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Origins of oblique‐slip faulting during caldera subsidence
Author(s) -
Holohan Eoghan P.,
Walter Thomas R.,
Schöpfer Martin P.J.,
Walsh John J.,
Wyk de Vries Benjamin,
Troll Valentin R.
Publication year - 2013
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/jgrb.50057
Subject(s) - caldera , geology , seismology , slip (aerodynamics) , oblique case , transtension , volcano , subsidence , geodesy , tectonics , geomorphology , linguistics , philosophy , physics , structural basin , thermodynamics , sinistral and dextral
Although conventionally described as purely dip‐slip, faults at caldera volcanoes may have a strike‐slip displacement component. Examples occur in the calderas of Olympus Mons (Mars), Miyakejima (Japan), and Dolomieu (La Reunion). To investigate this phenomenon, we use numerical and analog simulations of caldera subsidence caused by magma reservoir deflation. The numerical models constrain mechanical causes of oblique‐slip faulting from the three‐dimensional stress field in the initial elastic phase of subsidence. The analog experiments directly characterize the development of oblique‐slip faulting, especially in the later, non‐elastic phases of subsidence. The combined results of both approaches can account for the orientation, mode, and location of oblique‐slip faulting at natural calderas. Kinematically, oblique‐slip faulting originates to resolve the following: (1) horizontal components of displacement that are directed radially toward the caldera center and (2) horizontal translation arising from off‐centered or “asymmetric” subsidence. We informally call these two origins the “camera iris” and “sliding trapdoor” effects, respectively. Our findings emphasize the fundamentally three‐dimensional nature of deformation during caldera subsidence. They hence provide an improved basis for analyzing structural, geodetic, and geophysical data from calderas, as well as analogous systems, such as mines and producing hydrocarbon reservoirs.

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