleomagnetically defined brief lifespans for two large shield volcanoes in the Cascades Arc

Mafic to intermediate shield volcanoes with multi-cubic-kilometer eruptive volumes are common in the Cascades Volcanic Arc, but little is known about their eruptive histories as either singular or sustained episodes, or the total time required for their construction. Paleomagnetic data were collected from the lava flows of Ash Creek Butte (17 sites) and Crater Mountain (14 sites) in northern California; both volcanoes are large shields with total volumes of ∼11 km 3 each. Tightly clustered paleomagnetic results at both volcanoes, when coupled with analysis of geomagnetic secular variation, suggest that each edifice was built in only a few centuries, possibly in as little time as 50–90 years, indicating sub-century to century scale eruptive durations for two sizeable regional shield volcanoes within the Cascades Arc. These rapidly built shield volcanoes are substantially larger than typically defined monogenetic volcanoes, yet both are wholly formed within a single ‘episode’ at the limits of temporal resolution. Paleomagnetic methods provide a high-resolution tool that can be applied to understanding the tempo of regional volcanism in arcs.

California, Oregon, Washington

James Tributary summary: A summary of trends in tidal water quality and associated factors, 1985-2021

The James Tributary Summary outlines change over time for a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period 1985 – 2021 and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring and summer (June, July, August) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO4), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in an Appendix. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as wind-driven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submerged aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the James River. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who are looking at tidal water quality data and trying to understand why patterns are occurring, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. Our goal is for the Tributary Summary documents to be sources of readily available background for change over time in tidal water quality observed with monitoring data. The intended purpose of the Tributary Summary documents is to help answer questions related to water quality, show how landscape factors drive water quality change over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Virginia

Rappahannock tributary summary: A summary of trends in tidal water quality and associated factors, 1985-2022

The Rappahannock Tributary Summary outlines change over time for a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period of 1985 to 2022, and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring (March-May) and summer (JulySeptember) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO 4 ), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in Appendix B. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as winddriven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submerged aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the Rappahannock River. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who are looking at tidal water quality data and trying to understand why patterns are occurring, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. Our goal is for the Tributary Summary documents to be sources of readily available background for change over time in tidal water quality observed with monitoring data. The intended purpose of the Tributary Summary documents is to help answer questions related to water quality, show how landscape factors drive water quality change over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Virginia

Geology, palynology, and climatic significance of two pre-Pinedale Lake sediment sequences in and near Yellowstone National Park

Pollen analysis of a section of lake sediments at Grassy Lake Reservoir indicates a vegetational sequence changing from tundra, to spruce-fir-pine forest, to pine forest, to tundra at the top. Pollen analysis of a section of lake sediments on Beaverdam Creek indicates a tundra vegetation at the base, followed by a brief episode of spruce-fir forest and a return to a tundra vegetation at the top. The analyses of both sections suggest a cold to cool to cold climatic sequence, interpreted as interstadial in character. However, differences suggest that they represent separate interstadials. Pinedale Till disconformably overlies the lake deposits at Grassy Lake Reservoir. The upper sediments contain wood 14 C dated at >42,000 yr; the lowermost interfinger with till shown to be more than about 70,000 yr old. The deposits at Beaverdam Creek grade upward into proglacial Pinedale deposits, contain an ash that is probably about 70,000 yr old near their base, and rest comformably on gravel that grades down into lake sediments containing wood debris suggestive of an older climatic amelioration. We conclude that the warmest part of the interstadial at Grassy Lake Reservoir is probably more than 70,000 yr old, and that the warmest part of the interstadial analyzed at Beaverdam Creek is slightly younger than 70,000 yr old.

Wyoming

Potomac Tributary Summary: A summary of trends in tidal water quality and associated factors, 1985 - 2022

The Potomac Tributary Summary outlines change over time for a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period of 1985 to 2022, and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring (March-May) and summer (July-September) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO4), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in Appendix B. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as wind driven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submerged aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the Potomac River. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who are looking at tidal water quality data and trying to understand why patterns are occurring, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. Our goal is for the Tributary Summary documents to be sources of readily available background for change over time in tidal water quality observed with monitoring data. The intended purpose of the Tributary Summary documents is to help answer questions related to water quality, show how landscape factors drive water quality change over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Maryland, Pennsylvania, Virginia, West Virginia

U.S. Geological Survey National Water Census: Colorado River Basin Geographic Focus Area Study

Introduction The U.S. Geological Survey’s (USGS) concept of a national census (or accounting) of water resources has evolved over the last several decades as the Nation has experienced increasing concern over water availability for multiple competing uses. The implementation of a USGS National Water Census was described in the USGS 2007 science strategy document that identified the highest priority science topics for the decade 2007–17. In 2009, the SECURE Water Act (Public Law 111–11, subtitle F) authorized the USGS to create a Water Availability and Use Assess­ment Program for the Nation, and in 2012, the Department of the Interior WaterSMART initiative provided funding to begin implementation of the USGS National Water Census (NWC). Generally, the USGS NWC approaches water-availability assessment in terms of a “water budget.” The water-budget approach seeks to better quantify the inflows and outflows of water, as well as the change in storage volume, both nationally and at a regional scale and, by doing so, provides critical information to managers and stakeholders responsible for making water-availability decisions. The NWC has two primary components: Topical Studies and Geographic Focus Area Studies. Topical Studies do research on methods that can provide nationwide estimates of particular water-budget components at the subwatershed scale. Some examples of NWC Topical Studies include estimation of streamflow at ungaged locations; periodic quantification of evapotranspiration; and water use related to development of unconventional oil and gas. These efforts are planned to include additional topics in the future. Geographic Focus Area Studies (FASs) assess water availability and use within a defined geographic area, typically a surface-water drainage basin, to increase the understanding of factors affecting water availability in the region. In the FASs, local stakeholder input helps the USGS identify what components of the water budget are in most need of additional understanding or quantification. Focus Area Studies are planned as 3-year efforts and, typically, three FASs are ongoing in different parts of the country at any given time. The Colorado River Basin (CRB) and the Delaware and Apalachicola-Chattahoochee-Flint (ACF) River Basins were selected by the Department of the Interior for the first round of FASs because of the perceived water shortages in the basins and potential conflicts over water supply and allocations. After gathering input from numerous stakeholders in the CRB, the USGS determined that surface­-water resources in the basin were already being closely monitored and that the most important scientific contribution could be made by helping to improve estimates of four water­-budget components: evapotranspiration losses, snowpack hydrodynamics, water­-use information, and the relative importance of groundwater discharge in supporting streamflow across the basin. The purpose of this fact sheet is to provide a brief summary of the CRB FAS results as the study nears completion. Although some project results are still in the later stages of review and publication, this fact sheet provides an overall description of the work completed and cites the publications in which additional information can be found.

Arizona, California, Colorado, Nevada, New Mexico,

A conceptual model for river water and sediment dispersal in the Santa Barbara Channel, California

The ephemeral Santa Clara River delivers large amounts of freshwater and sediment to the eastern Santa Barbara Channel during brief, episodic discharge events. This discharge into the channel was characterized here with shipboard measurements during floods of 1997 and 1998. Within approximately 1-km of the river mouth, the river discharge quickly stratifies into a freshened, turbid surface plume and a bottom nephloid layer. Observations immediately off the Santa Clara River mouth on a peak day of river discharge revealed that sediment rapidly settled from the freshened surface waters, as suspended sediment in the freshened surface plume contained only ???6% of the sediment mass expected if the sediment mixed conservatively. On the two subsequent days the reduction of sediment mass in the surface plume continued at ???50% per day. These observations suggest that river sediment undergoes rapid initial settling within ???1-km of the river mouth, followed by somewhat slower rates of settling. Although we did not measure sedimentation or bottom boundary layer processes, our mass balance results suggest that almost all of the river sediment either escapes along or deposits upon the inner shelf seabed.

Continental Shelf Research

Behavior of the Hawaiian Hawaiian Hoary Bat (Lasiurus cinereus semotus) at wind turbines and its distribution across the North Ko'olau Mountains, O'ahu

We studied the landscape distribution of endemic Hawaiian hoary bats (Lasiurus cinereus semotus ) on the north Ko‘olau Mountains of O‘ahu, Hawai‘i, from May 2013 to May 2014, while simultaneously studying their behavior at wind turbines within the broader landscape. This research aimed to assess the risk that wind turbines pose to bats on the island and integrated a variety of methods, including acoustic monitoring, thermal videography, and fatality searches.Our findings indicate that hoary bats were acoustically cryptic and occurred sparsely in the region. Overall site occupancy rate was 55% during the 1-year period of acoustic monitoring at 23 sites, and there was only an 8% chance of acoustically detecting a bat on a given night if it was present. We detected bats less frequently in windward northern parts of the study area and at windy, lower-elevation sites with rough terrain. Bats were detected more frequently in leeward southern parts of the study area and at wind-sheltered, higher-elevation sites with flat ridgetops. Acoustic detections were consistently low from October through February and increased at most sites to peak in April through August. However, meteorological conditions were not found to be associated with the acoustic prevalence of bats on a night-to-night basis. We observed more than three thousand events involving bats during six months of nightly video surveillance at four wind turbines. Video monitoring revealed several links to weather at the local scale, despite acoustic detections not clearly relating to weather in our broader landscape analysis. Video demonstrated bats occurring near turbines more often on nights with little rain, warmer temperatures, moderate wind speeds, low humidity, and the low but rising barometric pressures indicative of fair weather and improved foraging conditions. Video monitoring also demonstrated that the presence of bats near turbines strongly correlates with insect presence. We detected bats on video rather infrequently, averaging only one to two passes per hour. Most detections were brief (median = 4.0 sec) and involved single bats (97%), with the amount of time during which bats were observed totaling to only 0.10% of the video analyzed (about 3.8 hours of 3,847 total hours). Bats frequently foraged in the airspace near turbines. These results differ from a recent similar study on the mainland (continental North America) and may indicate that Hawaiian hoary bats spend less time closely approaching wind turbines and show less interest in them than their more-migratory mainland conspecifics. We speculate that the Hawaiian hoary bats we observed were locally resident and frequenting high-quality habitat near familiar structures. In contrast, hoary bats observed at wind facilities on the mainland appear to approach and investigate unfamiliar landscape structures that they mistake for trees as they migrate long distances. Consequently, Hawaiian hoary bats may be less susceptible to fatality at wind turbines on a per-encounter basis than hoary bats in North America. Only one bat carcass was found at the four turbines searched daily for six months. The relatively high probability of finding carcasses provided strong assurance that few carcasses were likely missed—there was less than a 10% chance that total fatality at the four turbines monitored for half a year exceeded three bats.

Hawaii

Revisiting seismological discoveries of the inner core

Seismology has been used as a tool for understanding the current physical properties of the interior of the Earth and its dynamic evolution with remarkable success over the last century. Much of this progress is due to the ever‐expanding set of high‐quality quantitative observations of teleseismic waveforms recorded at seismographic stations worldwide. In this work, we revisit historical seismological studies that helped first identify a core distinct in physical properties from the overlying mantle, followed by the detection of an inner core that was eventually verified to be solid based on normal‐mode eigenperiods. Along with a brief overview of past studies of the Earth’s inner core, we examine the reproducibility of these results and discuss how historical data compare against modern observations. After accounting for past normal‐mode misidentifications, we confirm that introducing a solid inner core is required to afford significant improvements in fits to both radial modes and core‐sensitive spheroidal overtones. Strong shear dissipation in the inner core of the radial reference Earth model, REM1D ( ⁠⁠ Q u = 89.54 ), fits the reference datasets of both normal‐mode eigenperiods and quality factors accounting for physical dispersion. Because a liquid region would only have bulk dissipation, a narrow range of low Q u values that are preferred by the reference datasets affords additional evidence of a solid inner core. In addition, we find that there is little systematic bias in the timing accuracy of historical data, although large variances exist. Investigations into the temperature, composition, and evolution of the inner core, as well as the reproducibility of past studies, can benefit from the reconciliation of historical and modern seismological datasets.

Seismological Research Letters

The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism

The thick sequence of Miocene lava flows exposed on Steens Mountain in southeastern Oregon is well known for containing a detailed record of a reversed‐to‐normal geomagnetic polarity transition. Paleomagnetic samples were obtained from the sequence for a combined study of the directional and intensity variations recorded; the paleointensity study is reported in a companion paper. This effort has resulted in the first detailed history of total geomagnetic field behavior during a reversal of polarity. A comparison of the directional variation history of the reversed and normal polarity intervals on either side of the transition with the Holocene record has allowed an estimate of the duration of these periods to be made. These time estimates were then used to calculate accumulation rates for the volcanic sequence and thereby provide a means for estimating time periods within the transition itself. The polarity transition was found to consist of two phases, each with quite different characteristics. At the onset of the first phase, a one‐third decrease in magnetic field intensity may have preceded the first intermediate field directions by about 600 years. Changes in field direction were confined near the local north‐south vertical plane when the actual reversal in direction occurred and normal polarity directions may have been attained within 550±150 years. The end of the first phase of the transition was marked by a brief (possibly 100–300 years) period with normal polarity and a pretransitional intensity which suggests a quasi‐normal dipole field structure existed during this interval. The second phase of the transition was characterized by a return to very low field intensities with the changes in direction describing a long counterclockwise loop in contrast to the earlier narrowly constrained changes. This second phase lasted 2900±300 years, and both normal directions and intensities were recovered at the same time. Both directional and intensity data document very erratic geomagnetic field behavior during the polarity transition. Changes in magnetic field direction were variable and occurred either (1) in a regular, progressive manner, (2) with sudden, extremely rapid angular changes (58°±21°/year), or (3) with little or no movement for periods of the order of 600±200 years. Changes in magnetic intensity occurred in a like manner and were sometimes correlated with changes in direction, but during other periods both directional and intensity changes occurred independently. Directional changes following the polarity transition occurred in a seemingly normal manner, although intensity fluctuations attest to some instability of the newly reestablished dipole.

Journal of Geophysical Research B: Solid Earth

Geologic map of northeastern Seattle (part of the Seattle North 7.5' x 15' quadrangle), King County, Washington

This geologic map, approximately coincident with the east half of the Seattle North 7.5 x 15’ quadrangle (herein, informally called the “Seattle NE map”), covers nearly half of the City of Seattle and reaches from Lake Washington across to the Puget Sound shoreline. Land uses are mainly residential, but extensive commercial districts are located in the Northgate neighborhood, adjacent to the University of Washington, and along the corridors of Aurora Avenue North and Lake City Way. Industrial activity is concentrated along the Lake Washington Ship Canal and around Lake Union. One small piece of land outside of the quadrangle boundaries, at the west edge of the Bellevue North quadrangle, is included on this map for geographic continuity. Conversely, a small area in the northeast corner of the Seattle North quadrangle, on the eastside of Lake Washington, is excluded from this map. Within the boundaries of the map area are two large urban lakes, including the most heavily visited park in the State of Washington (Green Lake Park); a stream (Thornton Creek) that still hosts anadromous salmon despite having its headwaters in a golfcourse and a shopping center; parts of three cities, with a combined residential population of about 300,000 people; and the region’s premier research institution, the University of Washington. The north boundary of the map is roughly NE 168th Street in the cities of Shoreline and Lake Forest Park, and the south boundary corresponds to Mercer Street in Seattle. The west boundary is 15th Avenue W (and NW), and the east boundary is formed by Lake Washington. Elevations range from sea level to a maximum of 165 m (541 ft), the latter on a broad till-covered knob in the city of Shoreline near the northwest corner of the map. Previous geologic maps of this area include those of Waldron and others (1962), Galster and Laprade (1991), and Yount and others (1993). Seattle lies within the Puget Lowland, an elongate structural and topographic basin between the Cascade Range and Olympic Mountains. The Seattle area has been glaciated repeatedly during the past two million years by coalescing glaciers that advanced southward from British Columbia. The landscape we see today was molded by cyclic glacial scouring and deposition and later modified by landsliding and stream erosion. The last ice sheet reached the central Puget Sound region about 14,500 years ago, as measured by 14 C dating, and it had retreated from this area by 13,650 14 C yr B.P. (equivalent calendar years are about 17,600 and 16,600 years ago; Porter and Swanson, 1998). Seattle now sits atop a complex and incomplete succession of interleaved glacial and nonglacial deposits that overlie an irregular bedrock surface. These glacial and nonglacial deposits vary laterally in both texture and thickness, and they contain many local unconformities. In addition, they have been deformed by faults and folds, at least as recently as 1,100 years ago, and this deformation further complicates the geologic record. The landforms and near-surface deposits that cover much of the Seattle NE map area record a relatively brief, recent interval of the region’s geologic history. The topography is dominated in the north by a broad, fluted, and south-sloping upland plateau, which gives way to a more complex set of elongated hills in the map’s southern half. The valleys of Pipers Creek, Green Lake, and Thornton Creek mark the transition between these two topographic areas. Most of the uplands are mantled by a rolling surface of sand (unit Qva) and till (unit Qvt) deposited during the last occupation of the Puget Lowland by a continental ice sheet. Beneath these ice sheet deposits is a complex succession of older sediments that extends far below sea level across most of the map area. These older sediments are now locally exposed where modern erosion and landslides have sliced through the edge of the upland, and where subglacial processes apparently left these older sediments largely free of overlying sediments. Lack of overlying sediments is particularly evident on the hillslopes above Thornton Creek, adjacent to Lake Washington, and on the flanks of Capitol Hill.

Washington

Introduction - The impacts of the 2008 eruption of Kasatochi Volcano on terrestrial and marine ecosystems in the Aleutian Islands, Alaska

The Aleutian Islands are situated on the northern edge of the so-called “Pacific Ring of Fire,” a 40,000-km-long horseshoe-shaped assemblage of continental landmasses and islands bordering the Pacific Ocean basin that contains many of the world's active and dormant volcanoes. Schaefer et al. (2009) listed 27 historically active volcanoes in the Aleutian Islands, of which nine have had at least one major eruptive event since 1990. Volcanic eruptions are often significant natural disturbances, and ecosystem responses to volcanic eruptions may vary markedly with eruption style (effusive versus explosive), frequency, and magnitude of the eruption as well as isolation of the disturbed sites from potential colonizing organisms (del Moral and Grishin, 1999). Despite the relatively high frequency of volcanic activity in the Aleutians, the response of island ecosystems to volcanic disturbances is largely unstudied because of the region's isolation. The only ecological studies in the region that address the effects of volcanic activity were done on Bogoslof Island, a remote, highly active volcanic island in the eastern Aleutians, which grew from a submarine eruption in 1796 (Merriam, 1910; Byrd et al., 1980; Byrd and Williams, 1994). Nevertheless, in the 214 years of Bogoslof's existence, the island has been visited only intermittently. Kasatochi Island is a small (2.9 km by 2.6 km, 314 m high) volcano in the central Aleutian Islands of Alaska (52.17°N latitude, 175.51°W longitude; Fig. 1) that erupted violently on 7-8 August 2008 after a brief, but intense period of precursory seismic activity (Scott et al., 2010 [this issue]; Waythomas et al., in review). The island is part of the Aleutian arc volcanic front, and is an isolated singular island. Although the immediate offshore areas are relatively shallow (20–50 m water depth), the island is about 10 km south of the 2000 m isobath, north of which, ocean depths increase markedly. Kasatochi is located between the deepwater basin of the Bering Sea to the north and shallower areas of intense upwelling in Atka and Fenimore Passes in the North Pacific Ocean to the south. This area apparently produces high marine productivity based on concentrations of feeding marine birds and mammals (see Drew et al., 2010 [this issue]). Kasatochi is about 85 km northeast of Adak, the nearest community and a regional transportation hub, and about 19 km northwest of the western end of Atka Island. The nearest historically active volcanoes are Great Sitkin volcano, about 35 km to the west, and Korovin volcano on Atka Island, about 94 km to the east. Koniuji Island, another small volcanic island, is located about 25 km east of Kasatochi (Fig. 1).

Alaska