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Sediment signatures of the 25th December 2016 Chile earthquake to constrain detection thresholds of tidal marsh records

2016 年 12 月 25 日智利地震的沉积物特征限制潮汐沼泽记录的检测阈值

基本信息

批准号：
NE/R00210X/1
负责人：
Ian Shennan
金额：
$ 6.68万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FR00210X%2F1
关键词：
Sediment signatures 25th December 2016

项目摘要

On 25th December 2016 a magnitude 7.6 subduction zone earthquake struck south central Chile. The earthquake occurred within the rupture zone of the AD 1960 magnitude (M) 9.5 earthquake, the largest earthquake ever recorded during the instrumental era. The 25th December earthquake is the largest recorded within the 1960 rupture zone since the original event. While the sparse population spared the region from fatalities or substantial economic losses, this earthquake provides a critical opportunity to investigate variability in earthquake rupture zones and the contribution of earthquakes of this magnitude to releasing accumulated strain. Paleoseismological investigations Holocene sediments provide a means to assess the temporal and spatial variability of different earthquake rupture modes in many subduction zones, including Alaska, Cascadia, Chile, Japan, Indonesia and New Zealand. Crucially, we seek to assess the lower limit for detecting pre-20th century earthquakes using established paleoseismological methods and the potential for geological records to underestimate the frequency of major earthquakes.We seek urgency funding to make a rapid assessment of the coseismic surface deformation and sedimentation resulting from the 25th December earthquake. Two field campaigns, either side of the austral winter, will test the preservation potential of any recorded coseismic signal through the first few months of incorporation into the sediment profile, including survival through winter storms and any post-seismic vertical deformation caused by post-seismic creep on the plate interface. Sedimentary and microfossil analysis will reveal the sedimentary signature of the earthquake and constrain the lower limit of deformation detection. This proposal builds on our previous research and the recent shift in coastal paleoseismologgy from identifying the largest amounts of crustal deformation within the rupture segments of late Holocene earthquakes to seeking the spatial extent, therefore limits, of a rupture segment. This requires a methodology focussed on identifying the lower limit of vertical crustal deformation. We recently proposed a revised research framework to accomplish this, based on our own research and a comprehensive review of the paleoseismological literature, but noted the lack of sufficient detailed modern equivalents. The 2015 Chile earthquake provides a rare opportunity to collect time-critical samples from the contemporary environments in coastal areas affected by small coseismic vertical land motions, ground shaking and any associated tsunami.

2016年12月25日，智利中南部发生7.6级俯冲带地震。这次地震发生在公元1960年9.5级地震的破裂带内，这是仪器时代有记录以来最大的地震。12月25日的地震是自1960年地震以来有记录以来最大的一次地震。虽然人口稀少使该地区免于死亡或遭受重大经济损失，但这次地震为研究地震破裂带的变异性以及这种规模的地震对释放累积应变的贡献提供了一个重要机会。全新世古地震学研究为评估阿拉斯加、卡斯卡迪亚、智利、日本、印度尼西亚和新西兰等许多俯冲带不同地震破裂模式的时空变异性提供了一种手段。至关重要的是，我们寻求评估利用既定的古地震学方法探测20世纪以前地震的下限，以及地质记录低估大地震发生频率的可能性。我们寻求紧急资金，以快速评估12月25日地震造成的同震地表变形和沉积。南半球冬季两侧的两个实地活动将测试任何记录的同震信号在被并入沉积物剖面的头几个月的保存潜力，包括在冬季风暴中的生存能力，以及地震后板块界面上的震后蠕变造成的任何震后垂直变形。沉积和微化石分析将揭示地震的沉积特征，并约束形变检测的下限。这一建议建立在我们以前的研究和最近沿海古地震学的转变基础上，从确定晚全新世地震破裂段内最大的地壳形变到寻找破裂段的空间范围，从而确定破裂段的界限。这就需要一种侧重于确定地壳垂直形变下限的方法。我们最近根据自己的研究和对古地震学文献的全面审查，提出了一个修订后的研究框架来实现这一点，但注意到缺乏足够详细的现代对应文献。2015年智利地震提供了一个难得的机会，可以从受小同震垂直陆地运动、地面震动和任何相关海啸影响的沿海地区的当代环境中收集时间紧迫的样本。