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The thickness of subduction plate boundary faults from the seafloor into the seismogenic zone

Christie D. Rowe, J. Casey Moore and Francesca Remitti
The thickness of subduction plate boundary faults from the seafloor into the seismogenic zone
Geology (Boulder) (July 2013) 41 (9): 991-994

Abstract

The thickness of an active plate boundary fault is an important parameter for understanding the strength and spatial heterogeneity of fault behavior. We have compiled direct measurements of the thickness of subduction thrust faults from active and ancient examples observed by ocean drilling and field studies in accretionary wedges. We describe a general geometric model for subduction thrust decollements, which includes multiple simultaneously active, anastomosing fault strands tens of meters thick. The total thickness encompassing all simultaneously active strands increases to approximately 100-350 m at approximately 1-2 km below seafloor, and this thickness is maintained down to a depth of approximately 15 km. Thin sharp faults representing earthquake slip surfaces or other discrete slip events are found within and along the edges of the tens-of-meters-thick fault strands. Although flattening, primary inherited chaotic fabrics, and fault migration through subducting sediments or the frontal prism may build melange sections that are much thicker (to several kilometers), this thickness does not describe the active fault at any depth. These observations suggest that models should treat the subduction thrust plate boundary fault as <1-20 cm thick during earthquakes, with a concentration of postseismic and interseismic creep in single to several strands 5-35 m thick, with lesser distributed interseismic deformation in stratally disrupted rocks surrounding the fault strands.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 9
Title: The thickness of subduction plate boundary faults from the seafloor into the seismogenic zone
Affiliation: McGill University, Department of Earth and Planetary Sciences, Montreal, QC, Canada
Affiliation: Integrated Ocean Drilling Program, Expedition 343/343T ScientistsCollege Station, TXUnited States
Pages: 991-994
Published: 20130703
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 41
Accession Number: 2013-057565
Categories: Solid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2013277
Illustration Description: illus. incl. 1 table
N32°21'05" - N32°21'11", E134°56'34" - E134°56'46"
N31°30'00" - N32°45'00", E134°00'00" - E135°15'00"
N09°39'16" - N09°39'16", W86°11'09" - W86°11'09"
Secondary Affiliation: University of California at Santa Cruz, USA, United StatesUniversity of Modena and Reggio Emilia, ITA, Italy
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201335
Program Name: ODPOcean Drilling Program
Program Name: IODPIntegrated Ocean Drilling Program
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