Synthesized investigation of seismotectonic vertical processes in the forearc coastal area of the plate convergence zone

板块辐合带弧前沿岸地区地震构造垂直过程综合研究

• 批准号: 16300293
• 负责人: MIYAUCHI Takahiro
• 金额: $ 9.73万
• 依托单位: Chiba University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16300293/
• 关键词: plate convergence; non-seismic subsidence; coseismic uplift; Sanriku Coast; core-boring; radiocarbon dating; Holocene; unusual large earthquake; 機械ボーリング; 広域テフラ; 巨大地震履歴; 簡易掘削

We investigated the dynamic combination model of seismotecotonic uplift and non-seismotectonic subsidence, in order to understand tectonic processes originated from the plate convergence between the Pacific Plate and the Eurasia Plate, using Quaternary and geomorphological techniques. The obtained results are as follows.1. A succession of nine marine terraces is recognized, which were formed at interglacial stages at least after MIS21 (ca.800ka). Average uplift rate is estimated to be 0.2 to 0.4m/ka.2. At least Holocene marine terrace is recognizable at the height in 3 to 5 meters along the 120km long, northern coast of the Sanriku Coast. The emergence age is probably between 7ka and 5ka.3. Boring core data of 13 short drilling and 2 long drilling show the tectonic history : successive subsidence in rate of 7-9mm/yr between 8ka and 7ka, a possible episodic uplift producing the emergence of shallow marine topography around 2.9ka, and continuous subsidence with the rate of more than 1mm/yr after 2.9ka.4. Tidal records in the past 50 years at the five ports indicate that the Sanriku Coast is continuously subsiding. The subsidence rate ranges in 2 to 11mm/yr and tend to increase at the port closer to the Japan Trench.5. At least two co-seismic uplift events are practically estimated in the late Holocene, which likely occurred at 7-5ka and 3ka. This seismic scenario prevides that the recurrence time is about 3000 years and the uplift exceeds 10 meters.6. The extreme coseismic event of large uplift along the more than 100km long coast requires the extensive interplate faulting or the branching faulting from the plate boundary for the stress release by plate convergence. Such catastrophic faulting is probably associated with the M8-class earthquakes.

为了理解太平洋板块与欧亚板块会聚所引起的构造过程，利用第四纪和地貌学技术，研究了地震构造抬升与非地震构造沉降的动态组合模式。主要研究结果如下：1.一系列的9个海洋阶地被确认，这是形成于间冰期阶段至少在MIS 21（约800 ka）。平均抬升速率估计为0.2 - 0.4m/ka.2。在三陆海岸的北方沿岸，沿120公里长的海岸线，至少在沿着3 - 5米的高度上可以辨认出全新世海阶。其出现时代可能在7 ka ~ 5 ka之间. 13个短钻孔和2个长钻孔的岩心资料揭示了该地区的构造历史：8 ka ~ 7 ka期间以7-9mm/a的速率连续沉降，2.9ka前后可能出现一次幕式抬升，形成浅海地形，2.9ka以后以1 mm/a以上的速率持续沉降.五个港口过去50年的潮汐记录表明，三陆海岸正在不断下沉。沉降速率范围在2至11毫米/年之间，在靠近日本海沟的港口趋于增加。晚全新世至少发生了两次同震隆升事件，可能发生在7- 5 ka和3 ka。这一地震情景预示着重现时间约为3000年，抬升超过10米。沿沿着100多公里海岸线的大幅度隆升的同震极端事件，需要广泛的板间断裂或从板块边界的分支断裂，以实现板块会聚的应力释放。这种灾难性的断层活动可能与8级地震有关。

项目成果

西南日本外帯の地殻構造:2002年四国-瀬戸内海横断地殻構造探査の成果.

日本西南部外围地区的地壳结构：2002 年四国-濑户内海地壳结构勘探的结果。

• 发表时间: 2006
• 期刊: 地震研究所彙報 80
• 作者: Tagiri;M.;Oba;T.;Fujinawa;A.;三好建正;三好建正;佐藤比呂志・児島悠司・村田明広・伊藤谷生・高須 晃他
• 通讯作者: 佐藤比呂志・児島悠司・村田明広・伊藤谷生・高須 晃他

日本の地形3 東北

日本地形 3 东北

• 发表时间: 2005
• 作者: Suzuki;T.;小池一之
• 通讯作者: 小池一之

Earthquake Source Fault Beneath Tokyo

• DOI: 10.1126/science.1110489
• 发表时间: 2005-07
• 期刊: Science
• 影响因子: 56.9
• 作者: Hiroshi P. Sato;N. Hirata;K. Koketsu;D. Okaya;S. Abe;R. Kobayashi;M. Matsubara;T. Iwasaki;T. Ito;T. Ikawa;T. Kawanaka;K. Kasahara;S. Harder

長井盆地西縁断層帯の第四紀後期活動性と地形発達

长井盆地西缘断裂带晚第四纪活动与地形发育

• 发表时间: 2004
• 期刊: 活断層研究 24
• 作者: 宮内崇裕;平柳幸彦;今泉俊文
• 通讯作者: 今泉俊文

日本の地形6 近畿・中国・四国

日本地形 6 近畿、中国、四国

• 发表时间: 2004
• 作者: Naruse;T.;成瀬 敏郎;太田陽子ほか(編)
• 通讯作者: 太田陽子ほか(編)