NSFGEO-NERC: Global ultralow-velocity zone properties from seismic waveform modeling
Lead Research Organisation:
University of Oxford
Department Name: Earth Sciences
Abstract
The Earth's core-mantle boundary (CMB) region is of critical importance for understanding Earth dynamics and harbors a wide variety of heterogeneous structures. Ultra-low velocity zones (ULVZs) are regions of reduced seismic velocities at the CMB, which have been associated with hot spot volcanism,
Large Igneous Provinces, core-mantle interaction and Large-Low Shear Velocity Provinces and thus are essential in assessing Earth dynamics. ULVZs are typically studied using seismic waveform analysis, but these studies suffer from large uncertainties in ULVZ parameters due to modeling tradeoffs.
Fundamental questions related to the physical nature of ULVZs remain unanswered, including their compositional variability, size distribution, location with respect to other structures, and 3-D geometry. Additionally, only a small fraction of the CMB area has been probed for ULVZs. Here, we seek to fundamentally reassess ULVZs from all angles, and reduce uncertainties in their properties, location, and composition.
Large Igneous Provinces, core-mantle interaction and Large-Low Shear Velocity Provinces and thus are essential in assessing Earth dynamics. ULVZs are typically studied using seismic waveform analysis, but these studies suffer from large uncertainties in ULVZ parameters due to modeling tradeoffs.
Fundamental questions related to the physical nature of ULVZs remain unanswered, including their compositional variability, size distribution, location with respect to other structures, and 3-D geometry. Additionally, only a small fraction of the CMB area has been probed for ULVZs. Here, we seek to fundamentally reassess ULVZs from all angles, and reduce uncertainties in their properties, location, and composition.
Planned Impact
This work will be the focus of research for two postdoctoral research fellows at the University of Utah and the University of Oxford, and will provide support for an Associate Research Scholar at Princeton University. The research will also enhance new international research collaboration between US/UK based researchers Michael Thorne (U. Utah), Tarje Nissen-Meyer (U. Oxford), Sebastian Rost (U. Leeds) and June Wicks (Princeton). All data and results from this study will be shared openly on University of Utah web space. All software developed will be made freely available through GitHub and Oxford webpages.
Publications
Abreu R
(2023)
Deep Earth rotational seismology
in Geophysical Journal International
Daubar I
(2020)
A New Crater Near InSight: Implications for Seismic Impact Detectability on Mars
in Journal of Geophysical Research: Planets
Denolle MA
(2020)
Quiet Anthropocene, quiet Earth.
in Science (New York, N.Y.)
Ermert L
(2021)
Multifrequency inversion of global ambient seismic sources
in Geophysical Journal International
Haindl C
(2021)
A 3D complexity-adaptive approach to explore sparsity in elastic wave propagation
in GEOPHYSICS
Hansen S
(2021)
Historical Interstation Pattern Referencing (HIPR): An Application to PcP Waves Recorded in the Antarctic for ULVZ Imaging
in Journal of Geophysical Research: Solid Earth
Hansen S
(2020)
Investigating ultra-low velocity zones in the southern hemisphere using an Antarctic dataset
in Earth and Planetary Science Letters
Hosseini K
(2020)
Global mantle structure from multifrequency tomography using P, PP and P-diffracted waves
in Geophysical Journal International
Krier J
(2021)
A Compositional Component to the Samoa Ultralow-Velocity Zone Revealed Through 2- and 3-D Waveform Modeling of SKS and SKKS Differential Travel-Times and Amplitudes
in Journal of Geophysical Research: Solid Earth
| Description | We made significant progress on two fronts: 1) Development of novel modeling methods for wave propagation inside Earth to improve the accuracy and thus understanding of features in Earth's interior and 2) a series of publications constraining the locations and properties of the most mysterious and complex structure in the deep Earth: Ultra-low-velocity zones above the core mantle boundary. These are expected to hold key insights into Earth's heat budget, chemical composition, dynamics and evolution. Our maps of these curious features across the core mantle boundary are state-of-the-art, based on novel datasets and our own modeling software. More publications to follow, possibly with high impact. Given the inability to travel due to the pandemic, we have not been able to do our intended in-depth collaborative stays and overall workshop-style meetings with our overseas partners (as part of the NSF/NERC scheme). This will be crucial to wrap up the science project, and is the justification to ask for an extension. We published more papers, are still working on yet a few more, and currently writing a proposal to follow this award. I consider this project massively successful, especially given the pandemic circumstances. Some more papers have the potential for very high impact, and our follow up proposal is geared towards unravelling first-order questions of the deep Earth. |
| Exploitation Route | Our software has already been used by numerous other groups worldwide, and will lead to a code release. Our papers on ULVZs are emerging as the basis for further work for ourselves and other groups. |
| Sectors | Digital/Communication/Information Technologies (including Software),Education |
| Description | The methods developed with this award have been used worldwide since then, including on Mars' InSight mission, for visualisation projects, featured on youtube etc. |
| First Year Of Impact | 2019 |
| Sector | Digital/Communication/Information Technologies (including Software),Education,Other |
| Impact Types | Cultural,Policy & public services |