Co-seismic vertical displacement associated with the 2016 Kumamoto earthquake (Mw7.0) and activity of the Futagawa fault around Futa, Nishihara Village, Kumamoto prefecture
Co-seismic vertical displacement associated with the 2016 Kumamoto earthquake (Mw7.0) and activity of the Futagawa fault around Futa, Nishihara Village, Kumamoto prefecture
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与 2016 年熊本地震 (Mw7.0) 相关的同震垂直位移和熊本县西原村 Futa 周围的 Futakawa 断层活动
DOI：
10.11462/afr.2019.50_33
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
石村大輔
中科院分区：
文献类型：
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作者：
Fukushima Yo;Ishimura Daisuke;石村大輔
2016年熊本地震（Mw 7. 0）时，二川断裂带的二川段和日那古断裂带的高野-白幡段的一部分发生破裂，并出现了一条30 km长的右旋走滑地表破裂。虽然在2016年地震之后已经揭示了地表破裂分布、同震位移和古地震活动性，但没有估计二川段中部的滑动速率。为了揭示垂直和水平滑动率，我们在熊本县西原村富田及其周围进行了地貌分析和实地调查。通过利用LiDAR数据建立的地震前后数字高程模型（DEM）的高程差估算地震同震垂直位移，并利用这些DEM测量地貌特征的累积垂直和水平位移。此外，我们调查了一个露头，以揭示浅断层结构和估计地貌表面的年龄。根据地貌面和高柳河熔岩的累积位移和年龄，估计二川断层的垂直和水平滑动速率为1 mm/年或更大。此外，通过使用2016年事件的估计滑动率和同震位移，估计复发间隔为一千到两千年，这与最近对二川段进行的古地震调查结果一致。这些结果，二川断层的滑动速率和复发间隔，高于以前的估计，并表明二川断层是九州地区最活跃的断层之一。
During the 2016 Kumamoto earthquake (Mw7. 0), the Futagawa segment of the Futagawa fault zone and a part of Takano-Shirahata segment of the Hinagu fault zone ruptured and a 30-km-long surface rupture with right-lateral strike slip appeared. Although surface rupture distribution, co-seismic displacement and paleoseisimicity have been revealed after the 2016 event, the slip rate in the central part of the Futagawa segment is not estimated. In order to reveal vertical and horizontal slip rates, we conducted geomorphic analysis and field survey in and around Futa, Nishihara Village, Kumamoto prefecture. Co-seismic vertical displacement was estimated by elevation difference between pre-and post-earthquake digital elevation models (DEMs) created from LiDAR survey data and accumulated vertical and horizontal displacements of geomorphic features were measured by using those DEMs. Additionally, we investigated an outcrop to reveal the shallow fault structure and to estimate an age of geomorphic surface. From accumulated displacement and ages of geomorphic surface and Takayubaru lava, vertical and horizontal slip rates of the Futagawa fault were estimated to be 1 mm/yr or larger. Moreover, recurrence interval was estimated to be a thousand to two thousand years by using estimated slip rates and co-seismic displacements of the 2016 event, consistent with results of recent paleoseisimic surveys on the Futagawa segment. These results, slip rate and recurrence interval of the Futagawa fault, are higher than previous estimation and suggests that the Futagawa fault is one of the most active faults in Kyushu region.