Volcanic deformation of Atosanupuri volcanic complex in the Kussharo caldera, Japan, from 1993 to 2016 revealed by JERS-1, ALOS, and ALOS-2 radar interferometry

Satoshi Fujiwara,Tomokazu Kobayashi,Makoto Murakami,Mikio Tobita,Takuya Nishimura,Hiroshi Yarai

doi:10.1186/s40623-017-0662-y

Abstract

A series of uplifts and subsidences of a volcanic complex in the Kussharo caldera in eastern Hokkaido (Japan) has been revealed by interferometric analysis using archived satellite synthetic aperture radar data. A time series of interferograms from 1993 to 1998 showed the temporal evolution of a ground deformation process. The horizontal dimension of the deformation field was about 10 km in diameter, and the maximum amplitude of the deformation was >20 cm. Uplift started in 1994, and concurrent earthquake swarm activity was observed around the uplift area; however, no other phenomena were observed during this period. A subsidence process then followed, with the shape of the deformation forming a mirror image of the uplift. Model simulations suggest deformation was caused by a source at the depth of about 6 km and that the position of the source remained static throughout the episode. Subsidence of the volcanic complex was also observed by another satellite from 2007 to 2010, and likely continued for more than 10 years. In addition to the main uplift–subsidence sequence, small deformation patterns with short spatial wavelengths were observed at the center of the deforming area. Data from three satellites recorded small-scale subsidence of the Atosanupuri and Rishiri lava domes at a constant rate of approx. 1 cm/year from 1993 to 2016.Graphical abstractTemporal evolution of the maximum vertical displacement and average yearly rate of height change

Highlights

Observation of crustal deformation around a volcano provides important information about the dynamic processes of the transfer of volcanic fluids that could lead to an eruption
The horizontal dimension of the deforming area is about 10 km in diameter, and it covers almost the entire area of the Atosanupuri volcanic complex
Concluding remarks The InSAR observations revealed that two types of deformation occurred silently under the Atosanupuri volcanic complex

Summary

Introduction

Observation of crustal deformation around a volcano provides important information about the dynamic processes of the transfer of volcanic fluids that could lead to an eruption. Geological data suggest that the latest phreatic eruption occurred at the Atosanupuri lava dome several hundred years ago, there is no historical record of the eruption because of the remoteness of the site from cultural centers of the time (e.g., Japan Meteorological Agency 2013; Katsui et al 1986). This suggests the possibility of a future eruption and the need for further studies to understand the underlying magmatic system

Results

Discussion

Conclusion