Constraints on Mantle Dynamics From a Massive Seismic Dataset
Description:
Shear wave speeds in Earth's mantle that vary with wave propagation and polarization direction -- a property called seismic anisotropy -- offer insights into mantle convection. Investigations of mantle dynamics through analyses of seismic anisotropy are often conducted with data limited to regional investigations; however, seismic data are available on a tera- or petabyte scale, and data availability is exponentially growing.
I have analyzed shear-wave splitting, which is indicative of seismic anisotropy, using a massive seismic dataset. This dataset contains seismograms for earthquakes with magnitudes ≥5.9 from the year 2000 to the present, retrieved from 24 data centers worldwide (~5,000 events). My measurements allow the inference of seismic anisotropy in two poorly sampled parts of the mantle, the lowermost mantle and the upper mantle beneath ocean basins: 1. I present lowermost mantle anisotropy results inferred from core-refracted phases from the massive dataset, which cover 75% of the lowermost mantle, mostly in the Earth’s faster mantle volumes. In these regions, seismic anisotropy is widespread, and my observations suggest a close link between the subduction of tectonic plates and convective flow in the deepest mantle. 2. By utilizing specific combinations of seismic phases, I infer body wave constraints on upper mantle seismic anisotropy beneath ocean basins using land-based seismic stations. One intriguing observation is that, where the seafloor beneath the Pacific Plate is oldest, shear wave fast polarization directions are oriented 60–90 degrees away from the absolute plate motion. This likely reflects fossil anisotropy in the lithosphere, offering valuable insights into ancient deformation events.
Session: Earth’s Structure from the Crust to the Core - III
Type: Oral
Date: 4/16/2025
Presentation Time: 03:00 PM (local time)
Presenting Author: Jonathan
Student Presenter: No
Invited Presentation: Yes
Poster Number:
Authors
Jonathan Wolf Presenting Author Corresponding Author jonathan.wolf@berkeley.edu University of California, Berkeley |
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Constraints on Mantle Dynamics From a Massive Seismic Dataset
Session
Earth’s Structure from the Crust to the Core