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Earth, Planets and Space
Fig. 9 | Earth, Planets and Space

Fig. 9

From: Detection of hidden earthquakes after the 2011 Tohoku earthquake by automatic hypocenter determination combined with machine learning

Fig. 9

Precise hypocentral distribution in northern Akita Prefecture (region 6 in Fig. S1); except (b), symbol colors indicate depth. a Hypocentral distribution of the merged catalog with events recalculated by the DD method with cross-correlation (1 March–30 April 2011, 0–20 km depth). Blue triangles show observation stations, and the black triangle indicates the Moriyoshi-zan volcano. Bottom panels show cross sections X–X′ and Y–Y′. Green and blue dotted circles indicate probable scatterers estimated by Kosuga (2014) and Amezawa et al. (2019), respectively. b Magnitude-time diagram of events in (a). Red and gray circles are events in the JMA unified catalog and our merged catalog, respectively. c, d Spatiotemporal and depth-time distributions, respectively, projected on line X–X′. e, f Spatiotemporal and depth-time distributions, respectively, projected on line Y–Y′. Vertical blue dashed lines indicate the origin time of the 2011 Tohoku earthquake

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