Locations of the Tatun volcano group (TVG) in the northern tip of Taiwan and two perpendicular depth-profiles across the Dayoukeng area to show the clustering seismicity (pluses) within a narrow vertical conduit at depths shallower than 2 km. The black, yellow, green and pink triangles in the left panel mark the locations of seismic stations, Mt. Chihsin, Chintenkeng and Dayoukeng fumarole in the TVG, respectively. The dashed line shows the surface trace of the Shanchiao fault. The relocated micro-earthquakes are plotted along the profiles within a width of 0.5 km.