气候变化领域集成服务门户(CCPortal): Post-depositional alteration of onshore tsunami deposits – Implications for the reconstruction of past events

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DOI	10.1016/j.earscirev.2019.103068
	Post-depositional alteration of onshore tsunami deposits – Implications for the reconstruction of past events
	Spiske M.; Tang H.; Bahlburg H.
发表日期	2020
ISSN	00128252
卷号	202
英文摘要	Sediments provide information on parameters governing their deposition. However, this information gets blurred by post-depositional processes. Here, we document post-depositional alteration processes that affected an onshore tsunami deposit from its deposition in February 2010 until 2014. Post-depositional changes proceeded in three stages. First, the thickness was reduced by 20% within the first months because of erosion by runoff. Second, vegetation returned and bioturbation destroyed the sedimentary structures and obliterated the basal contact. The thickness was reduced further to 20–40% of its initial thickness. The mean grain size decreased as silt and mud from the enclosing soil horizons were mixed into the deposit. Finally, as post-seismic subsidence together with damming by a coastal dune transformed the coastal plain into a wetland, aqueous microbial magnetite reduction set in and dissolved up to 57% of the magnetite. Inverse models are used to reconstruct onshore tsunami flow parameters in order to quantify the intensity of ancient events. Thickness, grain size and bulk density are input parameters to any model. Thus, post-depositional processes affect the reliability of the modeled flow parameters. Of the three documented processes, the post-depositional alteration of the grain size has the highest influence, followed by the reduction of the thickness. The change of the bulk density hardly had any effect. Our sensitivity analysis shows that the calculated flow velocity decreased by 60% from 4.2 m/s for the pristine sediments to 2.5 m/s for the altered deposits. Consequently, inverse models will significantly underestimate tsunami intensity because of the alteration of the deposits. © 2019 Elsevier B.V.
关键词	Flow velocity Inverse modeling Magnetite dissolution Post-depositional changes Sediment modification Tsunami
英文关键词	bulk density; coastal plain; deposition; grain size; magnetite; reconstruction; sediment thickness; sedimentary structure; soil horizon; tsunami
语种	英语
来源期刊	Earth Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203892
作者单位	Universität Basel, Departement Umweltwissenschaften, Bernoullistrasse 32, Basel, 4056, Switzerland; GFZ Helmholtz Centre Potsdam, Telegrafenberg, Potsdam, 14473, Germany; University of Arizona, Department of Geosciences, Tuscon, AZ 85721, United States; Westfälische Wilhelms-Universität, Corrensstrasse 24, Münster, 48149, Germany
推荐引用方式 GB/T 7714	Spiske M.,Tang H.,Bahlburg H.. Post-depositional alteration of onshore tsunami deposits – Implications for the reconstruction of past events[J],2020,202.
APA	Spiske M.,Tang H.,&Bahlburg H..(2020).Post-depositional alteration of onshore tsunami deposits – Implications for the reconstruction of past events.Earth Science Reviews,202.
MLA	Spiske M.,et al."Post-depositional alteration of onshore tsunami deposits – Implications for the reconstruction of past events".Earth Science Reviews 202(2020).