The earthquake occurred off the east coast of Chiba Prefecture on the twenty sixth, and in Chiba and Ibaraki Prefectures, a protracted, sluggish tremor, class 2 long-period seismic floor movement, was noticed.
Source
Observation of long-period floor movement “class 2” in Choshi City, Chiba Prefecture and Kashima City, Ibaraki Prefecture | NHK
