41. Development of the Aftershock Area and the Block Structure of the Focal Region of the 1968 Tokachi-Oki Earthquake
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概要
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Studying the development of the aftershock area in the case of the 1968 Tokachi-Oki earthquake, several interesting features have been found for the block structure of the focal region and for their roles in the development of aftershock activity. The main results are as follows. 1)The focal region is composed of several blocks, as shown in Fig. 3. 2)The development of the aftershock area proceeds with the successive excitation of these blocks. 3)The activity of each block is excited by the main shock or each new large aftershock. 4)The above characteristics is represented by such characteristics of the magnitude~frequency relation that the earthquakes of large magnitude precede and aftershocks of smaller magnitude follow. 5)The approximate extent of the region of the aftershock activities were determined in the first two days. About a month after the main shock, a large aftershock took place and the aftershock area was newly extended to the southern region. 6) The above feature will be seen in such magnitude～frequency relation that major aftershocks take place in the same population as the main shock. 7) There was such a feature that when activity of one block became violent the activity in other regions decreased. 8) The so-called 1968 Tokachi-Oki earthquake is one of the large earthquakes which took place repeatedly in the region of the Sanriku-Oki earthquake province. 9) The aftershock areas of the earthquakes of 1933, 1945, 1952 and 1960 are closely related to the blocks which appeared in the 1968 Tokachi-Oki earthquake. 10) The earthquake block structure of the 1968 Tokachi-Oki earthquake seems to be inherent to the focal region off the coast of Sanriku along the Japan trench.|1968年十勝沖地震における余震域の発達を調べてみると,震源域のブロック構造およびその余震活動の発達における役割について二三の面白い特徴が見出された.
- 1970-12-05
論文 | ランダム
- さいたま新都心駅・東西自由通路
- 変わりゆく街・人・自然-2-さいたま新都心
- さいたま新都心における物流システム
- 人と人とのふれあいと先進のハード--さいたま新都心で実現したバリアフリーについて (特集 次世代への継承をめざして--公共建築に求められる価値とは)
- 随想 さいたま新都心アートプロジェクトに参加して (特集 次世代への継承をめざして--公共建築に求められる価値とは)