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- Description:
- The dataset contains velocity measurements along the fiber optic cable connecting the University of Utah campus to the University of Utah Downtown data center (875 West Temple, Salt Lake City, UT). The data has been collected using the Distributed acoustic sensing (DAS) system that records the vibration signals along 8.4 km long optical fiber every 4.9-m interval with a sampling rate of approximately 1000 Hz. The fiber is mainly installed along the red line of TRAX, which is the light rail system of the Utah Transit Authority. The route intersects the East Bench fault, which is known as an active fault segment of the Wasatch Fault zone. Although no earthquake signals were detected, the velocity data converted to strain rate clearly show the operation of trains between the stations at 450 S Main Street and 900 South 200 West. Analysis of this dataset is expected to provide insights into seismic velocities at shallow depths and structures associated with fault scarps. and See README file for data retrieval instructions.
- Keyword:
- seismology, urban seismology, distributed acoustic sensing, fiber optic cable, and strain rate
- Subject:
- Geophysics, Seismology, Seismology--Observations, and Surface fault ruptures
- Creator:
- Kim, HyeJeong and Lin, Fan-Chi
- Contributor:
- Chambers, Derrick
- Owner:
- Kaylee Alexander
- Based Near Label Tesim:
- Salt Lake City, Utah, United States
- Language:
- English
- Date Uploaded:
- 07/01/2024
- Date Modified:
- 10/10/2024
- Date Created:
- 20230524 to 20230526 (period 1), 20230803 to 20230811 (period 3), 20231222 to 20240102 (period 4), and 20230629 to 20230710 (period 2)
- License:
- CC BY NC - Allows others to use and share your data non-commercially and with attribution.
- Identifier:
- https://doi.org/10.7278/S5d-kgxx-ev8y
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- 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:
- 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