Why short-term crustal shortening leads to mountain building in the Andes, but not in Cascadia?
|
|
- Adela Cunningham
- 5 years ago
- Views:
Transcription
1 Click Here for Full Article GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L08301, doi: /2009gl037347, 2009 Why short-term crustal shortening leads to mountain building in the Andes, but not in Cascadia? Gang Luo 1 and Mian Liu 1 Received 16 January 2009; revised 16 March 2009; accepted 20 March 2009; published 16 April [1] Subduction-induced crustal shortening, now measured by the GPS across many subduction zones, has led to mountain building in the Andes but not in Cascadia and some other Andean-type convergent plate boundaries. Here we use a two-dimensional viscoelastoplastic finite element model to explore how the GPS-measured short-term strain relates to long-term mountain building. We show that previously proposed causative factors of mountain building can be represented by two model parameters: the strength of mechanical coupling on the plate interface, and the yield strength of the overriding plate. The critical condition for producing permanent (plastic) crustal shortening, hence mountain building, is for the plastic yield strength of the plate interface to be higher than that of the overriding plate. Strong trench coupling and a weak lithosphere explain the Andean mountain building, whereas weak trench coupling in Cascadia allows short-term crustal shortening to be restored periodically by trench earthquakes and aseismic slips. Citation: Luo, G., and M. Liu (2009), Why short-term crustal shortening leads to mountain building in the Andes, but not in Cascadia?, Geophys. Res. Lett., 36, L08301, doi: / 2009GL Introduction [2] Most workers have concluded that the Andes, the archetype of the Andean-type orogens formed along active continental margins (Figure 1a), have resulted mainly from crustal shortening associated with subduction of the oceanic Nazca plate under South America [Allmendinger et al., 1997; Isacks, 1988]. Recent Global Positioning System (GPS) measurements in the central Andes show that present-day crustal shortening absorbs roughly half of the 65 mm/yr Nazca-South American plate convergence [e.g., Kendrick et al., 2001; Khazaradze and Klotz, 2003; Norabuena et al., 1998] (Figure 1a). This rate is higher than that estimated from geological record (<15 mm/yr) [Kley and Monaldi, 1998], implying that much of the present-day crustal shortening is transient and will be recovered during future earthquakes [Liu et al., 2000; Norabuena et al., 1998]. [3] If all crustal shortening in the subduction zone is transient, then no permanent crustal shortening, and hence no mountain building, can be produced. This situation seems applicable to the Cascadia subduction zone, where the Farallon plate (now the Juan de Fuca plate) has been 1 Department of Geological Sciences, University of Missouri, Columbia, Missouri, USA. Copyright 2009 by the American Geophysical Union /09/2009GL037347$05.00 subducting under the North American plate since the Mesozoic (Figure 1b). Despite the GPS measurements of mm/yr crustal shortening in Cascadia, no significant mountain building has occurred there since the Eocene [Gabrielse and Yorath, 1992]. [4] Previous studies have suggested many factors contributing to mountain building in subduction zones, including the change of plate convergence rate, trenchward absolute motion of the overriding plate, age and angle of the subducting slab, subduction of oceanic ridge and seamounts, the amount of subducted sediments, and thinning of mantle lithosphere of the overriding plate [e.g., Allmendinger et al., 1997; Lamb and Davis, 2003; Silver et al., 1998]. We show here that these factors can be represented by two competing parameters in a mechanical model: the strength of trench coupling versus the strength of the overriding plate. Using a two-dimensional viscoelastoplastic finite element model, we explore how these two parameters control whether or not short-term strain associated with the cycles of trench earthquakes leads to long-term mountain building in subduction zones. 2. Numerical Model [5] Previous models of the Andean-type plate boundaries have focused either on short- or long-term deformation. The models of short-term deformation, using elastic or viscoelastic rheology, simulate transient strain during seismic cycles without linking the strain to mountain building [e.g., Bevis et al., 2001; Norabuena et al., 2004]. The models of mountain building, using viscous or viscoplastic rheology, assume continuous and permanent crustal shortening [e.g., Sobolev and Babeyko, 2005], and thus do not explain why subduction-induced crustal shortening leads to mountain building in the Andes but not in other subduction zones. [6] We have developed a two-dimensional viscoelastoplastic finite element model for the Andes [Luo and Liu, 2009]. Here we generalize this model for Andean-type plate boundaries (Figure 2). The oceanic plate subducts under the continental plate at the angle of 30 with relative convergence rate of 50 mm/yr. We take the top 30 km of the subducting plate to be elastic, and the top 20 km of the overriding plate to be brittle (elastoplastic). A viscoelastic layer is used for the lower crust and the upper mantle of both plates. The subduction interface is modeled with two layers of special finite elements: the bottom layer with relatively low and depth-variable viscosity to simulate interseismic creeping, and the top layer with elastoplastic rheology to simulate the stick-slip seismogenic zone. The plastic deformation, both within the continental crust and on the subduction interface, is simulated with the Mohr- L of5
2 Figure 1. GPS velocities, selected focal mechanism solutions, and topographic relief in the (a) central Andes and (b) Cascadia. The Andean GPS data are from Chlieh et al. [2004], Kendrick et al. [2001], Khazaradze and Klotz [2003] and Klotz et al. [2001]. WC, Western Cordillera; AP, Altiplano plateau; EC, Eastern Cordillera; FTB, Subandean fold and thrust belt. The Cascadia GPS data are from Mazzotti et al. [2003], McCaffrey et al. [2007] and Miller et al. [2001]. SAF, San Andreas Fault. Coulomb yield criterion and non-associated flow rule [Luo and Liu, 2009]. 3. Model Results [7] In the reference case, we allow 15 mm/yr of the 50 mm/yr plate convergence to be accommodated by creeping on the subduction interface; the remaining 35 mm/yr is absorbed by crustal shortening in the overriding plate during interseismic periods. The plate interface is allowed to slip every 200 years by choosing a proper stress drop (a few MPa), with 7 m coseismic slip averaged on the subduction thrust, which is typical for M w > 8.0 events in the Peru-Chile trench [Nishenko, 1991]. Once the model has reached a quasi-steady state, we calculate strain distribution and evolution during each seismic cycle. The results for each cycle are similar; one cycle is shown in Figure 3a. The interseismic displacement is evenly distributed across the overriding plate (Figure 3a), whose rheology is laterally homogeneous in this case. About half of the interseismic crustal shortening is restored during the trench earthquake; the rest is restored by postseismic viscous relaxation. In this case no plastic deformation, hence no mountain building, occurs in the overriding plate. Allowing the plate interface to slip in shorter intervals would produce smaller coseismic slips, but will not necessarily affect the partitioning between transient and permanent strains. Note that the co- and post-seismic displacement for one earthquake cycles is too small (<10 m) in comparison to the model domain (1000 km), hence cannot be seen in Figure 3a. [8] Permanent (plastic) crustal shortening needs to be produced and accumulated through the cycles of trench earthquakes to lead to mountain building. This requires 1) strong mechanical coupling on the plate interface to transmit sufficient compressive stress to the overriding plate, and 2) sufficiently low plastic yield strength in the overriding plate for plastic shortening to occur. With higher plastic yield strength on the plate interface than that in Figure 3a but otherwise the same parameters, the model produced both viscoelastic and plastic strains in the overriding plate (Figure 3b). While the viscoelastic strain is largely restored during coseismic rebound and postseismic relaxation, about 2 m of plastic shortening is accumulated Figure 2. Mesh and boundary conditions of the finite element model. The subduction interface is modeled with two layers: an elastoplastic layer for the stick-slip seismogenic thrust (red) and a viscous layer for aseismic slip (yellow). 2of5
3 Figure 3. (a) Predicted strain partitioning and evolution of one seismic cycle for the reference case. Predicted horizontal displacement and horizontal strain on the surface (note the nonlinear scale in the vertical axis). The coseismic curves show the cumulative displacement and horizontal strain immediately after the trench earthquake. The curves labeled P-50 yr are results for 50 years into the postseismic relaxation; similar for other curves. Predicted evolution of the horizontal strain in the depth-section. Residual strain from previous cycles is removed. Compressive strain (blue) is positive. The strain is capped at ± on the scale bar. (b) Predicted strain partitioning and evolution of one seismic cycle for the case of stronger plate coupling. Strain in the forearc-volcanic arc region is dominantly plastic, which survives coseismic rebound and postseismic relaxation. over each seismic cycle of 200 years (i.e., 10 mm/yr). The same results can be produced by reducing the plastic yield strength of the overriding plate. Furthermore, reducing the viscosity in the lower crust and upper mantle causes higher deviatoric stress in the brittle crust, and hence has similar effects. [9] Note the values of trench coupling and the yield strength of the overriding plate in the models are unconstrained. What matter here are their relative values: when the plastic yield strength on the plate interface is lower than that for the overriding plate, interseismic crustal shortening will be recovered by coseismic slip of the trench earthquake and associated postseismic viscous relaxation, hence no permanent crustal shortening occurs in the overriding plate. 4. Trench Coupling and Lithospheric Strength: Andes Versus Cascadia [10] The values of plastic yield strength on the plate interface and for the overriding plate, unfortunately, cannot be directly measured or constrained. Nonetheless, geological observations may provide useful proxies for these values. Interplate shear stress in the subduction zone, for example, is a good indicator of the plastic yield strength there, and force-balancing calculations indicated high shear stress in the Andean trench: MPa from a viscous model [Husson and Ricard, 2004], and 37 MPa from an analytic model [Lamb, 2006]. Lamb and Davis [2003] attributed the high shear stress to the lack of trench sediments, which reduces lubrication on the subduction interface. Strong trench coupling in the central Andes is consistent with deep trench and negative gravity anomalies there [Iaffaldano and Bunge, 2008]. [11] Similar force balance calculations, as well as forearc heat flow data, argue for low shear stress (<20 MPa) on the Cascadia subduction interface [Lamb, 2006; Wang and He, 1999; Wang et al., 1995]. The thick (2 3 km) Cascadia trench sediments [Flueh et al., 1998] imply lubrication, high pore fluid pressure and low shear stress on the plate interface [Lamb, 2006]. The stress state in the Cascadia forearc shown by small earthquakes also indicates weak plate coupling [Wang et al., 1995]. [12] Following the force balance analysis of Lamb [2006], we include the effects of sea water and found that the shear stress on subduction interface, t, can be determined as t ¼ sin 2q 4 rgh r sgd 2 h where q is the shallow dipping angle of the subducting slab; r and r s are the densities of forearc wedge and sea water, respectively; g is gravitational acceleration; h is the elevation difference between mountain and trench; and d is the trench depth (inset in Figure 4). The high elevation of the Andes and the deep Peru-Chile trench demand high interplate shear stresses; the opposite is true for Cascadia (Figure 4). ð1þ 3of5
4 measured by space geodesy links to long-term tectonics and mountain building. [15] In summary, we found that for subduction to lead to significant mountain building, the yield strength on the plate interface needs to be higher than that in the overriding plate. Strong interplate coupling in the Peru-Chile trench and thermal weakening of the Andean lithosphere explain the Andean mountain building, whereas weak trench coupling in Cascadia allows interseismic crustal shortening to be fully restored through the cycles of trench earthquakes and aseismic slip, leaving no significant plastic strain for mountain building. [16] Acknowledgments. This work is partially supported by NSF grants EAR and EAR , and NASA grant NNX08AF97G. We thank Seth Stein and an anonymous reviewer for their constructive comments. Figure 4. The interplate shear stress in the subduction zone of the central Andes and Cascadia from an analytic solution of force balance. The shadowed area and dashed lines respectively show effects from variations of h and d, compared with those from their average values (solid lines). Thick segments of the lines corresponds to shallow subduction angles for the two subduction zones; stars indicate averaged shear stress on subduction thrust from the models. r = kg/m 3 ; r s = kg/m 3 ; g = 10 m/s 2. Other parameters are from Lallemand et al. [2005], Lamb [2006], and Oleskevich et al. [1999]. Inset shows the force balance in the forearc of a subduction zone. [13] The plastic yield strength of the Andean and the Cascadian lithosphere is hard to quantify, but high surface heat flow, low seismic velocities, crustal partial melting, high temperature by xenolith thermobarometry, occurrence of ignimbrites and basaltic volcanism, and high electronic conductivity all point to a thermally weakened lithosphere in the Andes [Asch et al., 2006; Currie and Hyndman, 2006; Schilling et al., 2006]. This has been used to explain why significant mountain building in the Andes occurred in the past 30 Ma, although the Nazca plate has been subducting beneath the South American plate at least since early Jurassic [Allmendinger et al., 1997; Isacks, 1988]. The Cascadian lithosphere has also been thermally weakened [Currie and Hyndman, 2006], but likely not as much as the Andean lithosphere. The GPS-measured crustal shortening is concentrated to the forearc in Cascadia (Figure 1b), which can be predicted in the model with a strong backarc lithosphere. 5. Discussion and Conclusions [14] The importance of trench coupling and yield strength of the overriding plate is self-evident in mechanics. For subduction to produce permanent (plastic) crustal shortening, hence mountain building, it needs strong trench coupling to transmit sufficient compressive stress to the overriding plate, and the overriding plate to be sufficiently weak to deform plastically. By simulating strain evolution during cycles of trench earthquakes, our model provides a useful tool to explore how short-term crustal deformation as References Allmendinger, R. W., T. E. Jordan, S. M. Kay, and B. L. Isacks (1997), The evolution of the Altiplano-Plateau of the central Andes, Annu. Rev. Earth Planet. Sci., 25, Asch, G., et al. (2006), Seismological studies of the central and southern Andes, in The Andes, edited by O. Oncken et al., pp , Springer, Berlin. Bevis, M., E. Kendrick, R. Smalley Jr., B. Brooks, R. Allmendinger, and B. Isacks (2001), On the strength of interplate coupling and the rate of back arc convergence in the central Andes: An analysis of the interseismic velocity field, Geochem. Geophys. Geosyst., 2(11), 1067, doi: /2001gc Chlieh, M., J. B. de Chabalier, J. C. Ruegg, R. Armijo, R. Dmowska, J. Campos, and K. L. Feigl (2004), Crustal deformation and fault slip during the seismic cycle in the north Chile subduction zone, from GPS and InSAR observations, Geophys. J. Int., 158, Currie, C. A., and R. D. Hyndman (2006), The thermal structure of subduction zone back arcs, J. Geophys. Res., 111, B08404, doi: / 2005JB Flueh, E. R., et al. (1998), New seismic images of the Cascadia subduction zone from cruise SO 108-ORWELL, Tectonophysics, 293, Gabrielse, H., and C. J. Yorath (1992), Tectonic synthesis, in Geology of the Cordilleran Orogen in Canada, edited by H. Gabrielse and C. J. Yorath, pp , Geol. Surv. of Canada, Ottawa, Ont. Husson, L., and Y. Ricard (2004), Stress balance above subduction: Application to the Andes, Earth Planet. Sci. Lett., 222, Iaffaldano, G., and H.-P. Bunge (2008), Strong plate coupling along the Nazca-South America convergent margin, Geology, 36, Isacks, B. L. (1988), Uplift of the central Andean plateau and bending of the Bolivian orocline, J. Geophys. Res, 93, Kendrick, E., M. Bevis, R. Smalley Jr., and B. Brooks (2001), An integrated crustal velocity field for the central Andes, Geochem. Geophys. Geosyst., 2(11), 1066, doi: /2001gc Khazaradze, G., and J. Klotz (2003), Short- and long-term effects of GPS measured crustal deformation rates along the south central Andes, J. Geophys. Res., 108(B6), 2289, doi: /2002jb Kley, J., and C. R. Monaldi (1998), Tectonic shortening and crustal thickness in the central Andes: How good is the correlation?, Geology, 26, Klotz, J., G. Khazaradze, D. Angermann, C. Reigber, R. Perdomo, and O. Cifuentes (2001), Earthquake cycle dominates contemporary crustal deformation in central and southern Andes, Earth Planet. Sci. Lett., 193, Lallemand, S., A. Heuret, and D. Boutelier (2005), On the relationships between slab dip, back-arc stress, upper plate absolute motion, and crustal nature in subduction zones, Geochem. Geophys. Geosyst., 6, Q09006, doi: /2005gc Lamb, S. (2006), Shear stresses on megathrusts: Implications for mountain building behind subduction zones, J. Geophys. Res., 111, B07401, doi: /2005jb Lamb, S., and P. Davis (2003), Cenozoic climate change as a possible cause for the rise of the Andes, Nature, 425, Liu, M., Y. Q. Yang, S. Stein, Y. Q. Zhu, and J. Engeln (2000), Crustal shortening in the Andes: Why do GPS rates differ from geological rates?, Geophys. Res. Lett., 27, Luo, G., and M. Liu (2009), How does trench coupling lead to mountain building in the Subandes? A viscoelastoplastic finite element model, J. Geophys. Res., 114, B03409, doi: /2008jb of5
5 Mazzotti, S., H. Dragert, J. Henton, M. Schmidt, R. Hyndman, T. James, Y. Lu, and M. Craymer (2003), Current tectonics of northern Cascadia from a decade of GPS measurements, J. Geophys. Res., 108(B12), 2554, doi: /2003jb McCaffrey, R., A. I. Qamar, R. W. King, R. Wells, G. Khazaradze, C. A. Williams, C. W. Stevens, J. J. Vollick, and P. C. Zwick (2007), Fault locking, block rotation and crustal deformation in the Pacific Northwest, Geophys. J. Int., 169, Miller, M. M., D. J. Johnson, C. M. Rubin, H. Dragert, K. Wang, A. Qamar, and C. Goldfinger (2001), GPS-determination of along-strike variation in Cascadia margin kinematics: Implications for relative plate motion, subduction zone coupling, and permanent deformation, Tectonics, 20, Nishenko, S. P. (1991), Circum-Pacific seismic potential: , Pure Appl. Geophys., 135, Norabuena, E., et al. (2004), Geodetic and seismic constraints on some seismogenic zone processes in Costa Rica, J. Geophys. Res., 109, B11403, doi: /2003jb Norabuena, E., L. Leffler-Griffin, A. Mao, T. Dixon, S. Stein, I. S. Sacks, L. Ocola, and M. Ellis (1998), Space geodetic observations of Nazca- South America convergence across the central Andes, Science, 279, Oleskevich, D. A., R. D. Hyndman, and K. Wang (1999), The updip and downdip limits to great subduction earthquakes: Thermal and structural models of Cascadia, south Alaska, SW Japan, and Chile, J. Geophys. Res., 104, 14,965 14,991. Schilling, F. R., et al. (2006), Partial melting in the central Andean crust: A review of geophysical, petrophysical, and petrologic evidence, in The Andes, edited by O. Oncken et al., pp , Springer, Berlin. Silver, P. G., R. M. Russo, and C. Lithgow-Bertelloni (1998), Coupling of South American and African plate motion and plate deformation, Science, 279, Sobolev, S. V., and A. Y. Babeyko (2005), What drives orogeny in the Andes?, Geology, 33, Wang, K., and J. He (1999), Mechanics of low-stress forearcs: Nankai and Cascadia, J. Geophys. Res., 104, 15,191 15,205. Wang, K., T. Mulder, G. C. Rogers, and R. D. Hyndman (1995), Case for very low coupling stress on the Cascadia subduction fault, J. Geophys. Res., 100, 12,907 12,918. M. Liu and G. Luo, Department of Geological Sciences, University of Missouri, 101 Geology Building, Columbia, MO 65211, USA. (glk82@mizzou.edu) 5of5
Study megathrust creep to understand megathrust earthquakes
1 Study megathrust creep to understand megathrust earthquakes Kelin Wang Pacific Geoscience Centre, Geological Survey of Canada, kelin.wang@canada.ca Introduction Once upon a time, there was a belief that
More informationTopography growth drives stress rotations in the central Andes: Observations and models
Click Here for Full Article GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L08301, doi:10.1029/2007gl032782, 2008 Topography growth drives stress rotations in the central Andes: Observations and models Oliver
More informationThree-dimensional viscoelastic finite element model for postseismic deformation of the great 1960 Chile earthquake
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109,, doi:10.1029/2004jb003163, 2004 Three-dimensional viscoelastic finite element model for postseismic deformation of the great 1960 Chile earthquake Y. Hu, 1 K.
More informationSurface changes caused by erosion and sedimentation were treated by solving: (2)
GSA DATA REPOSITORY 214279 GUY SIMPSON Model with dynamic faulting and surface processes The model used for the simulations reported in Figures 1-3 of the main text is based on two dimensional (plane strain)
More informationSupplementary Material
1 Supplementary Material 2 3 4 Interseismic, megathrust earthquakes and seismic swarms along the Chilean subduction zone (38-18 S) 5 6 7 8 9 11 12 13 14 1 GPS data set We combined in a single data set
More informationDeformation cycles of great subduction earthquakes in a viscoelastic Earth
Deformation cycles of great subduction earthquakes in a viscoelastic Earth Kelin Wang Pacific Geoscience Centre, Geological Survey of Canada School of Earth and Ocean Science, University of Victoria????
More informationShear stresses on megathrusts: Implications for mountain building behind subduction zones
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111,, doi:10.1029/2005jb003916, 2006 Shear stresses on megathrusts: Implications for mountain building behind subduction zones Simon Lamb 1 Received 30 June 2005;
More information09/06/2017. The orogenic cycle in the Andes: Arc magmatism and delamination as control of the fold and thrust belts
The orogenic cycle in the Andes: Arc magmatism and delamination as control of the fold and thrust belts Victor A. Ramos Laboratorio de Tectónica Andina Instituto de Estudios Andinos Don Pablo Groeber Universidad
More informationParallel finite element modeling of multi-timescale faulting and lithospheric deformation in the western USA
C:/ITOOLS/WMS/CUP-NEW/2476227/WORKINGFOLDER/KKE/9780521897150C06.3D 68 [68 94] 10.1.2011 6:35PM 6 Parallel finite element modeling of multi-timescale faulting and lithospheric deformation in the western
More informationThe Andes Active Subduction Orogeny
Onno Oncken Guillermo Chong Gerhard Franz Peter Giese Hans-Jürgen Götze Victor A. Ramos Manfred R. Strecker Peter Wigger (Editors) The Andes Active Subduction Orogeny With 287 Figures, 159 in color Frontiers
More informationThe influence of short wavelength variations in viscosity on subduction dynamics
1 Introduction Deformation within the earth, driven by mantle convection due primarily to cooling and subduction of oceanic lithosphere, is expressed at every length scale in various geophysical observations.
More informationSlab pull, slab weakening, and their relation to deep intra-slab seismicity
GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L14305, doi:10.1029/2005gl022922, 2005 Slab pull, slab weakening, and their relation to deep intra-slab seismicity Susan L. Bilek Earth and Environmental Science
More informationActivity Pacific Northwest Tectonic Block Model
Activity Pacific Northwest Tectonic Block Model The Cascadia tectonic margin is caught between several tectonic forces, during the relentless motions of the giant Pacific Plate, the smaller subducting
More informationSendai Earthquake NE Japan March 11, Some explanatory slides Bob Stern, Dave Scholl, others updated March
Sendai Earthquake NE Japan March 11, 2011 Some explanatory slides Bob Stern, Dave Scholl, others updated March 14 2011 Earth has 11 large plates and many more smaller ones. Plates are 100-200 km thick
More informationSubduction zones are complex plate boundaries in which variable geometry and structure can be
1 Chapter 1 Introduction Subduction zones are complex plate boundaries in which variable geometry and structure can be seismically observed. The along-strike transition from flat to normal subduction is
More informationRegional Geodesy. Shimon Wdowinski. MARGINS-RCL Workshop Lithospheric Rupture in the Gulf of California Salton Trough Region. University of Miami
MARGINS-RCL Workshop Lithospheric Rupture in the Gulf of California Salton Trough Region Regional Geodesy Shimon Wdowinski University of Miami Rowena Lohman, Kim Outerbridge, Tom Rockwell, and Gina Schmalze
More informationDevelopment of a Predictive Simulation System for Crustal Activities in and around Japan - II
Development of a Predictive Simulation System for Crustal Activities in and around Japan - II Project Representative Mitsuhiro Matsu'ura Graduate School of Science, The University of Tokyo Authors Mitsuhiro
More informationThree-dimensional viscoelastic interseismic deformation model for the Cascadia subduction zone
Earth Planets Space, 53, 295 306, 2001 Three-dimensional viscoelastic interseismic deformation model for the Cascadia subduction zone Kelin Wang, Jiangheng He, Herb Dragert, and Thomas S. James Pacific
More informationGlobal Tectonics. Kearey, Philip. Table of Contents ISBN-13: Historical perspective. 2. The interior of the Earth.
Global Tectonics Kearey, Philip ISBN-13: 9781405107778 Table of Contents Preface. Acknowledgments. 1. Historical perspective. 1.1 Continental drift. 1.2 Sea floor spreading and the birth of plate tectonics.
More informationThe importance of the South-American plate motion and the Nazca Ridge subduction on flat subduction below South Peru
Chapter 7 The importance of the South-American plate motion and the Nazca Ridge subduction on flat subduction below South Peru Abstract Flat subduction near Peru occurs only where the thickened crust of
More informationANOTHER MEXICAN EARTHQUAKE! Magnitude 7.1, Tuesday Sept. 19, 2017
ANOTHER MEXICAN EARTHQUAKE! Magnitude 7.1, Tuesday Sept. 19, 2017 Why is there no oceanic crust older than 200 million years? SUBDUCTION If new oceanic crust is being continuously created along the earth
More informationNumerical modelling: The governing equation used in this study is: (K T ) c T H 0,
GSA DATA REPOSITORY 2012254 Cozzens and Spinelli Numerical modelling: The governing equation used in this study is: (K T ) c T H 0, where K is thermal conductivity, T is temperature, ρ is density, c is
More informationSUPPLEMENTARY INFORMATION
doi: 1.138/nature962 Data processing A network of 5 continuously recording GPS stations (LAGU, CHIN, ENAP, GUAD and JUAN) was installed after the earthquake (Figure 1, main text). The data considered in
More informationInterseismic locking of the plate interface in the northern Cascadia subduction zone, inferred from inversion of GPS data
Earth and Planetary Science Letters 231 (5) 239 247 www.elsevier.com/locate/epsl Interseismic locking of the plate interface in the northern Cascadia subduction zone, inferred from inversion of GPS data
More informationPredicted reversal and recovery of surface creep on the Hayward fault following the 1906 San Francisco earthquake
GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L19305, doi:10.1029/2008gl035270, 2008 Predicted reversal and recovery of surface creep on the Hayward fault following the 1906 San Francisco earthquake D. A. Schmidt
More informationDETAILS ABOUT THE TECHNIQUE. We use a global mantle convection model (Bunge et al., 1997) in conjunction with a
DETAILS ABOUT THE TECHNIQUE We use a global mantle convection model (Bunge et al., 1997) in conjunction with a global model of the lithosphere (Kong and Bird, 1995) to compute plate motions consistent
More informationPlate Tectonics. entirely rock both and rock
Plate Tectonics I. Tectonics A. Tectonic Forces are forces generated from within Earth causing rock to become. B. 1. The study of the origin and arrangement of Earth surface including mountain belts, continents,
More informationKinematics of the Southern California Fault System Constrained by GPS Measurements
Title Page Kinematics of the Southern California Fault System Constrained by GPS Measurements Brendan Meade and Bradford Hager Three basic questions Large historical earthquakes One basic question How
More informationUSU 1360 TECTONICS / PROCESSES
USU 1360 TECTONICS / PROCESSES Observe the world map and each enlargement Pacific Northwest Tibet South America Japan 03.00.a1 South Atlantic Arabian Peninsula Observe features near the Pacific Northwest
More information3. PLATE TECTONICS LAST NAME (ALL IN CAPS): FIRST NAME: PLATES
LAST NAME (ALL IN CAPS): FIRST NAME: PLATES 3. PLATE TECTONICS The outer layers of the Earth are divided into the lithosphere and asthenosphere. The division is based on differences in mechanical properties
More informationPlate Tectonics. Structure of the Earth
Plate Tectonics Structure of the Earth The Earth can be considered as being made up of a series of concentric spheres, each made up of materials that differ in terms of composition and mechanical properties.
More informationA mechanical model of the San Andreas fault and SAFOD Pilot Hole stress measurements
GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L15S13, doi:10.1029/2004gl019521, 2004 A mechanical model of the San Andreas fault and SAFOD Pilot Hole stress measurements Jean Chéry Laboratoire Dynamique de la
More informationEarth Science, (Tarbuck/Lutgens) Chapter 10: Mountain Building
Earth Science, (Tarbuck/Lutgens) Chapter 10: Mountain Building 1) A(n) fault has little or no vertical movements of the two blocks. A) stick slip B) oblique slip C) strike slip D) dip slip 2) In a(n) fault,
More informationA viscoelastic model of interseismic strain concentration in Niigata-Kobe Tectonic Zone of central Japan
Earth Planets Space, 55, 667 675, 2003 A viscoelastic model of interseismic strain concentration in Niigata-Kobe Tectonic Zone of central Japan Mamoru Hyodo 1 and Kazuro Hirahara 2 1 Graduate School of
More information} based on composition
Learning goals: Predict types of earthquakes that will happen at different plate boundaries based on relative plate motion vector vs. strike (vector subtraction) Understand interseismic and coseismic deformation,
More informationKinematics and geodynamics of the Cascadia convergent margin A proposal from the PANGA Investigator Community*
Kinematics and geodynamics of the Cascadia convergent margin A proposal from the PANGA Investigator Community* Observing North America s plate boundary The Cascadia subduction zone (Fig. 1a) occupies nearly
More informationEffect of an outer-rise earthquake on seismic cycle of large interplate earthquakes estimated from an instability model based on friction mechanics
Effect of an outer-rise earthquake on seismic cycle of large interplate earthquakes estimated from an instability model based on friction mechanics Naoyuki Kato (1) and Tomowo Hirasawa (2) (1) Geological
More informationDOWNLOAD OR READ : SHALLOW SUBDUCTION ZONES SEISMICITY MECHANICS AND SEISMIC POTENTIAL PDF EBOOK EPUB MOBI
DOWNLOAD OR READ : SHALLOW SUBDUCTION ZONES SEISMICITY MECHANICS AND SEISMIC POTENTIAL PDF EBOOK EPUB MOBI Page 1 Page 2 shallow subduction zones seismicity mechanics and seismic potential shallow subduction
More informationCONTINENTAL PLATE BOUNDARY ZONES
CONTINENTAL PLATE BOUNDARY ZONES Plate boundaries initially viewed as narrow Now recognize that many plate boundaries - especially continental - are deformation zones up to 1000 km wide, with motion spread
More informationHigh-Harmonic Geoid Signatures due to Glacial Isostatic Adjustment, Subduction and Seismic Deformation
High-Harmonic Geoid Signatures due to Glacial Isostatic Adjustment, Subduction and Seismic Deformation L.L.A. Vermeersen (1), H. Schotman (1), M.-W. Jansen (1), R. Riva (1) and R. Sabadini (2) (1) DEOS,
More informationFar-reaching transient motions after Mojave earthquakes require broad mantle flow beneath a strong crust
Click Here for Full Article GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L19302, doi:10.1029/2007gl030959, 2007 Far-reaching transient motions after Mojave earthquakes require broad mantle flow beneath a strong
More informationDeformation of Rocks. Orientation of Deformed Rocks
Deformation of Rocks Folds and faults are geologic structures caused by deformation. Structural geology is the study of the deformation of rocks and its effects. Fig. 7.1 Orientation of Deformed Rocks
More informationPresent-day deformation across the southwest Japan arc: Oblique subduction of the Philippine Sea plate and lateral slip of the Nankai forearc
LETTER Earth Planets Space, 55, 643 647, 2003 Present-day deformation across the southwest Japan arc: Oblique subduction of the Philippine Sea plate and lateral slip of the Nankai forearc Takao Tabei 1,
More informationCaptain s Tryouts 2017
Captain s Tryouts 2017 Dynamic Planet Test Written by: Araneesh Pratap (Chattahoochee High School) Name: Date: Answer all questions on the answer sheet. Point values are given next to each question or
More informationLong-term Crustal Deformation in and around Japan, Simulated by a 3-D Plate Subduction Model
Long-term Crustal Deformation in and around Japan, Simulated by a 3-D Plate Subduction Model Chihiro Hashimoto (1) and Mitsuhiro Matsu ura (2) (1) Institute of Frontier Research for Earth Evolution, Japan
More informationThermal models of the Middle America Trench at the Nicoya Peninsula, Costa Rica
GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 0, XXXX, doi:10.1029/2002gl015406, 2002 Thermal models of the Middle America Trench at the Nicoya Peninsula, Costa Rica Robert N. Harris Department of Geology
More informationSplay fault and megathrust earthquake slip in the Nankai Trough
Earth Planets Space, 53, 243 248, 2001 Splay fault and megathrust earthquake slip in the Nankai Trough Phil R. Cummins, Takane Hori, and Yoshiyuki Kaneda Frontier Research Program for Subduction Dynamics,
More informationMountain Building. Mountain Building
Mountain Building Mountain building has occurred during the recent geologic past American Cordillera the western margin of the Americas from Cape Horn to Alaska Includes the Andes and Rocky Mountains Alpine
More informationNorth America subducted under Rubia. Are there modern analogs for Hildebrand s model of North America subducting under Rubia?
North America subducted under Rubia Are there modern analogs for Hildebrand s model of North America subducting under Rubia? In the Geological Society of America Special Papers Did Westward Subduction
More informationUsing deformation rates in Northern Cascadia to constrain time-dependent stress- and slip-rate on the megathrust
Using deformation rates in Northern Cascadia to constrain time-dependent stress- and slip-rate on the megathrust Lucile Bruhat Paul Segall Stanford University 1 50 Interseismic period for the Cascadia
More informationSeismotectonics of intraplate oceanic regions. Thermal model Strength envelopes Plate forces Seismicity distributions
Seismotectonics of intraplate oceanic regions Thermal model Strength envelopes Plate forces Seismicity distributions Cooling of oceanic lithosphere also increases rock strength and seismic velocity. Thus
More informationGEOL 321 Structural Geology and Tectonics
GEOL 321 Structural Geology and Tectonics Geology 321 Structure and Tectonics will be given in Spring 2017. The course provides a general coverage of the structures produced by brittle and ductile rock
More informationoverlie the seismogenic zone offshore Costa Rica, making the margin particularly well suited for combined land and ocean geophysical studies (Figure
Chapter 1 Introduction Historically, highly destructive large magnitude (M w >7.0) underthrusting earthquakes nucleate along the shallow segment of subduction zone megathrust fault, and this region of
More information12. The diagram below shows the collision of an oceanic plate and a continental plate.
Review 1. Base your answer to the following question on the cross section below, which shows the boundary between two lithospheric plates. Point X is a location in the continental lithosphere. The depth
More informationOCN 201: Seafloor Spreading and Plate Tectonics I
OCN 201: Seafloor Spreading and Plate Tectonics I Revival of Continental Drift Theory Kiyoo Wadati (1935) speculated that earthquakes and volcanoes may be associated with continental drift. Hugo Benioff
More informationToday: Basic regional framework. Western U.S. setting Eastern California Shear Zone (ECSZ) 1992 Landers EQ 1999 Hector Mine EQ Fault structure
Today: Basic regional framework Western U.S. setting Eastern California Shear Zone (ECSZ) 1992 Landers EQ 1999 Hector Mine EQ Fault structure 1 2 Mojave and Southern Basin and Range - distribution of strike-slip
More informationParts of the Sevier/ Laramide Orogeny
Parts of the Sevier/ Laramide Orogeny AA. Accretionary Prism BB. Forearc Basin Sediment scraped off of subducting plate Sediment derived from the volcanic arc CC. Volcanic Arc Magmatic intrusion into the
More informationFrequency of large crustal earthquakes in Puget Sound Southern Georgia Strait predicted from geodetic and geological deformation rates
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. B1, 2033, doi:10.1029/2001jb001710, 2003 Frequency of large crustal earthquakes in Puget Sound Southern Georgia Strait predicted from geodetic and geological
More informationElizabeth H. Hearn modified from W. Behr
Reconciling postseismic and interseismic surface deformation around strike-slip faults: Earthquake-cycle models with finite ruptures and viscous shear zones Elizabeth H. Hearn hearn.liz@gmail.com modified
More informationImpact of megathrust geometry on inversion of coseismic slip from geodetic data: Application to the 1960 Chile earthquake
GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L16310, doi:10.1029/2009gl039276, 2009 Impact of megathrust geometry on inversion of coseismic slip from geodetic data: Application to the 1960 Chile earthquake M.
More informationEvolution of Continents Chapter 20
Evolution of Continents Chapter 20 Does not contain complete lecture notes. Mountain belts Orogenesis the processes that collectively produce a mountain belt Includes folding, thrust faulting, metamorphism,
More informationCopyright McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education
Copyright McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education Tibetan Plateau and Himalaya -southern Asia 11.00.a VE 10X
More informationWhen you are standing on a flat surface, what is the normal stress you exert on the ground? What is the shear stress?
When you are standing on a flat surface, what is the normal stress you exert on the ground? What is the shear stress? How could you exert a non-zero shear stress on the ground? Hydrostatic Pressure (fluids)
More informationLab 1: Plate Tectonics April 2, 2009
Name: Lab 1: Plate Tectonics April 2, 2009 Objective: Students will be introduced to the theory of plate tectonics and different styles of plate margins and interactions. Introduction The planet can be
More informationGENERAL GEOLOGY Fall Chapter 18: The Sea Floor. Partial Examination IV Study Guide Dr. Glen S. Mattioli
GENERAL GEOLOGY 1113-005 Fall 2008 Partial Examination IV Study Guide Dr. Glen S. Mattioli Note that these are NOT questions, but rather are a list of topics that we have covered either in class or are
More informationB6 Isostacy. B6.1 Airy and Pratt hypotheses. Geophysics 210 September 2008
B6 Isostacy B6.1 Airy and Pratt hypotheses Himalayan peaks on the Tibet-Bhutan border In the 19 th century surveyors used plumblines and theodolites to map India. A plumb line was used when measuring the
More informationAzimuth with RH rule. Quadrant. S 180 Quadrant Azimuth. Azimuth with RH rule N 45 W. Quadrant Azimuth
30 45 30 45 Strike and dip notation (a) N30 E, 45 SE ("Quadrant"): the bearing of the strike direction is 30 degrees east of north and the dip is 45 degrees in a southeast (SE) direction. For a given strike,
More information4 Deforming the Earth s Crust
CHAPTER 7 4 Deforming the Earth s Crust SECTION Plate Tectonics BEFORE YOU READ After you read this section, you should be able to answer these questions: What happens when rock is placed under stress?
More informationMountains are then built by deforming crust: Deformation & Mountain Building. Mountains form where stresses are high!
Deformation & Mountain Building Where are mountains located? Deformation and Folding Mountain building Mountains form where stresses are high! Mountains form at all three types of plate boundaries where
More informationQuestions and Topics
Plate Tectonics and Continental Drift Questions and Topics 1. What are the theories of Plate Tectonics and Continental Drift? 2. What is the evidence that Continents move? 3. What are the forces that
More informationSeptember 5, 2012 M 7.6 Costa Rica Earthquake
September 5, 2012 M 7.6 Costa Rica Earthquake On September 5, 2012, a Magnitude 7.6 earthquake occurred in the Nicoya Peninsula of northwestern Costa Rica, along a locked segment of the subduction boundary
More informationNormal and reverse faulting driven by the subduction zone earthquake cycle in the northern Chilean fore arc
Click Here for Full Article Normal and reverse faulting driven by the subduction zone earthquake cycle in the northern Chilean fore arc John P. Loveless, 1,2 Richard W. Allmendinger, 1 Matthew E. Pritchard,
More informationStrike-Slip Faults. ! Fault motion is parallel to the strike of the fault.
Strike-Slip Faults! Fault motion is parallel to the strike of the fault.! Usually vertical, no hanging-wall/footwall blocks.! Classified by the relative sense of motion. " Right lateral opposite block
More informationComment on A new estimate for present-day Cocos-Caribbean plate motion: Implications
Comment on A new estimate for present-day Cocos-Caribbean plate motion: Implications for slip along the Central American volcanic arc by Charles DeMets Marco Guzmán-Speziale Juan Martín Gómez Unidad de
More informationEarth s Tectonic Plates
MASTER 49 6.2 3.7 5.4 Philippine Pacific 5.4 North American Juan de Fuca Caribbean Cocos 10.0 9.2 2.3 2.5 2.3 1.8 3.0 Indian-Australian 10.5 7.1 17.2 16.8 6.0 Nazca South American 11.1 10.3 7.3 3.7 7.5
More informationMAR110 Lecture #5 Plate Tectonics-Earthquakes
1 MAR110 Lecture #5 Plate Tectonics-Earthquakes Figure 5.0 Plate Formation & Subduction Destruction The formation of the ocean crust from magma that is upwelled into a pair of spreading centers. Pairs
More informationAn Introduction to the Seafloor and Plate Tectonics 1
An Introduction to the Seafloor and Plate Tectonics 1 Objectives 1) Investigate the components of the lithosphere and lithospheric plates. 2) Identify the associations among various seafloor features,
More informationRheology III. Ideal materials Laboratory tests Power-law creep The strength of the lithosphere The role of micromechanical defects in power-law creep
Rheology III Ideal materials Laboratory tests Power-law creep The strength of the lithosphere The role of micromechanical defects in power-law creep Ideal materials fall into one of the following categories:
More informationDepth (Km) + u ( ξ,t) u = v pl. η= Pa s. Distance from Nankai Trough (Km) u(ξ,τ) dξdτ. w(x,t) = G L (x,t τ;ξ,0) t + u(ξ,t) u(ξ,t) = v pl
Slip history during one earthquake cycle at the Nankai subduction zone, inferred from the inversion analysis of levelling data with a viscoelastic slip response function Mitsuhiro Matsu'ura, Akira Nishitani
More informationRecent tectonic plate decelerations driven by mantle convection
Click Here for Full Article GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L23301, doi:10.1029/2009gl040224, 2009 Recent tectonic plate decelerations driven by mantle convection A. M. Forte, 1 R. Moucha, 1 D.
More information4-D Geodynamic Modeling With Data Assimilation: Subduction and Continental Evolution
4-D Geodynamic Modeling With Data Assimilation: Subduction and Continental Evolution PI: Lijun Liu Department of Geology, University of Illinois at Urbana-Champaign Corresponding author: Lijun Liu, ljliu@illinois.edu
More informationCrustal deformation and fault slip during the seismic cycle in the North Chile subduction zone, from GPS and InSAR observations
Geophys J Int (24) 158, 695 711 doi: 11111/j1365-246X242326x Crustal deformation and fault slip during the seismic cycle in the North Chile subduction zone, from GPS and InSAR observations M Chlieh, 1,
More informationThe Nazca South America Euler vector and its rate of change
Journal of South American Earth Sciences 16 (2003) 125 131 www.elsevier.com/locate/jsames The Nazca South America Euler vector and its rate of change Eric Kendrick a, Michael Bevis a, *, Robert Smalley
More informationA) B) C) D) 4. Which diagram below best represents the pattern of magnetic orientation in the seafloor on the west (left) side of the ocean ridge?
1. Crustal formation, which may cause the widening of an ocean, is most likely occurring at the boundary between the A) African Plate and the Eurasian Plate B) Pacific Plate and the Philippine Plate C)
More informationPlate Tectonics. By Destiny, Jarrek, Kaidence, and Autumn
Plate Tectonics By Destiny, Jarrek, Kaidence, and Autumn .The Denali Fault and San Andreas Fault - The San Andreas Fault is a continental transform fault that extends roughly 1300 km (810 miles) through
More informationInfluence of surrounding plates on 3D subduction dynamics
Click Here for Full Article GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L07303, doi:10.1029/2008gl036942, 2009 Influence of surrounding plates on 3D subduction dynamics P. Yamato, 1 L. Husson, 1 J. Braun, 1
More informationEarth Movement and Resultant Landforms
Earth Movement and Resultant Landforms Structure of the Earth Lithosphere : earth s crust Asthenosphere : upper mantle zone where material is near its melting point & acts almost like liquid (appprox.
More informationSedimentary Basin Analysis http://eqsun.geo.arizona.edu/geo5xx/geos517/ Sedimentary basins can be classified based on the type of plate motions (divergent, convergent), type of the lithosphere, distance
More informationGeologic Structures. Changes in the shape and/or orientation of rocks in response to applied stress
Geologic Structures Changes in the shape and/or orientation of rocks in response to applied stress Figure 15.19 Can be as big as a breadbox Or much bigger than a breadbox Three basic types Fractures >>>
More informationChapter. Graphics by Tasa Graphic Arts. Inc.
Earth Chapter Plate Science 9 Tectonics Graphics by Tasa Graphic Arts. Inc. 1 I. Earth s surface is made up of lithospheric plates. A. Lithospheric plates are composed of the crust and part of the upper
More informationEssentials of Geology, 11e
Essentials of Geology, 11e Crustal Deformation and Mountain Building Chapter 17 Instructor Jennifer Barson Spokane Falls Community College Geology 101 Stanley Hatfield Southwestern Illinois College Jennifer
More informationOriginally published as:
Originally published as: Lorenzo Martín, F., Wang, R., Roth, F. (2002): The effect of input parameters on visco-elastic models of crustal deformation. - Física de la Tierra, 14, 33-54 The effect of input
More informationto: Interseismic strain accumulation and the earthquake potential on the southern San
Supplementary material to: Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault system by Yuri Fialko Methods The San Bernardino-Coachella Valley segment of the
More informationAnswers: Internal Processes and Structures (Isostasy)
Answers: Internal Processes and Structures (Isostasy) 1. Analyse the adjustment of the crust to changes in loads associated with volcanism, mountain building, erosion, and glaciation by using the concept
More informationSUPPLEMENTARY INFORMATION
SUPPLEMENTARY INFORMATION doi: 10.1038/ngeo739 Supplementary Information to variability and distributed deformation in the Marmara Sea fault system Tobias Hergert 1 and Oliver Heidbach 1,* 1 Geophysical
More informationThe Non-volcanic tremor observation in Northern Cascadia. Hsieh Hsin Sung 3/22
The Non-volcanic tremor observation in Northern Cascadia Hsieh Hsin Sung 3/22 Reference Kao, H., S. J. Shan, H. Dragert, and G. Rogers (2009), Northern Cascadia episodic tremor and slip: A decade of observations
More informationEarthquakes. Earthquakes are caused by a sudden release of energy
Earthquakes Earthquakes are caused by a sudden release of energy The amount of energy released determines the magnitude of the earthquake Seismic waves carry the energy away from its origin Fig. 18.1 Origin
More informationData Repository of Paper: The role of subducted sediments in plate interface dynamics as constrained by Andean forearc (paleo)topography
Data Repository of Paper: The role of subducted sediments in plate interface dynamics as constrained by Andean forearc (paleo)topography Nicolás J. Cosentino 1*, Felipe Aron 2,3, Jorge G. F. Crempien 2,3,
More informationEarthquake distribution is not random: very narrow deforming zones (= plate boundaries) versus large areas with no earthquakes (= rigid plate
Earthquake distribution is not random: very narrow deforming zones (= plate boundaries) versus large areas with no earthquakes (= rigid plate interiors) Tectonic plates and their boundaries today -- continents
More informationGeologic Evolution of Latin America. Plate Tectonics: General Concepts & Applications to Latin America
Geologic Evolution of Latin America Plate Tectonics: General Concepts & Applications to Latin America Structure of Earth: 3 major divisions of Core, Mantle, and Crust Upper mantle differs in the way that
More information