GNSS Observation and Monitoring of the Hakone Volcano and the 2015 Unrest
Ryosuke Doke*,†, Masatake Harada*, and Kazuki Miyaoka**
*Hot Springs Research Institute of Kanagawa Prefecture
586 Iriuda, Odawara, Kanagawa 250-0031, Japan
**Meteorological Research Institute, Ibaraki, Japan
In recent years, earthquake swarm activities have occurred at the Hakone Volcano in the western area of Kanagawa Prefecture, Japan, with a frequency of once in several years. Global Navigation Satellite System (GNSS) observations have detected the inflation of volcanic edifice during these activities. Hot Springs Research Institute of Kanagawa Prefecture (HSRI) regularly observes crustal deformation for monitoring seismic and volcanic activities by using 16 sites of GNSS observation, which were installed in the western area of Kanagawa Prefecture. These observed data, together with those from other agencies, are analyzed routinely, and time-series graphs, displacement vector diagrams, and strain maps are illustrated to monitor seismic and volcanic activities. Given that GNSS monitoring detected the baseline extension about half a month or a month before the earthquake swarm activities, a stacking analysis is routinely performed for early detection of the extension. Some of the analysis results can be found on the website of HSRI. The Hakone Volcano had the largest earthquake swarm activity beginning at the end of April 2015, and a phreatic eruption occurred in Owakudani at the end of June 2015. The GNSS observed crustal deformation, which indicated the inflation of the volcanic edifice in early April 2015. This inflation can be explained by a volume change of a point pressure source located about 6.5 km below sea level.
-  Geological Society of Japan, “Geological Leaflet 1 Hakone Volcano,” Geol. Soc. Japan, 2007 (in Japanese).
-  T. Kasama and H. Yamashita, “Tokyo Pumice from Hakone Volcano, Central Japan,” Res. Rep. Kanagawa Prefect. Mus. Nat. Hist., Vol.13, pp. 91-110, 2008 (in Japanese with English abstract).
-  M. Kobayashi, K. Mannen, M. Okuno, T. Nakamura, and K. Hakamata, “The Owakidani tephra group: a newly discovered post-magmatic eruption product of Hakone Volcano, Japan,” Bull. Volcanol. Soc. Japan, Vol.51, pp. 245-256, doi:10.18940/kazan.51.4_245, 2006 (in Japanese with English abstract).
-  R. Honda, H. Ito, Y. Yukutake, M. Harada, and A. Yoshida, “Features of Hypocental Area of Swarm Earthquakes in Hakone Volcano in 1970’s Revealed by Re-Analysis Using S-P Data : Comparison with Recent Activities,” Bull. Volcanol. Soc. Japan, Vol.56, pp. 1-17, doi:10.18940/kazan.56.1_1, 2011 (in Japanese with English abstract).
-  M. Harada, Y. Yukutake, K. Miyaoka, R. Honda, K. Itadera, R. Doke, M. Satomura, and A. Yoshida, “The classification of earthquake swarm activities in Hakone volcano,” Bull. Hot Springs Res. Inst. Kanagawa Pref., Vol.45, pp. 1-8, 2013 (in Japanese with English abstract).
-  M. Harada, K. Hosono, H. Ito, T. Aketagawa, A. Kobayashi, R. Honda, Y. Yukutake, and A. Yoshida, “Dilatational crustal deformation preceding earthquake swarm activities in Hakone volcano,” Japan Geoscience Union Meeting 2011, SVC048-P02, http://www2.jpgu.org/meeting/2011/yokou_p_e/SVC48_p_e.pdf, 2011.
-  K. Miyaoka, M. Harada, and R. Doke, “Detection of GPS changes preceding the earthquake swarm activity in Hakone volcano,” Programme and Abstracts the Seismological Society of Japan 2013, Fall Meeting, P2-09, 2013 (in Japanese).
-  R. Dach, U. Hugentobler, P. Fridez, and M. Meindl (Eds.), “Bernese GPS Software Version 5.0,” Astronomical Inst. Univ. Bern, 2007.
-  P. Wessel and W. H. F. Smith, “New improved version of generic mapping tools released,” EOS Trans. AGU, Vol.79, p. 579, doi:10.1029/98EO00426, 1998.
-  R. Doke, M. Harada, and M. Satomura, “Estimation method of spatially homogeneous strain field: Attempt by using Nearest Neighbor method,” Bull. Hot Springs Res. Inst. Kanagawa Pref. Vol.46, pp. 21-26, 2014 (in Japanese).
-  M. Harada, K. Hosono, A. Kobayashi Y, Yukutake, and A. Yoshida, “Extensional Strains around Mt. Fuji and Hakone Volcano and Low-Frequency Earthquakes,” Bull. Volcanol. Soc. Japan, Vol.55, pp. 193-199, doi:10.18940/kazan.55.4_193, 2010 (in Japanese with English abstract).
-  M. Harada, R. Doke, K. Itadera, and M. Satomura, “GNSS crustal movement observed by volcanic activities of Hakone Volcano and estimated its pressure sources,” Programme and Abstracts the Seismological Society of Japan 2016, Fall Meeting, S03-P14, 2016 (in Japanese).
-  Y. Daita, T. Tanada, T. Tanbo, H. Ito, M. Harada, and K. Mannen, “Temporal change of the pressure source estimated by tilt records during the 2001 Hakone swarm activity,” Bull. Volcanol. Soc. Japan, Vol.54, pp. 223-234, doi:10.18940/kazan.54.5_223, 2009 (in Japanese with English abstract).
-  Y. Yukutake, R. Honda, M. Harada, R. Arai, and M. Matsubara, “A magma-hydrothermal system beneath Hakone volcano, central Japan, revealed by highly resolved velocity structures,” J. Geophys. Res. Solid Earth, Vol.120, pp. 3293-3308, doi:10.1002/2014JB011856, 2015.
-  M. Harada, K. Itadera, R. Honda, Y. Yukutake, and R. Doke, “Earthquake swarm activities and crustal movements of the 2015 volcanic event at Hakone Volcano (Rapid results),” Bull. Hot Springs Res. Inst. Kanagawa Pref., Vol.47, pp. 1-10, 2015 (in Japanese with English abstract).
-  K. Miyaoka, M. Harada, and R. Doke, “Monitoring of crustal deformation by GNSS data with appling the Stacking method,” Bull. Hot Springs Res. Inst. Kanagawa Pref., Vol.46, pp. 1-8, 2014 (in Japanese with English abstract).
-  K. Miyaoka and A. Takagi, “Detection of crustal deformation prior to the 2014 Mt. Ontake eruption by the stacking method,” Earth, Planets Sp., Vol.68, 60, doi:10.1186/s40623-016-0439-8, 2016.
-  Y. Yukutake, R. Honda, M. Harada, R. Doke, T. Saito, T. Ueno, S. Sakai, and Y. Morita, “Analyzing the continuous volcanic tremors detected during the 2015 phreatic eruption of the Hakone volcano,” Earth, Planets Sp., Vol.69, 164, doi:10.1186/s40623-017-0751-y, 2017.
-  K. Mannen, Y. Yukutake, G. Kikugawa, M. Harada, K. Itadera, and J. Takenaka, “Chronology of the 2015 eruption of Hakone volcano, Japan: geological background, mechanism of volcanic unrest and disaster mitigation measures during the crisis,” Earth, Planets and Space, Vol.70, Vo.68, doi: 10.1186/s40623-018-0844-2, 2018.
-  R. Doke, M. Harada, and J. Takenaka, “InSAR analysis of surface displacements in Owakudani associated with the 2015 Hakone volcanic activity,” Bull. Hot Springs Res. Inst. Kanagawa Pref., Vol.47, pp. 23-29, 2015 (in Japanese).
-  S. Yamada, Y. Miura, M. Yamanaka, H. Nakai, K. Wada, Y. Kakiage, H. Ueshima, H. Yarai, T Kobayashi, and Y. Morishita, “Ground surface deformation at Owakudani on Hakone Volcano detected with InSAR using ALOS-2 data,” J. of the Geospatial Information Authority of Japan, Vol.128, pp. 67-75, 2016 (in Japanese).
-  H. Yarai, T. Kobayashi, Y. Morishita, S. Yamada, Y. Miura, K. Wada, H. Nakai, M. Yamanaka, Y. Kakiage, and H. Ueshiba, “Active volcano monitoring using ALOS-2 SAR interferometry,” J. of Japan Soc. Photogramm. and Remote Sens. Vol.55, pp. 6-11, doi:10.4287/jsprs.55.6, 2016 (in Japanese).
-  R. Honda, Y. Yukutake, M. Harada, K. Kato, K. Uhira, Y. Morita, and S. Sakai, “Tilt changes and volcanic tremor observed prior to a small eruption of Hakone in 29 June, 2015,” Programme and Abstracts of the Volcanological Society of Japan 2015 Fall Meeting, P48, doi:10.18940/vsj.2015.0_146, 2015 (in Japanese).
-  R. Doke, M. Harada, K. Mannen, K. Itadera, and J. Takenaka, “InSAR analysis for detecting the route of hydrothermal fluid to the surface during the 2015 phreatic eruption of Hakone Volcano, Japan,” Earth, Planets and Space, Vol.70, No.68, doi:10.1186/s40623-018-0844-2, 2018.
-  M. Harada, R. Doke, K. Itadera, and M. Satomura, “Temporal Change of the Pressure Source associated with Volcanic Activities of Hakone Volcano (2015),” Programme and Abstracts of the Volcanological Society of Japan 2017 Fall Meeting, P048, doi:10.18940/vsj.2017.0_168, 2017 (in Japanese).
-  K. Fukui, S. Ando, K. Fujiwara, S. Kitagawa, K. Kokubo, S. Onizawa, T. Sakai, T. Shimbori, A. Takagi, T. Yamamoto, H. Yamasato, and A. Yamazaki, “MaGCAP-V: Windows-based software to analyze ground deformation and geomagnetic change in volcanic areas, ” IAVCEI 2013 Scientific Assembly July 20-24, Kagoshima, Japan, 2C-P8, http://www.kazan.or.jp/iavcei2013/iavcei_hp/PDF/4W_2C-P8.pdf, 2013.
-  K. Mogi, “Relations between the eruptions of various volcanoes and the deformations of the ground surfaces around them,” Bull. Earthq. Res. Inst. Vol.36, pp. 99-134, 1958.
-  T. Tanada, H. Ueda, M. Nagai, and M. Ukawa, “NIED’s V-net, the Fundamental Volcano Observation Network in Japan,” J. of Disaster Research, Vol.5, pp. 926-931, doi:10.20965/jdr.2017.p0926, 2017.
-  S. Matsumura, Y. Okada, and S. Hori, “Procedures for Seismic Data Processings by the Analyzing System for Precursors of Earthquakes (APE),” Report of the National Research Center for Disaster Prevention, Vol.48, pp. 45-64, 1988 (in Japanese with English abstract).
-  S. Hori and S. Matsuura, “Automatic Hypocenter Determination by the Analyzing System for Precursors of Earthquakes, ” Report of the National Research Center for Disaster Prevention, Vol.41, pp. 89-100, 1988 (in Japanese with English abstract).