Increasing public awareness that the Cascadia subduction zone in the Pacific Northwest is capable of great earthquakes (magnitude 9 and greater) motivates the Cascadia Initiative, an ambitious onshore/offshore seismic and geodetic experiment that takes advantage of an amphibious array to study questions ranging from megathrust earthquakes, to volcanic arc structure, to the formation, deformation and hydration of the Juan De Fuca and Gorda Plates. Here, we provide an overview of the Cascadia Initiative, including its primary science objectives, its experimental design and implementation, and a preview of how the resulting data are being used by a diverse and growing scientific community. The Cascadia Initiative also exemplifies how new technology and community-based experiments are opening up frontiers for marine science. The new technology—shielded ocean bottom seismometers—is allowing more routine investigation of the source zone of megathrust earthquakes, which almost exclusively lies offshore and in shallow water. The Cascadia Initiative offers opportunities and accompanying challenges to a rapidly expanding community of those who use ocean bottom seismic data.

Toomey, D.R., R.M. Allen, A.H. Barclay, S.W. Bell, P.D. Bromirski, R.L. Carlson, X. Chen, J.A. Collins, R.P. Dziak, B. Evers, D.W. Forsyth, P. Gerstoft, E.E.E. Hooft, D. Livelybrooks, J.A. Lodewyk, D.S. Luther, J.J. McGuire, S.Y. Schwartz, M. Tolstoy, A.M. Tréhu, M. Weirathmueller, and W.S.D. Wilcock. 2014. The Cascadia Initiative: A sea change in seismological studies of subduction zones. Oceanography 27(2):138–150, https://doi.org/10.5670/oceanog.2014.49.

> Science Objectives of the Cascadia Initiative (77 KB pdf)

Abers, G.A., L.S. MacKenzie, S. Rondenay, Z. Zhang, A.G. Wech, and K.C. Creager. 2009. Imaging the source region of Cascadia tremor and intermediate-depth earthquakes. Geology 37:1,119–1,122, https://doi.org/10.1130/G30143A.1.

Atwater, B.F. 1987. Evidence for great Holocene earthquakes along the outer coast of Washington State. Science 236:942–944, https://doi.org/10.1126/science.236.4804.942.

Bécel, A., J. Diaz, M. Laigle, A. Hirn, and TTWRCR Group. 2013. Searching for unconventional seismic signals on a subduction zone with a submerged forearc: OBS offshore the Lesser Antilles. Tectonophysics 603:21–31, https://doi.org/10.1016/j.tecto.2012.10.031.

Bromirski, P.D., and F.K. Duennebier. 2002. The near-coastal microseism spectrum: Spatial and temporal wave climate relationships. Journal of Geophysical Research 107(B8), https://doi.org/10.1029/2001JB000265.

Bromirski, P.D., R.A. Stephen, and P. Gerstoft. 2013. Are deep‐ocean‐generated surface‐wave microseisms observed on land? Journal of Geophysical Research 118:3,610–3,629, https://doi.org/10.1002/jgrb.50268.

Burgette, R.J., R.J. Weldon II, and D.A. Schmidt. 2009. Interseismic uplift rates for western Oregon and along-strike variation in locking on the Cascadia subduction zone. Journal of Geophysical Research 114(B1), https://doi.org/10.1029/2008JB005679.

Buskirk, R.E., C. Frohlich, G.V. Latham, A.T. Chen, and J. Lawton. 1981. Evidence that biological activity affects ocean bottom seismograph recordings. Marine Geophysical Researches 5:189–205.

Chapman, J.S., and T.I. Melbourne. 2009. Future Cascadia megathrust rupture delineated by episodic tremor and slip. Geophysical Research Letters 36, L22301, https://doi.org/10.1029/2009GL040465.

Clarke, S.H. Jr., and G.A. Carver. 1992. Late Holocene tectonics and paleoseismicity, southern Cascadia subduction zone. Science 255:188–192, https://doi.org/10.1126/science.255.5041.188.

Connolly, T.P., B.M. Hickey, S.L. Geier, and W.P. Cochlan. 2010. Processes influencing seasonal hypoxia in the northern California Current System. Journal of Geophysical Research 115, C03021, https://doi.org/10.1029/2009JC005283.

Croll, D.A., C.W. Clark, A. Acevedo, B. Tershy, S. Flores, J. Gedamke, and J. Urban. 2002. Bioacoustics: Only male fin whales sing loud songs. Nature 417:809–809, https://doi.org/10.1038/417809a.

Cummins, P.F., and H.J. Freeland. 1993. Observations and modeling of wind-driven currents in the Northeast Pacific. Journal of Physical Oceanography 23:488–502, https://doi.org/10.1175/1520-0485(1993)023<0488:OAMOWD>2.0.CO;2.

Dragert, H., R.D. Hyndman, G.C. Rogers, and K. Wang. 1994. Current deformation and the width of the seismogenic zone of the northern Cascadia subduction thrust. Journal of Geophysical Research 99(B1):653–668, https://doi.org/10.1029/93JB02516.

Duennebier, F.K., and G.H. Sutton. 1995. Fidelity of ocean bottom seismic observations. Marine Geophysical Researches 17:535–555, https://doi.org/10.1007/BF01204343.

Dunn, R.A., and O. Hernandez. 2009. Tracking blue whales in the eastern tropical Pacific with an ocean-bottom seismometer and hydrophone array. Journal of the Acoustical Society of America 126:1,084–1,094, https://doi.org/10.1121/1.3158929.

Egbert, G.D., and R.D. Ray. 2001. Estimates of M2 tidal energy dissipation from TOPEX/Poseidon altimeter data. Journal of Geophysical Research 106(C10):22,475–22,502, https://doi.org/10.1029/2000JC000699.

Flück, P., R.D. Hyndman, and K. Wang. 1997. Three-dimensional dislocation model for great earthquakes of the Cascadia Subduction Zone. Journal of Geophysical Research 102(B9):20,539–20,550, https://doi.org/10.1029/97JB01642.

Goldfinger, C. 2011. Submarine paleoseismology based on turbidite records. Annual Review of Marine Science 3:35–66, https://doi.org/10.1146/annurev-marine-120709-142852.

Goldfinger, C., C.H. Nelson, A. Morey, J.E. Johnson, J. Gutierrez-Pastor, A.T. Eriksson, E. Karabanov, J. Patton, E. Gracia, and R. Enkin. 2012. Turbidite Event History: Methods and Implications for Holocene Paleoseismicity of the Cascadia Subduction Zone. US Geological Survey Professional Paper (1661-F), 184 pp., http://pubs.usgs.gov/pp/pp1661f.

Hagerty, M.T., and S.Y. Schwartz. 1996. The 1992 Cape Mendocino earthquake: Broadband determination of source parameters. Journal of Geophysical Research 101(B7):16,043–16,058, https://doi.org/10.1029/96JB00528.

Harris, D., L. Matias, L. Thomas, J. Harwood, and W.H. Geissler. 2013. Applying distance sampling to fin whale calls recorded by single seismic instruments in the Northeast Atlantic. Journal of the Acoustical Society of America 134:3,522–3,535, https://doi.org/10.1121/1.4821207.

Haubrich, R.A., and K. McCamy. 1969. Microseisms: Coastal and pelagic sources. Reviews of Geophysics 7:539–571, https://doi.org/10.1029/RG007i003p00539.

Heesemann, M., T.L. Insua, M. Scherwath, S.K. Juniper, and K. Moran. 2014. Ocean Networks Canada: From geohazards research laboratories to Smart Ocean Systems. Oceanography 27(2):151–153, https://doi.org/10.5670/oceanog.2014.50.

Holtkamp, S., and M.R. Brudzinski. 2010. Determination of slow slip episodes and strain accumulation along the Cascadia margin. Journal of Geophysical Research 115, B00A17, https://doi.org/10.1029/2008JB006058.

Hyndman, R.D. 2013. Downdip landward limit of Cascadia great earthquake rupture. Journal of Geophysical Research 118:5,530–5,549, https://doi.org/10.1002/jgrb.50390.

Kelsey, H.M., A.R. Nelson, E. Hemphill-Haley, and R.C. Witter. 2005. Tsunami history of an Oregon coastal lake reveals a 4600 yr record of great earthquakes on the Cascadia subduction zone. Geological Society of America Bulletin 117:1,009–1,032, https://doi.org/10.1130/B25452.1.

Livelybrooks, D. 2013. Community college at sea. Earth Magazine 58:38–45.

Matano, R.P. 1995. Numerical experiments on the effects of a meridional ridge on the transmission of energy by barotropic Rossby waves. Journal of Geophysical Research 100(C9):18,271–18,280, https://doi.org/10.1029/95JC02090.

McCaffrey, R., M.D. Long, C. Goldfinger, P.C. Zwick, J.L. Nabelek, C.K. Johnson, and C. Smith. 2012. Rotation and plate locking at the southern Cascadia subduction zone. Geophysical Research Letters 27:3,117–3,120, https://doi.org/10.1029/2000GL011768.

McCaffrey, R., R.W. King, S.J. Payne, and M. Lancaster. 2013. Active tectonics of northwestern US inferred from GPS‐derived surface velocities. Journal of Geophysical Research 118:709–723, https://doi.org/10.1029/2012JB009473.

McCrory, P.A., J.L. Blair, F. Waldhauser, and D.H. Oppenheimer. 2012. Juan de Fuca slab geometry and its relation to Wadati-Benioff zone seismicity. Journal of Geophysical Research 117, B09306, https://doi.org/10.1029/2012JB009407.

McDonald, M.A., J.A. Hildebrand, and S.C. Webb. 1995. Blue and fin whales observed on a seafloor array in the Northeast Pacific. Journal of the Acoustical Society of America 98:712–721, https://doi.org/10.1121/1.413565.

Mitchell, C.E., P. Vincent, R.J. Weldon II, and M.A. Richards. 1994. Present-day vertical deformation of the Cascadia Margin, Pacific Northwest, United States. Journal of Geophysical Research 99(B6):12,257–12,277, https://doi.org/10.1029/94JB00279.

Olofsson, B. 2010. Marine ambient seismic noise in the frequency range 1–10 Hz. Leading Edge 29:418, https://doi.org/10.1190/1.3378306.

Oppenheimer, D., J. Eaton, A. Jayko, M. Lisowski, G. Marshall, M. Murray, R. Simpson, R. Stein, G. Beroza, M. Magee, and others. 1992. The Cape Mendocino, California, earthquakes of April 1992: Subduction at the triple junction. Science 261:433–438, https://doi.org/10.1126/science.261.5120.433.

Sabra, K.G., P. Gerstoft, P. Roux, and W.A. Kuperman. 2005. Extracting time-domain Green’s function estimates from ambient seismic noise. Geophysical Research Letters 32, L03310, https://doi.org/10.1029/2004GL021862.

Satake, K., K. Shimazaki, Y. Tsuji, and K. Ueda. 1996. Time and size of a giant earthquake in Cascadia inferred from Japanese tsunami records of January 1700. Nature 379:246–249, https://doi.org/10.1038/379246a0.

Shapiro, N.M., M. Campillo, L. Stehly, and M.H. Ritzwoller. 2005. High-resolution surface-wave tomography from ambient seismic noise. Science 307:1,615–1,618, https://doi.org/10.1126/science.1108339.

Soule, D.C., and W.S. Wilcock. 2013. Fin whale tracks recorded by a seismic network on the Juan de Fuca Ridge, Northeast Pacific Ocean. The Journal of the Acoustical Society of America 133:1,751–1,761, https://doi.org/10.1121/1.4774275.

Tréhu, A.M. 1985. Coupling of ocean bottom seismometers to sediment: Results of tests with the US Geological Survey ocean bottom seismometer. Bulletin of the Seismological Society of America 75:271–289.

Tréhu, A.M., R.J. Blakely, and M.C. Williams. 2012. Subducted seamounts and recent earthquakes beneath the central Cascadia forearc. Geology 40:103–106, https://doi.org/10.1130/G32460.1.

Tréhu, A.M., J. Braunmiller, and J.L. Nabelek. 2008. Probable low-angle thrust earthquakes on the Juan de Fuca–North America plate boundary. Geology 36:127–130, https://doi.org/10.1130/G24145A.1.

Velasco, A.A., C.J. Ammon, and T. Lay. 1994. Recent large earthquakes near Cape Mendocino and in the Gorda plate: Broadband source time functions, fault orientations, and rupture complexities. Journal of Geophysical Research 99(B1):711–728, https://doi.org/10.1029/93JB02390.

Wang, K. 2003. A revised dislocation model of interseismic deformation of the Cascadia subduction zone. Journal of Geophysical Research 108(B1), https://doi.org/10.1029/2001JB001227.

Webb, S.C. 1998. Broadband seismology and noise under the ocean. Reviews of Geophysics 36:105–142, https://doi.org/10.1029/97RG02287.

Webb, S.C., A.H. Barclay, D. Gassier, and T. Koczynski. 2013. Seismic observations in shallow water. Paper presented at the American Geophysical Union, Fall Meeting 2013, Abstract S12-02, http://adsabs.harvard.edu/abs/2013AGUFM.S12A..02W.

Wells, R.E., C.S. Weaver, and R.J. Blakely. 1998. Fore-arc migration in Cascadia and its neotectonic significance. Geology 26:759–762, https://doi.org/10.1130/0091-7613(1998)026<0759:FAMICA>2.3.CO;2.

Witter, R.C., Y. Zhang, K. Wang, C. Goldfinger, G.R. Priest, and J.C. Allan. 2012. Coseismic slip on the southern Cascadia megathrust implied by tsunami deposits in an Oregon lake and earthquake-triggered marine turbidites. Journal of Geophysical Research 117, B10303, https://doi.org/10.1029/2012JB009404.

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.