Earthquake-induced transformation of the lower crust

The structural and metamorphic evolution of the lower crust has direct effects on the lithospheric response to plate tectonic processes involved in orogeny, including subsidence of sedimentary basins, stability of deep mountain roots and extension of high-topography regions. Recent research shows th...

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Bibliographic Details
Published in:Nature (London) 2018-04, Vol.556 (7702), p.487-491
Main Authors: Jamtveit, Bjørn, Ben-Zion, Yehuda, Renard, François, Austrheim, Håkon
Format: Article
Language:English
Subjects:
704/2151/210
704/2151/431
704/2151/508
704/2151/562
Aftershocks
Analysis
Basins (Geology)
Crust (Geology)
Earthquakes
Evolution
Fault lines
Fluids
Geodynamics
Geological faults
Humanities and Social Sciences
Infiltration
Laboratories
Letter
Lithosphere
Magma
Metamorphism
multidisciplinary
Norway
Orogeny
Plate tectonics
Science
Science (multidisciplinary)
Sedimentary basins
Seismic activity
Seismic engineering
Seismic response
Seismic stability
Seismology
Stress
Tectonic processes
Tectonics
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Summary:The structural and metamorphic evolution of the lower crust has direct effects on the lithospheric response to plate tectonic processes involved in orogeny, including subsidence of sedimentary basins, stability of deep mountain roots and extension of high-topography regions. Recent research shows that before orogeny most of the lower crust is dry, impermeable and mechanically strong 1 . During an orogenic event, the evolution of the lower crust is controlled by infiltration of fluids along localized shear or fracture zones. In the Bergen Arcs of Western Norway, shear zones initiate as faults generated by lower-crustal earthquakes. Seismic slip in the dry lower crust requires stresses at a level that can only be sustained over short timescales or local weakening mechanisms. However, normal earthquake activity in the seismogenic zone produces stress pulses that drive aftershocks in the lower crust 2 . Here we show that the volume of lower crust affected by such aftershocks is substantial and that fluid-driven associated metamorphic and structural transformations of the lower crust follow these earthquakes. This provides a ‘top-down’ effect on crustal geodynamics and connects processes operating at very different timescales. During continent collision and associated mountain building, a surprisingly large volume of the lower crust is shown to be affected by earthquake aftershocks, producing a top-down effect on crustal geodynamics.
ISSN:0028-0836
1476-4687
DOI:10.1038/s41586-018-0045-y