Unprocessed seismic reflection shot gathers from Ghost Ridge, Thwaites Glacier, West Antarctica (2024)
GB/NERC/BAS/PDC/02183
Abstract:
In 2024, a 14.4 km long seismic reflection profile was collected near to Ghost Ridge, Thwaites Glacier, West Antarctica (~65 km upstream of the grounding line). Normal-incidence and wide-angle data were collected with the aim of studying basal conditions. Data were collected using 8 geometrics geode systems and 96 georods (four-element geophones) placed at intervals of 20 m. Explosive sources were buried in hot water drilled holes. This dataset consists of 40 unprocessed shot gathers.
These data were acquired as part of the Geophysical Habitat of Subglacial Thwaites (GHOST) project, a component of the International Thwaites Glacier Collaboration, with support provided by US Support from National Science Foundation (NSF: Grant NSF-NERC-PLR-1738934) and Natural Environment Research Council (NERC: Grant NE/S006672/1).
Citation:
Agnew, R., Anandakrishnan, S., Brisbourne, A., Borthwick, L., Melton, S., & Willet, A. (2026). Unprocessed seismic reflection shot gathers from Ghost Ridge, Thwaites Glacier, West Antarctica (2024) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/5923905d-edb4-459a-b744-5a684b1592fa
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License
| Access: | None |
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| Use: | Data supplied under Open Government Licence v3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
Basic Information
| Creation Date: | 2026-04-16 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
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| Parameters: |
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Additional Information
| Reference: | Associated paper: Agnew RS, Anandakrishnan S, Brisbourne A, Hank K, Muto A, Zoet L, Borthwick L, Melton S, Willet A, Alley R, Smith A (2026). Seismic evidence for heterogeneous subglacial sediments at Thwaites Glacier, West Antarctica. Submitted to Journal of Geophysical Research: Earth Surface. Preprint at ESS Open Archive: https://doi.org/10.22541/essoar.15001803/v1 | |
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| Quality: | 4000Hz sample rate with shot initiation and Geode trigger using GPS timing Source locations surveyed with RTK GPS. Receiver locations determined using takeouts on seismic cable. Source location/elevation accuracy <0.5m. Receiver location/elevation accuracy <0.3m. Source depth accuracy ~2m. Elevation reference WGS-84 Ellipsoid. Elevations converted to orthometric heights using EGM-2008 Geoid. Common Midpoint (CMP) locations at 10m intervals. The dominant frequency of the wavelet is 200 Hz and the first unmigrated Fresnel radius is 140 m for 2 km thick ice. |
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| Lineage/Methodology: | Data were acquired with 96 40 Hz georods with 20 m spacing between georods (1920m spread length). The downstream-most georod was placed at 0m on the seismic profile (channel 1). Sources were detonated at 20m, 1940m and 3860m offset upstream from the last georod channel in each spread (channel 191). Shots were buried in hot water drilled boreholes to depths of between 2m and 52m (median 36m), backfilled with snow and left to sinter for at least 24 hours. Approximate source depths and charge sizes are given in the accompanying csv file GHOST_seismic_shotlocdepth.csv. Source depths were estimated from the remaining length above ground of a known length of wire placed down shotholes and used to detonate shots. Surveying procedure: Source locations were determined using real-time kinematic (RTK) surveying with Stonex S900+ GNSS receivers. Base station locations were recorded in RINEX format on each day of GNSS surveying (5 total) and processed using the Canadian Spatial Reference System Precise Point Positioning (PPP) service. Errors on source locations were calculated by combining the root-sum square of the base station location errors with the root-mean squared error from the RTK survey. Absolute errors on source locations are less than 0.5m. Shot point coordinates are given in the csv file GHOST_seismic_shotflag_locations.csv . Receiver locations were determined from seismic cable takeouts. In the SEG-Y headers, the x direction is along the seismic line. The y direction is directly perpendicular to the line, which is why y coordinates are zero. The units of x are determined by the header SourceGroupScalar such that x (m) = x (header value)*abs(SourceGroupScalar) for SourceGroupScalar>0, and x(m) = x(header value)/abs(SourceGroupScalar) for SourceGroupScalar<0. This dataset has SourceGroupScalar=-100 for each trace so units of x are cm. The archived data presented here consist of 40 unprocessed shot gathers. The data were originally recorded on 192 channels with georods connected at intervals of 2 channels. On the original dataset, dead channels are all even channels, as georods were connected every other channel. In this archived segy, there are no dead channels. The TraceSequenceLine header therefore has an increment of 2 while the traceSequenceFile header has increments of 1.Channel numbers in the segy headers therefore run from 1 to 191 in intervals of 2. |
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Extent
| Temporal Coverage: | |
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| Start Date | 2024-01-01 |
| End Date | 2024-01-09 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -76.14745 |
| Northernmost | -75.99552 |
| Longitude | |
| Westernmost | -107.5073 |
| Easternmost | -107.4165 |
| Altitude | |
| Min Altitude | 851.3 |
| Max Altitude | 968.8 |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Data Resolution: | |
| Latitude Resolution | N/A |
| Longitude Resolution | N/A |
| Horizontal Resolution Range | 1 meter - < 30 meters |
| Vertical Resolution | N/A |
| Vertical Resolution Range | N/A |
| Temporal Resolution | N/A |
| Temporal Resolution Range | N/A |
| Location: | |
| Location | Antarctica |
| Detailed Location | Thwaites Glacier |
Instrumentation
| Sensor(s): |
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| Data Collection: | Seismic data recorded on 8x 24 channel Geometrics Geode with 96x 40Hz Georods (20m spacing, channels occupied in intervals of 2). Record length 4 seconds. Geophone elements: Four in series vertical - OYO Geospace 40Hz natural frequency miniature geophone elements, 270 Ohm damping resistance Source: Pentolite shots (cast primers). Source sizes and depths are given in accompanying table. Surveying: Stonex S900+ GNSS receivers used to record source positions. GNSS data processed using Canadian Spatial Reference System Precise Point Positioning service and Python. Software: Raw SEG-D files processed in Halliburton ProMax and Mathworks MATLAB to create gathers and add headers. |
Storage
| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 241 MB |
| Distribution Format | N/A |
| Fees | N/A |
| Data Storage: | The dataset consists of: - One single file of IBM Real SEGY; 4 sec records, 4 kHz sampling 96 channels, 20m channel interval. Geometry is assigned in trace headers. Trace header runs from 1 to 191 in intervals of 2: GHOST_all_gathers_2024 ~240 MB - 1 CSV file with the seismic shot point coordinates: GHOST_seismic_shotflag_locations.csv. ~2 kB - 1 CSV file with the seismic approximate source depths and charge sizes:GHOST_seismic_shotlocdepth.csv ~3 kB |