Fossil tubeworms link coastal uplift of the northern Noto Peninsula to rupture of the Wajima-oki fault in AD 1729
Fossil tubeworms link coastal uplift of the northern Noto Peninsula to rupture of the Wajima-oki fault in AD 1729
复制标题
DOI：
10.1016/j.tecto.2015.12.019
复制
发表时间：
2016-02-22
期刊：
影响因子：
2.9
通讯作者：
Yamaguchi, Hiroyuki
中科院分区：
文献类型：
--
作者：
Hamada, Masaaki;Hiramatsu, Yoshihiro;Yamaguchi, Hiroyuki
日本中部野户半岛北部海岸附近海底的活动断裂带从西到东分为四个部分：门前木、Saruyama-oki、Wajima-oki和Suzu-oki。为了考察发生在这些地段的最新事件，我们利用放射性碳测年和全球定位测量，调查了诺托半岛北部海岸潮间带管虫化石的日期和海拔，该海岸位于断层的悬壁两侧。对于每一块化石，我们计算了过去和现在的海拔之间的差异，从而使用海平面变化曲线来估计化石出现时的海平面高度。这一计算为我们提供了每个地点的海拔变化。根据潮间带管虫的海拔高度和年龄估计的垂直变化表明，沿海的出现可能发生在公元1600年至1800年之间。这一沿海涌出区位于Wajima-oki段内的活动断裂附近。Wajima-oki段具有三个断层面、矩震级为6.6的矩形断层模型很好地再现了观测到的海岸涌出模式。据了解，在公元1600年至1800年期间，诺托半岛北部的这一地区只发生过一次破坏性地震，那是1729年的地震，自公元1800年以来就再也没有发生过一次。该模型预测的断层滑动分布与1729年记录的与震动相关的破坏分布是一致的。我们得出结论，1729年的地震是由Wajima-oki段的破裂引起的。(C)2016爱思唯尔B.V.保留所有权利。
The active fault zone on the seafloor off the northern coast of the Noto Peninsula of central Japan is divided into four segments from west to east: Monzen-oki, Saruyama-oki, Wajima-oki, and Suzu-oki. To examine the latest event that occurred in these segments, we investigated the dates and elevations of fossilized intertidal tubeworms along the northern coast of the Noto Peninsula, located on the hanging-wall sides of the faults, using radioactive carbon dating and global positioning measurements. For each fossil, we calculated the difference between the past and present elevation, thereby estimating the elevation of the sea level at the date of the fossil, using a curve for sea level change. This calculation provided us with the elevation change at each site. The vertical changes estimated from the elevations and ages of the intertidal tubeworms revealed that the coastal emergence probably occurred between 1600 and 1800 AD. This area of coastal emergence lies adjacent to active faults within the Wajima-oki segment. A model for rectangular faults with three fault planes and a moment magnitude of 6.6 for the Wajima-oki segment reproduced the observed pattern of coastal emergence well. Only one damaging earthquake, that in 1729, is known to have occurred in this part of the northern Noto Peninsula between 1600 and 1800 AD, and there has not been one since 1800 AD. The slip distribution of the fault predicted by the model is consistent with the distribution of shaking-related damage documented in 1729. We conclude that rupture of the Wajima-oki segment caused the 1729 earthquake. (C) 2016 Elsevier B.V. All rights reserved.