Current State of Strain in the Central Cascadia Margin Derived from Changes in Distance between GPS Stations

Kenneth M. Cruikshank, Curt D. Peterson

Department of Geology, Portland State University, Portland, Oregon, USA.

DOI: 10.4236/ojer.2015.41003                

Abstract

Using continuously operating Global Positioning Stations in the Pacific Northwest of the United States, over 100 station-station baseline length changes were determined along seven West-East transects, two North-South transects and in three localized areas to determine both the average annual strains over the past several years, and the variation in strain over the central Cascadia convergent margin. The North-South transects (composed of multiple baselines) show shortening. Along West-East transects some baselines show shortening and others extension. The direction of the principle strains calculated for two areas 100 km from the deformation front are close to per-pendicular to the deformation front. The North-South strains are 10?8 a?1, which is an order-of-magnitude less than the West-East strains (10?7 a?1). Along several West-East transects, the magnitude of the strain increases away from the deformation front. All West-East transects showed a change in strain 250 km inland from deformation front.

Keywords

Convergent Margin, Cascadia, Strain, Strain-Energy, GPS

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Atwater, B.F. (1987) Evidence for Great Holocene Earthquakes along the Outer Coast of Washington State (USA). Science, 236, 942-944. http://dx.doi.org/10.1126/science.236.4804.942
[2]	Darienzo, M.E. and Peterson, C.D. (1990) Episodic Tectonic Subsidence of Late Holocene Salt Marshes, Northern Oregon Central Cascadia Margin. Tectonics, 9, 1-22. http://dx.doi.org/10.1029/TC009i001p00001
[3]	Parsons, T., Blakely, R.J., Brocher, T.M., Christensen, N.I., Fisher, M.A., Flueh, E., Kilbride, F., Luetgert, J.H., Miller, K., ten Brink, U.S., Trehu, A.M. and Wells, R.E. (2005) Crustal Structure of the Cascadia Fore Arc of Washington, United States Geological Survey, P-1661-D.
[4]	CORS (2014) RINEX Data Files for NOAA CORS Stations. http://geodesy.noaa.gov/CORS/
[5]	PANGA (2014) RINEX Files for GPS Stations in Pacific Northwest Geodetic Array. http://www.geodesy.cwu.edu/
[6]	McCaffrey, R., Long, M.D., Goldfinger, C., Zwick, P.C., Nabelek, J.L., Johnson, C.K. and Smith, C. (2000) Rotation and Plate Locking at the Southern Cascadia Subduction Zone. Geophysical Research Letters, 27, 3117-3120. http://dx.doi.org/10.1029/2000GL011768
[7]	Peterson, C.D. and Cruikshank, K.M. (2014) Quaternary Tectonic Deformation, Holocene Paleoseismicity, and Modern Strain in the Unusually-Wide Coupled Zone of the Central Cascadia Margin, Washington and Oregon, USA and British Columbia, Canada. Journal of Geography and Geology, 6, 33. http://dx.doi.org/10.5539/jgg.v6n3p1
[8]	Peterson, C.D., Cruikshank, K.M. and Darienzo, M. (2014), Coastal Tectonic Strain and Paeloseismicity in the South Central Cascadia Margin, Oregon, USA. In: Vidovic, M., Ed., Earthquakes: Triggers, Environmental Impact and Potential Hazards, NOVA Open Access Publisher, Hauppauge.
[9]	Reid, H.F. (1908) The California Earthquake of April 18, 1906: The Mechanics of the Earthquake. Vol. 2, The Carnegie Institution of Washington, Washington, D.C.
[10]	Cruikshank, K.M. and Peterson, C.D. (2013) Strain Energy Release from the 2011 9.0 Mw Tōhoku Earthquake, Japan. Open Journal of Earthquake Research, 2, 75-83. http://dx.doi.org/10.4236/ojer.2013.24008
[11]	McCaffrey, R., King, R.W., Payne, S.J. and Lancaster, M. (2013) Active Tectonics of Northwestern US Inferred from GPS-Derived Surface Velocities. Journal of Geophysical Research, 118, 709-723.
[12]	Active Tectonics and Seafloor Mapping Lab (2014) Cascadia Neotetonic Map. Oregon State University. http://activetectonics.oce.orst.edu/casc_structure.htm
[13]	Fung, Y.C. (1965) Foundations of Solid Mechanics. Prentice-Hall, Englewood Cliffs.
[14]	Malvern, L.E. (1969) Introduction to the Mechanics of Continuous Medium. Prentice-Hall, Inc., Englewood Cliffs.
[15]	Strang, G. and Borre, K. (1997) Linear Algebra, Geodesy, and GPS. Wellesley Press, Cambridge.
[16]	Borre, K. and Strang, G. (2012) Algorithms for Global Positioning. Wellesley Cambridge Press, Cambridge.
[17]	Torge, W. (2001) Satellite Geodesy. Walter de Gruyter, Berlin.
[18]	International GPS Service (2014) Final Orbit Ephemeris.
[19]	Vermeer, M. (2006) Geodetic Baseline GPS Processing by a Simple Sequential Technique. ION GNSS 19th International Technical Meeting of the Satellite Division, Fort Worth, 26-29 September 2006, 2977-2882.
[20]	Tolman, B., Harris, R.B., Gaussiran, T., Munton, D., Little, J., Mach, R., Nelsen, S., Renfro, B. and Schlossberg, D. (2004) The GPS Toolkit—Open Source GPS Software. Proceedings of the 17th International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS 2004), Long Beach, 24 September 2004, 9 p.
[21]	Blewitt, G. and Lavallée, D. (2002) Effect of Annual Signals on Geodetic Velocity. Journal of Geophysical Research, 107, ETG 9-1-ETG 9-11. http://dx.doi.org/10.1029/2001JB000570
[22]	R Development Core Team (2008) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna.
[23]	Davis, J.C. (2002) Statistics and Data Analysis in Geology. 3rd Edition, John Wiley & Sons, New York.
[24]	Baum, R.L., Johnson, A.M. and Fleming, R.W. (1988) Measurement of Slope Deformation Using Quadrilaterals. United States Geological Survey. 23 p.
[25]	Vincenty, T. (1975) Direct and Inverse Solutions of Geodesics on the Ellipsoid with Application of Nested Equations. Survey Review, 23, 88-93. http://dx.doi.org/10.1179/sre.1975.23.176.88
[26]	Smith, S.W. (1997) The Scientist and Engineer’s Guide to Digital Signal Processing. California Technical Publication, San Diego, 628 p.
[27]	Mazzotti, S., Dragert, H., Hyndman, R.D., Miller, M.H. and Henton, J.A. (2002) GPS Deformation in a Region of High Crustal Seismicity: N. Cascadia Forearc. Earth and Planetary Science Letters, 198, 41-48. http://dx.doi.org/10.1016/S0012-821X(02)00520-4
[28]	Zoback, M. and Zoback, M. (1980) State of Stress in the Conterminous United States. Journal of Geophysical Research, 85, 6113-6155. http://dx.doi.org/10.1029/JB085iB11p06113
[29]	Balfour, N.J. (2011) Sources of Seismic Hazard in British Columbia: What Controls Earthquakes in the Crust? University of Victoria, Victoria, 165 p.
[30]	Balfour, N.J., Cassidy, J.F., Dosso, S.E. and Mazzotti, S. (2011) Mapping Crustal Stress and Strain in Southwest British Columbia. Journal of Geophysical Research, 116, 11 p.
[31]	Jaeger, J.C., Cook, N.G.W. and Zimmerman, R.W. (2007) Fundamentals of Rock Mechanics. 4th Edition, Chapman and Hall, London.