EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Groundwater anomaly related to the 2018 Hokkaido Eastern Iburi earthquake in Northern Japan

Yuji Sano1, Takanori Kagoshima1, Naoto Takahata1, Kotaro Shirai1, Jin-Oh Park1, Tomo Shibata2, Junji Yamamoto3, Yoshiro Nishio4, Sheng Xu5, Ai-Ti Chen6, and Pinti Daniele7
Yuji Sano et al.
  • 1Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan (
  • 2Institute for Geothermal Sciences, Kyoto University, Kyoto, Japan
  • 3University Museum, Hokkaido University, Sapporo, Japan
  • 4Faculty of Agriculture and Marine Sciences, Kochi University, Nangoku, Japan
  • 5Institute of Surface-Earth System Sciences, Tianjin University, Tianjin, China
  • 6Department of Geosciences, National Taiwan University, Taiwan
  • 7Research Center on the dynamics of the Earth System, University of Quebec at Montreal

In order to study groundwater anomaly related to the 2018 Hokkaido Eastern earthquake (Mw6.6) occurred on 6th September, we have measured δD and δ18O values of commercial bottled mineral water at two sites in Iburi region, Hokkaido, Northern Japan from June 2015 to May 2019. At the Uenae site, 21km west of the epicenter, both δD and δ18O values are constant from June 2015 to February 2018. Then these values have decreased substantially from April 2018 to December 2018 with significant fluctuations. These variations may be attributable to a mixing of groundwater with light δD and δ18O values. At the Eniwa site 34km northwest of the epicenter, δD values have decreased slightly and monotonically, while δ18O values are constant from June 2016 to October 2018. Observed isotopic variations of the Uenae site are different from those found at the 2016 Tottori earthquake where the δ18O value of groundwater increased a couple of months before the seismic event, while the δD value was constant. These data were attributable to water-rock interaction in the aquifer. Thus, the mechanism of groundwater isotopic anomaly may be different between Tottori and Hokkaido earthquakes. In addition to the M6.7 earthquake, CO2 injection by CCS project at Tomakomai, 13km southwest of the Uene site may be another factor to induce such variations. In order to evaluate the environmental impact of CO2 injection, we should measure total carbonate concentration and δ13C value of carbonate at both sites. Then we will discuss mechanism of groundwater anomaly.

How to cite: Sano, Y., Kagoshima, T., Takahata, N., Shirai, K., Park, J.-O., Shibata, T., Yamamoto, J., Nishio, Y., Xu, S., Chen, A.-T., and Daniele, P.: Groundwater anomaly related to the 2018 Hokkaido Eastern Iburi earthquake in Northern Japan , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2287,, 2020