Fig. 4From: Deep low-frequency earthquake activity associated with the 2018 eruptions in the Kirishima volcanic complex, JapanWaveform examples of DLF earthquakes. Top three component waveforms show an DLF earthquakes in 2010 with the low FI value (FI = − 1.835). Bottom three component waveforms show an DLF earthquakes in 2017 with the high FI value (FI = − 0.079). These waveforms were normalized by the maximum value written on the right side of the boxBack to article page