A high-resolution map of Hawaiian ULVZ morphology from ScS phases

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

“…ULVZs beneath Iceland (Yuan & Romanowicz, 2017) or Hawaii (Cottaar & Romanowicz, 2012;Kim et al, 2020) may rival the Samoa ULVZ in size, but at least initially appeared to be rounded features, rather than the long linear feature observed beneath Samoa. However, we note that recent studies suggest that ULVZ structure beneath Hawaii may also be significantly larger and more complicated than originally imaged (Jenkins et al, 2021;Zhao et al, 2016). KRIER ET AL.…”

“…ULVZs beneath Iceland (Yuan & Romanowicz, 2017) or Hawaii (Cottaar & Romanowicz, 2012;Kim et al, 2020) may rival the Samoa ULVZ in size, but at least initially appeared to be rounded features, rather than the long linear feature observed beneath Samoa. However, we note that recent studies suggest that ULVZ structure beneath Hawaii may also be significantly larger and more complicated than originally imaged (Jenkins et al, 2021;Zhao et al, 2016 The Samoa hot spot shows one of the clearest whole mantle plume signatures in seismic tomography (French & Romanowicz, 2015;Montelli et al, 2006). However, volcanism along the Samoa line shows a wide array of isotopic taxonomies spanning the major Ocean Island Basalt end members.…”

Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations

“…Based on these calculations, we determined that pyrite‐structured (Al 1‐X ,Fe X )O 2 H with X = 0.4–0.5 can simultaneously reproduce ∼10% V P and ∼20% V S reductions relative to the bulk mantle (i.e., bridgmanite) characteristic of ULVZs (e.g., Jenkins et al., 2021). Solid solutions in this compositional range are 10%–11% denser than bridgmanite, providing gravitational stability at the CM​B (McNamara et al., 2010), although this density contrast may be reduced at the high temperatures of the mantle and by thermochemical convection.…”

Strong ULVZ and Slab Interaction at the Northeastern Edge of the Pacific LLSVP Favors Plume Generation

“…Apart from the lateral variation in ULVZ thicknesses, the region toward the edge is thought to be more complex with layers of fast and slow velocity compared to the region with the thickest ULVZ. Jenkins et al (2021) further expanded on the ScS pre-and post-cursors study by Zhao et al (2017) and suggested an asymmetric ULVZ ridge, increasing in thickness toward northeast along this margin. Sun et al (2019) also showed there are strong multipathing of ScS at two distinct patches along this boundary for several earthquakes (Figure S1 and Table S1 in Supporting Information S1).…”

“…Sun et al (2019) also showed there are strong multipathing of ScS at two distinct patches along this boundary for several earthquakes (Figure S1 and Table S1 in Supporting Information S1). The northern patch (Figure 1, Box 2) is modeled extensively as a ULVZ structure in Sun et al (2019) and Jenkins et al (2021). (Simmons et al, 2010) at the CMB.…”