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- Description:
- This dataset includes electrical resistivity tomography (ERT) measurements collected around the Great Salt Lake (GSL). This was supported through an NSF Rapid proposal. These preliminary measurements form a baseline by which to do ERT measurements to detect ground-water changes around GSL.
- Keyword:
- Great Salt Lake, geophysics, electrical resistivity tomography, and groundwater
- Subject:
- Geophysics and Geology
- Creator:
- Thorne, Michael S.
- Owner:
- Michael Thorne
- Based Near Label Tesim:
- Great Salt Lake, Utah, United States
- Language:
- English
- Date Uploaded:
- 06/19/2024
- Date Modified:
- 06/20/2024
- Date Created:
- 2023-06-06 to 2023-10-09
- License:
- Public Domain – This data is free of copyright restrictions (e.g. government sponsored data).
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S5d-mdx6-v88s
- Description:
- Ultralow-velocity zones (ULVZs) have been studied using a variety of seismic phases; however, their physical origin is still poorly understood. Short period ScP (S wave converted to, and reflected as, P wave from the core-mantle boundary) waveforms are extensively used to infer ULVZ properties because they may be sensitive to all ULVZ elastic moduli. However, ScP waveforms are additionally complicated by the effects of path attenuation, coherent noise, and source-time function (STF) complexity. To address these complications, we developed a hierarchical Bayesian inversion method that allows us to invert ScP waveforms from multiple events simultaneously and accounts for path attenuation and correlated noise. The inversion method is tested with synthetic predictions which show that the inclusion of attenuation is imperative to recover ULVZ parameters and that the ULVZ thickness and S-wave velocity decrease (δVS) are most reliably recovered. Utilizing multiple events reduces the effects of coherent noise and STF complexity, which in turns allows for the inclusion of more data to be used in the analyses. We next applied the method to ScP data recorded in Australia for 291 events that sample the CMB beneath the Coral Sea. Our results indicate that S-wave velocity across the region is ~-14% in average, but there is a greater variability in the south than that in the north. P-wave velocity reductions and density perturbations are mostly below 10%. These ScP data show more than one ScP post-cursor in some areas which may indicate complex 3-D ULVZ structures. Seismic data are provided for 291 earthquakes in Northern Territory, Australia.
- Keyword:
- seismology, mantel phases, ULVZ, and short period ScP waveforms
- Subject:
- Geology, Seismology, and Geophysics
- Creator:
- Pachhai, Surya and Thorne, Michael S.
- Owner:
- Surya Pachhai
- Based Near Label Tesim:
- Northern Territory, Northern Territory, Australia
- Language:
- English
- Date Uploaded:
- 12/10/2022
- Date Modified:
- 06/03/2024
- Date Created:
- 2005-01-01 to 2021-12-30.
- License:
- Public Domain – This data is free of copyright restrictions (e.g. government sponsored data).
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S50d-a67s-y717
- Description:
- Classification of barrier island morphology stems from the seminal work of M. O. Hayes and others, which linked island shape to tidal range and wave height and defined coastal energy regimes (i.e., wave-dominated, mixed energy, tide-dominated). If true, this general relationship represents a process-based framework to link modern and ancient systems, and is key for determining paleomorphodynamic relationships. Here we present a new semi-global database of barrier islands and spits (n = 702). Shape parameters (aspect, circularity, and roundness) are used to quantify island boundary shape, and assess potential correlation with coastal energy regime using global wave and tide models. In adopting the original energy classification as originally put forth (i.e., wave dominated, wave-influenced mixed, tide-influenced mixed, tide dominated), results show that wave-dominated islands have statistically different mean shape values from those in the mixed energy fields, but the two mixed energy designations are not distinct from each other. Furthermore, each energy regime field contains a wide range of island shapes, with no clear trends present. Linear regression modeling shows that tidal range and wave height account for < 10% of the documented variance in island shape, a strong indication that other controls must be considered. Therefore, while energy regime distinctions can be used descriptively, their utility in predicting and constraining island shape is limited: barrier island shape is not indicative of coastal energy regime, and vice versa. Our analysis also demonstrates empirical scaling relationships among modern barrier islands for the first time, with implications for subsurface prediction. and This is the dataset of the Modern Barrier Island Database published in Mulhern et al., 2017 Marine Geology paper titled "Is Barrier Island Morphology a Function of Wave and Tide Regime?" with the DOI https://doi.org/10.1016/j.margeo.2017.02.016. If using this dataset please cite both the dataset and the paper.
- Keyword:
- paleomorphodynamic relationships, geology, barrier island, shallow marine, island shape, wave-dominated islands, shoreline morphology, Modern Barrier Island Database, and coastal geomorphology
- Subject:
- Geology
- Creator:
- Johnson, Cari L., Mulhern, Julia S., and Martin, John M.
- Owner:
- Julia Mulhern
- Language:
- English
- Date Uploaded:
- 09/08/2021
- Date Modified:
- 06/03/2024
- Date Created:
- 2015-01-01 to 2017-12-31
- License:
- CC BY NC - Allows others to use and share your data non-commercially and with attribution.
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S50d-5pzj-r9vr
- Description:
- This dataset accompanies the research article entitled, "Vibration of Natural Rock Arches and Towers Excited by Helicopter-Sourced Infrasound," where we investigate the vibration response of seven landforms to helicopter-sourced infrasound during controlled flight. Included are time-series vibration data of the landforms and nearby ground during and before helicopter flight, time-series infrasound data, 3D photogrammetry models of the studied landforms, and GPS data from the helicopter.
- Keyword:
- human environmental impacts, natural arches, helicopters, vibration response, natural towers, and rock landforms
- Subject:
- Geology, Environmental Seismology, and Geophysics
- Creator:
- Finnegan, Riley, Moore, Jeffrey R., and Geimer, Paul R.
- Owner:
- Riley Finnegan
- Based Near Label Tesim:
- Utah, Utah, United States
- Language:
- English
- Date Uploaded:
- 04/20/2021
- Date Modified:
- 04/16/2024
- Date Created:
- 2017-01-01 to 2019-12-31
- License:
- CC BY NC - Allows others to use and share your data non-commercially and with attribution.
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S50D-41SW-THMA
- Description:
- We analyzed 4,754 broadband seismic recordings of the SKS, SKKS, and SPdKS wavefield from 13 high quality events sampling the Samoa ultralow-velocity zone (ULVZ). We measured differential travel-times and amplitudes between the SKKS and SKS arrivals, which are highly sensitive to the emergence of the SPdKS seismic phase, which is in turn highly sensitive to lowermost mantle velocity perturbations such as generated by ULVZs. We modeled these data using a 2-D axi-symmetric waveform modeling approach and are able to explain these data with a single ULVZ. In order to predict both travel-time and amplitude perturbations we found that a large ULVZ length in the great circle arc direction on the order of 10° or larger is required. The large ULVZ length limits acceptable ULVZ elastic parameters. Here we find that δVS and δVP reductions from 20% to 22% and 15% to 17% respectively gives us the best fit, with a thickness of 26 km. Initial 3-D modeling efforts do not recover the extremes in the differential measurements, demonstrating that 3-D effects are important and must be considered in the future. However, the 3-D modeling is generally consistent with the velocity reductions recovered with the 2-D modeling. These velocity reductions are compatible with a compositional component to the ULVZ. Furthermore, geodynamic predictions for a compositional ULVZ that is moving predict a long linear shape similar to the shape of the Samoa ULVZ we confirm in this study. and This collection includes radial component displacement seismograms in the time window including the SKS, SKKS and SPdKS seismic arrivals. These data all interact with the Samoa ultra-low velocity zone at the core-mantle boundary. All data used in the study of Krier et al., 2021 (JGR) is included in this collection.
- Keyword:
- seismology, Samoa hot spot, geodynamic predictions model, 3-D model, ULVZ, and ultra-low velocity zone
- Subject:
- Geology, seismology, and Geophysics
- Creator:
- Thorne, Michael S. , Nissen-Meyer, Tarje , Krier, Justin D. , and Leng, Kuangdai
- Owner:
- Michael Thorne
- Based Near Label Tesim:
- Tonga Trench, , Tonga
- Language:
- English
- Date Uploaded:
- 02/17/2021
- Date Modified:
- 10/25/2024
- Date Created:
- 2019-01-01 to 2020-01-31
- License:
- Public Domain – This data is free of copyright restrictions (e.g. government sponsored data).
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S50DT3X22GGB
- Description:
- Subglacial water pressures influence groundwater conditions in proximal alpine valley rock slopes, varying with glacier advance and retreat in parallel with changing ice thickness. Fluctuating groundwater pressures in turn increase or reduce effective joint normal stresses, affecting the yield strength of discontinuities. Here we extend simplified assumptions of glacial debuttressing to investigate how glacier loading cycles together with changing groundwater pressures generate rock slope damage and prepare future slope instabilities. Using hydromechanical coupled numerical models closely based on the Aletsch Glacier valley in Switzerland, we simulate Late Pleistocene and Holocene glacier loading cycles including long-term and annual groundwater fluctuations. Measurements of transient subglacial water pressures from ice boreholes in the Aletsch Glacier ablation area, as well as continuous monitoring of bedrock deformation from permanent GNSS stations helps verify our model assumptions. While purely mechanical glacier loading cycles create only limited rock slope damage in our models, introducing a fluctuating groundwater table generates substantial new fracturing. Superposed annual groundwater cycles increase predicted damage. The cumulative effects are capable of destabilizing the eastern valley flank of our model in toppling-mode failure, similar to field observations of active landslide geometry and kinematics. We find that hydromechanical fatigue is most effective acting in combination with long-term loading and unloading of the slope during glacial cycles. Our results demonstrate that hydromechanical stresses associated with glacial cycles are capable of generating substantial rock slope damage and represent a key preparatory factor for paraglacial slope instabilities.
- Keyword:
- Aletsch Glacier, boreholes, numerical models, subglacial water pressure, Switzerland, Late Pleistocene, Holocene, ground water, and geology
- Subject:
- Geology
- Creator:
- Moore, Jeffrey R., Loew, Simon, Limpach, Philippe, Gischig, Valentin, Grämiger, Lorenz, and Funk, Martin
- Owner:
- Jeff Moore
- Based Near Label Tesim:
- Aletsch Glacier, Valais, Switzerland
- Language:
- English
- Date Uploaded:
- 01/03/2020
- Date Modified:
- 10/29/2024
- Date Created:
- Borehole P1 2013-07-12 09:28:09 to 2014-08-08 09:11:14 and Borehole P2: 2013-07-16 05:00:03 to 2014-08-08 22:10:44
- License:
- CC BY NC - Allows others to use and share your data non-commercially and with attribution.
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S50D-A50H-3TE4