@article{fdi:010046215,
  title = {{H}ow summit calderas collapse on basaltic volcanoes : new insights from the {A}pril 2007 caldera collapse of {P}iton de la {F}ournaise volcano},
  author = {{M}ichon, {L}. and {V}illeneuve, {N}icolas and {C}atry, {T}. and {M}erle, {O}livier},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n {A}pril 2007, {P}iton de la {F}ournaise volcano experienced a caldera collapse during its largest historical eruption. {W}e present here a structural analysis both of the caldera and the surrounding area, and precise {GPS} data recorded with a dense {GPS} network specifically dedicated to the analysis of deformation related to the summit collapse structures. {D}espite a collapse of more than 300 m in the central zone, the geometry of the new caldera is similar in map view to that of the pre-existing collapsed structure, which was formed from the coalescence of several pit craters. {T}he caldera shows an asymmetric inner geometry with sub-vertical walls in the {NW} quadrant and steep scarps composed of inward tilted blocks in the southern half {T}he presence of preserved polished surfaces on the lower part of the sub-vertical scarp indicates that it corresponds to the caldera north-western ring fault. {T}he {A}pril 2007 caldera collapse led to the development and the reactivation of concentric fractures on the caldera rim, mostly along the southern limit of the caldera. {GPS} data show that fractures result from radial extensional stresses that are restricted within the first tens of meters of the caldera edge. {GPS} data also reveal that the caldera collapse was coeval with a centripetal deflation, whose magnitude is largest along the southern half of the caldera. {T}he displacements recorded by {GPS} result from both a general deflation, due to magma withdrawal from {P}iton de la {F}ournaise's summit magma chamber, and additional local effects related to the caldera collapse. {C}omparison of the caldera collapses at {P}iton de la {F}ournaise. {M}iyakejima and {F}ernandina reveals striking similarities, with cyclic seismic signals accompanying small-scale deflation-inflation cycles. {T}his strongly suggests a common mode of collapse. {H}ence, we propose a unifying model of caldera collapse in basaltic setting, in which the inward deflation due to magma withdrawal from the magma chamber prevents the collapse of the caldera roof until the gravitational stress acting on the rock column above the magma chamber exceeds the shear strength along pre-existing ring faults. {T}he downward displacement stops when the pressure increase into the magma chamber is able to again sustain the rock column. {T}he succession of (1) inward deflation that prevents the collapse, (2) collapse due to gravitational stress and (3) stopping of the downward motion is repeated many times. {T}he frequency of the cycles is influenced by the rate of magma withdrawal and by the amount of intrusion of magma along the ring faults.},
  keywords = {caldera ; collapse dynamics ; {P}iton de la {F}ournaise},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {184},
  numero = {1-2},
  pages = {138--151},
  ISSN = {0377-0273},
  year = {2009},
  DOI = {10.1016/j.jvolgeores.2008.11.003},
  URL = {https://www.documentation.ird.fr/hor/fdi:010046215},
}