Structural control on the nucleation of megathrust earthquakes in the Nankai subduction zone

Xin Liu, Dapeng Zhao

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

To clarify the causal mechanisms of megathrust earthquakes, we studied the detailed three-dimensional P and S wave velocities (V), attenuation (Q), and Poisson's ratio (σ) structures of the Nankai subduction zone in southwest Japan, using a large number of high-quality arrival time and t∗ data measured precisely from seismograms of local earthquakes. The suboceanic earthquakes used are relocated precisely using sP depth phase and ocean bottom seismometer data. Our results show the existence of two prominent high-V, high-Q, and low-σ patches separated by low-V, low-Q, and high-σ anomalies in the Nankai megathrust zone. Megathrust earthquakes during 1900 to 2013 nucleated in or around the high-V, high-Q, and low-σ patches, which may represent strongly coupled areas (i.e., asperities) in the megathrust zone. Our results indicate that structural heterogeneities in the megathrust zone, such as the subducting seafloor topography and compositional variations, control the nucleation of the Nankai megathrust earthquakes.

Original languageEnglish
Pages (from-to)8288-8293
Number of pages6
JournalGeophysical Research Letters
Volume41
Issue number23
DOIs
Publication statusPublished - 2014 Dec 16

Keywords

  • Nankai subduction zone
  • megathrust earthquakes
  • seafloor topography
  • seismic tomography
  • structural heterogeneity

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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