Sub-Lithospheric Small-Scale Convection Tomographically Imaged Beneath the Pacific Plate

Zachary C. Eilon, Lun Zhang, James B. Gaherty, Donald W. Forsyth, Joshua B. Russell

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Small-scale convection beneath the oceanic plates has been invoked to explain off-axis nonplume volcanism, departure from simple seafloor depth-age relationships, and intraplate gravity lineations. We deployed 30 broadband ocean bottom seismometer stations on ∼40 Ma Pacific seafloor in a region notable for gravity anomalies, measured by satellite altimetry, elongated parallel to plate motion. P-wave teleseismic tomography reveals alternating upper mantle velocity anomalies on the order of ±2%, aligned with the gravity lineations. These features, which correspond to ∼300°–500°K lateral temperature contrast, and possible hydrous or carbonatitic partial melt, are—surprisingly—strongest between 150 and 260 km depth, indicating rapid vertical motions through a low-viscosity asthenospheric channel. Coherence and admittance analysis of gravity and topography using new multibeam bathymetry soundings substantiates the presence of mantle density variations, and forward modeling predicts gravity anomalies that qualitatively match observed lineations. This study provides observational support for small-scale convective rolls beneath the oceanic plates.

Original languageEnglish (US)
Article numbere2022GL100351
JournalGeophysical Research Letters
Issue number18
StatePublished - Sep 28 2022


  • asthenosphere
  • body wave tomography
  • mantle convection
  • ocean bottom seismometer
  • oceanic lithosphere

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


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