Fig. 7

a Flow rate changes at the springs a:YKI, b:TNB, c:KYH, d:IKN, e:SOY, f:SOI, and g:YSM and the relative precipitation at ASOT during the period from 2016 to 2017. The flow rate was manually measured and its precision was estimated to be about a few to 10%. Vertical red broken line indicates the occurrence of the main shock of the 2016 Kumamoto earthquake. At the springs a:YKI, d:IKN, e:SOY, f:SOI, and g:YSM, the flow rate was measured before the 2016 Kumamoto earthquake. Before 2016 at a:YKI, d:IKN, and f:SOI, the flow rate was respectively measured on February 1, 2014; September 6, 2014; and February 1, 2014. b Flow rate changes at the springs h:SMR, i:TDR, j:MTR, and k:DMZ and the relative precipitation at KMMT during the period 2016–2017. The precision is about a few to 10%. Vertical red broken line indicates the occurrence of the main shock of the 2016 Kumamoto earthquake. At the springs h:SMR and k:DMZ, the flow rate was measured before the 2016 Kumamoto earthquake