Letter | Published:

Dynamics of a seafloor-spreading episode at the East Pacific Rise

Nature volume 540, pages 261265 (08 December 2016) | Download Citation

Abstract

Seafloor spreading is largely unobserved because 98 per cent of the global mid-ocean-ridge system is below the ocean surface. Our understanding of the dynamic processes that control seafloor spreading is thus inferred largely from geophysical observations of spreading events on land at Afar in East Africa and Iceland1. However, these are slow-spreading centres1 influenced by mantle plumes2,3. The roles of magma pressure and tectonic stress in the development of seafloor spreading are still unclear. Here we use seismic observations to show that the most recent eruption at the fast-spreading East Pacific Rise just North of the Equator initiated at a melt-rich segment about 5 kilometres long4. The change in static stress then promoted almost-concurrent rupturing along at least 35 kilometres of the ridge axis, where tectonic stress had built up to a critical level, triggering magma movement. The location of impulsive seismic events indicative of lava reaching the seafloor5 suggests that lava subsequently erupted from multiple isolated6,7 magma lenses (reservoir chambers) with variable magma ascent rates, mostly within 48 hours. Therefore, even at magmatically robust fast-spreading ridges, a substantial portion of the spreading may be due to tectonic stress building up to a critical level rather than magma overpressure in the underlying magma lenses.

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Acknowledgements

Y.J.T. thanks W. R. Buck for discussions and reading of the manuscript. Y.J.T. thanks A. H. Barclay and R. S. Matoza for discussions. We thank R. P. Dziak and D. R. Bohnenstiehl for providing the T-wave earthquake catalogue. We thank the captains, crews and science parties of the RV Knorr and RV Atlantis. This work was supported by NSF grant OCE-0961594.

Author information

Affiliations

  1. Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA

    • Yen Joe Tan
    • , Maya Tolstoy
    •  & Felix Waldhauser
  2. School of Oceanography, University of Washington, Seattle, Washington 98195, USA

    • William S. D. Wilcock

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Contributions

Y.J.T., advised by M.T. and F.W., analysed the seismic data and wrote the manuscript. M.T. and F.W. conceived and ran the experiment. W.S.D.W.’s identification of impulsive lava signals at Axial inspired this study. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Yen Joe Tan.

Reviewer Information Nature thanks J. Karson and V. Schlindwein for their contribution to the peer review of this work.

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https://doi.org/10.1038/nature20116

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