Cascadia Open-Access Seismic Transects

 

PIs:  Steve Holbrook (University of Wyoming), Graham Kent (University of Nevada), Katie Keranen (University of Oklahoma)
 
Cruise Dates: July 12-24, to and from Astoria, Oregon
 
Location: Cascadia subduction margin
 
During COAST (Cascadia Open-Access Seismic Transects), we collected geophysical data on the Cascadia subduction margin on cruise MGL1212 of the R/V Marcus G. Langseth, from July 12-24, 2012 (from the cruise report). The purpose of the cruise, which was funded by the NSF Marine Geology and Geophysics program, was to acquire a grid of 2D seismic reflection profiles and associated geophysical data in a high-priority GeoPRISMS corridor off Grays Harbor, Washington. An important secondary goal was to conduct an open-participation, open-access cruise, with an organized shipboard education and training program, and immediate, full release to the community of all geophysical data. The COAST data will provide benchmark seismic images to address key scientific issues regarding the location, physical state, fluid budget, and associated methane systems of the subducting plate boundary and overlying crust. These include (1) determining the location of the offshore plate boundary beneath a segment of the Cascadia margin that ruptures in very large, infrequent earthquakes, (2) constraining sediment subduction and plate boundary roughness, (3) estimating pore fluid pathways, (4) determining controls on methane distribution, and (5) imaging compressional and extensional structures that may pose geohazards on the Cascadia margin.
 
The open-participation aspect of the cruise was a great success. From a group of about 60 applicants, the PI's selected 17 participants from 14 institutions, comprising thirteen graduate students, two postdocs, and two faculty. The focus on introducing this diverse group of scientists to the science conducted aboard the U.S. National Marine Seismic Facility resulted in an empowered, highly motivated shipboard science party that was actively involved in all phases of shipboard operations, data processing, and analysis. Shipboard seismic data processing was conducted primarily by the "newbies," most of whom had little or no previous experience with marine seismic reflection processing. LDEO greatly assisted the open-participation effort by making every berth on the ship available; we sailed with 55 people aboard, including a visiting science party of 20.
 
Blog:   COAST
 
News:  EOS article, published by the American Geophysical Union (AGU) December 2012
 
JPEGS of Data Examples and Photos