Cascadia Subduction Zone Structure

Since 1989, we have conducted a series of experiments to image the crust and upper mantle structure beneath the Cascadia subduction zone in order to better understand plate interactions and seismic hazards. In 1989, we piggybacked on an multichannel seismic reflection survey offshore to conduct an onshore/offshore experiment to image a transect across the margin from the subduction zone deformation front to the Willamette Valley (funded by NSF). This was extended to the Cascades during an onshore active source experiment in 1991 (funded by USGS-NEHRP). In 1993 and 1994, with colleagues from USGS and from Stanford, Lehigh, and Rice Universities) we moved to northern California to image the southern Cascadia subduction zone and northern San Andreas Fault (funded by NSF and USGS). We also conducted a broadband experiment using earthquakes to image deeper structure across Oregon (TORTISS). In 1995 and 1996, we conducted profiles in southwest Washington, in collaboration with USGS and other universities. In 1998 and 1999, we participated in SHIPS (Seismic Hazards in Puget Sound), focusing on the structure beneath the Olympic Peninsula.

 

Related Links:

http://walrus.wr.usgs.gov/ships/

http://quakes.oce.orst.edu/mendocino/

PUBLICATIONS:

Trehu, A.M., I. Asudeh, T.M. Brocher, J. Luetgert, W.D. Mooney, J.L. Nabelek, Y. Nakamura, Crustal architecture of the Cascadia forearc, Science,v. 265, pp. 237-243, 1994.

Trehu, A.M., G. Lin, E. Maxwell, C. Goldfinger, A seismic reflection profile across the Cascadia subduction zone offshore central Oregon: new constraints on the deep crustal structure and on the distribution of methane in the accretionary prism, Jour. Geophys. Res, v. 100, pp. 15,101-15,116, 1995.

Gerdom, M. A.M. Trehu, E. R. Flueh, D. Klaeschen, The continental margin off Oregon from seismic investigations, Tectonophysics, v. 329, p. 79-97, 2000. (PDF)

Trehu, A.M., T.M. Brocher, K. Creager, M. Fisher, L. Preston, G. Spence, and the SHIPS98 working group, Geometry of the subducting Juan de Fuca plate: new constraints from SHIPS98, in The Cascadia Subduction Zone and Related Subduction Systems-Seismic Structure, Intraslab Earthquakes and Processes, and Earthquake Hazards: U.S. Geological Survey Open-File Report 02-328, and Geological Survey of Canada Open File 4350; Kirby, Stephen, Wang, Kelin, and Dunlop, Susan, eds., http://geopubs.wr.usgs.gov/open-file/of02-328, p. 25-32, 2002. (PDF)

Last Updated 20-JUL-2003 - Under Construction!