Sakaguchi, Arito; Kimura, Gaku; Strasser, Michael; Screaton, Elizabeth J.; Curewitz, Daniel; Murayama, Masafumi (2011): Episodic seafloor mud brecciation due to great subduction zone earthquakes. Geological Society of America (GSA), Boulder, CO, United States, Geology (Boulder), 39 (10), 919-922, georefid:2011-097142
Abstract:
The Nankai Trough off southwest Japan has an approximately 1300 yr historical record of great earthquakes, including the most recent, the A.D. 1944 Tonankai (M = 8.2) earthquake. Evaluation of the activity of an individual submarine fault is difficult when only onland observations are available. Submarine core records can pinpoint individual fault activity. Here we present Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment data from the shallow portion. IODP Expedition 316 drilled and cored several holes in the shallow portion of the offshore Tonankai earthquake area, including sites in the hanging wall of a margin-dominating splay fault that has previously been interpreted to have ruptured coseismically during megathrust earthquakes. X-ray computed tomography scanning revealed that the uppermost core at one site contains repeated occurrences of mud breccia. Radioisotope dating of the uppermost mud breccia indicates a deposition time consistent with the 1944 Tonankai earthquake, suggesting that the mud-breccia layers result from episodic brecciation caused by seismic shaking. Mud brecciation provides a potential new tool to reconstruct ancient earthquake history in subduction zones.
Coverage:
West: 136.4300 East: 136.4800 North: 33.1400 South: 33.0100
Relations:
Supplemental Information:
Includes appendix
Data access: