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Earthquake scaling relations for mid-ocean ridge transform faults

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dc.contributor.author Boettcher, Margaret S.
dc.contributor.author Jordan, T. H.
dc.date.accessioned 2010-05-24T18:29:15Z
dc.date.available 2010-05-24T18:29:15Z
dc.date.issued 2004-12-09
dc.identifier.citation Journal of Geophysical Research 109 (2004): B12302 en_US
dc.identifier.uri http://hdl.handle.net/1912/3501
dc.description Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): B12302, doi:10.1029/2004JB003110. en_US
dc.description.abstract A mid-ocean ridge transform fault (RTF) of length L, slip rate V, and moment release rate dot above M can be characterized by a seismic coupling coefficient χ = A E/A T, where A E ∼ dot above M/V is an effective seismic area and A T ∝ L 3/2 V −1/2 is the area above an isotherm T ref. A global set of 65 RTFs with a combined length of 16,410 km is well described by a linear scaling relation (1) A E ∝ A T, which yields χ = 0.15 ± 0.05 for T ref = 600°C. Therefore about 85% of the slip above the 600°C isotherm must be accommodated by subseismic mechanisms, and this slip partitioning does not depend systematically on either V or L. RTF seismicity can be fit by a truncated Gutenberg-Richter distribution with a slope β = 2/3 in which the cumulative number of events N 0 and the upper cutoff moment M C = μD C A C depend on A T. Data for the largest events are consistent with a self-similar slip scaling, D C ∝ A C 1/2, and a square root areal scaling (2) A C ∝ A T 1/2. If relations 1 and 2 apply, then moment balance requires that the dimensionless seismic productivity, ν0 ∝ inline equation 0/A T V, should scale as ν0 ∝ A T −1/4, which we confirm using small events. Hence the frequencies of both small and large earthquakes adjust with A T to maintain constant coupling. RTF scaling relations appear to violate the single-mode hypothesis, which states that a fault patch is either fully seismic or fully aseismic and thus implies A C ≤ A E. The heterogeneities in the stress distribution and fault structure responsible for relation 2 may arise from a thermally regulated, dynamic balance between the growth and coalescence of fault segments within a rapidly evolving fault zone. en_US
dc.description.sponsorship M.B. was supported by a NSF Graduate Research Fellowship, a MIT Presidential Fellowship, and the WHOI DOEI Fellowship. This research was supported by the Southern California Earthquake Center. SCEC is funded by NSF Cooperative Agreement EAR-0106924 and USGS Cooperative Agreement 02HQAG0008. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.uri http://dx.doi.org/10.1029/2004JB003110
dc.subject Earthquakes en_US
dc.subject Scaling relations en_US
dc.subject Fault mechanics en_US
dc.title Earthquake scaling relations for mid-ocean ridge transform faults en_US
dc.type Article en_US
dc.identifier.doi 10.1029/2004JB003110


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