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Senior Research Scientist
Ph.D., Massachusetts Institute of Technology-Woods Hole Oceanographic Institution (1990);
B.S., Brown University (1985)
Marine Geophysics and Statistical
Geomorphology
Seafloor mapping and characterization; statistical analysis of geophysical fields,
including abyssal hills, shelf bathymetry, sea ice draft, and crustal
heterogeneity.
John's Spotlights:
In September, 2008 I was a co-pi on a rapid response survey following
hurricane Ike,
near Galveston, TX.
I am a co teacher (with Sean Gulick and Mead
Allison) of the
Marine Geology and Geophysics Field Course. We completed our second
course in May/June, 2009.
I am the proud father of son
Cameron
and daughter Megan (updated June, 2006).
Research Interests
My primary current field research interest is in mapping and characterization of
seafloor morphology and sedimentary properties in continental shelf settings
using swath sonar, grain size analysis of samples from grabs and cores, and
measurements of physical properties of seabed sediments.
 Past
research included shallow-water surveys of active (northern
California) and passive (New Jersey) continental margins. Both
efforts were part of the Office of Naval Research's STRATAFORM
program. The New Jersey shelf has since become an ongoing focus of my
research, with continued funding by the Navy as it looks to this area as one of
its premier natural laboratories for acoustic experimentation in shallow water
environments. As part of ONR's Geoclutter
program, which aims to understand the nature of signal-like acoustic
returns from the natural shallow water environment, I have participated in an
intensive, multidisciplinary, multi-institution effort to characterize seabed
stratigraphy properties in this region. The geological and geophysical
goals are centered on understanding the morphologic and stratigraphic evolution
of this setting during the last ~40 kyr of geologic history. Geoclutter
G&G field work has included chirp seismic data acquisition, grab sampling and short coring to characterize lithology and grain size of seafloor
sediments, in situ geotechnical measurements, and coring using the
AHC-800
and
vibracoring system (photo above). The outer New Jersey shelf was also the focus of
a large, ONR-sponsored "Shallow Water Experiment" in 2006, which included
participants from low-frequency, mid-frequency, and clutter acoustic
experimentalists as well as additional G&G characterization. Another
recent focus
of my field efforts fell within ONR's Mine
Burial Prediction program, which sought to understand how man-made objects
placed on the seafloor are buried and exposed by nearshore processes. The
Martha's Vineyard Coastal Observatory
was one of the primary focus sites, and in
2002 I led a multi-institution effort to characterize the geology and geophysics
of this area (see figures below). Our primary scientific goal was to understand the nature of
so-called rippled scour depressions, the dominant seabed morphology in this
setting and in many other near-shore environments where sediment input is very
low. This work, primarily in collaboration with colleagues at UNH,
included multiple swath mapping campaigns to investigate temporal evolution of
the seabed, chirp seismic reflection, grab sampling, in situ measurements of
acoustic velocity and porosity, and vibracoring.
My most recent field work involved a
rapid response survey
of coastal and inlet regions near Galveston, TX, following Hurricane Ike in 2008
(see figures below). This
work is in collaboration with Mead Allison
and Sean Gulick. We compare
the results from marine geophysical surveys conducted before and just after the
passage of Hurricane. Through the ability to do a pre and post-storm comparison
of the seafloor and shallow subseafloor in the area that Hurricane Ike made
landfall, we are able to demonstrate that, surprisingly, the storm-surge ebb
provided the dominant forcing for sediment transport. The storm-surge ebb moved
a substantial amount of sand, the foundation for beach barrier systems, far
enough off shore that it will not be reincorporated by coastal processes or
future storms. Offshore transport of sand during storms is not presently
considered in models of beach barrier evolution, which tend to focus on inland
“rollover” in response to storms and sea level rise. If representative, the net
loss of sand indicated by our results will have a significant negative impact on
the sustainability of barrier systems in the Gulf of Mexico and other parts of
the world impacted by cyclonic storms, with strong relevance for maintenance of
both coastal communities and coastal ecosystems.
 Statistical characterization provides quantitative tools necessary for relating complex
morphology to the geological processes which form or interact with them, and a means for
digitally simulating chaotic natural phenomena. My work in this
field of interest has led to analysis of a diverse range of data sets, including
abyssal hill morphology (my thesis), sea ice drafts, continental shelf sand
ridges, shelf stratigraphy, crustal heterogeneity, and seafloor sediment
variability. The latter topic is a recent research focus. In
particular, I've conducted a collaborative effort with the USGS and Colorado
University to analyze the SEABED data base, which includes estimates of grain
size from many thousands of locations world wide. We are interested in
understanding how sediment properties vary as a function of geologic
environment, and in developing methodologies for robust interpolation of noisy
point measurements. I have been working on project to discern
abyssal
hill roughness properties from satellite altimetry data (image above). This project,
funded by ONR, is a collaborative with Brian Arbic
and Walter Smith. Brian is a physical oceanographer, now at USF, who will utilize my seafloor roughness inputs to predict the formation of
internal waves in the ocean.
Hurricane Ike Rapid Response
Survey
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Fig. 1. Location map for the
survey areas, indicating geographic features identified in the text. Box
core locations are indicated by dots and labeled BC1-3. The approximate
pathway of Hurricane Ike during landfall is indicated by the heavy arrow
The longest buoy displacement within the inlet channel is indicated by
dashed arrow. |
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Fig. 2. (a) Multibeam bathymetric
data collected within the Bolivar Roads inlet in May, 2008. Small arrows
point to fields of small-scale bedforms on top of the shell-gravel
ridges. The Houston Ship Channel runs along the top of the mapped
region. The Big Reef area is a nature preserve at the northern tip of
Galveston Island, and was heavily damaged by erosion. Location in Fig.
1. (b) Multibeam bathymetry data collected from the same region as
(a) in September, 2008, a week and a half after the passage of Hurricane
Ike. Small arrows point to fields of small-scale bedforms among the
highly degraded shell-gravel ridge morphology. A newly-formed deposit is
also identified. (c) The difference map formed by subtracting the
“after” bathymetry from the “before” bathymetry. Blues indicate areas of
erosion, whereas reds indicate regions of deposition. The orientation of
erosional flow crossing the Big Reef area is derived from examination of
pre- and post-hurricane satellite photos |
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Fig. 3. Nearly
coincident CHIRP seismic reflection profiles (a) before and (b)
after Hurricane Ike, in a region of broad deposition seaward of the
shell-gravel ridges. Locations shown in Fig. 2c. Heavy arrows in (b)
identify new shallow reflector that developed after the hurricane,
approximately 0.2-0.5 m below the seafloor. The new reflector is
indicative of an event layer associated with the hurricane. |
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Fig. 4.
X-radiographs of box cores collected offshore of the Bolivar
Peninsula in ~13 m (BC1), ~11 m (BC2) and ~8 m (BC3) water
depths. Locations shown in Fig. 1. |
Current Research Projects:
Vibracoring on the New Jersey Shelf: Investigating the Stratigraphic Response to ~50,000 Years of Eustasy
Stratigraphic and
Geoacoustic Characterization of the Outer New Jersey Shelf
Effects of small-scale bathymetric roughness on the global internal wave field
Rapid Response Survey
After Hurricane Ike
Completed Research Projects:
Spatial
variability and robust interpolation of seafloor sediment properties
using the SEABED data bases
ONR
Geoclutter Program
Seabed
Variability and its Influence on Acoustic Prediction Uncertainty
Site
Survey of the Mine Burial/Coastal Processes Experiment Site at the WHOI
Coastal Observatory, Martha’s Vineyard
Building
a Statistical Framework for Mine Burial Predictions
Geophysical
Investigation of En Echelon Cracks Along the Outer Shelf Off Virginia/North Carolina -
Implications for Slope Stability
Realistic
Interpolation of Buried Channel Systems within the New Jersey Geoclutter Natural
Laboratory
Statistical
Characterization of Bathymetry and Stratigraphy on Continental Margins
Geologic
and Geophysical Support for the Geoclutter acoustic reconnaissance field
program.
JOI Site Survey
Augmentation - Grab Sampling and Chirp Sonar on the New Jersey Margin
Quantitative Characterization of
Crustal Heterogeneity: Implications for Seismic Wave Propagation
Stochastic Modeling of
Abyssal Hill Morphology: New Seafloor Models Based on Analysis of Fine Scale Basement
Topography and Separate Characterization of Tectonic and Volcanic Morphology
Reprints for published and submitted papers:
Seismic and bathymetric evidence for
four different episodes of iceberg scouring on the New Jersey outer shelf:
possible correlation to Heinrich events (PDF
reprint)
Shallow stratigraphy and complex transgressive ravinement
on the New Jersey middle and outer continental shelf (PDF
reprint)
Statistical characterization of Geosat
altimetry noise: Dependence on environmental parameters (PDF
reprint)
Seabed mapping and
characterization of sediment variability using the usSEABED database (please
email
John to obtain pdf reprint. For copyright reasons I am unable to post
for distribution)
Seismic facies of incised valley-fills, New Jersey continental shelf:
Implications for erosion and preservation processes acting during late
Pleistocene/Holocene transgression (PDF
reprint)
Maximum a posteriori resampling of noisy, spatially correlated data (PDF
reprint)
Recent and modern marine erosion on the New Jersey
outer shelf (PDF
reprint)
Seismic geomorphology of buried channel systems on the New Jersey outer shelf:
Assessing past environmental conditions (PDF
reprint)
The contributions of abyssal hill morphology
and noise to altimetric gravity fabric (PDF
reprint)
The correspondence of altimetric gravity
texture to abyssal hill morphology (PDF
reprint)
Detailed investigation of sorted bedforms, or
“rippled scour depressions,” within the Martha’s Vineyard Coastal Observatory,
Massachusetts (PDF reprint)
Seabed characterization on the New Jersey middle and outer shelf: Correlability
and spatial variability of seafloor sediment properties (PDF
reprint)
Interpolation of fluvial morphology using
channel-oriented coordinate transformation: A case study from the New Jersey
shelf (PDF reprint)
Mine
Burial Prediction Technical Report: A Statistical Framework for Monte Carlo Mine
Burial Modeling Experiments (PDF file)
Spatial
Variability of Shelf Sediments in the STRATAFORM Natural Laboratory, Northern
California (PDF Reprint)
Quantitative
classification of canyon systems on continental slopes and a possible
relationship to slope curvature (PDF
Reprint)
Relict
iceberg keel marks on the New Jersey outer shelf, southern Hudson Apron (PDF Reprint)
Tracking
the last sea level cycle: Seafloor morphology and shallow stratigraphy of the
latest Quaternary New Jersey middle continental shelf (PDF Reprint)
Potential for large-scale submarine slope failure
and tsunami generation along the U.S. mid-Atlantic coast (PDF Reprint)
Correlation
of sidescan backscatter intensity with grain-size distribution of shelf
sediments, New Jersey margin (PDF Reprint)
High resolution swath
sonar investigation of sand ridge, dune and ribbon morphology in the offshore
environment of the New Jersey margin (PDF
Reprint)
Nature and origin of upper crustal seismic velocity
fluctuations and associated scaling properties: combined stochastic analyses of KTB
velocity and lithology logs (PDF Reprint)
Detailed investigation of continental shelf
morphology using a high resolution swath sonar survey: The Eel margin, northern California (PDF Reprint)
Simulation of stratigraphic
architecture from statistical and geometrical characterizations (PDF Reprint)
Improvement of Fourier-based unconditional and
conditional simulations for band limited fractal (von Karman) statistical models (PDF Reprint)
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