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How do volcanic rift zones relate to flank instability? Evidence from collapsing rifts at Etna
Author(s) -
Ruch Joel,
Pepe Susi,
Casu Francesco,
Acocella Valerio,
Neri Marco,
Solaro Giuseppe,
Sansosti Eugenio
Publication year - 2012
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 - 10.1029/2012gl053683
Subject(s) - geology , dike , rift , volcano , flank , rift zone , seismology , lava , basalt , rift valley , instability , petrology , geophysics , tectonics , physics , sociology , anthropology , mechanics
Volcanic rift zones, characterized by repeated dike emplacements, are expected to delimit the upper portion of unstable flanks at basaltic edifices. We use nearly two decades of InSAR observations excluding wintertime acquisitions, to analyze the relationships between rift zones, dike emplacement and flank instability at Etna. The results highlight a general eastward shift of the volcano summit, including the northeast and south rifts. This steady‐state eastward movement (1–2 cm/yr) is interrupted or even reversed during transient dike injections. Detailed analysis of the northeast rift shows that only during phases of dike injection, as in 2002, does the rift transiently becomes the upper border of the unstable flank. The flank's steady‐state eastward movement is inferred to result from the interplay between magmatic activity, asymmetric topographic unbuttressing, and east‐dipping detachment geometry at its base. This study documents the first evidence of steady‐state volcano rift instability interrupted by transient dike injection at basaltic edifices.