The 2008 Iwate-Miyagi earthquake (M7.2) and arc volcanism: Insight from irregular-grid tomography

Wei Wei, Dapeng Zhao

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


To better understand the seismotectonics and arc magmatism in the Northeast Japan subduction zone, we studied high-resolution 3-D P-and S-wave velocity structures of the crust and upper mantle under this region using a large number of high-quality arrival-time data from the local shallow and intermediate-depth earthquakes recorded by the high-sensitivity seismic network installed on the Japan Islands. We adopt an irregular-grid parameterization to conduct the tomographic inversion in order to extract more useful information from the data used. Our results show that the mainshock of the 2008 Iwate-Miyagi earthquake (M7.2) was located in a boundary zone where seismic velocity changed dramatically, indicating that the crustal medium in the source area is very heterogeneous. A pronounced low-velocity anomaly is revealed in the lower crust and uppermost mantle under the mainshock hypocenter, which may reflect the arc magma and fluids ascending from the upper-mantle wedge released by the dehydration process of the subducting Pacific slab. The fluids and arc magma may have influenced the nucleation and rupture process of the large crustal earthquakes.

Original languageEnglish
Pages (from-to)155-171
Number of pages17
JournalEarth Science Frontiers
Issue number2
Publication statusPublished - 2013 Mar


  • 2008 Iwate-Miyagi earthquake
  • Arc magma and fluids
  • Irregular-grid parameterization
  • Low-frequency earthquakes
  • Slab dehydration


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