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Spatial Variation in the Slip Zone Thickness of a Seismogenic Fault
Author(s) -
Kirkpatrick J. D.,
Shervais K. A. H.,
Ronayne M. J.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl078767
Subject(s) - slip (aerodynamics) , geology , seismology , crust , spatial variability , geophysics , physics , thermodynamics , statistics , mathematics
Fault slip is predominantly localized onto narrow slip zones embedded within broader zones of fault rock and subsidiary damage. As earthquakes re‐rupture the same slip zone multiple times, the composition and geometry of the slip zone significantly affect dynamic processes. Here we use three large cross‐sectional exposures of an exhumed fault to show that the thickness of a slip zone that accommodated seismic slip varies by an order of magnitude over tens of meters along strike. Geostatistical analyses show that the thickness variations are characterized by a correlation length scale of ~1 m and a characteristic spacing of 2–4 m. We suggest that the spacing between regions of correlated thickness represents the dimension of contact asperities on the fault. Similar magnitude variations in slip zone thickness should be generic to faults in the brittle crust, implying that slip‐weakening mechanisms such as thermal pressurization are spatially variable during seismic slip.