Detecting seismic signatures in the rock record at the Japan Trench

Author(s): Rabinowitz, H. S.; Savage, H. M.; Polissar, P. J.; Plank, T. A.; Rowe, C. D.; Kirkpatrick, J. D.
Author Affiliation(s): Primary:
Columbia University of New York, Palisades, NY, United States
Lamont Doherty Earth Observatory, Palisades, NY, United States
McGill University, Montreal, QC, Canada
Colorado State University, Fort Collins, CO, United States
Volume Title: AGU 2014 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2014; American Geophysical Union 2014 fall meeting, San Francisco, CA, Dec. 15-19, 2014. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: IODP Expedition 343 (JFAST) drilled through the plate boundary at the Japan Trench where potentially several megathrust earthquakes have occurred, most recently the 2011 Mw 9.1 Tohoku-oki earthquake. Here, we investigate structural features of the plate boundary at the JFAST site to determine their seismic history. Using trace element geochemistry as a tool to fingerprint sedimentary units, we develop a stratigraphy of the JFAST core that shows significant plate boundary complexity. To determine the seismic history of the faults identified in the core, we use a novel method to detect temperature rise along faults: the thermal destruction of organic molecules. We interpret the destruction of alkenones, a common biomarker found in marine sediments, along faults to be a result of coseismic heating. In order to constrain initial alkenone concentration, we use our trace element stratigraphy to correlate individual JFAST samples with their protolith in the DSDP Site 436 reference core. We find that at least three faults demonstrate significant destruction of alkenones, implying that these faults have experienced shallow seismic slip. In the past, frictional work has been difficult to measure on faults due to a paucity of available coseismic temperature proxies preserved in the rock record. By coupling experimentally determined reaction kinetics of alkenone destruction with models of temperature rise during earthquakes, we convert the alkenone destruction measurements into estimates of maximum temperature rise on faults in the JFAST core. This novel measurement allows us to explore energy budgets at the subduction interface.
Year of Publication: 2014
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
Key Words: 19 Geophysics, Seismology; DSDP Site 436; Deep Sea Drilling Project; Earthquakes; Expedition 343; Expeditions 343/343T; Geophysical methods; Geophysical surveys; IPOD; Integrated Ocean Drilling Program; Japan Trench; Japan Trench Fast Drilling Project; Leg 56; North Pacific; Northwest Pacific; Pacific Ocean; Seismic methods; Surveys; Tohoku-Oki earthquake 2011; West Pacific
Coordinates: N375619 N375620 E1435449 E1435447
N395557 N395558 E1453329 E1453328
Record ID: 2015078750
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