The postearthquake stress state on the Tohoku megathrust as constrained by reanalysis of the JFAST breakout data Academic Article uri icon


  • 2017. American Geophysical Union. All Rights Reserved. The Japan Trench Fast Drilling Project (JFAST) endeavored to establish the stress state on the shallow subduction megathrust that slipped during the M9 Tohoku earthquake. Borehole breakout data from the drill hole can constrain both the orientation and magnitude of the principal stresses. Here we reanalyze those data to refine our understanding of the stress state on the fault. In particular, we (1) improve the identification of breakouts, (2) consider a fuller range of stress states consistent with the data, and (3) incorporate new and more robust laboratory constraints on rock strength. The original conclusion that the region is in a normal faulting regime after the earthquake is strengthened by the new analysis. The combined analysis suggests that the earthquake released sufficient elastic strain energy to reset the local stress field.

published proceedings


altmetric score

  • 0.75

author list (cited authors)

  • Brodsky, E. E., Saffer, D., Fulton, P., Chester, F., Conin, M., Huffman, K., Moore, J. C., & Wu, H.

citation count

  • 21

complete list of authors

  • Brodsky, Emily E||Saffer, Demian||Fulton, Patrick||Chester, Frederick||Conin, Marianne||Huffman, Katelyn||Moore, J Casey||Wu, Hung-Yu

publication date

  • August 2017