New insight into the crust and upper mantle structure under Alaska

Cheng Qi, Dapeng Zhao, Yong Chen, Natalia A. Ruppert

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


To better understand the seismic structure of the subducting Pacific plate under Alaska, we determined the three-dimensional P-wave velocity structure to a depth of approximately 200 km beneath Alaska using 438,146 P-wave arrival times from 10,900 earthquakes. In this study an irregular grid parameterization was adopted to express the velocity structure under Alaska. The number of grid nodes increases from north to south in the study area so that the spacing between grid nodes is approximately the same in the longitude direction. Our results suggest that the subducting Pacific slab under Alaska can be divided into three different parts based on its geometry and velocity structure. The western part has features similar to those in other subduction zones. In the central part a thick low-velocity zone is imaged at the top of the subducting Pacific slab beneath north of the Kenai Peninsula, which is believed to be most likely the oceanic crust plus an overlying serpentinized zone and the coupled Yakutat terrane subducted with the Pacific slab. In the eastern part, significant high-velocity anomalies are visible to 60-90 km depth, suggesting that the Pacific slab has only subducted down to that depth.

Original languageEnglish
Pages (from-to)85-100
Number of pages16
JournalPolar Science
Issue number2-4
Publication statusPublished - 2007 Dec


  • Alaska
  • Arc volcanism
  • Seismic tomography
  • Subduction zone
  • Yakutat terrane


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