USAP-DC

{"dp_type": "Dataset", "free_text": "Tomography"}

[{"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": "Thu, 27 Feb 2025 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. The results are highlighted in Hansen and Emry (2025).", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Ambient Seismic Noise; Antarctica; Cryosphere; Full-Waveform Inversion; Seismic Tomography; Shear Wave Velocity", "locations": "Antarctica; Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences", "persons": "Emry, Erica; Hansen, Samantha", "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": "601909", "west": -180.0}, {"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": "1644013 Gaetani, Glenn", "bounds_geometry": ["POLYGON((164.1 -77.1,164.65 -77.1,165.2 -77.1,165.75 -77.1,166.3 -77.1,166.85 -77.1,167.4 -77.1,167.95 -77.1,168.5 -77.1,169.05 -77.1,169.6 -77.1,169.6 -77.235,169.6 -77.37,169.6 -77.505,169.6 -77.64,169.6 -77.775,169.6 -77.91,169.6 -78.045,169.6 -78.18,169.6 -78.315,169.6 -78.45,169.05 -78.45,168.5 -78.45,167.95 -78.45,167.4 -78.45,166.85 -78.45,166.3 -78.45,165.75 -78.45,165.2 -78.45,164.65 -78.45,164.1 -78.45,164.1 -78.315,164.1 -78.18,164.1 -78.045,164.1 -77.91,164.1 -77.775,164.1 -77.64,164.1 -77.505,164.1 -77.37,164.1 -77.235,164.1 -77.1))"], "date_created": "Wed, 12 Jan 2022 00:00:00 GMT", "description": "G170 Raman Spectroscopy \u0026 Tomography Volumes of Melt Inclusions and Vapor Bubbles", "east": 169.6, "geometry": ["POINT(166.85 -77.775)"], "keywords": "Antarctica; Chemistry:rock; Chemistry:Rock; Geochemistry; Melt Inclusions; Raman Spectroscopy; Ross Island; Vapor Bubbles; Volcanic", "locations": "Antarctica; Ross Island", "north": -77.1, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Gaetani, Glenn", "project_titles": "Collaborative Research: Determining Magma Storage Depths and Ascent Rates for the Erebus Volcanic Province, Antarctica Using Diffusive Water Loss from Olivine-hosted Melt Inclusion", "projects": [{"proj_uid": "p0010081", "repository": "USAP-DC", "title": "Collaborative Research: Determining Magma Storage Depths and Ascent Rates for the Erebus Volcanic Province, Antarctica Using Diffusive Water Loss from Olivine-hosted Melt Inclusion"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -78.45, "title": "G170 Raman Spectroscopy \u0026 Tomography Volumes of Melt Inclusions and Vapor Bubbles", "uid": "601508", "west": 164.1}, {"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": "1148982 Hansen, Samantha", "bounds_geometry": ["POLYGON((153.327 -73.032547,154.5063012 -73.032547,155.6856024 -73.032547,156.8649036 -73.032547,158.0442048 -73.032547,159.223506 -73.032547,160.4028072 -73.032547,161.5821084 -73.032547,162.7614096 -73.032547,163.9407108 -73.032547,165.120012 -73.032547,165.120012 -73.3530275,165.120012 -73.673508,165.120012 -73.9939885,165.120012 -74.314469,165.120012 -74.6349495,165.120012 -74.95543,165.120012 -75.2759105,165.120012 -75.596391,165.120012 -75.9168715,165.120012 -76.237352,163.9407108 -76.237352,162.7614096 -76.237352,161.5821084 -76.237352,160.4028072 -76.237352,159.223506 -76.237352,158.0442048 -76.237352,156.8649036 -76.237352,155.6856024 -76.237352,154.5063012 -76.237352,153.327 -76.237352,153.327 -75.9168715,153.327 -75.596391,153.327 -75.2759105,153.327 -74.95543,153.327 -74.6349495,153.327 -74.314469,153.327 -73.9939885,153.327 -73.673508,153.327 -73.3530275,153.327 -73.032547))"], "date_created": "Thu, 20 Apr 2017 00:00:00 GMT", "description": "Using data from the Transantarctic Mountains (TAMs) Northern Network, the shear wave velocity structure beneath the northern TAMs was investigated with surface wave tomography. Rayleigh wave phase velocities were calculated using a two-plane wave approximation and were then inverted for shear velocity structure. The resulting model shows a low velocity zone (~4.24 km/s) at ~160 km depth offshore and adjacent to Mt. Melbourne that extends inland and vertically upwards to ~100 km depth beneath the northern TAMs and Victoria Land. Another low velocity zone (~4.16-4.24 km/s) is also seen at ~150 km depth beneath Ross Island, and relatively slow velocities (~4.24-4.32 km/s) along the Terror Rift connect the two low velocity zones. This structure has been interpreted to reflect rift-related decompression melting along the TAMs front, which would provide thermal buoyancy to uplift the mountain range.", "east": 165.120012, "geometry": ["POINT(159.223506 -74.6349495)"], "keywords": "Antarctica; Geology/Geophysics - Other; Model; Seismology; Solid Earth; Tomography; Transantarctic Mountains", "locations": "Antarctica; Transantarctic Mountains", "north": -73.032547, "nsf_funding_programs": null, "persons": "Hansen, Samantha", "project_titles": "CAREER: Deciphering the Tectonic History of the Transantarctic Mountains and the Wilkes Subglacial Basin", "projects": [{"proj_uid": "p0000300", "repository": "USAP-DC", "title": "CAREER: Deciphering the Tectonic History of the Transantarctic Mountains and the Wilkes Subglacial Basin"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -76.237352, "title": "Upper Mantle Shear Wave Velocity Structure beneath the Northern Transantarctic Mountains", "uid": "601018", "west": 153.327}, {"awards": "1148982 Hansen, Samantha", "bounds_geometry": ["POLYGON((153.327 -73.032547,154.5063012 -73.032547,155.6856024 -73.032547,156.8649036 -73.032547,158.0442048 -73.032547,159.223506 -73.032547,160.4028072 -73.032547,161.5821084 -73.032547,162.7614096 -73.032547,163.9407108 -73.032547,165.120012 -73.032547,165.120012 -73.3530275,165.120012 -73.673508,165.120012 -73.9939885,165.120012 -74.314469,165.120012 -74.6349495,165.120012 -74.95543,165.120012 -75.2759105,165.120012 -75.596391,165.120012 -75.9168715,165.120012 -76.237352,163.9407108 -76.237352,162.7614096 -76.237352,161.5821084 -76.237352,160.4028072 -76.237352,159.223506 -76.237352,158.0442048 -76.237352,156.8649036 -76.237352,155.6856024 -76.237352,154.5063012 -76.237352,153.327 -76.237352,153.327 -75.9168715,153.327 -75.596391,153.327 -75.2759105,153.327 -74.95543,153.327 -74.6349495,153.327 -74.314469,153.327 -73.9939885,153.327 -73.673508,153.327 -73.3530275,153.327 -73.032547))"], "date_created": "Thu, 06 Apr 2017 00:00:00 GMT", "description": "Stretching ~3,500 km across Antarctica, with peak elevations up to 4,500 m, the Transantarctic Mountains (TAMs) are the largest non-compressional mountain range on Earth and represent a tectonic boundary between the East Antarctica (EA) craton and the West Antarctic Rift System. The origin and uplift mechanism associated with the TAMs is controversial, and multiple models have been proposed. Seismic investigations of the TAMs\u0027 subsurface structure can provide key constraints to help evaluate these models, but previous studies have been primarily focused only on the central TAMs near Ross Island. Using data from the new 15-station Transantarctic Mountain Northern Network as well as data from several smaller networks, this study investigates the upper mantle velocity structure beneath a previously unexplored portion of the northern TAMs through regional body wave tomography. Relative travel-times were calculated for 11,182 P-wave and 8,285 S-wave arrivals from 790 and 581 Mw \u2265 5.5 events, respectively, using multi-channel cross correlation, and these data were then inverted for models of the upper mantle seismic structure. Resulting P- and S-wave tomography images reveal two focused low velocity anomalies beneath Ross Island (RI; \u03b4VP \u2248 -2.0%; \u03b4VS \u2248 -1.5% to -4.0%) and Terra Nova Bay (TNB; \u03b4VP \u2248 -1.5% to -2.0%; \u03b4VS \u2248 -1.0% to -4.0%) that extend to depths of ~200 and ~150 km, respectively. The RI and TNB slow anomalies also extend ~50-100 km laterally beneath the TAMs front and sharply abut fast velocities beneath the EA craton (\u03b4VP \u2248 0.5% to 2%; \u03b4VS \u2248 1.5% to 4.0%). A low velocity region (\u03b4VP \u2248 -1.5%), centered at ~150 km depth beneath the Terror Rift (TR) and primarily constrained within the Victoria Land Basin, connects the RI and TNB anomalies. The focused low velocities are interpreted as regions of partial melt and buoyancy-driven upwelling, connected by a broad region of slow (presumably warm) upper mantle associated with Cenozoic extension along the TR. Dynamic topography estimates based on the imaged S-wave velocity perturbations are consistent with observed surface topography in the central and northern TAMs, thereby providing support for uplift models that advocate for thermal loading and a flexural origin for the mountain range.", "east": 165.120012, "geometry": ["POINT(159.223506 -74.6349495)"], "keywords": "Antarctica; Geology/Geophysics - Other; Model; Seismology; Solid Earth; Tomography; Transantarctic Mountains", "locations": "Antarctica; Transantarctic Mountains", "north": -73.032547, "nsf_funding_programs": null, "persons": "Hansen, Samantha", "project_titles": "CAREER: Deciphering the Tectonic History of the Transantarctic Mountains and the Wilkes Subglacial Basin", "projects": [{"proj_uid": "p0000300", "repository": "USAP-DC", "title": "CAREER: Deciphering the Tectonic History of the Transantarctic Mountains and the Wilkes Subglacial Basin"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -76.237352, "title": "Upper Mantle Seismic Structure beneath the Northern Transantarctic Mountains from Regional P- and S-wave Tomography", "uid": "601017", "west": 153.327}, {"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}]

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