[{"awards": "1914698 Hansen, Samantha", "bounds_geometry": ["POLYGON((90 -65,99 -65,108 -65,117 -65,126 -65,135 -65,144 -65,153 -65,162 -65,171 -65,180 -65,180 -67.5,180 -70,180 -72.5,180 -75,180 -77.5,180 -80,180 -82.5,180 -85,180 -87.5,180 -90,171 -90,162 -90,153 -90,144 -90,135 -90,126 -90,117 -90,108 -90,99 -90,90 -90,90 -87.5,90 -85,90 -82.5,90 -80,90 -77.5,90 -75,90 -72.5,90 -70,90 -67.5,90 -65))"], "date_created": "Wed, 24 Jan 2024 00:00:00 GMT", "description": "Recent investigations in polar environments have examined solid-Earth-ice-sheet feedbacks and have emphasized that glacial isostatic adjustment, tectonic, and geothermal forcings exert first-order control on the physical conditions at and below the ice-bed interface and must be taken into account when evaluating ice-sheet evolution. However, the solid-Earth structure beneath much of Antarctica is still poorly constrained given the sparse distribution of seismic stations across the continent and the generally low seismicity rate. One region of particular interest is the Wilkes Subglacial Basin (WSB) in East Antarctica. During the mid-Pliocene warm period, the WSB may have contributed 3-4 m to the estimated 20 m rise in sea-level, indicating that this region could also play an important role in future warming scenarios. However, the WSB may have experienced notable bedrock uplift since the Pliocene; therefore, past geologic inferences of instability may not serve as a simple analogue for the future.\r\n\r\nUsing records of ambient seismic noise recorded by both temporary and long-term seismic networks, along with a full-waveform tomographic inversion technique, we have developed improved images of the lithospheric structure beneath East Antarctica, including the WSB. Empirical Green\u2019s Functions with periods between 40 and 340 s have been extracted using a frequency-time normalization technique, and a finite-difference approach with a spherical grid has been employed to numerically model synthetic seismograms. Associated sensitivity kernels have also been constructed using a scattering integral method. Our results suggest the WSB is underlain by slow seismic velocities, with faster seismic structure beneath the adjacent Transantarctic Mountains and the Belgica Subglacial Highlands. This may indicate that the WSB is associated with a region of thinner lithosphere, possibly associated with prior continental rifting. The seismic heterogeneity highlighted in our model could have significant implications for understanding the geodynamic origin of WSB topography and its influence on ice-sheet behavior.\r\n\r\nThe model file and associated plotting scripts are provided.", "east": 180.0, "geometry": ["POINT(135 -77.5)"], "keywords": "Ambient Noise; Antarctica; East Antarctica; Geoscientificinformation; Seismic Tomography; Seismology", "locations": "East Antarctica; Antarctica", "north": -65.0, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Hansen, Samantha; Emry, Erica", "project_titles": "Collaborative Research: Resolving earth structure influence on ice-sheet stability in the Wilkes\r\nSubglacial Basin (RESISSt)", "projects": [{"proj_uid": "p0010204", "repository": "USAP-DC", "title": "Collaborative Research: Resolving earth structure influence on ice-sheet stability in the Wilkes\r\nSubglacial Basin (RESISSt)"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Full Waveform Ambient Noise Tomography for East Antarctica", "uid": "601763", "west": 90.0}, {"awards": "1643798 Emry, Erica; 1643873 Hansen, Samantha", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Mon, 16 Oct 2023 00:00:00 GMT", "description": "This dataset provides the shear wave velocity model resulting from a full-waveform inversion that was constrained using long-period empirical Green\u0027s functions extracted from ambient seismic noise. These results were presented by Emry and Hansen at the 2022 Fall Meeting of the American Geophysical Union.", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Ambient Seismic Noise; Antarctica; Full-Waveform Inversion; Seismic Tomography; Shear Wave Velocity; Solid Earth", "locations": "Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences", "persons": "Emry, Erica", "project_titles": "Collaborative Research: Imaging Seismic Heterogeneity within the Antarctic Mantle with Full Waveform Ambient Noise Tomography", "projects": [{"proj_uid": "p0010139", "repository": "USAP-DC", "title": "Collaborative Research: Imaging Seismic Heterogeneity within the Antarctic Mantle with Full Waveform Ambient Noise Tomography"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Shear Wave Velocity of the Antarctic Upper Mantle from Full Waveform Inversion and Long Period Ambient Seismic Noise", "uid": "601744", "west": -180.0}, {"awards": "1643795 Mikesell, Thomas", "bounds_geometry": ["POLYGON((-134.5 -75,-130.85 -75,-127.2 -75,-123.55 -75,-119.9 -75,-116.25 -75,-112.6 -75,-108.95 -75,-105.3 -75,-101.65 -75,-98 -75,-98 -75.85,-98 -76.7,-98 -77.55,-98 -78.4,-98 -79.25,-98 -80.1,-98 -80.95,-98 -81.8,-98 -82.65,-98 -83.5,-101.65 -83.5,-105.3 -83.5,-108.95 -83.5,-112.6 -83.5,-116.25 -83.5,-119.9 -83.5,-123.55 -83.5,-127.2 -83.5,-130.85 -83.5,-134.5 -83.5,-134.5 -82.65,-134.5 -81.8,-134.5 -80.95,-134.5 -80.1,-134.5 -79.25,-134.5 -78.4,-134.5 -77.55,-134.5 -76.7,-134.5 -75.85,-134.5 -75))"], "date_created": "Fri, 15 Jan 2021 00:00:00 GMT", "description": "This data set includes observations of Rayleigh and Love wave group and phase velocity dispersion curves from ambient noise crosscorrelation functions. The data set includes the corresponding shear wave velocity model produced by joint inversion of these dispersion curves. This investigators developed a new crust and upper mantle model directly beneath the seismic stations used in this study. Data are in NetCDF and GeoCSV formats. The Python code used to generate the NetCDF files from the GeoCSV files is also contained in the data set.", "east": -98.0, "geometry": ["POINT(-116.25 -79.25)"], "keywords": "Antarctica; Crust; Moho; Seismic Tomography; Seismology; Seismometer; Shear Wave Velocity; Surface Wave Dispersion; West Antarctica", "locations": "West Antarctica; Antarctica", "north": -75.0, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Mikesell, Dylan", "project_titles": "Collaborative Research: Monitoring Antarctic Ice Sheet Changes with Ambient Seismic Noise Methods", "projects": [{"proj_uid": "p0010155", "repository": "USAP-DC", "title": "Collaborative Research: Monitoring Antarctic Ice Sheet Changes with Ambient Seismic Noise Methods"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "POLENET", "south": -83.5, "title": "2D shear-wave velocity model across the West Antarctic Rift System from POLENET-ANET seismic data", "uid": "601423", "west": -134.5}, {"awards": "1139739 Hansen, Samantha", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Wed, 01 Jan 2014 00:00:00 GMT", "description": "Intellectual Merit: Numerous candidate models for the geologic processes that have shaped the Antarctic continent have been proposed. To discriminate between them, detailed images of the upper mantle structure are required; however, the only existing continental-scale images of seismic structure beneath Antarctica lack sufficient resolution to delineate important, diagnostic features. Using newly available data from various Antarctic seismic networks, the PI will employ the adaptively parameterized tomography method to develop a high-resolution, continental-scale seismic velocity model for all of Antarctica. The proposed tomography method combines regional seismic travel-time datasets in the context of a global model to create a composite continental-scale model of upper mantle structure. The proposed method allows for imaging of finer structure in areas with better seismic ray coverage while simultaneously limiting the resolution of features in regions with less coverage. This research will help advance understanding of important global processes, such as craton formation, mountain building, continental rifting and associated magmatism. Additionally, the proposed research will have important impacts on other fields of Antarctic science. Constraints provided by tomographic results can be used to develop thermal models of the lithosphere needed to characterize the history and dynamics of ice sheets. Also, further constraints on lithospheric structure are required by climate-ice models, which are focused on understanding the cooling history of the Antarctic continent.\n\nBroader impacts: The PI is a new faculty member at the University of Alabama after having been funded as a National Science Foundation Postdoctoral Fellow in Polar Regions Research. The graduate student supported by this project is new to polar research. Through the UA-Tuscaloosa Magnet School partnership program, the PI will educate K-12 students about the Antarctic environment and associated career opportunities through various online and hands-on activities. University of Alabama dedicates a significant percentage of its enrollment space to underrepresented groups.\n", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Geology/Geophysics - Other; Lithosphere; Seismic Tomography; Solid Earth", "locations": "Antarctica", "north": -60.0, "nsf_funding_programs": null, "persons": "Hansen, Samantha", "project_titles": "New Approach to Investigate the Seismic Velocity Structure beneath Antarctica", "projects": [{"proj_uid": "p0000354", "repository": "USAP-DC", "title": "New Approach to Investigate the Seismic Velocity Structure beneath Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "A New Approach to Investigate the Seismic Velocity Structure beneath Antarctica", "uid": "600132", "west": -180.0}]

Help on the Results MapX

This window can be dragged by its header, and can be resized from the bottom right corner.

The Results Map and the Results Table

The Results Map displays the centroids of the geographic bounds of all the results returned by the search.
Results that are displayed in the current map view will be highlighted in blue and brought to the top of the Results Table.
As the map is panned or zoomed, the highlighted rows in the table will update.
If you click on a centroid on the map, it will turn yellow and display a popup with details for that project/dataset - including a link to the landing page. The bounds for the project(s)/dataset(s) selected will be displayed in red. The selected result(s) will be highlighted in red and brought to the top of the table.
The default table sorting order is: Selected, Visible, Date (descending), but this can be changed by clicking on column headers in the table.
Selecting Show on Map for an individual row will both display the geographic bounds for that result on a mini map, and also display the bounds and highlight the centroid on the Results Map.
Clicking the 'Show boundaries' checkbox at the top of the Results Map will display all the bounds for the filtered results.

Defining a search area on the Results Map

If you click on the Rectangle or Polygon icons in the top right of the Results Map, you can define a search area which will be added to any other search criteria already selected.
After you have drawn a polygon, you can edit it using the Edit Geometry dropdown in the search form at the top.
Clicking Clear in the map will clear any drawn polygon.
Clicking Search in the map, or Search on the form will have the same effect.
The returned results will be any projects/datasets with bounds that intersect the polygon.
Use the Exclude project/datasets checkbox to exclude any projects/datasets that cover the whole Antarctic region.

Viewing map layers on the Results Map

Clicking the Layers button - the blue square in the top left of the Results Map - will display a list of map layers you can add or remove from the currently displayed map view.

Search USAP-DC Datasets

Free Text Search

Title (free text)

Science Program

Person

Award

NSF Funding Program

Spatial Bounds of Data Use the Results Map below to draw a polygon over the required search area, or edit the WKT geometry here:

Any WKT polygon, with longitudes in a 0-360 ° range. Example: Ross Sea is between 160 and 210. Read about the WKT format here.

Exclude datasets that cover the whole Antarctic from map-based search

4 record(s) found

To sort the table of search results, click the header of the column you wish to search by. To sort by multiple columns, hold down the shift key whilst selecting the sort columns in order.

Dataset Title/Abstract/Map	NSF Award(s)	Date Created	PIs / Scientists	Project Links	Abstract	Bounds Geometry	Geometry	Selected	Visible
Full Waveform Ambient Noise Tomography for East Antarctica	1914698	2024-01-24	Hansen, Samantha; Emry, Erica	Collaborative Research: Resolving earth structure influence on ice-sheet stability in the Wilkes Subglacial Basin (RESISSt)	Recent investigations in polar environments have examined solid-Earth-ice-sheet feedbacks and have emphasized that glacial isostatic adjustment, tectonic, and geothermal forcings exert first-order control on the physical conditions at and below the ice-bed interface and must be taken into account when evaluating ice-sheet evolution. However, the solid-Earth structure beneath much of Antarctica is still poorly constrained given the sparse distribution of seismic stations across the continent and the generally low seismicity rate. One region of particular interest is the Wilkes Subglacial Basin (WSB) in East Antarctica. During the mid-Pliocene warm period, the WSB may have contributed 3-4 m to the estimated 20 m rise in sea-level, indicating that this region could also play an important role in future warming scenarios. However, the WSB may have experienced notable bedrock uplift since the Pliocene; therefore, past geologic inferences of instability may not serve as a simple analogue for the future. Using records of ambient seismic noise recorded by both temporary and long-term seismic networks, along with a full-waveform tomographic inversion technique, we have developed improved images of the lithospheric structure beneath East Antarctica, including the WSB. Empirical Green’s Functions with periods between 40 and 340 s have been extracted using a frequency-time normalization technique, and a finite-difference approach with a spherical grid has been employed to numerically model synthetic seismograms. Associated sensitivity kernels have also been constructed using a scattering integral method. Our results suggest the WSB is underlain by slow seismic velocities, with faster seismic structure beneath the adjacent Transantarctic Mountains and the Belgica Subglacial Highlands. This may indicate that the WSB is associated with a region of thinner lithosphere, possibly associated with prior continental rifting. The seismic heterogeneity highlighted in our model could have significant implications for understanding the geodynamic origin of WSB topography and its influence on ice-sheet behavior. The model file and associated plotting scripts are provided.	["POLYGON((90 -65,99 -65,108 -65,117 -65,126 -65,135 -65,144 -65,153 -65,162 -65,171 -65,180 -65,180 -67.5,180 -70,180 -72.5,180 -75,180 -77.5,180 -80,180 -82.5,180 -85,180 -87.5,180 -90,171 -90,162 -90,153 -90,144 -90,135 -90,126 -90,117 -90,108 -90,99 -90,90 -90,90 -87.5,90 -85,90 -82.5,90 -80,90 -77.5,90 -75,90 -72.5,90 -70,90 -67.5,90 -65))"]	["POINT(135 -77.5)"]	false	false
Shear Wave Velocity of the Antarctic Upper Mantle from Full Waveform Inversion and Long Period Ambient Seismic Noise	1643798 1643873	2023-10-16	Emry, Erica	Collaborative Research: Imaging Seismic Heterogeneity within the Antarctic Mantle with Full Waveform Ambient Noise Tomography	This dataset provides the shear wave velocity model resulting from a full-waveform inversion that was constrained using long-period empirical Green's functions extracted from ambient seismic noise. These results were presented by Emry and Hansen at the 2022 Fall Meeting of the American Geophysical Union.	["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"]	["POINT(0 -89.999)"]	false	false
2D shear-wave velocity model across the West Antarctic Rift System from POLENET-ANET seismic data	1643795	2021-01-15	Mikesell, Dylan	Collaborative Research: Monitoring Antarctic Ice Sheet Changes with Ambient Seismic Noise Methods	This data set includes observations of Rayleigh and Love wave group and phase velocity dispersion curves from ambient noise crosscorrelation functions. The data set includes the corresponding shear wave velocity model produced by joint inversion of these dispersion curves. This investigators developed a new crust and upper mantle model directly beneath the seismic stations used in this study. Data are in NetCDF and GeoCSV formats. The Python code used to generate the NetCDF files from the GeoCSV files is also contained in the data set.	["POLYGON((-134.5 -75,-130.85 -75,-127.2 -75,-123.55 -75,-119.9 -75,-116.25 -75,-112.6 -75,-108.95 -75,-105.3 -75,-101.65 -75,-98 -75,-98 -75.85,-98 -76.7,-98 -77.55,-98 -78.4,-98 -79.25,-98 -80.1,-98 -80.95,-98 -81.8,-98 -82.65,-98 -83.5,-101.65 -83.5,-105.3 -83.5,-108.95 -83.5,-112.6 -83.5,-116.25 -83.5,-119.9 -83.5,-123.55 -83.5,-127.2 -83.5,-130.85 -83.5,-134.5 -83.5,-134.5 -82.65,-134.5 -81.8,-134.5 -80.95,-134.5 -80.1,-134.5 -79.25,-134.5 -78.4,-134.5 -77.55,-134.5 -76.7,-134.5 -75.85,-134.5 -75))"]	["POINT(-116.25 -79.25)"]	false	false
A New Approach to Investigate the Seismic Velocity Structure beneath Antarctica	1139739	2014-01-01	Hansen, Samantha	New Approach to Investigate the Seismic Velocity Structure beneath Antarctica	Intellectual Merit: Numerous candidate models for the geologic processes that have shaped the Antarctic continent have been proposed. To discriminate between them, detailed images of the upper mantle structure are required; however, the only existing continental-scale images of seismic structure beneath Antarctica lack sufficient resolution to delineate important, diagnostic features. Using newly available data from various Antarctic seismic networks, the PI will employ the adaptively parameterized tomography method to develop a high-resolution, continental-scale seismic velocity model for all of Antarctica. The proposed tomography method combines regional seismic travel-time datasets in the context of a global model to create a composite continental-scale model of upper mantle structure. The proposed method allows for imaging of finer structure in areas with better seismic ray coverage while simultaneously limiting the resolution of features in regions with less coverage. This research will help advance understanding of important global processes, such as craton formation, mountain building, continental rifting and associated magmatism. Additionally, the proposed research will have important impacts on other fields of Antarctic science. Constraints provided by tomographic results can be used to develop thermal models of the lithosphere needed to characterize the history and dynamics of ice sheets. Also, further constraints on lithospheric structure are required by climate-ice models, which are focused on understanding the cooling history of the Antarctic continent. Broader impacts: The PI is a new faculty member at the University of Alabama after having been funded as a National Science Foundation Postdoctoral Fellow in Polar Regions Research. The graduate student supported by this project is new to polar research. Through the UA-Tuscaloosa Magnet School partnership program, the PI will educate K-12 students about the Antarctic environment and associated career opportunities through various online and hands-on activities. University of Alabama dedicates a significant percentage of its enrollment space to underrepresented groups.	["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"]	["POINT(0 -89.999)"]	false	false

USAP-DC

U.S. ANTARCTIC PROGRAM DATA CENTER

The Results Map and the Results Table

Defining a search area on the Results Map

Viewing map layers on the Results Map

Search USAP-DC Datasets

To sort the table of search results, click the header of the column you wish to search by. To sort by multiple columns, hold down the shift key whilst selecting the sort columns in order.