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USGS2016

Documentation and hydrologic analysis of Hurricane Sandy in New Jersey, October 29–30, 2012

In 2012, a late season tropical depression developed into a tropical storm and later a hurricane. The hurricane, named “Hurricane Sandy,” gained strength to a Category 3 storm on October 25, 2012, and underwent several transitions on its approach to the mid-Atlantic region of the eastern coast of the United States. By October 28, 2012, Hurricane Sandy had strengthened into the largest hurricane ever recorded in the North Atlantic and was tracking parallel to the east coast of United States, heading toward New Jersey. On October 29, 2012, the storm turned west-northwest and made landfall near Atlantic City, N.J. The high winds and wind-driven storm surge caused massive damage along the entire coastline of New Jersey. Millions of people were left without power or communication networks. Many homes were completely destroyed. Sand dunes were eroded, and the barrier island at Mantoloking was breached, connecting the ocean with Barnegat Bay. Several days before the storm made landfall in New Jersey, the U.S. Geological Survey (USGS) made a decision to deploy a temporary network of storm-tide sensors and barometric pressure sensors from Virginia to Maine to supplement the existing USGS and National Oceanic and Atmospheric Administration (NOAA) networks of permanent tide monitoring stations. After the storm made landfall, the USGS conducted a sensor data recovery and high-water-mark collection campaign in cooperation with the Federal Emergency Management Agency (FEMA). Peak storm-tide elevations documented at USGS tide gages, tidal crest-stage gages, temporary storm sensor locations, and high-water-mark sites indicate the area from southern Monmouth County, N.J., north through Raritan Bay, N.J., had the highest peak storm-tide elevations during this storm. The USGS tide gages at Raritan River at South Amboy and Raritan Bay at Keansburg, part of the New Jersey Tide Telemetry System, each recorded peak storm-tide elevations of greater than 13 feet (ft)—more than 5 ft higher than the previously recorded period-of-record maximum. A comparison of peak storm-tide elevations to preliminary FEMA Coastal Flood Insurance Study flood elevations indicated that these areas experienced the highest recurrence intervals along the coast of New Jersey. Analysis showed peak storm-tide elevations exceeded the 100-year FEMA flood elevations in many parts of Middlesex, Union, Essex, Hudson, and Bergen Counties, and peak storm-tide elevations at many locations in Monmouth County exceeded the 500-year recurrence interval. A level 1 HAZUS (HAZards United States) analysis was done for the counties in New Jersey affected by flooding to estimate total building stock losses. The aggregated total building stock losses estimated by HAZUS for New Jersey, on the basis of the final inundation verified by USGS high-water marks, was almost $19 billion. A comparison of Hurricane Sandy with historic coastal storms showed that peak storm-tide elevations associated with Hurricane Sandy exceeded most of the previously documented elevations associated with the storms of December 1992, March 1962, September 1960, and September 1944 at many coastal communities in New Jersey. This scientific investigation report was prepared in cooperation with FEMA to document flood processes and flood damages resulting from this storm and to assist in future flood mitigation actions in New Jersey.

New Jersey↗

USGS2014

A century of ocean warming on Florida Keys coral reefs: historic in situ observations

There is strong evidence that global climate change over the last several decades has caused shifts in species distributions, species extinctions, and alterations in the functioning of ecosystems. However, because of high variability on short (i.e., diurnal, seasonal, and annual) timescales as well as the recency of a comprehensive instrumental record, it is difficult to detect or provide evidence for long-term, site-specific trends in ocean temperature. Here we analyze five in situ datasets from Florida Keys coral reef habitats, including historic measurements taken by lighthouse keepers, to provide three independent lines of evidence supporting approximately 0.8 °C of warming in sea surface temperature (SST) over the last century. Results indicate that the warming observed in the records between 1878 and 2012 can be fully accounted for by the warming observed in recent decades (from 1975 to 2007), documented using in situ thermographs on a mid-shore patch reef. The magnitude of warming revealed here is similar to that found in other SST datasets from the region and to that observed in global mean surface temperature. The geologic context and significance of recent ocean warming to coral growth and population dynamics are discussed, as is the future prognosis for the Florida reef tract.

Florida↗

USGS2004

Long-Term Oceanographic Observations in Western Massachusetts Bay Offshore of Boston, Massachusetts: Data Report for 1989-2002

This data report presents long-term oceanographic observations made in western Massachusetts Bay at two locations: (1) 42 deg 22.6' N., 70 deg 47.0' W. (Site A, 33 m water depth) from December 1989 through December 2002 (figure 1), and (2) 42 deg 9.8' N., 70 deg 38.4' W. (Site B, 21 m water depth) from October 1997 through December 2002. Site A is approximately 1 km south of the new ocean outfall that began discharging treated sewage effluent from the Boston metropolitan area into Massachusetts Bay on September 6, 2000. These long-term oceanographic observations have been collected by the U.S. Geological Survey (USGS) in partnership with the Massachusetts Water Resources Authority (MWRA) and with logistical support from the U.S. Coast Guard (USCG - http://www.uscg.mil). This report presents time series data through December 2002, updating a similar report that presented data through December 2000 (Butman and others, 2002). In addition, the Statistics and Mean Flow sections include some new plots and tables and the format of the report has been streamlined by combining yearly figures into single .pdfs. Figure 1 (PDF format) The long-term measurements are planned to continue at least through 2005. The long-term oceanographic observations at Sites A and B are part of a USGS study designed to understand the transport and long-term fate of sediments and associated contaminants in the Massachusetts bays. (See http://woodshole.er.usgs.gov/project-pages/bostonharbor/ and Butman and Bothner, 1997.) The long-term observations document seasonal and inter-annual changes in currents, hydrography, and suspended-matter concentration in western Massachusetts Bay, and the importance of infrequent catastrophic events, such as major storms or hurricanes, in sediment resuspension and transport. They also provide observations for testing numerical models of circulation. This data report presents a description of the field program and instrumentation, an overview of the data through summary plots and statistics, and the data in NetCDF and ASCII format for the period December 1989 through December 2002 for Site A and October 1997 through December 2002 for Site B. The objective of this report is to make the data available in digital form and to provide summary plots and statistics to facilitate browsing of the long-term data set.

Data Series↗

USGS1997

Mass balance approach to selenium cycling through the San Joaquin Valley, sources to river to bay

Surface and ground waters of the Central Valley of California (e.g., rivers, dams, off-stream storage reservoirs, pumping facilities, irrigation and drinking water supply canals, agricultural drainage canals) are part of a hydrologic system that makes up a complex ecosystem extending from the riparian wetlands of the Sacramento and San Joaquin Rivers through the San Francisco Bay/Delta Estuary to the Pacific Ocean (Fig. 1). Water quality concerns center on elevated selenium (Se) and salt concentrations in irrigation drainage water discharged into the waterways of the relatively arid San Joaquin Valley (SJV), including the San Joaquin River (SJR). These waters are made unique by dissolved Se, weathered from marine sedimentary rocks of the Coast Ranges to the west, being ultimately concentrated to toxic levels in aquatic wildlife in the wetlands of the SJV/SJR trough (Figs. 1 and 2) (Presser and Ohlendorf, 1987; Presser, 1994). Scientific and environmental concerns focus on the bioreactive properties of Se and its partitioning among biota, water, and sediment, and on whether simple dilution models can be applied to an element that bioaccumulates. Because of state and federal commitments to provide water for irrigation, as well as drainage of irriga tion wastewater by the year 2000 drainage from over 180,000 ha of seleniferous, salinized farmland within the western SJV will create approximately 387 million cubic meters of potentially toxic drainage water annually (i.e., “problem water,” as defined by the San Joaquin Valley Drainage Program, 1990), thus lending urgency to an understanding of the biogeochemistry of Se in this environment.

California↗

USGS2017

Drivers of Holocene sea-level change in the Caribbean

We present a Holocene relative sea-level (RSL) database for the Caribbean region (5°N to 25°N and 55°W to 90°W) that consists of 499 sea-level index points and 238 limiting dates. The database was compiled from multiple sea-level indicators (mangrove peat, microbial mats, beach rock and acroporid and massive corals). We subdivided the database into 20 regions to investigate the influence of tectonics and glacial isostatic adjustment on RSL. We account for the local-scale processes of sediment compaction and tidal range change using the stratigraphic position (overburden thickness) of index points and paleotidal modeling, respectively. We use a spatio-temporal empirical hierarchical model to estimate RSL position and its rates of change in the Caribbean over 1-ka time slices. Because of meltwater input, the rates of RSL change were highest during the early Holocene, with a maximum of 10.9 ± 0.6 m/ka in Suriname and Guyana and minimum of 7.4 ± 0.7 m/ka in south Florida from 12 to 8 ka. Following complete deglaciation of the Laurentide Ice Sheet (LIS) by ∼7 ka, mid-to late-Holocene rates slowed to < 2.4 ± 0.4 m/ka. The hierarchical model constrains the spatial extent of the mid-Holocene highstand. RSL did not exceed the present height during the Holocene, except on the northern coast of South America, where in Suriname and Guyana, RSL attained a height higher than present by 6.6 ka (82% probability). The highstand reached a maximum elevation of +1.0 ± 1.1 m between 5.3 and 5.2 ka. Regions with a highstand were located furthest away from the former LIS, where the effects from ocean syphoning and hydro-isostasy outweigh the influence of subsidence from forebulge collapse.

Quaternary Science Reviews↗

USGS2024

Projections of multiple climate-related coastal hazards for the US Southeast Atlantic

Faced with accelerating sea level rise and changing ocean storm conditions, coastal communities require comprehensive assessments of climate-driven hazard impacts to inform adaptation measures. Previous studies have focused on flooding but rarely on other climate-related coastal hazards, such as subsidence, beach erosion and groundwater. Here, we project societal exposure to multiple hazards along the Southeast Atlantic coast of the United States. Assuming 1 m of sea level rise, more than 70% of the coastal residents and US \ $ 1 trillion in property are in areas projected to experience shallow and emerging groundwater, 15 times higher than daily flooding. Storms increase flooding exposure by an order of magnitude over daily flooding, which could impact up to ~50% of all coastal residents and US \ $ 770 billion in property value. The loss of up to ~80% of present-day beaches and high subsidence rates that currently affect over 1 million residents will exacerbate flooding and groundwater hazard risks.

Florida, Georgia, North Carolina, South Carolina, ↗

USGS2015

Groundwater quality in the Northern Coast Ranges Basins, California

The Northern Coast Ranges (NOCO) study unit is 633 square miles and consists of 35 groundwater basins and subbasins (California Department of Water Resources, 2003; Mathany and Belitz, 2015). These basins and subbasins were grouped into two study areas based primarily on locality. The groundwater basins and subbasins located inland, not adjacent to the Pacific Ocean, were aggregated into the Interior Basins (NOCO-IN) study area. The groundwater basins and subbasins adjacent to the Pacific Ocean were aggregated into the Coastal Basins (NOCO-CO) study area (Mathany and others, 2011). The primary aquifer system in the NOCO-IN study area occurs in alluvial basins made up of sand, silt, gravel, clay, and thin volcanic ash layers or lenses. Groundwater movement in the NOCO-IN study area follows the topography and direction of surface-water features. In the NOCO-CO study area, groundwater is present in alluvial fan, floodplain, and terrace deposits. Groundwater movement in the NOCO-CO study area is from east to west towards the Pacific Ocean. The primary aquifer system in the study unit generally is defined as those parts of the aquifer system corresponding to the perforated intervals of sites listed in the California Department of Public Health (CDPH) database of public drinking-water supply sources. Well depths in the NOCO-IN study area ranged from 36 to 400 feet below land surface (ft bls), and depths to top-of-perforations ranged from 15 to 148 ft bls. In the NOCO-CO study area, well depths ranged from 15 to 400 ft bls, and depths to top-of-perforations ranged from 10 to 356 ft bls. Water quality in the primary aquifer system may differ from that in the shallower and deeper parts of the aquifer system. Average annual rainfall in the NOCO study unit ranges from 22 to 79 inches. In the NOCO-IN study area, the climate is classified as Mediterranean, with warm to hot, dry summers and cold, wet winters. In the NOCO-CO study area, the climate is influenced by the Pacific Ocean and is characterized by cool to mild summers and cold, wet winters. The study unit is drained by several rivers and their principal tributaries: the Eel, Russian, Mad, Navarro, Smith, Klamath, Noyo, and Big Rivers. Land use in the study unit is about 60 percent (%) natural (mostly grassland and forest), 29% agricultural, and 11% urban. The primary uses of agricultural lands are pasture, row crops, hay, vineyards, and timberlands. The largest urban areas are the cities of Crescent City, Arcata, Eureka, Fort Bragg, Willits, Ukiah, and Lakeport. Recharge to the groundwater system is primarily from mixture of ambient sources, including direct percolation of precipitation and irrigation waters, infiltration of runoff from surrounding hills/areas, seepage from rivers and creeks, and subsurface inflow (from non-alluvial geologic units that bound the alluvial basins). The primary sources of discharge are evaporation, discharge to streams, and water pumped for municipal supply and irrigation.

California↗

USGS2023

Wind-modulated groundwater discharge along a microtidal Arctic coastline

Groundwater discharge transports dissolved constituents to the ocean, affecting coastal carbon budgets and water quality. However, the magnitude and mechanisms of groundwater exchange along rapidly transitioning Arctic coastlines are largely unknown due to limited observations. Here, using first-of-its-kind coastal Arctic groundwater timeseries data, we evaluate the magnitude and drivers of groundwater discharge to Alaska's Beaufort Sea coast. Darcy flux calculations reveal temporally variable groundwater fluxes, ranging from −6.5 cm d −1 (recharge) to 14.1 cm d −1 (discharge), with fluctuations in groundwater discharge or aquifer recharge over diurnal and multiday timescales during the open-water season. The average flux during the monitoring period of 4.9 cm d −1 is in line with previous estimates, but the maximum discharge exceeds previous estimates by over an order-of-magnitude. While the diurnal fluctuations are small due to the microtidal conditions, multiday variability is large and drives sustained periods of aquifer recharge and groundwater discharge. Results show that wind-driven lagoon water level changes are the dominant mechanism of fluctuations in land–sea hydraulic head gradients and, in turn, groundwater discharge. Given the microtidal conditions, low topographic relief, and limited rainfall along the Beaufort Sea coast, we identify wind as an important forcing mechanism of coastal groundwater discharge and aquifer recharge with implications for nearshore biogeochemistry. This study provides insights into groundwater flux dynamics along this coastline over time and highlights an oft overlooked discharge and circulation mechanism with implications towards refining solute export estimates to coastal Arctic waters.

Alaska↗

USGS2005

Radioisotopic and biostratigraphic age relations in the Coast Range Ophiolite, northern California: Implications for the tectonic evolution of the Western Cordillera

The Coast Range ophiolite (CRO) in northern California includes two distinct remnants. The Elder Creek ophiolite is a classic suprasubduction zone ophiolite with three sequential plutonic suites (layered gabbro, wehrlit-pyroxenite, quartz diorite), a mafic to felsic dike complex, and mafic-felsic volcanic rocks; the entire suite is cut by late mid-oceanic-ridge basalt (MORB) dikes and overlain by ophiolitic breccia. The Stonyford volcanic complex (SFVC) comprises three volcanic series with intercalated chert horizons that form a submarine volcano enclosed in sheared serpentinite. Structurally below this seamount are mélange blocks of CRO similar to Elder Creek. U/Pb zircon ages from plagiogranite and quartz diorites at Elder Creek range in age from 165 Ma to 172 Ma. U/Pb zircon ages obtained from CRO mélange blocks below the SFVC are similar (166–172 Ma). 40 Ar- 39 Ar ages of alkali basalt glass in the upper SFVC are all younger at ≈164 Ma. Radiolarians extracted from chert lenses intercalated with basalt in the SFVC indicate that the sedimentary strata range in age from Bathonian (Unitary Association Zone 6–6 of Baumgartner et al., 1995a ) near the base of the complex to late Callovian to early Kimmeridgian (Unitary Association Zones 8–10) in the upper part. The SFVC sedimentary record preserves evidence of a major faunal change wherein relatively small sized, polytaxic radiolarian faunas were replaced by very robust, oligo-taxic, nassellarian-dominated faunas that included Praeparvicingula spp. We suggest that CRO formation began after the early Middle Jurassic (172–180 Ma) collision of an exotic or fringing arc with North America and initiation of a new or reconfigured east-dipping subduction zone. The data show that the CRO formed prior to the Late Jurassic Nevadan orogeny, probably by rapid forearc extension above a nascent subduction zone. We infer that CRO spreading ended with the collision of an oceanic spreading center ca. 164 Ma, coincident with the oldest high-grade blocks in the structurally underlying Franciscan assemblage. We further suggest that the “classic” Nevadan orogeny represents a response to spreading center collision, with shallow subduction of young lithosphere causing the initial compressional deformation and with a subsequent change in North American plate motion to rapid northward drift (J2 cusp) causing sinistral transpression and transtension in the Sierra foothills. These data are not consistent with models for Late Jurassic arc collision in the Sierra foothills or a backarc origin for the CRO.

California↗

USGS2008

Multidecadal climate-induced variability in microseisms

Microseisms are the most ubiquitous continuous seismic signals on Earth at periods between approximately 5 and 25 s (Peterson 1993; Kedar and Webb 2005). They arise from atmospheric energy converted to (primarily) Rayleigh waves via the intermediary of wind-driven oceanic swell and occupy a period band that is uninfluenced by common anthropogenic and wind-coupled noise processes on land (Wilson et al. 2002; de la Torre et al. 2005). "Primary" microseisms (near 8-s period) are generated in shallow water by breaking waves near the shore and/or the nonlinear interaction of the ocean wave pressure signal with the sloping sea floor (Hasselmann 1963). Secondary microseisms occur at half of the primary period and are especially strongly radiated in source regions where opposing wave components interfere (Longuett-Higgins 1950; Tanimoto 2007), which principally occurs due to the interaction of incident swell and reflected/scattered wave energy from coasts (Bromirski and Duennebier 2002; Bromirski, Duennebier, and Stephen 2005). Coastal regions having a narrow shelf with irregular and rocky coastlines are known to be especially efficient at radiating secondary microseisms (Bromirski, Duennebier, and Stephen 2005; Shulte-Pelkum et al. 2004). The secondary microseism is globally dominant, and its amplitudes proportional to the square of the standing wave height (Longuett-Higgins 1950), which amplifies its sensitivity to large swell events (Astiz and Creager 1994; Webb 2006).

Seismological Research Letters↗

USGS1914

San Francisco folio, California, Tamalpais, San Francisco, Concord, San Mateo, and Haywards quadrangles

The five sheets of the San Francisco folio the Tamalpais, Ban Francisco, Concord, Ban Mateo, and Haywards sheets map a territory lying between latitude 37° 30' and 38° and longitude 122° and 122° 45'. Large parts of four of these sheets cover the waters of the Bay of San Francisco or of the adjacent Pacific Ocean. (See fig. 1.) Within the area mapped are the cities of San Francisco, Oakland, Berkeley, Alameda, Ban Rafael, and San Mateo, and many smaller towns and villages. These cities, which have a population aggregating about 750,000, together form the largest and most important center of commercial and industrial activity on the west coast of the United States. The natural advantages afforded by a great harbor, where the railways from the east meet the ships from all ports of the world, have determined the site of a flourishing cosmopolitan, commercial city on the shores of San Francisco Bay. The bay is encircled by hilly and mountainous country diversified by fertile valley lands and divides the territory mapped into two rather contrasted parts, the western part being again divided by the Golden Gate. It will therefore be convenient to sketch the geographic features under four headings (1) the area east of San Francisco Bay; (2) the San Francisco Peninsula; (3) the Marin Peninsula; (4) San Francisco Bay. (See fig. 2.)

California↗

USGS2015

Sea-floor morphology and sedimentary environments in southern Narragansett Bay, Rhode Island

Multibeam echosounder data collected by the National Oceanic and Atmospheric Administration along with sediment samples and still and video photography of the sea floor collected by the U.S. Geological Survey were used to interpret sea-floor features and sedimentary environments in southern Narragansett Bay, Rhode Island, as part of a long-term effort to map the sea floor along the northeastern coast of the United States. Sea-floor features include rocky areas and scour depressions in high-energy environments characterized by erosion or nondeposition, and sand waves and megaripples in environments characterized by coarse-grained bedload transport. Two shipwrecks are also located in the study area. Much of the sea floor is relatively featureless within the resolution of the multibeam data; sedimentary environments in these areas are characterized by processes associated with sorting and reworking. This report releases bathymetric data from the multibeam echosounder, grain-size analyses of sediment samples, and photographs of the sea floor and interpretations of the sea-floor features and sedimentary environments. It provides base maps that can be used for resource management and studies of topics such as benthic ecology, contaminant inventories, and sediment transport.

Rhode Island↗

USGS1974

Structure of the continental margin of Liberia, West Africa

Geophysical surveys made by R/V Unitedgeo I (USGS–IDOE Cruise Leg 5), combined with earlier surveys and available geologic information, provide the basis for interpreting the structure of the continental margin of Liberia. This area lies at the junction of the Americas and Africa in published reconstructions of Gondwanaland prior to the opening of the North and South Atlantic in Jurassic and Cretaceous time, respectively. Three fracture zones (St. Paul, Cape Palmas, and Grand Cess) are inferred in the area southeast of 9°30′ W. on the basis of magnetic and gravity data, which is supported by bathymetric and seismic reflection data. The three fracture zones appear to exist as separate lineaments near the African coast. Farther seaward, they may be part of the same transform fault crossing the Atlantic (St. Paul fracture zone). The magnetic anomalies associated with these fracture zones, which may have originated in Cretaceous time at the opening of the South Atlantic, are continuous with magnetic anomalies over crust of Eburnean age (∼2,000 m.y.) in southeast Liberia and its continental shelf. This suggests that Eburnean age structures may have been zones of weakness that were reactivated in Cretaceous time. A positive gravity anomaly (∼50 mgal) along the coast and continental shelf of Liberia is attributed to deep crustal rocks that were uplifted and exposed in Pan-African time (∼550 m.y.). The land boundary of this anomaly coincides with a shear zone that marks the boundary between the Pan-African and the Liberian age province (∼2,700 m.y.); the shearing (in a thrust-fault sense) may be the result of compressive stress associated with the closing of a proto-Atlantic ocean. Liberian age magnetic anomalies in the area northwest of 9°30′ W. cross the Pan-African province (and the positive coastal gravity anomaly) and continue over the continental shelf and slope to about the 3,000-m bathymetric contour; the seaward limit of the anomalies is interpreted as representing the seaward limit of the old continental crust. This westward extension of the continental crust does not completely fill the gap in fit in various published reconstructions of Gondwanaland, and we suggest that the northern Florida block may have been located near the Liberian margin at one time. Magnetic data indicate a thick section of sedimentary rock, possibly as great as 8 km, on the continental slope. Comparison of gravity data over magnetically inferred basins in the shelf, slope, and rise suggests that low-density sedimentary rocks constitute a greater proportion of the section in basins beneath the shelf and beneath the slope and rise northwest of 9°30' W. than beneath the slope and rise in the area of the fracture zones. The gravitational attraction that corresponds to a crust-mantle boundary dipping 45° to 60° can be computed to fit observed data – as might be expected at a rifted continental margin. A shallow high-density block beneath the coast and continental shelf is required to fit the coastal positive anomaly; this block is represented by exposures on land of granulite-grade metamorphic rock of the Pan-African province.

Atlantic Ocean↗

USGS2000

Nearshore fish distributions in an Alaskan estuary in relation to stratification, temperature, and salinity

Fish were sampled with beach seines and small-meshed beam trawls in nearshore ( < 1 km) and shallow ( < 25 m) habitats on the southern coast of Kachemak Bay, Cook Inlet, Alaska, from June to August, 1996-1998. Fish distributions among habitats were analysed for species composition, catch-per-unit-effort (CPUE) and frequency of occurrence. Two oceanographically distinct areas of Kachemak Bay were sampled and compared: the Outer Bay and the Inner Bay. Outer Kachemak Bay is exposed and receives oceanic, upwelled water from the Gulf of Alaska, whereas the Inner Bay is more estuarine. Thermohaline properties of bottom water in the Outer and Inner Bay were essentially the same, whereas the Inner Bay water-column was stratified with warmer, less saline waters near the surface. Distribution and abundance of pelagic schooling fish corresponded with area differences in stratification, temperature and salinity. The Inner Bay supported more species and higher densities of schooling and demersal fish than the Outer Bay. Schooling fish communities sampled by beach seine differed between the Outer and Inner Bays. Juvenile and adult Pacific sand lance (Ammodytes hexapterus), Pacific herring (Clupea harengus pallasi), osmerids (Osmeridae) and sculpins (Cottidae) were all more abundant in the Inner Bay. Gadids (Gadidae) were the only schooling fish taxa more abundant in the Outer Bay. Thermohaline characteristics of bottom water were similar throughout Kachemak Bay. Correspondingly, bottom fish communities were similar in all areas. Relative abundances (CPUE) were not significantly different between areas for any of the five demersal fish groups: flatfishes (Pleuronectidae), ronquils (Bathymasteridae), sculpins (Cottidae), gadids (Gadidae) and pricklebacks (Stichaeidae).

Estuarine, Coastal and Shelf Science↗

USGS2026

A process-based model for forecasting wave runup along the coast of Georgia

Wave runup is an important nearshore process that impacts total water level, sediment transport, and coastal design. Current methods for forecasting wave runup implement an empirical model that considers offshore wave height, wave period, and generalized beach slope. In this study, the authors generated wave runup forecasts from offshore wave conditions and a system of polynomial equations derived from numerical simulations at three different still water datums for each beach profile. They developed a process-based methodology that incorporated site-specific cross-shore topobathy into the phase-resolving numerical model. A comparison between the system of equations, deterministic hydrodynamic simulations, and observed high-water marks was made using Hurricanes Matthew (2016) and Irma (2017) for 12 cases, and it showed that the polynomials were capable of being consistent with the results from full simulation runs, while not requiring hours of runtime when a forecast was needed—the differences between the polynomial and the observed high water marks ranged from 3 to 32 cm for the Irma hindcast and 9–70 cm for Matthew. Then, using forcings from Hurricanes Ian and Nicole (2022), the model predicted the occurrence of dune collision, overwash, and inundation for the coast of Georgia and suggested that wave runup was impacted by the still water level and local topobathy.

Georgia↗

USGS2010

Fragmentation and hydration of tektites and microtektites

An examination of data collected over the last 30 years indicates that the percent of glass fragments vs. whole splash forms in the Cenozoic microtektite strewn fields increases towards the source crater (or source region). We propose that this is due to thermal stress produced when tektites and larger microtektites fall into water near the source crater while still relatively hot (>1150 °C). We also find evidence (low major oxide totals, frothing when melted) for hydration of most of the North American tektite fragments and microtektites found in marine sediments. High-temperature mass spectrometry indicates that these tektite fragments and microtektites contain up to 3.8 wt% H 2 O. The H 2 O-release behavior during the high-temperature mass-spectrometric analysis, plus high CI abundances (0.05 wt%), indicate that the North American tektite fragments and microtektites were hydrated in the marine environment ( i.e. , the H 2 O was not trapped solely on quenching from a melt). The younger Ivory Coast and Australasian microtektites do not exhibit much evidence of hydration (at least not in excess of 0.5 wt% H 2 O); this suggests that the degree of hydration increases with age. In addition, we find that some glass spherules (with <65 wt% SiO 2 ) from the upper Eocene clinopyroxene-bearing spherule layer in the Indian Ocean have palagonitized rims. These spherules appear to have been altered in a similar fashion to the splash form K/T boundary spherules. Thus, our data indicate that tektites and microtektites that generally contain >65 wt% SiO 2 can undergo simple hydration in the marine environment, while impact glasses (with <65 wt% SiO 2 ) can also undergo palagonitization.

Meteoritics and Planetary Science↗

USGS2001

Density and velocity relationships for digital sonic and density logs from coastal Washington and laboratory measurements of Olympic Peninsula mafic rocks and greywackes

Three-dimensional velocity models for the basins along the coast of Washington and in Puget Lowland provide a means for better understanding the lateral variations in strong ground motions recorded there. We have compiled 16 sonic and 18 density logs from 22 oil test wells to help us determine the geometry and physical properties of the Cenozoic basins along coastal Washington. The depth ranges sampled by the test-well logs fall between 0.3 and 2.1 km. These well logs sample Quaternary to middle Eocene sedimentary rocks of the Quinault Formation, Montesano Formation, and Hoh rock assemblage. Most (18 or 82%) of the wells are from Grays Harbor County, and many of these are from the Ocean City area. These Grays Harbor County wells sample the Quinault Formation, Montesano Formation, and frequently bottom in the Hoh rock assemblage. These wells show that the sonic velocity and density normally increase significantly across the contacts between the Quinault or the Montesano Formations and the Hoh rock assemblage. Reflection coefficients calculated for vertically traveling compressional waves from the average velocities and densities for these units suggest that the top of the Hoh rock assemblage is a strong reflector of downward-propagating seismic waves: these reflection coefficients lie between 11 and 20%. Thus, this boundary may reflect seismic energy upward and trap a substantial portion of the seismic energy generated by future earthquakes within the Miocene and younger sedimentary basins found along the Washington coast. Three wells from Jefferson County provide data for the Hoh rock assemblage for the entire length of the logs. One well (Eastern Petroleum Sniffer Forks #1), from the Forks area in Clallam County, also exclusively samples the Hoh rock assemblage. This report presents the locations, elevations, depths, stratigraphic, and other information for all the oil test wells, and provides plots showing the density and sonic velocities as a function of depth for each well log. We also present two-way traveltimes for 15 of the wells calculated from the sonic velocities. Average velocities and densities for the wells having both logs can be reasonably well related using a modified Gardner’s rule, with p=1825v(1/4), where p is the density (in kg/m3) and v is the sonic velocity (in km/s). In contrast, a similar analysis of published well logs from Puget Lowland is best matched by a Gardner’s rule of p=1730v(1/4), close to the p=1740v(1/4) proposed by Gardner et al. (1974). Finally, we present laboratory measurements of compressional-wave velocity, shear-wave velocity, and density for 11 greywackes and 29 mafic rocks from the Olympic Peninsula and Puget Lowland. These units have significance for earthquake-hazard investigations in Puget Lowland as they dip eastward beneath the Lowland, forming the “bedrock” beneath much of the lowland. Average Vp/Vs ratios for the mafic rocks, mainly Crescent Formation volcanics, lie between 1.81 and 1.86. Average Vp/Vs ratios for the greywackes from the accretionary core complex in the Olympic Peninsula show greater scatter but lie between 1.77 and 1.88. Both the Olympic Peninsula mafic rocks and greywackes have lower shear-wave velocities than would be expected for a Poisson solid (Vp/Vs=1.732). Although the P-wave velocities and densities in the greywackes can be related by a Gardner’s rule of p=1720v(1/4), close to the p=1740v(1/4) proposed by Gardner et al. (1974), the velocities and densities of the mafic rocks are best related by a Gardner’s rule of p=1840v(1/4). Thus, the density/velocity relations are similar for the Puget Lowland well logs and greywackes from the Olympic Peninsula. Density/velocity relations are similar for the Washington coastal well logs and mafic rocks from the Olympic Peninsula, but differ from those of the Puget Lowland well logs and greywackes from the Olympic Peninsula.

Washington↗

USGS2022

Hydrology, water quality, and biological characteristics of Levittown Lake, Toa Baja, Puerto Rico, April 2010–June 2011

Levittown Lake is a 30-hectare, brackish waterbody located in the municipality of Toa Baja, on the northern coast of Puerto Rico. The lake is a small, man-made feature formed by draining the marshland over which the Levittown community was built. Levittown Lake has an average depth of about 5 meters and a water level at/near mean sea level. Tidal oscillations within the lake were minimal during the study, about 10 centimeters regardless of ocean tides, and the daily flushing rate of the lake was about 2 percent of its entire water volume. Hydrologic, water-quality, and biological data were collected in Levittown Lake and adjacent areas (specifically, the inlet/outlet channel and Caño El Hato drainage canal) between April 2010 and June 2011 (1) to establish baseline conditions and determine the water quality of the lake on the basis of preestablished standards and (2) for contrast with other, more healthy coastal lagoons. The study provides a baseline for an assessment of the potential of Levittown Lake to function as a coastal lagoon. Water-quality properties measured onsite (temperature, pH, dissolved oxygen concentration, specific conductance, salinity, and water transparency) varied diurnally and seasonally. In general, water-quality properties were in compliance with current regulatory Class SB standards established by the Puerto Rico Environmental Quality Board, except for some dissolved oxygen concentration and pH measurements. Some dissolved oxygen concentration measurements at the water surface and all dissolved oxygen concentration measurements at the lake bottom were lower than the values recommended by the Puerto Rico Environmental Quality Board. The pH of the water at the lake surface ranged from 7.3 to 9.1, with the upper value exceeding the recommended pH values. Nutrient concentrations were below the current regulatory standards of less than 5 milligrams per liter (mg/L) for total nitrogen and 1 mg/L for total phosphorus. The measured concentrations of chlorophyll a varied throughout the year of sampling and indicate that eutrophic conditions predominate in Levittown Lake. The phytoplankton yielded an average net productivity of 0.5 milligram of oxygen per liter per hour, as determined by light and dark bottle primary productivity studies conducted on a monthly basis and measured in the early morning hours. Because these measurements were restricted to the morning hours, a qualification of the representativeness of the results to the full diurnal cycle is necessary. The measured hourly respiration rate averaged 0.39 milligram of oxygen per liter. Diel studies were planned in the lake to assess dissolved oxygen concentration diurnal curves and ultimately to compute the community net primary productivity, respiration, and gross productivity. Conditions during the diel studies were later determined to be unsuitable, limiting the assessment of community metabolism. Another biological indicator evaluated during the study was the phytoplankton biomass, and results indicated that phytoplankton biomass measured at the Levittown Lake ranged from 6.0 to 112.5 mg/L. Fecal indicator bacteria concentrations ranged from 10 to 1,540,000 colonies per 100 milliliters of water. Concentrations generally were greatest in and near the Caño El Hato drainage canal and, during the study, exceeded current regulatory standards established for Puerto Rico.

Puerto Rico↗