Shallow soft sediment deformation at IODP sites C0006 and C0007, Nankai Trough, Japan: evidence for strong ground motion at the frontal thrust

Drake Singelton
Drake Singleton
San Diego State University
Wednesday April 18th, 2018
CSL 422 – 1pm

For over 50 years the International Ocean Drilling Program (IODP) has provided the platform to further research about the oceanic lithosphere.  The Japanese Islands are located at a complex tectonic margin, susceptible to large earthquakes. This talk focuses on research conducted during the Core-Log-Seismic Investigation at Sea (CLSI@Sea) workshop, held concurrently with IODP expedition 380 aboard the D/V Chikyu. The devastating 2011, Mw 9.0 Tohoku earthquake demonstrated the significance that coseismic slip to the trench axis has on generating large earthquakes and subsequent tsunamis. CLSI@Sea promotes collaboration between early career scientists and senior research mentors to investigate the role of the frontal thrust during large earthquakes.  The workshop focused on the well-studied Nankai Trough in southwest Japan, which has been identified as having a high likelihood for large magnitude earthquakes and possible tsunamis.  Recovered cores of the very shallow subsurface at the frontal thrust were examined with Computer Tomography imaging techniques for evidence of soft sediment deformation associated with coseismic slip to the trench. Preliminary results show evidence for high intensity ground shaking at the trench axis, which may indicate coseismic slip near to, or at the trench axis.