Open AccessHorizontal compressive stress regime on the northern C ascadia margin inferred from borehole breakouts
Author(s) -
Riedel M.,
Malinverno A.,
Wang K.,
Goldberg D.,
Guerin G.
Publication year - 2016
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2016gc006443
Subject(s) - geology , borehole , seismology , breakout , subduction , drilling , décollement , accretionary wedge , margin (machine learning) , stress (linguistics) , trench , geotechnical engineering , tectonics , linguistics , philosophy , mechanical engineering , chemistry , organic chemistry , finance , layer (electronics) , engineering , economics , machine learning , computer science
During Integrated Ocean Drilling Program Expedition 311 five boreholes were drilled across the accretionary prism of the northern Cascadia subduction zone. Logging‐while‐drilling borehole images are utilized to determine breakout orientations to define maximum horizontal compressive stress orientations. Additionally, wireline logging data at two of these sites and from Site 889 of Ocean Drilling Program Leg 146 are used to define breakouts from differences in the aperture of caliper arms. At most sites, the maximum horizontal compressive stress S Hmax is margin‐normal, consistent with plate convergence. Deviations from this trend reflect local structural perturbations. Our results do not constrain stress magnitudes. If the margin‐normal compressional stress is greater than the vertical stress, the margin‐normal S Hmax direction we observe may reflect current locking of a velocity‐weakening shallow megathrust and thus potential for trench‐breaching, tsunamigenic rupture in a future megathrust earthquake.