Fig. 7
![Fig. 7](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40623-020-01349-1/MediaObjects/40623_2020_1349_Fig7_HTML.png)
a Locations of estimated tremor source. The color of each plot corresponds to a contour bar in b. Gray dots also show epicenters of volcanic earthquakes in Fig. 2. A plot with a green square is the fixed source location for the reference time window. b Analyzed filtered (5–20 Hz) vertical ground velocity at KSW, estimated source elevations, and the minimum \(RES\) value of each time window. The origin time of the horizontal axis is 09:59:00