Exposed plate interface in the European Alps reveals fabric styles and gradients related to an ancient seismogenic coupling zone

Bachmann, R.; Oncken, Onno; Glodny, Johannes; Seifert, Wolfgang; Georgieva, Viktoria; Sudo, Masafumi

doi:10.1029/2008jb005927

Cited by 68 publications

(116 citation statements)

References 108 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…Most ruptures propagate along one of the material interfaces (e.g., Figure b), as they experience largest differential slip rates. These preferred locations of shear localization agree with field observations on subduction channel melanges that were exhumed from depths just below the seismogenic zone [e.g., Andersen and Austrheim , ; Bachmann et al , ; Angiboust et al , ]. We also observe that the active fault zone typically widens as it approaches the surface (Figure b).…”

Section: Discussionsupporting

confidence: 89%

The seismic cycle at subduction thrusts: Insights from seismo‐thermo‐mechanical models

et al. 2013

View full text Add to dashboard Cite

[1] The underestimation of the size of recent megathrust earthquakes illustrates our limited understanding of their spatiotemporal occurrence and governing physics. To unravel their relation to associated subduction dynamics and long-term deformation, we developed a 2-D continuum viscoelastoplastic model that uses an Eulerian-Lagrangian finite difference framework with similar on-and off-fault physics. We extend the validation of this numerical tool to a realistic subduction zone setting that resembles Southern Chile. The resulting quasi-periodic pattern of quasi-characteristic M8-M9 megathrust events compares quantitatively with observed recurrence and earthquake source parameters, albeit at very slow coseismic speeds. Without any data fitting, surface displacements agree with GPS data recorded before and during the 2010 M8.8 Maule earthquake, including the presence of a second-order flexural bulge. These surface displacements show cycle-to-cycle variations of slip deficits, which overall accommodate 5% of permanent internal shortening. We find that thermally (and stress) driven creep governs a spontaneous conditionally stable downdip transition zone between temperatures of 350 ı C and 450 ı C. Ruptures initiate above it (and below the forearc Moho), propagate within it, interspersed by small intermittent events, and arrest below it as ductile shearing relaxes stresses. Ruptures typically propagate upward along lithological boundaries and widen as pressures drop. The main thrust is constrained to be weak due to fluid-induced weakening required to sustain regular subduction and to generate events with natural characteristics (fluid pressures of 75-99% of solid pressures). The agreement with a range of seismological, geodetic, and geological observations demonstrates the validity and strength of this physically consistent seismo-thermo-mechanical approach.

show abstract

Section: Discussionsupporting

confidence: 89%

The seismic cycle at subduction thrusts: Insights from seismo‐thermo‐mechanical models

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Similar structural features have been observed in numerous exhumed subduction-related mélanges (e.g. Moore & Wheeler 1978;Ujiie 2002;Fukui & Kano 2007;Vannucchi et al 2008;Bachmann et al 2009), indicating that continuous-discontinuous deformation of a tabular zone of trench-fill sediments is common along subduction margins. The thickness of this deforming zone at any one time has, however, still not been determined.…”

Section: Comparison Of the Chrystalls Beach Complex To Modern Analoguesmentioning

confidence: 62%

Geology of the seismogenic subduction thrust interface

Fagereng

2011

View full text Add to dashboard Cite

A microseismically active layer of underthrust sediments is commonly inferred along subduction thrust interfaces. The exhumed Chrystalls Beach Complex, in the Otago Schist, New Zealand, may be analogous to an actively deforming underthrust rock assemblage. The complex contains asymmetric competent lenses of sandstone, chert and basalt enclosed in a cleaved mudstone matrix. Continuous fabrics such as folds, boudins and asymmetric phacoids formed by distributed cataclasis and dissolution-precipitation creep. Discontinuous deformation is evident in an extensive fault-fracture mesh involving mutually cross-cutting subvertical extension veins and subhorizontal slickenfibre shear surfaces.The Hikurangi margin provides an example of along-strike variations in seismic style, possibly related to heterogeneous fluid-pressure state and interface geology. In both the ancient and active subduction-related shear zone, fluid-pressure state appears to be a critical control on frictional failure, which primarily occurs on weak, fluid-overpressured discontinuities. Continuous, aseismic deformation occurs where other mineral deformation mechanisms, such as dissolutionprecipitation creep, are preferred. The geometry and composition of the underthrust rock assemblage appear to be first-order controls on megathrust fluid-pressure distribution, bulk rheology and dominant deformation mechanism, and thus may be significant controls on megathrust seismic style.

show abstract

“…The anomalously rapid 14th century rate at Lewak may suggest a period of increased coupling under the site and/or a period during which the locked zone extended farther downdip, to the northeast of the site. One explanation is suggested by Bachmann et al [2009], who present evidence from an exhumed subduction zone for fluids circulating along the plate interface and for transient changes in pore pressure; they argue that these changes may give rise to variations in coupling over the seismic cycle. Although we may not yet fully understand the reasons or appreciate the implications, the observation of twofold to fourfold variations in the interseismic subsidence rate at a given site, from one earthquake cycle to another, appears to be robust.…”

Section: Discussionmentioning

confidence: 99%

Coral evidence for earthquake recurrence and an A.D. 1390–1455 cluster at the south end of the 2004 Aceh–Andaman rupture

et al. 2010

View full text Add to dashboard Cite

Coral records of relative sea level change provide a history of vertical interseismic and coseismic deformation along the coast of northern Simeulue Island, Sumatra, and reveal details about earthquakes in the 10th and 14th–15th centuries A.D. along the southern end of the December 2004 Mw 9.2 Sunda megathrust rupture. Over a 56 year period between A.D. 1390 and 1455, northern Simeulue experienced a cluster of megathrust ruptures, associated with total uplift that was considerably more than in 2004. Uplifted corals at two sites constrain the first event of the cluster to A.D. 1393 ± 3 and 1394 ± 2 (2σ). A smaller but well‐substantiated uplift occurred in northern Simeulue in 1430 ± 3. An inferred third uplift, in A.D. 1450 ± 3, killed all corals on the reef flats of northern Simeulue. The amount of uplift during this third event, though confirmed only to have exceeded 28 and 41 cm at two sites, probably surpassed the 100 and 44 cm that occurred, respectively, at those sites in 2004, and it was likely more than in 2004 over all of northern Simeulue. The evidence for past earthquake clustering combined with the inference of considerably greater uplift in A.D. 1390–1455 than in 2004 suggests that strain may still be stored along the southernmost part of the 2004 rupture. Interseismic subsidence rates recorded by northern Simeulue coral microatolls have varied by up to a factor of 4 at some sites from one earthquake cycle to another.

show abstract

Exposed plate interface in the European Alps reveals fabric styles and gradients related to an ancient seismogenic coupling zone

Cited by 68 publications

References 108 publications

The seismic cycle at subduction thrusts: Insights from seismo‐thermo‐mechanical models

The seismic cycle at subduction thrusts: Insights from seismo‐thermo‐mechanical models

Geology of the seismogenic subduction thrust interface

Coral evidence for earthquake recurrence and an A.D. 1390–1455 cluster at the south end of the 2004 Aceh–Andaman rupture

Contact Info

Product

Resources

About