Appended figure2-2 Recent seismic activity, including small earthquakes II (M 2 or greater, May 1975 - April 1995).
(Note) In Aomori Prefecture, Fukushima Prefecture, and Niigata Prefecture, networks of stations were successively arranged beginning in the late 1980s. Subsequently, the greater of hypocenter determinations has improved.
[Prepared from data of Tohoku University and Hirosaki University]
Shallow earthquakes with a hypocenter of 30 km or less in depth.
Deeper earthquakes with a hypocenter over 30 km in depth.
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