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Shear-zone thickness and the seismicity of Chilean- and Marianas-type subduction zones

1996; Geological Society of America; Volume: 24; Issue: 2 Linguagem: Inglês

10.1130/0091-7613(1996)024 2.3.co;2

1943-2682

Mark Cloos, Ronald L. Shreve,

Geological and Geochemical Analysis

Research Article| February 01, 1996 Shear-zone thickness and the seismicity of Chilean- and Marianas-type subduction zones Mark Cloos; Mark Cloos 1Department of Geological Sciences and Institute for Geophysics, University of Texas, Austin, Texas 78713-7909 Search for other works by this author on: GSW Google Scholar Ronald L. Shreve Ronald L. Shreve 2Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90024-1567 Search for other works by this author on: GSW Google Scholar Author and Article Information Mark Cloos 1Department of Geological Sciences and Institute for Geophysics, University of Texas, Austin, Texas 78713-7909 Ronald L. Shreve 2Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90024-1567 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1996) 24 (2): 107–110. https://doi.org/10.1130/0091-7613(1996)024 2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Mark Cloos, Ronald L. Shreve; Shear-zone thickness and the seismicity of Chilean- and Marianas-type subduction zones. Geology 1996;; 24 (2): 107–110. doi: https://doi.org/10.1130/0091-7613(1996)024 2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Chilean-type convergent margins have many large (M > 7.6) earthquakes, whereas Marianas-type ones do not. This dichotomy is enigmatic if the plate interface is viewed as a thin frictional decollement, whereas it becomes understandable if it is viewed as a relatively thick, sediment-filled shear zone, which thins or thickens arcward depending on subduction speed and sediment supply. Chilean-type margins have thick trench fills, and their shear zones generally thin arcward from inlets as much as several thousand metres high, the most pronounced thinning being located near backstops. Tall (up to several kilometres) seamounts are subducted essentially intact to relatively great depths and confining pressures before jamming into the roof of the channel and becoming seismogenic asperities. Their near-basal ruptures can generate large thrust-type earthquakes, mainly concentrated in seismic fronts near backstops. Marianas-type margins, in contrast, have thin trench fills, and their shear zones generally thicken arcward from inlets that can be as little as 300 m high. Seamounts are truncated near the inlet at low confining pressures and generate only small earthquakes. After passing the inlet, they do not touch the roof and therefore cannot generate large earthquakes. A similar mechanism may explain seismic gaps at sediment-poor regions of subduction zones. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.