Skip to main content


Fig. 6 | Earth, Planets and Space

Fig. 6

From: Characteristics of relocated hypocenters of the 2018 M6.7 Hokkaido Eastern Iburi earthquake and its aftershocks with a three-dimensional seismic velocity structure

Fig. 6

Relocated hypocenters in the present study plotted on the horizontal cross-sections of seismic attenuation structure (Qp-1) of Kita et al. (2014) shown by the color scale at the bottom at depths of a 10 km, b 20 km, and c 30 km. White dots indicate the hypocenters of aftershocks within 2.5 km in the depth direction, and the yellow star in c indicates the mainshock. White stars indicate the hypocenters of the 1982 and 1970 events. Large circles indicate damaging inland type earthquakes (M5.0–6.5) by Utsu (1999) and Kita et al. (2014). The dashed black lines indicate the locations of tectonic lines. Areas enclosed by black lines indicate the locations of the metamorphic belts. The black curved thick lines and the black vertical line show the costal lines and the boundary of the northeastern and Kuril arc, respectively. Red triangles and the thin black curved line show, respectively, Quaternary volcanoes and the 100-km-depth contour of the subducting Pacific Plate by Kita et al. (2010). The black thick dashed line at the south-central Hokkaido in c shows the contact zone of the forearc crustal materials with the upper interface of the Pacific Plate (Kita et al. 2010). Black dots and gray thin lines show hypocenters of the JMA catalog from 2003 to 2012 and active faults, respectively. White-shaded areas show the areas in which hit count is < 80. df Vertical cross-sections of Qp-1 along the three profiles shown in c. The horizontal bold black lines at the top of each plot represent the land area. The dashed black line delineates the upper surface of the subducting Pacific slab. The pink squares and gray line on the dashed black line indicate the locations of the upper-plane seismic belt in the slab crust and the contact zone of the slab upper surface (Kita et al. 2010) with the anomalously deepened crustal materials, respectively. Black and white stars, respectively, show the 2018 Eastern Iburi and 1982 Urakawa-oki earthquakes. White dots represent aftershocks of the 2018 Eastern Iburi earthquake within 5 km of each profile. Black dots represent ordinary earthquakes that occurred within 10 km of each profile. Red triangles represent active volcanoes and Quaternary volcanoes. White-shaded areas show the areas in which the hit count is < 80

Back to article page