Canada's Active Western Margin

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Washington Division of Geology and Earth Resources Open File Report

l 122 EARTHQUAKES AND SEISMOLOGY - LEGAL ASPECTS OPEN FILE REPORT 92-2 EARTHQUAKES AND Ludwin, R. S.; Malone, S. D.; Crosson, R. EARTHQUAKES AND SEISMOLOGY - LEGAL S.; Qamar, A. I., 1991, Washington SEISMOLOGY - 1946 EVENT ASPECTS eanhquak:es, 1985. Clague, J. J., 1989, Research on eanh- Ludwin, R. S.; Qamar, A. I., 1991, Reeval Perkins, J. B.; Moy, Kenneth, 1989, Llabil quak:e-induced ground failures in south uation of the 19th century Washington ity of local government for earthquake western British Columbia [abstract). and Oregon eanhquake catalog using hazards and losses-A guide to the law Evans, S. G., 1989, The 1946 Mount Colo original accounts-The moderate sized and its impacts in the States of Califor nel Foster rock avalanches and auoci earthquake of May l, 1882 [abstract). nia, Alaska, Utah, and Washington; ated displacement wave, Vancouver Is Final repon. Maley, Richard, 1986, Strong motion accel land, British Columbia. erograph stations in Oregon and Wash Hasegawa, H. S.; Rogers, G. C., 1978, EARTHQUAKES AND ington (April 1986). Appendix C Quantification of the magnitude 7.3, SEISMOLOGY - NETWORKS Malone, S. D., 1991, The HAWK seismic British Columbia earthquake of June 23, AND CATALOGS data acquisition and analysis system 1946. [abstract). Berg, J. W., Jr.; Baker, C. D., 1963, Oregon Hodgson, E. A., 1946, British Columbia eanhquak:es, 1841 through 1958 [ab Milne, W. G., 1953, Seismological investi earthquake, June 23, 1946. gations in British Columbia (abstract). stract). Hodgson, J. H.; Milne, W. G., 1951, Direc Chan, W.W., 1988, Network and array anal Munro, P. S.; Halliday, R. J.; Shannon, W.
Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information

Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information Index Abancay Deﬂection, 201, 204–206, 223 Allmendinger, R. W., 206 Abant, Turkey, earthquake of 1957 Ms 7.0, 286 allochthonous terranes, 26 Abdrakhmatov, K. Y., 381, 383 Alpine fault, New Zealand, 482, 486, 489–490, 493 Abercrombie, R. E., 461, 464 Alps, 245, 249 Abers, G. A., 475–477 Alquist-Priolo Act, California, 75 Abidin, H. Z., 464 Altay Range, 384–387 Abiz, Iran, fault, 318 Alteriis, G., 251 Acambay graben, Mexico, 182 Altiplano Plateau, 190, 191, 200, 204, 205, 222 Acambay, Mexico, earthquake of 1912 Ms 6.7, 181 Altunel, E., 305, 322 Accra, Ghana, earthquake of 1939 M 6.4, 235 Altyn Tagh fault, 336, 355, 358, 360, 362, 364–366, accreted terrane, 3 378 Acocella, V., 234 Alvarado, P., 210, 214 active fault front, 408 Álvarez-Marrón, J. M., 219 Adamek, S., 170 Amaziahu, Dead Sea, fault, 297 Adams, J., 52, 66, 71–73, 87, 494 Ambraseys, N. N., 226, 229–231, 234, 259, 264, 275, Adria, 249, 250 277, 286, 288–290, 292, 296, 300, 301, 311, 321, Afar Triangle and triple junction, 226, 227, 231–233, 328, 334, 339, 341, 352, 353 237 Ammon, C. J., 464 Afghan (Helmand) block, 318 Amuri, New Zealand, earthquake of 1888 Mw 7–7.3, 486 Agadir, Morocco, earthquake of 1960 Ms 5.9, 243 Amurian Plate, 389, 399 Age of Enlightenment, 239 Anatolia Plate, 263, 268, 292, 293 Agua Blanca fault, Baja California, 107 Ancash, Peru, earthquake of 1946 M 6.3 to 6.9, 201 Aguilera, J., vii, 79, 138, 189 Ancón fault, Venezuela, 166 Airy, G.
Geology 111 • Discovering Planet Earth • Steven Earle • 2010

H1) Earthquakes The plates that make up the earth's lithosphere are constantly in motion. The rate of motion is a few centimetres per year, or approximately 0.1 mm per day (about as fast as your fingernails grow). This does not mean, however, that the rocks present at the places where plates meet (e.g., convergent boundaries and transform faults) are constantly sliding past each other. Under some circumstances they do, but in most cases, particularly in the upper part of the crust, the friction between rocks at a boundary is great enough so that the two plates are locked together. As the plates themselves continue to move, deformation takes place in the rocks close to the locked boundary and strain builds up in the deformed rocks. This strain, or elastic deformation, represents potential energy stored within the rocks in the vicinity of the boundary between two plates. Eventually the strain will become so great that the friction and rock-strength that is preventing movement between the plates will be overcome, the rocks will break and the plates will suddenly slide past each other - producing an earthquake [see Fig. 10.4]. A huge amount of energy will suddenly be released, and will radiate away from the location of the earthquake in the form of deformation waves within the surrounding rock. S-waves (shear waves), and P-waves (compression waves) are known as body waves as they travel through the rock. As soon as this happens, much of the strain that had built up along the fault zone will be released1.
Geology and Geochemistry of the Southern Explorer Ridge Seafloor Hydrothermal Site Using an Integrated GIS Database and 3D Modeling

Physiology, Geology and Geochemistry of the Southern Explorer Ridge Seafloor Hydrothermal Site Using an Integrated GIS Database and 3D Modeling Yannick C. Beaudoin A thesis subrnitted in conformity with the requirements for the degree of Master of Science Graduate Department of Geology University of Toronto O March 2001 National Library Bibliothèque nationale If1 of Canada du Canada Acquisitions and Acquisitions et Bibliogmphic Sewices services bibliogrâphiques 395 Wellington Street 395. rue Wellington Ottawa ON K1A ON4 Ottawa ON K1A ON4 Canada Canada Yow Ne votro nlfémma Our fiie Notre réfdrenw The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exciusive permettant à la National Lhrary of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fkom it Ni la thèse ni des extraits substantiels may be printed or othe*se de celle-ci ne doivent être imprimes reproduced without the author's ou autrement reproduits sans son permission. autorisation. Physiology, Geology and Geochemistry of the Southern Explorer Ridge Seafloor Hydrothermal Site Using an Integrated GIS Database and 3D Modeling by Yannick Beaudoin in partial fulfillment of the requirements for the degree of Master's of Science, March 2001, Graduate Department of Geology, University of Toronto Southem Explorer Ridge (SER) is an anomalously-rate shallow, intemediate spreading ridge located 200 kilometers off the west Coast of Vancouver Island, Canada.
Mantle Flow Through the Northern Cordilleran Slab Window Revealed by Volcanic Geochemistry

Downloaded from geology.gsapubs.org on February 23, 2011 Mantle fl ow through the Northern Cordilleran slab window revealed by volcanic geochemistry Derek J. Thorkelson*, Julianne K. Madsen, and Christa L. Sluggett Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada ABSTRACT 180°W 135°W 90°W 45°W 0° The Northern Cordilleran slab window formed beneath west- ern Canada concurrently with the opening of the Californian slab N 60°N window beneath the southwestern United States, beginning in Late North Oligocene–Miocene time. A database of 3530 analyses from Miocene– American Holocene volcanoes along a 3500-km-long transect, from the north- Juan Vancouver Northern de ern Cascade Arc to the Aleutian Arc, was used to investigate mantle Cordilleran Fuca conditions in the Northern Cordilleran slab window. Using geochemi- Caribbean 30°N Californian Mexico Eurasian cal ratios sensitive to tectonic affi nity, such as Nb/Zr, we show that City and typical volcanic arc compositions in the Cascade and Aleutian sys- Central African American Cocos tems (derived from subduction-hydrated mantle) are separated by an Pacific 0° extensive volcanic fi eld with intraplate compositions (derived from La Paz relatively anhydrous mantle). This chemically defi ned region of intra- South Nazca American plate volcanism is spatially coincident with a geophysical model of 30°S the Northern Cordilleran slab window. We suggest that opening of Santiago the slab window triggered upwelling of anhydrous mantle and dis- Patagonian placement of the hydrous mantle wedge, which had developed during extensive early Cenozoic arc and backarc volcanism in western Can- Scotia Antarctic Antarctic 60°S ada.
Recent Movements of the Juan De Fuca Plate System

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 89, NO. B8, PAGES 6980-6994, AUGUST 10, 1984 Recent Movements of the Juan de Fuca Plate System ROBIN RIDDIHOUGH! Earth PhysicsBranch, Pacific GeoscienceCentre, Departmentof Energy, Mines and Resources Sidney,British Columbia Analysis of the magnetic anomalies of the Juan de Fuca plate system allows instantaneouspoles of rotation relative to the Pacific plate to be calculatedfrom 7 Ma to the present.By combiningthese with global solutions for Pacific/America and "absolute" (relative to hot spot) motions, a plate motion sequencecan be constructed.This sequenceshows that both absolute motions and motions relative to America are characterizedby slower velocitieswhere younger and more buoyant material enters the convergencezone: "pivoting subduction."The resistanceprovided by the youngestportion of the Juan de Fuca plate apparently resulted in its detachmentat 4 Ma as the independentExplorer plate. In relation to the hot spot framework, this plate almost immediately began to rotate clockwisearound a pole close to itself such that its translational movement into the mantle virtually ceased.After 4 Ma the remainder of the Juan de Fuca plate adjusted its motion in responseto the fact that the youngest material entering the subductionzone was now to the south. Differencesin seismicityand recent uplift betweennorthern and southernVancouver Island may reflect a distinction in tectonicstyle betweenthe "normal" subductionof the Juan de Fuca plate to the south and a complex "underplating"occurring as the Explorer plate is overriddenby the continent.The history of the Explorer plate may exemplifythe conditionsunder which the self-drivingforces of small subductingplates are overcomeby the influenceof larger, adjacent plates. The recent rapid migration of the absolutepole of rotation of the Juan de Fuca plate toward the plate suggeststhat it, too, may be nearingthis condition.
Tidally Controlled Gas Bubble Emissions: a Comprehensive 10.1002/2016GC006528 Study Using Long-Term Monitoring Data from the NEPTUNE

PUBLICATIONS Geochemistry, Geophysics, Geosystems RESEARCH ARTICLE Tidally controlled gas bubble emissions: A comprehensive 10.1002/2016GC006528 study using long-term monitoring data from the NEPTUNE Key Points: cabled observatory offshore Vancouver Island Continuous monitoring of transient gas bubble emissions over 1 year was Miriam Romer€ 1, Michael Riedel2, Martin Scherwath3, Martin Heesemann3, and George D. Spence4 enabled by the NEPTUNE cabled observatory 1 Flare onsets were triggered and MARUM-Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Germany, controlled by tidally induced bottom 2GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, 3Ocean Networks Canada, University of Victoria, British pressure changes Columbia, Canada, 4School of Earth and Ocean Sciences, University of Victoria, British Columbia, Canada Decreasing pressure allowing gas to migrate and shifting the CH4 solubility in pore waters leads to ebullition Abstract Long-term monitoring over 1 year revealed high temporal variability of gas emissions at a cold seep in 1250 m water depth offshore Vancouver Island, British Columbia. Data from the North East Paciﬁc Supporting Information: Time series Underwater Networked Experiment observatory operated by Ocean Networks Canada were Figure S1 used. The site is equipped with a 260 kHz Imagenex sonar collecting hourly data, conductivity-temperature- Table S1 Movie S1 depth sensors, bottom pressure recorders, current meter, and an ocean bottom seismograph. This enables correlation of the data and analyzing trigger mechanisms and regulating criteria of gas discharge activity. Correspondence to: Three periods of gas emission activity were observed: (a) short activity phases of few hours lasting several M. Romer,€ months, (b) alternating activity and inactivity of up to several day-long phases each, and (c) a period of sev- [email protected] eral weeks of permanent activity.
Forwards Geology,Seismology & Geotechnical

- c. x . @ , , C PUBLIC DOCUMENT ROOM , , , , UNITED STATES //- - / #,% O[ ~ !" o NUCLEAR REGULATORY COMMISSION 2 9 . 3 ; ,E WASHINGTON, D. C. 20555 @@ %...../ g e October 3, 1979 . a Valentine B. Deale, Esq., Chairman Dr. Frank F. Hooper Atomic Safety and Licensing Board School of Natural Resources 1001 Connecti:ut Avenue, N.W. University of Michigan Washington, DC 20036 Ann Arbor, MI 48109 Mr. Gustave A. Linenberger Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission Washington, DC 20555 In the Matter of Puget Sound Power & Light Company,~et al. (Skagit Nuclear Power Project, Units 1 and 2) ~~ - , Docket Nos. STN 50-522 and STN 50-523 Gentlemen: Enclosed is the NRC Staff's geology, seismology and geotechnical engineering review report which will be incorporated as Section 2.5 of the Final Supple- ment to the Staff's Safety Evaluation Report (SER). This report will also constitute the Staff's direct testimony on geology-seismology issues in this proceeding. The Staff's witnesses will consist of H. Lefevre, S. Wastler, Dr. J. Kelleher, and Dr. R. Regan. Also enclosed is the supplemental testi- many of Dr. Kelleher which addresses the Board request for testimony concerning the methods used by the Staff to estimate strong ground motion. The U.S. Geological Survey has assisted the NRC Staff in the review of the Skagit site. The U.S.G.S.'s review reports of February 23, 1978 and Sep- tember 17, 1979 (these reports have been previously distributed to the Board and parties), are attached as Appendix D to the Staff's report.
Seismic Structure of the Endeavour Segment, Juan De Fuca Ridge: Correlations with Seismicity and Hydrothermal Activity E

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, B02401, doi:10.1029/2005JB004210, 2007 Click Here for Full Article Seismic structure of the Endeavour Segment, Juan de Fuca Ridge: Correlations with seismicity and hydrothermal activity E. M. Van Ark,1 R. S. Detrick,2 J. P. Canales,2 S. M. Carbotte,3 A. J. Harding,4 G. M. Kent,4 M. R. Nedimovic,3 W. S. D. Wilcock,5 J. B. Diebold,3 and J. M. Babcock4 Received 9 December 2005; revised 23 June 2006; accepted 21 September 2006; published 3 February 2007. [1] Multichannel seismic reflection data collected in July 2002 at the Endeavour Segment, Juan de Fuca Ridge, show a midcrustal reflector underlying all of the known high-temperature hydrothermal vent fields in this area. On the basis of the character and geometry of this reflection, its similarity to events at other spreading centers, and its polarity, we identify this as a reflection from one or more crustal magma bodies rather than from a hydrothermal cracking front interface. The Endeavour magma chamber reflector is found under the central, topographically shallow section of the segment at two-way traveltime (TWTT) values of 0.9–1.4 s (2.1–3.3 km) below the seafloor. It extends approximately 24 km along axis and is shallowest beneath the center of the segment and deepens toward the segment ends. On cross-axis lines the axial magma chamber (AMC) reflector is only 0.4–1.2 km wide and appears to dip 8–36° to the east. While a magma chamber underlies all known Endeavour high-temperature hydrothermal vent fields, AMC depth is not a dominant factor in determining vent fluid properties.
On the Dynamics of the Juan De Fuca Plate

Earth and Planetary Science Letters 189 (2001) 115^131 www.elsevier.com/locate/epsl On the dynamics of the Juan de Fuca plate Rob Govers *, Paul Th. Meijer Faculty of Earth Sciences, Utrecht University, P.O. Box 80.021, 3508 TA Utrecht, The Netherlands Received 11 October 2000; received in revised form 17 April 2001; accepted 27 April 2001 Abstract The Juan de Fuca plate is currently fragmenting along the Nootka fault zone in the north, while the Gorda region in the south shows no evidence of fragmentation. This difference is surprising, as both the northern and southern regions are young relative to the central Juan de Fuca plate. We develop stress models for the Juan de Fuca plate to understand this pattern of breakup. Another objective of our study follows from our hypothesis that small plates are partially driven by larger neighbor plates. The transform push force has been proposed to be such a dynamic interaction between the small Juan de Fuca plate and the Pacific plate. We aim to establish the relative importance of transform push for Juan de Fuca dynamics. Balancing torques from plate tectonic forces like slab pull, ridge push and various resistive forces, we first derive two groups of force models: models which require transform push across the Mendocino Transform fault and models which do not. Intraplate stress orientations computed on the basis of the force models are all close to identical. Orientations of predicted stresses are in agreement with observations. Stress magnitudes are sensitive to the force model we use, but as we have no stress magnitude observations we have no means of discriminating between force models.
Seismotectonics of Western Canada from Regional Moment Tensor Analysis

Seismotectonics of Western Canada From Regional Moment Tensor Analysis Johannes Peter Ristau University of Victoria 2004 Seismotectonics of Western Canada From Regional Moment Tensor Analysis Johannes Peter Ristau B.Sc., University of Manitoba, 1995 M.Sc., University of Manitoba, 1999 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in the School of Earth and Ocean Sciences @ Johannes Peter Ristau, 2004 University of Victoria All rights reserved. This dissertation may not be reproduced in whole or in part, by photocopying or other means, without permission of the author. Supervisor: Dr. Garry C. Rogers Abstract Moment tensor analysis of regional earthquakes (distances .v< 1000 km) in western Canada is now possible due to the installation of more than 40 three-component broad- band seismometers in western Canada and adjacent regions. In this study, regional moment tensor (RMT) analysis using robust waveform fitting techniques are employed to routinely caIcuIate source mechanisms, moments, and depths of earthquakes with M 2~ 4.0 in and near western Canada. This has resulted in about 10 times as many solutions per year for this region than have been calculated with teleseismic methods which are limited to earthquakes about M > 5.0. To date, more than 380 RMT solutions have been calculated in this study for west- ern Canada and adjacent regions for the years 1995-2004. These solutions provide new insights into a number of tectonic problems in western Canada. Local magnitudes (ML) have been calibrated with moment magnitudes (M,) providing a more consistent estimate of the magnitude of an earthquake.
The Gorda Deformation Zone

The Gorda Deformation Zone Miles Bodmer University of Oregon Goals • Better understand deformation of the Gorda Plate • Look at deformation at a range of depths (crust – lithosphere - asthenosphere) • Highlight some of my research What Makes The Gorda Interesting? • The Gorda is the oceanic plate outboard of southern Cascadia subduction zone • Southern Cascadia is where large megathrust earthquakes are thought to nucleate • 1/3 of the plate configuration that makes up the Mendocino triple junction • Seismically active Modified from Byrnes et al. (2017) Tectonic History • ~10 Ma Pacific plate motion changes • Ridges begin to reorganize • ~5 Ma the Blanco transform develops • ~4 MA Explorer plate breaks off • The Mendocino transform and Gorda ridge fail to reorient Atwater and Stock, 1998 Magnetic Anomalies • Clear bending of anomalies in Gorda • Juan de Fuca shows signs of reorganization • Formation of new segments • Ridge rotation • Pacific side near Gorda does not show similar signs of reorganization • Variable spreading rates Wilson (2002) Gorda Is Stagnating • Gorda motion becomes increasingly independent in the last 3 Ma • At 0.5 Ma the Pacific controls Gorda motion Riddihough (1984) Seismicity Throughout The Plate 1964 – 1980 Star: M 5.7 (Jay Patton http://earthjay.com/) Wilson (1989) Historic seismicity (USGS www.earthquake.usgs.gov) Large Events In The Plate Correlate With Bathymetry Chaytor (http://activetectonics.coas.oregonstate.edu/gorda.htm) Deformation Accommodated By Left-lateral Faults • Bathymetry clearly shows ridges associated with faulting • Ridges appear smoothly deformed, kinked, or undeformed depending on the region • Moment tensors show dominantly left-lateral strike-slip motion with some normal faulting • Faults show clear regions of deformation Chaytor et al.