IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

1A1_2D-O2Room B1

Date/Time: July 21 9:15-9:30

Volcano deformation in Kyushu (SW Japan) through InSAR data
Adriano Nobile1 , Daniele Trippanera1 , Susanna Pepe2 , Francesco Casu2 , Pietro Tizzani2 , Joel Ruch1 ,Yosuke Aoki3 , Nobuo Geshi4 , Valerio Acocella1 , Eugenio Sansosti2 , Valeria Siniscalchi5 , Sven
Borgstrom5 , Zoffoli Silvia61Universita degli Studi Roma Tre, italy, 2 IREA - CNR - Naples, italy, 3 University of Tokyo, Earthquake
Research Institute, Japan, 4 Geological Survey of Japan, AIST, Japan, 5 INGV - Osservatorio Vesuviano,italy, 6 ASI - Italian Space Agency, italy
E-mail: adriano.nobile@uniroma3.it

Kyushu Island (SW Japan) hosts several active arc volcanoes. Despite being closely monitored, our knowledge on
their deformation history with regard to their activity is poor. In order to improve our understanding, we use InSAR
processing of ALOS, ERS, ENVISAT and COSMO−SkyMed images. We study the surface deformation of three ofthe most active volcanoes in Kyushu: Aso Caldera (between 1993−2011), Aira Caldera (2006−2011), Kirishima
volcano (2006−2011). The SAR images have been processed to obtain time series through the SBAS technique.
Aso caldera has several vents in its central part. Of these, Naka Dake crater is the only currently active, erupting
7 times since 1993. Between January 1996 − November 1998, after the important 1994−1995 eruption, weobserved a subsidence of ∼1.5 cm/yr in the central caldera. Analytical models suggest a deflating source (withvarious possible shapes) at 6−7 km of depth, implying a magmatic nature for the deformation. Inversion results areconsistent with available seismic and GPS data.
Aira Caldera hosts Sakurajima volcano along its southern rim, with a persistent eruptive activity since 1950s.
Between May 2007−January 2009, we observe a broad uplift of ∼1.5 cm on most of Aira Caldera, with the exceptionof the eastern part. A preliminary analytical inversion of these data suggests a deformation source in the Caldera
center, at depth of 12−15 km, implying a magmatic nature of the deformation. Inversion results are in agreementwith GPS and InSAR data inversions for other periods of activity.
Kirishima is a group of volcanoes, including the most active Shinmoedake, which lately erupted in 2008 and 2011;in particular, between January−September 2011 Shinmoedake erupted several times, with a peak of activity inFebruary. InSAR data show an uplift of 2−4 cm in the Shinmoedake area between early 2010 − April 2011,
immediately predating the onset of the latest eruptive sequence, and continuing also after the onset of thesequence.
Our preliminary results suggest that the minor deformation at these three volcanoes, related to deep or relatively
deep magmatic sources, may be explained by their open system.
This research has been partially performed within the frame of Italian Space Agency (ASI) and Japan Aerospace
Exploration Agency (JAXA) bilateral cooperation. COSMO−SkyMed and ALOS SAR data have been provided by
ASI and JAXA within the SAR4Volcanoes project (ASI agreement n. I/034/11/0). ERS and ENVISAT SAR data
have been provided through the GEO Geohazards Supersite initiative and ESA Category 1 proposal 7486.

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