地震活動に関係した地殻変動(5B) ―近畿地方北西部の地震活動と生野で観測された地殻変動―

Abstract

前論文(5A)では, 北東一南西系の淀川地震帯から北西一一南東系の山崎断層に沿う地震帯への地震活動域の転換ないしは移動があれば, それに伴なって生野付近では傾動運動の方向転換が起ることを指摘した。その後1969年6月に入って, 生野のすぐ東側を北東一南西方向にのびる帯(前論文のB地域〉に沿って地震活動が活濃化したので, その結果について述べる。なお前論文の緒言にものべたように, 地震活動に関連した地殻変動の一連の論文の目的の一つは, 各観測室に関する過去の資料の総括にある。5Aは紙面の都合でこれを果し得なかったが, 今回はこの地域の地殼変動観測の基礎資料として, 記すことにした。

In the previous paper (5A), the peculiar mode of secular ground tilts observed at Ikuno wasnoted. Namely, the directional turnings of tilting movements appeared twice, in 1956 and 1964, and the shift of seismically active regions in the northwestern part of the Kinki district coincidedwith those turnings.After that, earthquakes began to occur in the zone passing east of Ikuno and extending fromthe northeast to the southwest. This zone is parallel to the seismic zone of Yodogawa which hasbeen in action since 1964, and it seems that both zones belong to the same system from the viewpoint of geotectonics. So, it is possible therefore that directional turnings in gradual tilting move-ments have not occurred since 1964.However, as epicenters of this series of earthquakes were very near to Ikuno, anomalous groundtilt toward the northeast appeared from June, 1969 to April, 1970 and there remained a permanentset of ground tilting.