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... timing and amplitude of these phases may be slightly altered by possible interference with smaller reverberations from discontinuities internal to the crust. However, although the possibility of such interference leads to uncertainties in the depth and gradient associated with a discontinuity at the ...
... timing and amplitude of these phases may be slightly altered by possible interference with smaller reverberations from discontinuities internal to the crust. However, although the possibility of such interference leads to uncertainties in the depth and gradient associated with a discontinuity at the ...
Structure and Serpentinization of the Subducting Cocos Plate
... 2008, 2010] and South America [Ranero and Sallarès, 2004; Contreras‐Reyes et al., 2008a] with ocean bottom seismometer (OBS) refraction profiles has shown that seismic wave speeds are reduced in both the oceanic crust and upper mantle between the outer rise of the subduction zone and the trench axis ...
... 2008, 2010] and South America [Ranero and Sallarès, 2004; Contreras‐Reyes et al., 2008a] with ocean bottom seismometer (OBS) refraction profiles has shown that seismic wave speeds are reduced in both the oceanic crust and upper mantle between the outer rise of the subduction zone and the trench axis ...
Lithosphere structure underneath the Tibetan Plateau inferred from
... sensitive to shallow structures, elevation, geoid height and longwavelength heat flow variations are more sensitive to deep structures. Seismic data provide valuable information on both the geometry of crustal layers and the depth distribution of P-wave velocities. Geopotential, lithostatic and heat ...
... sensitive to shallow structures, elevation, geoid height and longwavelength heat flow variations are more sensitive to deep structures. Seismic data provide valuable information on both the geometry of crustal layers and the depth distribution of P-wave velocities. Geopotential, lithostatic and heat ...
Chapter 11 Section 2
... • Some of the largest volcanic mountains are part of the midocean ridges along divergent plate boundaries. • Other large volcanic mountains form on the ocean floor at hot spots, which are volcanically active areas that seem to correspond to places where hot material rises through Earth’s interior an ...
... • Some of the largest volcanic mountains are part of the midocean ridges along divergent plate boundaries. • Other large volcanic mountains form on the ocean floor at hot spots, which are volcanically active areas that seem to correspond to places where hot material rises through Earth’s interior an ...
Clutch tectonics and the partial attachment of lithospheric layers
... Abstract. Clutch zones, in analogy to the clutch in an automobile, explain the mechanical communication between the necessarily different displacement fields of rheologicallydistinct lithospheric layers. In contrast to detachment zones, these sub-horizontal shear zones act as partial attachment zone ...
... Abstract. Clutch zones, in analogy to the clutch in an automobile, explain the mechanical communication between the necessarily different displacement fields of rheologicallydistinct lithospheric layers. In contrast to detachment zones, these sub-horizontal shear zones act as partial attachment zone ...
Kerguelen plateau : a volcanic passive margin fragment ?
... structure beneath the southern Kerguelen Plateau also differs significantly from that determined in the northern Kerguelen Plateau, which exhibits a classical crustal structure for an oceanic plateau with high seismic velocities (6.6-7.4 km/s) in the lower crust (Charvis et al., 1993). Furthermore, ...
... structure beneath the southern Kerguelen Plateau also differs significantly from that determined in the northern Kerguelen Plateau, which exhibits a classical crustal structure for an oceanic plateau with high seismic velocities (6.6-7.4 km/s) in the lower crust (Charvis et al., 1993). Furthermore, ...
Dynamics of intraoceanic subduction initiation
... therefore linked the formation of SSZ ophiolites to the subduction initiation process. This notion was consistent with conclusions drawn from an additional puzzling feature of many ophiolites, frequently with a SSZ-type geochemistry: metamorphic soles. Metamorphic soles form intensely foliated and s ...
... therefore linked the formation of SSZ ophiolites to the subduction initiation process. This notion was consistent with conclusions drawn from an additional puzzling feature of many ophiolites, frequently with a SSZ-type geochemistry: metamorphic soles. Metamorphic soles form intensely foliated and s ...
Ambient seismic noise tomography of the southern East Sea (Japan
... other places. A similar pattern is observed in our group velocity map for the 5 s period (Fig 3a). ...
... other places. A similar pattern is observed in our group velocity map for the 5 s period (Fig 3a). ...
How Did Early Earth Become Our Modern World?
... moderately volatile elements such as Na and S compared with other meteorite groups and Earth (Palme & O’Neill 2003). The isotopic results have reopened a long-running debate (Herndon 1979, Javoy 1995) about whether carbonaceous or enstatite chondrites serve as better reference points to model the bu ...
... moderately volatile elements such as Na and S compared with other meteorite groups and Earth (Palme & O’Neill 2003). The isotopic results have reopened a long-running debate (Herndon 1979, Javoy 1995) about whether carbonaceous or enstatite chondrites serve as better reference points to model the bu ...
Early cretaceous subduction-related adakite
... of zircons that had previously been dated by SHRIMP yielded positive initial eHf(t) values ranging from +11.0 to +15.5. A model calculation using trace element and Sr–Nd–Pb isotopic data indicates that several percent of subducted sediment is required to generate the Mamen andesites, which were deri ...
... of zircons that had previously been dated by SHRIMP yielded positive initial eHf(t) values ranging from +11.0 to +15.5. A model calculation using trace element and Sr–Nd–Pb isotopic data indicates that several percent of subducted sediment is required to generate the Mamen andesites, which were deri ...
From Lithospheric Thickening and Divergent Collapse to Active
... tensile horizontal stresses that may trigger divergent collapse: The gravity-driven flow that reduces lateral variation of gravitational potential energy. As collapse proceeds, the thickened crust tends to recover its normal thickness and, assuming homogeneous deformation, the lithospheric mantle be ...
... tensile horizontal stresses that may trigger divergent collapse: The gravity-driven flow that reduces lateral variation of gravitational potential energy. As collapse proceeds, the thickened crust tends to recover its normal thickness and, assuming homogeneous deformation, the lithospheric mantle be ...
Weakening of the subduction interface and its effects on surface
... Figure 1. Schematic illustration of a typical warm-slab subduction zone and its surface heat flow. (a) Forearc mantle wedge and its environment. Stars represent intraplate earthquakes. ETS is episodic slip and tremor observed at Cascadia and Nankai, to be discussed in section 5.1. ETS may be rare in ...
... Figure 1. Schematic illustration of a typical warm-slab subduction zone and its surface heat flow. (a) Forearc mantle wedge and its environment. Stars represent intraplate earthquakes. ETS is episodic slip and tremor observed at Cascadia and Nankai, to be discussed in section 5.1. ETS may be rare in ...
Shape and origin of the East-Alpine slab constrained by the
... During the last two decades teleseismic studies yielded valuable information on the structure of the upper mantle below the Alpine–Mediterranean area. Subducted oceanic lithosphere forms a broad anomaly resting on but not penetrating the 670 km discontinuity. More shallow slabs imaged below the Alpi ...
... During the last two decades teleseismic studies yielded valuable information on the structure of the upper mantle below the Alpine–Mediterranean area. Subducted oceanic lithosphere forms a broad anomaly resting on but not penetrating the 670 km discontinuity. More shallow slabs imaged below the Alpi ...
Earthquakes and Volcanoes
... movement of the rock along the fault. • Energy is released. The earthquake will continue until the energy is used up. ...
... movement of the rock along the fault. • Energy is released. The earthquake will continue until the energy is used up. ...
Imaging the lithosphere beneath NE Tibet: teleseismic P and S body
... International Deep Profiling of Tibet and the Himalaya, Phase IV broad-band seismometer deployments. We analyse these arrival times to determine tomographic images of P- and S-wave velocities in the upper mantle beneath this part of the plateau. To account for the effects of major heterogeneity in c ...
... International Deep Profiling of Tibet and the Himalaya, Phase IV broad-band seismometer deployments. We analyse these arrival times to determine tomographic images of P- and S-wave velocities in the upper mantle beneath this part of the plateau. To account for the effects of major heterogeneity in c ...
Doglioni et al Mantle wedge asymmetries and geochemical
... mantle wedge to compensate for slab rollback, this flow being distorted by the corner flow associated with the subduction. These ...
... mantle wedge to compensate for slab rollback, this flow being distorted by the corner flow associated with the subduction. These ...
Earth`s heterogeneous mantle: A product of convection
... analyses of oceanic basalts. Despite the ever-increasing amount of data, the way in which compositional heterogeneity is manifest in the Earth's mantle, as well as the processes leading to mantle heterogeneity remain fundamental questions. The large amount of available isotope data in oceanic basalt ...
... analyses of oceanic basalts. Despite the ever-increasing amount of data, the way in which compositional heterogeneity is manifest in the Earth's mantle, as well as the processes leading to mantle heterogeneity remain fundamental questions. The large amount of available isotope data in oceanic basalt ...
Earthquakes In Southwestern British Columbia
... coastlines and inlets along the west coast of Vancouver Island and the United States will bear the brunt of a tsunami. There will be only a 15 to 30 minutes between the earthquake and the arrival of the first tsunami waves. The last megathrust earthquake on the Cascadia Subduction Zone occurred on J ...
... coastlines and inlets along the west coast of Vancouver Island and the United States will bear the brunt of a tsunami. There will be only a 15 to 30 minutes between the earthquake and the arrival of the first tsunami waves. The last megathrust earthquake on the Cascadia Subduction Zone occurred on J ...
Upper mantle anisotropy beneath Australia and Tahiti from P
... and the great circle azimuth, independent of back azimuth and frequency; in this case, one should not expect any back azimuthal periodicity in the P wave polarization. [8] 2. For seismic anisotropy, upper mantle anisotropy is commonly interpreted as a result of intrinsic elastic anisotropy of rock-f ...
... and the great circle azimuth, independent of back azimuth and frequency; in this case, one should not expect any back azimuthal periodicity in the P wave polarization. [8] 2. For seismic anisotropy, upper mantle anisotropy is commonly interpreted as a result of intrinsic elastic anisotropy of rock-f ...
A tensile, flexural model for the initiation of subduction
... consider the flow field that results purely kinematically for Fig. 2(a), assuming the non-subducting plate is at rest and is bounded on the right by a ridge. If the ridge is spreading symmetrically and migrating to the right, it creates a clockwise circulation, while the subducting slab creates a co ...
... consider the flow field that results purely kinematically for Fig. 2(a), assuming the non-subducting plate is at rest and is bounded on the right by a ridge. If the ridge is spreading symmetrically and migrating to the right, it creates a clockwise circulation, while the subducting slab creates a co ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.