Steady subsidence of a repeatedly erupting caldera through InSAR observations: Aso, Japan
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractThe relation between unrest and eruption at calderas is still poorly understood. Aso caldera, Japan, shows minor episodic phreatomagmatic eruptions associated with steady subsidence. We analyse the deformation of Aso using SAR images from 1993 to 2011 and compare it with the eruptive activity. Although the dataset suffers from limitations (e.g. atmospheric effects, coherence loss, low signal-to-noise ratio), we observe a steady subsidence signal from 1996 to 1998, which suggests an overall contraction of a magmatic source below the caldera centre, from 4 to 5 km depth. We propose that the observed contraction may have been induced by the release of the magmatic fluids feeding the eruptions. If confirmed by further data, this hypothesis suggests that degassing processes play a crucial role in triggering minor eruptions within open conduit calderas, such as at Aso. Our study underlines the importance of defining any eruptive potential also from deflating magmatic systems with open conduit.
CitationNobile A, Acocella V, Ruch J, Aoki Y, Borgstrom S, et al. (2017) Steady subsidence of a repeatedly erupting caldera through InSAR observations: Aso, Japan. Bulletin of Volcanology 79. Available: http://dx.doi.org/10.1007/s00445-017-1112-1.
SponsorsThis study was made in the framework of an ESA Category 1 proposal 7486 (V. Acocella responsible). The Supersite initiative (F. Amelung and S. Gross) is gratefully acknowledged for providing Envisat images. PALSAR level 1.0 data from the ALOS satellite are shared among PIXEL (PALSAR Interferometry Consortium to Study our Evolving Land surface) and provided by the Japan Aerospace Exploration Agency (JAXA) under a cooperative research contract with the Earthquake Research Institute, University of Tokyo. The ownership of PALSAR data belongs to the Ministry of Economy, Trade and Industry, and JAXA. G. Chiodini, E. Sansosti and M. Poland provided useful suggestions on an earlier version of the manuscript. We also would like to thank F. Costa and an anonymous reviewer who provided detailed reviews to improve the manuscript. Finally, thanks to the Associated Editor K.V. Cashman and to the Executive Editor J.D.L. White for additional comments that enhanced this work.
JournalBulletin of Volcanology