Science Seminar Series Archives

Science Center Objects

A list of past science seminars hosted by the Pacific Coastal and Marine Science Center, Santa Cruz, California

Please see our upcoming seminar schedule.


Tuesday, September 21, 2021, 10:00 a.m. PDT

Derek Sawyer, Ohio State University

Impacts of earthquake shaking on seafloor sediment stability and landslide hazards

Join seminar via Microsoft Teams

Two graphs, one showing curves with bars and one showing scatter plots.

Abstract: Earthquakes are a primary trigger of submarine landslides yet some of the most seismically active areas on Earth show a surprisingly low frequency of submarine landslides. Our recent work has explored this apparent paradox using shear strength measurements from 50 years of scientific ocean drilling over the world’s oceans. We find that within the uppermost 100 meters below seafloor sediment, active margins have elevated shear strength by a factor of 2-3 relative to the same interval on passive margins. The elevated shear strength is seen in a global survey of undrained shear strength with depth, as well as a normalized analysis that accounts for lithological and effective stress differences. The mechanisms that lead to the strengthening are not fully clear but is consistent with the seismic strengthening hypothesis: repeated exposure to earthquake energy over time gradually increases shear strength by shear-induced compaction. These results indicate that large areas of modern-day slopes on earthquake-prone margins have enhanced slope stability. This may help explain the relative paucity of landslides observed on active margins, especially those typified by relatively low sedimentation rates and hydrostatic pore pressure conditions. However, a different result is observed in a high-sedimentation rate and high-seismicity setting such as the southern Alaskan offshore margin where extreme sedimentation rates from glacially enhanced mountain erosion constructs the large Surveyor Fan. Shear strength measurements acquired by Integrated Ocean Drilling Program Expedition 341 on the continental slope and Surveyor Fan reveal lower-than-expected sediment strength. We interpret that high sedimentation rates and fluid overpressure within the slope and Surveyor Fan offset potential strength gains from seismic shaking. This is supported because shear strength follows an active margin profile outside of the fan, where slower background sedimentation rates occur. Finally, we are extending our research through a recent NSF CAREER grant to understand the relative influence of earthquake shaking, sedimentation rate, and sediment lithology on overall slope stability. We will use a combination of field observations from 3 active margins sites with geophysical data and cores, controlled dynamic shaking laboratory experiments, and numerical simulations. The field sites span 2 primary types of active margins (convergent megathrust subduction zones (Cascadia and Japan Trench) and strike-slip (Queen Charlotte Fault Margin). Controlled laboratory experiments will be performed using state-of-the-art dynamic shear experiments on samples from each field site to clarify relationships between seismic shaking, sediment physical properties, shear strength response over a range of materials and shaking intensities. To understand more complex behavior in multiple dimensions within heterogeneous margin stratigraphy, numerical models will quantify depth limits (vertical effective stress) where sediments are no longer subjected to seismic strengthening, how seismic strengthening varies between different active margins with differing lithologies, sedimentation rates, and earthquake histories.


Three photos show smoke from a fire in the mountains, a murky river flooding a park, and a beach with sand and cliffs.

Tuesday, September 7, 2021 10:00am PDT

Jonathan Warrick, USGS Pacific Coastal and Marine Science Center

Fire + Flood = Beach: Shoreline response to an exceptional river sediment discharge event



Tuesday, August 10, 2021 10:00am PDT

Coastal Change Hazards Seminar
by Li Erikson and Ann Gibbs, USGS Pacific Coastal and Marine Science Center

Coastal bluff and barrier island morphodynamics and implications on infrastructure and bird habitats along a remote arctic coastal section

View looks at an angle along a coastline, image shows features such as beach bluff, buildings, and cars.

Barter Island lidar

Abstract: The permafrost bluffed coastline of Barter Island and nearby barrier islands have retreated hundreds of meters over the last 70-years and rates of change have seemingly accelerated over the past two decades. Processes driving the changes can be fundamentally reduced mechanical and thermal actions; shorelines anchored by permafrost-rich substrates, and those influenced by the presence of sea-ice, are highly vulnerable to the effects of climate change. Indications are that the observed increases in the duration of the ice-free season, air and ocean temperatures, thawing permafrost, and wave intensity and frequency in Alaska over the past decades will continue. In this presentation, we will summarize observed morphodynamics, discuss how trends in mechanical and thermal forcing agents have likely modulated the observed changes, and address the consequences these changes may impart on the local community and habitat in the future.


Tuesday, August 3, 2021 10:00am PDT

Sean Vitousek, USGS Pacific Coastal and Marine Science Center

Satellites enable national-scale predictions of coastal change

View from the sky looking down on a coastal town with a sandy beach and buildings.

Abstract: Scientists at the U.S. Geological Survey and elsewhere increasingly rely on computer modeling to help understand and predict large-scale, long-term coastal change. However, achieving accurate modeling predictions requires thorough and thoughtful integration with observational data to calibrate and validate models. Unfortunately, field observations of coastal change are often spatiotemporally sparse, since data-collection efforts are often limited to a handful of local monitoring sites. Satellites promise to dramatically increase the spatiotemporal resolution of observational data, enabling robust predictions of coastal change like never before. Here we present a coastal change modeling application (using the CoSMoS-COAST model – Vitousek et al., 2017, 2021) to the entire 1,350 km coastline of California. The model is assimilated with satellite-derived shoreline observations from the CoastSat toolbox (Vos et al., 2019). We demonstrate that Satellite observations show excellent agreement with traditional GPS surveys, when corrections for tide and wave setup are applied. We show that the model demonstrates good agreement with 5 years of validation data (achieving a median RMS error of ~10 m in the forecasted shoreline position across California). Finally, we contend that the combination of data-integrated coastal change models with satellite observations represents the basis for national-scale predictions of coastal change, and we suggest steps for realizing this EarthMAP-like system.


Illustration looking at an angle along a section of coastline to show the underground features along an active fault zone.

Tuesday, July 20, 2021 10:00am PDT

Jenna Hill, USGS Pacific Coastal and Marine Science Center

Submarine Canyons, Slope Stability, and Earthquake History along the Cascadia Subduction Zone 






Tuesday, July 6, 2021 10:00am PDT

Kyle Hardage, UC Santa Cruz

Regional scale climate influence on Late Holocene geomorphology and paleosalinity of Celestún Lagoon, Yucatán, Mexico

A photo from the sky of a coastal area with puffy clouds over the land.

Celestún in the Yucatán Peninsula of Mexico.

Abstract: Epikarst estuary response to hydroclimate change remains poorly understood despite the well-studied link between climate and karst groundwater aquifers. The influence of sea-level rise and coastal geomorphic change on these estuaries obscures climate signals, thus requiring careful development of paleoenvironmental history to interpret the paleoclimate archive. This talk presents a multi-proxy approach to develop the last 5,000 years of environmental history of Celestún Lagoon, the largest groundwater-fed estuary in the Yucatán Peninsula of Mexico. The estuary receives groundwater water through fractures from the Chicxulub Crater and Ticul Fault Zone, representing a catchment area of about 40% of the peninsula and a potentially a regionally integrated record of paleo-precipitation. Sediment core samples of foraminifera assemblages, δ13C and C:N ratios of organic matter suggest that Celestún Lagoon developed from an inland mangrove pond (5300 BP) to a shallow coastline with marine seagrass and barrier island initiation (4900 BP), followed by a protected brackish lagoon (3000 BP) and finally a protected mangrove lagoon (1700 BP). These changes were driven by barrier island geomorphic evolution and expansion. Superimposed on this geomorphic signal are regional wet and dry climatic episodes indicated by isotopes (δ18O, 87Sr/86Sr) and trace metals ( Sr, Ba) incorporated into benthic foraminifera Ammonia parkinsoniana. Paleosalinity change from 33 at 4,400 BP to 21 at present reflects barrier island restriction of sweater mixing into the lagoon, but detrending paleosalinity reveals salinity oscillations of ±4 units contemporaneous with North Atlantic Bond Events and southward shift of tropical moisture. Paleosalinity peaks temporally match known drought events at 3,500 BP, 2,400 BP and 1,300 suggesting that these events were peninsula-wide, impacting the regional groundwater table that sources spring discharge to the field site and potentially coastal rates of deposition. Yucatán coastal lagoon sediments provide paleoclimatology and paleoceanography records that link regionally integrated rainfall to large-scale atmospheric perturbations, but coastal geomorphic evolution must be known to extract the climatic signal. 


Tuesday, June 15, 2021 10:00am PDT

Rip Hale, Old Dominion University

Assessing the importance of sediment supply in southern Bangladesh

Long skiffs sit at the muddy edge of the water with a low coastal bluff with houses in the background.

Abstract: The Sundarbans National Forest (SNF), located on the modern topset of the Ganges-Brahmaputra-Meghna (GBM) Delta, is the world’s largest mangrove stand (~10,000 km2), and provides a wide range of cultural, environmental, and economic benefits to the nation of Bangladesh. At present, sediment accretion in the SNF occurs at a rate comparable to that of the locally accelerated relative sea-level rise (~1.1 cm/yr), despite substantial modification of the regional sediment dynamics resulting from the construction of channel embankments. As ~50% of the sediment deposited in the SNF each year is recently delivered (<6 mos) from the GBM rivers, the threat of a reduction in sediment supply as a result of water and sediment diversions associated with India’s National River Linking Project raises concerns over the SNF’s continued sustainability. In this talk, we will examine: 1) how rates of sediment transport vary both spatially and seasonally in this tidally forced, monsoon impacted system, 2) the hydrodynamic conditions responsible for delivering sediment to the mangrove platform, where it accretes at a rate comparable to local effective sea-level rise. Using in situ measurements of water velocity and suspended sediment concentration, we document how transport conditions change with across a variety of spatial scales.  These observations are then compared to an existing dataset of platform deposition rates, allowing us to project impacts associated with a reduction in the sediment supplied to this region.


Tuesday, June 8, 2021 10:00 PDT

Coastal Change Hazards Seminar

Remote Sensing Coastal Change - Sound-side inundation of a barrier island: rapid response, modeling, and long-term implications

Presented by USGS Scientists Chris Sherwood, Christie Hegermiller, Jin-Si Over, Alfredo Aretxabaleta, Andy Ritchie, Christine Kranenburg, Jon Warrick, Jenna Brown, Phillipe Wernette, Dan Buscombe, and Sara Ziegler


Tuesday, June 1, 2021 10:00am PDT

Jonathan Nye, University of California, Riverside Department of Earth Sciences

Ecological Crisis in the Salton Sea

Read the preprint: “Crisis at the Salton Sea: Research Gaps and Opportunities,” submitted to EarthArXiv
by Marilyn Fogel, Hoori Ajami, Emma Aronson, Roya Bahreini, Wilfred Elders, Darrel Jenerette, David Lo, Timothy Lyons, Michael McKibben, William Porter, Arun Raju, Kurt Schwabe, Caroline Hung, and Jonathan Nye

Photograph looking out across a calm lake with a fairly dried-up edge.

Abstract: The dynamic and unstable Salton Sea supports abundant wildlife ranging from a diverse array of microorganisms to endangered species of fish and birds. Terrestrial desert ecosystems give way to agricultural fields, riparian zones, natural and managed wetlands, and the aquatic ecosystems of the lake itself, supported by water and nutrients derived largely from agricultural inputs. Agricultural practices in the region encourage microbial production of greenhouse gases, lower air quality and result in excessive nutrient flows into the Salton Sea. This overabundance of nutrients entering the sea creates an imbalance of algal production resulting in Harmful Algal Blooms and anoxia, threatening wildlife and humans. Rising salinity, temperatures, and declining water levels may disrupt migration patterns for fish eating birds potentially leading to a catastrophic collapse of the aquatic food web. The endangered desert pupfish populations on the margins of the Salton Sea are at risk of becoming isolated, putting them at increased risk of extinction. While wetland habitat restoration may benefit certain species of birds, current plans to restore the sea do not address the core problems limiting ecosystem functioning. Without continued significant freshwater introduction to the Salton Sea, the ecosystem faces collapse due to excessive nutrients, rising salinity, and declining water levels, likely resulting in undesirable outcomes for recreational activities, the regional economy, and public health.


Tuesday, May 18, 2021 10:00am PDT

Benjamin K Norris, PCMSC

Small-scale Turbulence and its Influence on Forest-scale Morphodynamics within a Coastal Mangrove Forest

A swampy area with lots of trees and other plants that are standing in water.

Mangrove forest at high tide, on the southern edge of the island of Cù Lao Dung and situated in the lower Mekong Delta, Vietnam. Credit: Benjamin K Norris, USGS Pacific Coastal and Marine Science Center

Abstract: Growing in the interface between the coastal ocean and land, mangroves form a barrier to hazards such as wave attack, coastal flooding and erosion for many densely-populated areas that often lack hard coastal defense structures. By damping tidal currents and waves, mangroves also facilitate sedimentation, and may contribute to coastal stability in the face of rising sea levels. These valuable ecosystem services are the result of characteristic bio-physical feedbacks between the mangrove vegetation, hydrodynamics and sediment dynamics within intertidal zone. 

Here, the link between mangrove root density and turbulent dissipation was explored in a coastal mangrove forest that is exposed to a dynamic wave environment and tidal forcing. Measurements of turbulent kinetic energy (TKE) dissipation were collected at millimeter scales within clusters of mangrove pneumatophore roots (‘canopies’) spanning the unvegetated mudflat to the densely vegetated forest. High-resolution root geometries were reconstructed using a newly developed photogrammetric method and were compared with turbulence measurements. Across the forest, turbulence was positively correlated with root density and wave height and was negatively correlated with water depth. At small (1 m2) scales, high near-bed turbulence was the result of Von Kármán vortices shedding off upstream roots, and enhanced turbulence above the canopy was associated with velocity shear. Across small (1 m2) and forest scales, measurements demonstrated that the spatial variability in vegetation density was also a control on sediment transport. Waves were dissipated by the vegetation as they propagated landward, but dissipation at infragravity periods (> 30 s) was observed to be less than dissipation at shorter periods (< 30 s). Consequently, infragravity-frequency fluctuations in the bed level adjacent to the mangrove roots suggest that infragravity waves may help drive sediment transport in mangroves.


Tuesday, May 4, 2021 10:00am PDT

Maureen Walton, PCMSC

Massive pockmark fields, mysterious sand, and ancient faults: Characterizing geohazards offshore of central California

An illustration of the seafloor showing features like small and large pits.

Abstract: The California Deepwater Investigations and Groundtruthing (Cal DIG) I project focuses on the potential seafloor hazards and impacts of alternative energy infrastructure (i.e., floating wind turbines) in the outer continental shelf region offshore of south-central California. To investigate seabed stability and geohazards, comprehensive high-resolution sub-bottom (multi-channel and Chirp seismic reflection profiles), seafloor (bathymetry), and sampling (piston, gravity, and vibracore) data were collected in 2018-2019 during a series of seven seagoing geological and geophysical surveys. Specific targets of geohazard interest in the study area are geological structures such as faults and folds, seafloor pockmarks within a large field (the Big Sur pockmark field), submarine channels, and mass wasting (slope failure) features.

The vast majority of faults and other structures in the study occur within sediment and rock formations we interpret to be pre-Quaternary (older than 2.58 Myr BP), and thus we interpret that these structures are unlikely to present significant current hazard to seabed infrastructure, although we note that the numerous structures mapped in the study area may have the potential to become reactivated. Similarly, we find no new evidence of Holocene (younger than 11,650 years BP) fluid or gas advection in the Big Sur pockmark field. However, such fluid and gas hazards are currently difficult to assess, as additional analyses and sampling of existing core data is needed to better understand pockmark formation processes and potential gas accumulations we have mapped in the subsurface. Mass wasting along the eastern and western edges of the Santa Lucia Bank during earthquakes, as well as sediment transport down the Lucia Chica and San Simeon channels, are among the most significant, although still likely infrequent during the Holocene, hazards to seabed stability in the study area. Further analyses of the existing cores, including radiocarbon dating, stable isotope, and compositional analyses, are again needed to better understand the timing and sources of the numerous sand deposits found throughout the study area, which may have been transported downslope due to mass wasting and/or earthquake shaking processes.


Tuesday, April 20, 2021 10:00am PDT

Daniel Buscombe, PCMSC

Improved SfM reconstruction of coastal barrier islands using Machine Learning-based image segmentation

Two images show the same cliff region, one has fewer data points by eliminating the frothy beach waves.

Perspective view of large SfM point cloud of region of Fort Funston, CA, with and without automated data cleaning (masking). The cleaned data has 50% fewer points.

Abstract: As part of the Remote Sensing of Coastal Change and Florence Supplemental projects we have been developing novel workflows for repeat-mapping of ­­­coastal environments at order decimeter resolution over up to hundreds of kilometers in a single day, using Structure-from-Motion photogrammetry or SfM, from crewed aerial platforms. Typically, up to tens of thousands of aerial images collected per flight are used to create accurate digital elevation models (DEMs) and orthomosaics of a large region of coast. Regular repeat image acquisition at this scale and resolution captures coastal change due to storms, which can be both highly spatially variable, and manifest in subtle net topographic and morphological changes.

However, the computational demands of digital terrain reconstruction at such high resolution and large coverage are significant, and products require time-consuming manual editing to remove obviously erroneous data. Specifically, there are two outstanding issues with established SfM workflows. The first is that water does not reconstruct, therefore SfM pipelines spend too much time on a futile task and create erroneous outputs that must be manually removed afterwards. The workaround is to provide a bitmap for each input image, or ‘watermask’, in which water pixels are coded zero and land pixels are coded one, but manual creation of such masks are prohibitively time-consuming. In this talk, I will describe how we are using Machine Learning (ML) based image segmentation to automatically generate watermasks for each image used in an SfM pipeline, resulting in reduced reconstruction time and increased accuracy. The second issue is that output DEMs and orthomosaics contain other types of noise due to imperfect photogrammetric modeling that also must be manually removed, which is subjective and time-consuming. In this talk, I will describe how we are using ML to automatically flag and remove noise, however defined, from DEM and orthomosaic products. I will discuss the accuracy/time tradeoffs between masking inputs, masking outputs, and masking both.

I will illustrate this workflow using the post-Hurricane Florence aerial survey. This case study could be helpful to those developing similar systems for automated filtering and quality control of large datasets. The systems described here have involved the development of custom software for semi-automated creation of labeled data, model training and evaluation, and model deployment for automated prediction. This software could be repurposed for almost any automated image segmentation task.

An illustration of a coastal cliff looking from the sky at an angle.

without masking

An illustration of a coastal cliff looking from the sky at an angle.

with masking


Tuesday, March 16, 2021 10:00am PDT

Amy East, PCMSC

View looks across a steep, grassy hill at some trees on another hill, mountains in the distance with fog and the sun setting.

View from Hurricane Ridge in Olympic National Park, Washington, looking at the Elwha River basin. Credit: Amy East

Geomorphic and sedimentary effects of modern climate change in western U.S. landscapes: how much do we know?

Abstract: Climatic changes associated with global warming over the past 50 years have been documented widely, but physical landscape responses are poorly understood. Detecting landscape signals of modern climate change is difficult for many reasons, but is important because these problems relate closely to human health and safety, infrastructure, water security, and ecosystems. We reviewed the scientific literature to investigate landscape responses to modern climate change in the western United States, focusing on slope failures, watershed sediment yield, river morphology, and wind-blown sediment activity. Some changes to slope stability and wind-blown sediment are evident, whereas factors other than climate have been more important thus far in controlling sediment output and river morphology. We identify ways in which more information is needed from many more places, in the western U.S. and globally, to understand landscape response to ongoing climate change.


Tuesday, February 23, 2021, 10AM PST

Curt Storlazzi, PCMSC

A New Hope: Coastal Ecosystem Restoration to Protect Coasts (with insights from coral reefs)

Underwater image of wave breaking over a coral reef

Credit: Curt Storlazzi, USGS

Abstract: Tropical storms represent the most common and costliest natural disasters across the globe. As storm costs mount, communities are increasingly looking for effective measures to protect low-lying coastal communities that do not cause negative environmental impacts and that can contribute to coastal sustainability. Ecosystems such as reefs, beaches, dunes, and wetlands provide an effective first line of defense against these hazards and represent a promising option to adapt to the increasing climate impacts. However, these protection services are disappearing as ecosystems continue to be lost at alarming rates globally, both from natural and human pressures. Multilateral agencies (e.g., the World Bank), the US government (e.g., FEMA and USACE), and the insurance industry increasingly acknowledge the role of ecosystems in reducing losses and risk, but alignment of hazard mitigation and environmental management is still widely lacking. 

Risk reduction (e.g., pre-disaster mitigation and post-disaster restoration) funds could support ecosystem management goals if the natural coastal protection benefits were valued using rigorous approaches required by risk managers. The development of risk-based valuations of ecosystem-based flood protection has been limited by the lack of high-resolution data on bathymetry, topography, ecosystems, and economic assets, and the difficulty in modeling complex hydrodynamic processes across large regions. However, recent advances now make it possible to quantify and directly assess flood losses and the benefits of coastal ecosystems for reducing them with unprecedented rigor and spatial definition. These results can help identify areas where ecosystem management, recovery, and restoration reduce the risk to, and increase the resiliency of, the US’s coastal communities. Here, using US coral reefs as an example, we demonstrate the role of coastal ecosystems in hazard risk reduction, describe how USGS Coastal Change Hazards science can meet decision-makers needs, how that can open-up new financing options, and the next steps we are undertaking to address both the science gaps and our partner agencies’ needs.

A narrow waterway, in a wet, marshy area with brown grasses, winds its way to a larger body of water, hills in the background.

China Camp Marsh by Jessie Lacy.



Tuesday, February 9th, 2021, 10 AM PST

Jessie Lacy, PCMSC

Sediment delivery across the bay-marsh interface of an estuarine salt marsh

Coastal Change Hazards Seminar hosted by PCMSC


Photograph looking across a large body of calm water surrounded by mountains with a glacier and snow-capped peaks in distance.



Tuesday, January 26th, 2021, 10 AM PST

Drake Singleton, PCMSC

Calibrating Alaska’s natural seismograph: preliminary results of the sedimentary response to the 2018 Anchorage Earthquake in lakes and fjords of south-central Alaska






Thursday, February 13th, 2020, 2:00 PM

Dr. Tawny M. Mata and Dr. John Largier

UC Davis Coastal & Marine Sciences Institute

View from the sky of a coastal area with beaches, rocky shorelines, and a building complex on a peninsula.

UC Davis Coastal and Marine Sciences Institute: Catalyzing innovation and partnerships in research, education and engagement

Abstract: Established in 2013, the Coastal and Marine Sciences Institute at UC Davis brings together the university’s vast intellectual resources in coastal and marine sciences and policy: 100+ faculty and staff and 150+ graduate students and postdocs across six major academic units, ranging from the College of Biological Sciences to the School of Law. The Bodega Marine Laboratory (BML) anchors CMSI and allows our reach to extend from the capitol to the coast. Our goals are to 1) transform scientific understanding of coastal and marine systems; 2) educate and inspire future leaders and 3) engage stakeholders, colleagues and policymakers. We have already developed several novel partnerships that help us achieve our goals and are interested in how we can work more closely with USGS.


A person wearing a backpack walks across rocks in a rocky hilly area.

Tuesday, February 4th, 2020, 2:00 PM

Nora Nieminski

USGS Pacific Coastal and Marine Science Center

Investigations of a Neoproterozoic Ocean Basin and Implication for the Assembly of Gondwana: Stratigraphic Architecture, Provenance, and Tectonic Setting of the Zerrissene Group, Namibia





Evolutions in distributed ocean sensing

Tuesday, January 21st, 2020, 10:00 AM

Tim Janssen

Sofar Ocean

Evolutions in distributed ocean sensing

Questions that will be answered in the talk:

  • How might we get more ocean data?
  • How might we get data into models more effectively?
  • How might we more effectively disseminate ocean data and insights?


View looks out across a verdant marsh with a sinuous water channel running through it, a large body of water in background.

Friday, November 22nd, 2019, 2:00 PM

Jessie Lacy

USGS Pacific Coastal and Marine Science Center

Sediment delivery across the bay-marsh interface of an estuarine salt marsh





Tuesday, October 1st, 2019, 1:00 PM

Miya Pavlock McAuliffe

Moss Landing Marine Labs

Video observations of shoreline and sandbar at a wave dominated barred beach: northern Monterey Bay, California

A pole has two shaded cameras mounted on it and they are pointing at a beach from high up on a grassy bluff.

Abstract: This contribution presents results from a study of shoreline and sandbar evolution over nearly two years at Sunset State Beach, a sandy barred beach in the northern Monterey Bay of Central California. Shoreline and sandbar positions were extracted from rectified time exposure image mosaics derived from a dual camera Argus station. This micro-mesotidal sandy beach shows a strong seasonal signal and evidence of wave driven shoreline erosion and recovery within the 600m alongshore study area. The relatively calm winter of 2017-2018 corresponded with rapid shoreline erosion in early January after a peak in wave energy, followed by gradual accretion and stability with lower energy conditions. The relatively high energy winter of 2018-2019 resulted in rapid erosion followed by delayed accretion, with a larger range in shoreline position than the previous year. The sandbar followed expected seasonal trends, migrating seaward in the winter and landward in the summer. However, the sandbar appears to be more sensitive to small changes in wave conditions and possibly buffers the shoreline from smaller wave events. Sunset State Beach exhibits an equilibrium shoreline response: the shoreline erodes further landward under higher energy conditions and accretes further seaward during lower energy conditions. This study provides further understanding of the relationships between waves, shoreline, and sandbar using an automated data collection system yielding a dataset with temporal resolution difficult to obtain using traditional survey methods. 


Wednesday, August 21, 2019, 2:00 PM

Julia Moriarty

USGS Woods Hole Coastal and Marine Science Center

Marsh-Edge Erosion and Estuarine Transport Affect SEdiment Availability in Back-Barrier Marshes

The edge of a marsh is getting hit with waves and some kind of wooden structure that extends into the water has been damaged.

Abstract: Sediment availability affects the extent to which marshes laterally retreat and vertically accrete. This study uses a numerical modeling approach (COAWST) to analyze the role of marsh-edge erosion (lateral retreat) and estuarine hydrodynamics on sediment fluxes to and from marshes in a back-barrier estuary, Barnegat Bay, New Jersey. Preliminary results indicate that:

  1. marsh-edge erosion is highest near barrier island inlets;
  2. most eroded sediment remains near the marsh; and
  3. deposition on the marsh platform was highest near turbid estuarine channels.


Monday, July 8, 2019, 2:00 PM

Sam Johnson

USGS Pacific Coastal and Marine Science Center

Controls on Sediment Distribution in State Waters of the Central California Transform Continental Margin

Map of central California with tectonic fault lines and names and gradients to show offshore sediment distribution.


Nine photos of different beaches arranged in a grid of 3 rows and 3 columns, to show how waves affect them differently.

Monday, June 10, 2019, 11:30 AM

Ana Vila-Concejo

University of Sydney, Australia

and Shari L. Gallop

University of Waikato, New Zealand

What happens when sandy beaches are not just driven by ocean waves?


Most beach studies and models used for coastal management are based on research undertaken on sandy, open ocean beaches. However, many beaches lay outside this setting. This seminar focuses on the morphodynamics of beaches that are not long open-ocean beaches. Our seminar is divided in 3 parts:

  1. Embayed beaches: The important influence of headlands on beaches is well known but the processes are not
    well-understood. Headlands are important biodiversity areas, and ecosystem restoration is being undertaken (e.g., of crayweed). Here we present a new generalised embayment parameter which classifies embayed beaches based on their inundation and area, which has implications for beach processes and stability.

  2. Beaches in estuaries and bays: they can be small and vulnerable, yet provide a range of ecosystem services. They provide an important horizontal levee for other areas and can be affected by eco-engineering interventions such as oyster restoration or living seawalls. We show that these beaches are not just downscaled versions of open-ocean beaches, and we aim to establish the wave energy that they need to exist. We provide an example with a case study from Sydney.

  3. Current and future directions: We will discuss how this project is an international effort and will talk about
    work we are doing on our visit to California in collaboration with Prof. John Largier at UC Davis, including how our research on estuarine and bay beaches links with eco-engineering interventions such as oyster restoration and living seawalls. We will talk about future plans, and are keen to facilitate discussions.


Tuesday, May 21st, 2019, 1:00 PM

Lauren Toth

Two underwater divers wearing wet suits and oxygen tanks with an apparatus that is drilling into the seafloor.

USGS St. Petersburg Coastal and Marine Science Center

Geological perspectives on the degradation and restoration of Florida’s coral reefs

Over thousands of years, corals build complex geological structures that serve as the foundations for a myriad of critical ecosystem services. Ensuring that both ecological and geological reef functions are maintained is, therefore, critical to designing effective coral-reef management and restoration programs. Using the record of coral-reef development captured in reef cores collected throughout the Florida Keys reef tract, Lauren’s work provides a geological perspective on the management of Florida’s coral reefs with respect to processes like carbonate production and reef accretion. This talk will describe the Holocene history of coral-reef development in the region, the modern state of reefs with respect reef growth, and insights for optimizing future coral-reef restoration.


Wednesday, May 22nd, 2019, 2:00 PM 

Stuart Pearson

Delft University of Technology

Sediment Transport Processes and Pathways at Ameland Inlet

View looks down at a river outlet from the sky to illustrate various components of sediment transport.

Abstract: Which pathways does sediment follow at tidal inlets and on ebb-tidal deltas?  Quantifying these pathways is essential for estimating regional sediment budgets and answering key coastal management questions.  How will the coast respond to climate change or human interventions like dredging and nourishments?  These are especially pressing concerns for the Netherlands, where the country’s safety from flooding is directly dependent on the volume of sediment in its coastal system.

To improve our knowledge of sediment transport at tidal inlets and provide concrete guidance to the Dutch government about nourishment strategies in such environments, we conducted a field measurement campaign at Ameland Inlet, located in the Dutch Wadden Sea.  I will present a brief overview of our findings so far, and indicate future directions for our research.  We conducted a sediment tracer study on the ebb-tidal delta using fluorescent/magnetic sand, which has yielded insight into grain size sorting and dispersal.  We also measured particles in suspension on the ebb-tidal delta, and identified two distinct populations of suspended sediment. Estuarine fronts are persistent and ubiquitous in Ameland Inlet, and suggest a relationship between wind and density-driven flows. Lastly, we define a framework for quantifying sediment transport pathways in coastal environments, using the concept of “connectivity” as successfully applied in other disciplines. In the coming three months at USGS, I will be investigating sediment pathways at the mouth of the Columbia River.  We aim to apply this coastal sediment connectivity framework there, and to make a comparison with Ameland Inlet.


Two round, colored logos to signify the national oceanic and atmospheric administration and its coral reef conservation program.

Thursday, April 11th, 2019, 12:00 pm

Jennifer Koss

NOAA Coral Reef Conservation Program Director

20 Years of Coral Reef Conservation Conducted from the 10th Floor of a Federal Office in Washington, D.C.: How has NOAA approached coral reef conservation through changing administrations and ever-worsening conditions?

Questions that will be answered in the talk:

a.     How has coral reef conservation evolved over the past 20 years?
b.     Typhoons, Disease, Hot and Sour Soup -- Just how bad is it for coral reefs right now?
c.     What are some of the potential game changers in coral reef conservation happening right now?


Wednesday, April 10th, 2019, 2:00 pm

Alan Nelson

USGS Geologic Hazards Science Center

Searching for fossil subduction-zone earthquakes and tsunamis at 56°N and 44°S: A tale of two islands


The most direct, if not the cleverest, way to improve forecasts of the greatest earthquakes and highest tsunamis at subduction zones is to learn the history of the greatest events over the past few thousands of years. But finding sites with identifiable evidence of great earthquakes and tsunamis that can be dated is a tricky business—both scientifically and logistically. One might expect to find the most easily identified evidence of coseismic land-level changes and tsunamis nearest the megathrust plate boundary, where coseismic upper-plate deformation is greatest. At most subduction zones, the closest sites are on unusual islands near the edge of the continental shelf, but getting to and working at such sites brings special challenges not commonly encountered in paleoseismic studies.

Expeditions to two such islands—Chirikof Island near the Alaska-Aleutian megathrust west of Kodiak Island, and Isla Gaufo in south-central Chile southwest of Chiloe Island—offered contrasts in types of evidence and logistics. During our reconnaissance visit to Chirikof Island we found the first evidence of many tsunamis over many thousands of years along the Alaska-Aleutian megathrust. On Isla Gaufo continuing studies of dramatic historical and prehistoric land-level changes accompanied by high tsunamis add depth to the rapidly developing earthquake and tsunami history of southern Chile. The Gaufo data also constrain models of upper-plate deformation in this region at several scales.

Two photographs side-by-side, on left is a beach with arrows and words superimposed, on right is a river bank with people.


A man wearing a floatation vest and mud boots walks though a very muddy marsh area carrying a bag, while a jumbo jet flies over.

Tuesday, April 2nd, 2019, 2:00 pm

Neil Ganju

USGS Woods Hole Coastal and Marine Science Center

Marshes are the new beaches: integrating sediment transport into restoration planning


Recent coastal storms and associated recovery efforts have led to increased investment in salt marsh restoration due to their coastal protection benefits. Millions of dollars have been allocated or spent because of their perceived sustainability and ecologically positive co-benefits including habitat provision and carbon sequestration. However, these projects are often planned without full consideration of the sediment transport processes that control their sustainability. I contend that before significant investments are made in marsh restoration, sediment transport measurements and models that consider sediment dynamics should be integrated into the early phases of restoration planning. This will help identify where and under what conditions marsh restoration will most likely be successful and economically justified. Triaging and prioritizing is then possible, which is a sustainable approach for restoration, given the persistent vulnerability of marshes to sea-level rise, storms, and sediment deficits.


Man wearing safety gear stands ion beach near piles of sand bags lining grassy shore, nearby earth mover moves sand.

Wednesday, February 27th, 2:00 PM

Sean Vitousek

USGS Pacific Coastal and Marine Science Center

Modeling Coastal Change: Past, Present, & Future


Understanding and predicting coastal change depends on integrating data on natural systems with computer simulations.  Although many computer modeling approaches are available to simulate shoreline change, few are capable of making reliable long-term predictions.  Recent advancements have allowed convincing decadal to centennial-scale predictions of shoreline evolution. However, long-term coastal evolution, caused by the interaction of many geologic and hydrodynamic processes, is notoriously difficult to understand let alone predict. In this talk, I discuss my past, present, and future research efforts related coastal change.


Cartoon showing water being injected into various depths and the potential sizes of earthquakes labeled as stars.

Wednesday, February 13th, 2:00 PM

Thomas H.W. Goebel

Earth Sciences, UC Santa Cruz

The spacial footprint of fluid-injection wells and induced earthquakes


The assessment and mitigation of induced earthquakes remain a crucial scientific and societal issue in light of the on-going induced seismic activity in the central United States and newly emerging earthquake sequences related to fluid injection and hydraulic fracturing in Western Canada.

Fluid injection induced seismicity is commonly inferred to be driven by increasing pore pressures that infiltrate faults and allow
earthquakes to occur. However, this inference is challenged by induced sequences with observed far-field triggering. To unravel triggering mechanisms of injection-induced earthquakes, we examine the spatial seismicity decay from wells using a unique global compilation of induced earthquake sequences. We find many sequences, that show a power-law-like decay out to more than ~10 km distance from the well. The shape and extent of this decay can be explained by the complex coupling between fluid and solid elastic stresses. Elastic stresses result in far-reaching induced seismicity sequences which increase seismic hazard beyond expectations from previous models.


Map showing 3-D relief of the central California coastline, with fault lines labeled and drawn on top.

Wednesday, February 6th, 2:00 PM

Sam Johnson

USGS Pacific Coastal and Marine Science Center

The Northern San Andreas Fault: A Coastal and Marine Perspective


Two photos taken at different times from the same spot in from the sky show a river that flows into an ocean bay.

Weds., Sept. 12th, 2018, 2:00 PM

Mara Orescanin

Naval Postgraduate School

"Hydrodynamics and morphodynamics of a small bar built estuary: The Carmel River, CA"


The Carmel River is an ephemeral river/bar built estuary located in southern Carmel Bay, that is bounded by rocky headlands to the south and north of the 700m long pocket beach.  Observations are presented showing the hydrodynamics during the breaching and closure events that occurred during the transition from dry to wet seasons during winter 2016-2017. These observations suggest no correlation for breaching events with either tides or waves.  However, each closure event occurs during high tide with large waves. Morphological measurements made during the 2017-2018 winter show a net influx of sediment to the system during the winter months along with an onshore migration of the beach. In addition, the hydrodynamic and morphodynamic response of the system to mechanical breaching is assessed. 

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Collage of an underwater photo above and a computer model output below, photo is murky with reef, sand, and instrumentation.

Sample slide from seminar presenter's talk in July 2018.

July 25th, 2018, 2:00 pm

Andrew Pomeroy

University of Western Australia

“The impact of bathymetry and roughness on the transport of reef generated sediment”

Abstract: The three-dimensional structure of coral reef bathymetry and bottom roughness affects the hydrodynamic processes that mobilize and transport sediment. These processes vary both spatially and temporally due to the physical characteristics of the reef. Attempts to describe sediment suspended from the bed have typically focused on correct representation of these hydrodynamic processes (which can be readily measured) with bottom friction parameters often adjusted until predicted wave heights and flow match field measurements. While this approach yields ‘correct’ representation of the hydrodynamic processes, large roughness substantially alters the boundary layer structure. Sediment transport equations do not account for these boundary layer changes and this has important consequences for the prediction of sediment dynamics in these environments. This seminar will focus on what is known about the type of sediment being transported, the contribution of different physical processes as well as how a range of new techniques are being combined to improve insight into how sediment transport processes in reef environments. 

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A series of 4 circles running left to right, divers underwater, ocean waters with red contamination, flooded street, and canoes.

Introduction to NOAA National Centers for Coastal Ocean Science (NCCOS)

June 21st, 2018, 11:00 am

Steven Thur

NOAA National Centers for Coastal Ocean Science (NCCOS)

“Introduction to NOAA National Centers for Coastal Ocean Science (NCCOS)”

Abstract: The United States has been endowed with a tremendous asset: our ocean and coastal resources. The facts are incontrovertible. Coastal counties contribute over $6.6 trillion to our nation’s gross domestic product, which is nearly 50 percent of national output. Approximately 40 percent of U.S. citizens live in these counties, attracted by both the natural beauty of the coasts and plentiful employment opportunities. It is here that Americans live, work, recreate, and seek to reconnect with nature.

With such a concentration of human activity, there exists the potential for conflict between various uses of these resources. In addition, the coastal environment is a dynamic place; sea levels change, natural resources shift, patterns of human use vary, and industries wax and wane. Officials at the local, state, tribal, and federal level, along with those in the corporate and nonprofit sectors, must use the best available information to make decisions that affect livelihoods, property values, human health, preparedness for disasters, management of our natural resources, and protection of special places for future generations.

Our role is to conduct the research and provide the information necessary to address these complex coastal challenges. The mission of the National Centers for Coastal Ocean Science (NCCOS) is to deliver ecosystem science solutions for stewardship of the nation’s ocean and coastal resources to sustain thriving coastal communities and economies.

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View from the sky looking down on a coastal area with houses on winding streets near a beach, painted lines trace the coast.

June 13th, 2018, 2:00pm

Doug George

Greater Farallones National Marine Sanctuary (GFNMS) and Central and Northern California Ocean Observing System (CeNCOOS)

“The Sediment Swirl: Knowledge Gaps in Sediment Transport Along the North-Central California Coast”