Suchergebnisse

Measuring coastal subsidence is essential to evaluating hazards associated with sea-level rise. This Review discusses the processes driving coastal subsidence, space-borne and land-based measurement techniques, as well as models for simulating observed subsidence and predicting future trends. Coastal subsidence contributes to relative sea-level rise and exacerbates flooding hazards, with the at-risk population expected to triple by 2070. Natural processes of vertical land motion, such as tectonics, glacial isostatic adjustment and sediment compaction, as well as anthropogenic processes, such as fluid extraction, lead to globally variable subsidence rates. In this Review, we discuss the key physical processes driving vertical land motion in coastal areas. Use of space-borne and land-based techniques and the associated uncertainties for monitoring subsidence are examined, as are physics-based models used to explain contemporary subsidence rates and to obtain future projections. Steady and comparatively low rates of subsidence and uplift owing to tectonic processes and glacial isostatic adjustment can be assumed for the twenty-first century. By contrast, much higher and variable subsidence rates occur owing to compaction associated with sediment loading and fluid extraction, as well as large earthquakes. These rates can be up to two orders of magnitude higher than the present-day rate of global sea-level rise. Multi-objective predictive models are required to account for the underlying physical processes and socio-economic factors that drive subsidence. ; US National Aeronautics and Space AdministrationNational Aeronautics & Space Administration (NASA) [80NSSC170567, 80NSSC17K0566]; US National Science FoundationNational Science Foundation (NSF) [EAR-1735630, EAR-1349311, EAR-1624795, EAR-1624533]; EU Marie Skodowska-Curie Individual Fellowship [894476]; International Geoscience Programme (IGCP) project [639] ; Published version ; The authors thank the reviewers for providing insightful comments and suggestions and J. Flocks for providing constructive comments on the manuscript. M.S. is supported by the US National Aeronautics and Space Administration (grant no. 80NSSC170567) and the US National Science Foundation (grant no. EAR-1735630). J.F. is supported by the US National Aeronautics and Space Administration (grant no. 80NSSC17K0566). T.E.T. has been supported by the US National Science Foundation (grant no. EAR-1349311). T.D. is supported by the US National Science Foundation (grant nos. EAR-1624795 and EAR-1624533). P.S.J.M. is supported by an EU Marie Skodowska-Curie Individual Fellowship (grant no. 894476 - InSPiRED - H2020-MSCA-IF-2019). This work is a contribution to the PALSEA programme and International Geoscience Programme (IGCP) project 639. Any use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the US Government. ; Public domain authored by a U.S. government employee

We present a comprehensive relative sea-level (RSL) database for north, central, and south-central Chile (18.5 degrees S - 43.6 degrees S) using a consistent, systematic, and internationally comparable approach. Despite its latitudinal extent, this coastline has received little rigorous or systematic attention and details of its RSL history remain largely unexplored. To address this knowledge gap, we re-evaluate the geological context and age of previously published sea-level indicators, providing 78 index points and 84 marine or terrestrial limiting points spanning from 11 ka to the present day. Many data points were originally collected for research in other fields and have not previously been examined for the information they provide on sea-level change. Additionally, we describe new sea-level data from four sites located between the Gulf of Arauco and Valdivia. By compiling RSL histories for 11 different regions, we summarise current knowledge of Chilean RSL. These histories indicate mid Holocene sea levels above present in all regions, but at highly contrasting elevations from similar to 30 m to <5 m. We compare the spatiotemporal distribution of sea-level data points with a suite of glacial isostatic adjustment models and place first-order constraints on the influence of tectonic processes over 10(3)-10(4) year timescales. While seven regions indicate uplift rates <1 m ka(-1), the remaining regions may experience substantially higher rates. In addition to enabling discussion of the factors driving sea-level change, our compilation provides a resource to assist attempts to understand the distribution of archaeological, palaeoclimatic, and palaeoseismic evidence in the coastal zone and highlights directions for future sea-level research in Chile. (C) 2020 Elsevier Ltd. All rights reserved. ; European Union/Durham University (COFUND under the DIFeREns 2 scheme); Millennium Nucleus CYCLO "The Seismic Cycle Along Subduction Zones" - Millennium Scientific Initiative (ICM) of the Chilean Government [NC160025]; FONDECYT (Chile)Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)CONICYT FONDECYT [1190258]; US National Science Foundation (NSF)National Science Foundation (NSF) [EAR-1566253, EAR-1624795, EAR-1624533]; National Geographic Society (US)National Geographic Society [8577-08]; NSFNational Science Foundation (NSF) [EAR-1036057, EAR-1145170, EAR1624542]; Deutsche Forschungsgemeindschaft GrantGerman Research Foundation (DFG) [JA 2860/1-1]; International Geoscience Programme (IGCP) project [639] ; Published version ; EG undertook this work while in receipt of funding from the European Union/Durham University (COFUND under the DIFeREns 2 scheme). The authors acknowledge financial support from the Millennium Nucleus CYCLO "The Seismic Cycle Along Subduction Zones" funded by the Millennium Scientific Initiative (ICM) of the Chilean Government Grant Number NC160025. Additional support for MC and DM was provided by FONDECYT (Chile), project No 1190258. TD was supported by the US National Science Foundation (NSF) awards EAR-1566253, EAR-1624795, and EAR-1624533. LE was supported by National Geographic Society (US) Research Grant 8577-08 and NSF awards EAR-1036057, EAR-1145170, and EAR1624542. JJM was supported by the Deutsche Forschungsgemeindschaft Grant JA 2860/1-1. The authors acknowledge PALSEA (a PAGES/INQUA working group) and HOLSEA (an INQUA project) for useful discussions at the 2019 meeting, Dublin, Ireland. We thank Nicole Khan and Matteo Vacchi for their constructive reviews. This is a contribution to International Geoscience Programme (IGCP) project 639. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. ; Public domain authored by a U.S. government employee

The tsunami associated with the giant 9.5 M-w 1960 Chile earthquake deposited an extensive sand layer above organic-rich soils near Queule (39.3 degrees S, 73.2 degrees W), south-central Chile. Using the 1960 tsunami deposits, together with eye-witness observations and numerical simulations of tsunami inundation, we tested the tsunami inundation sensitivity of the site to different earthquake slip distributions. Stratigraphically below the 1960 deposit are two additional widespread sand layers interpreted as tsunami deposits with maximum ages of 4960-4520 and 5930-5740 cal BP. This >4500-year gap of tsunami deposits preserved in the stratigraphic record is inconsistent with written and geological records of large tsunamis in south-central Chile in 1575, 1837, and possibly 1737. We explain this discrepancy by: (1) poor preservation of tsunami deposits due to reduced accommodation space from relative sea-level fall during the late Holocene; (2) recently evolved coastal geomorphology that increased sediment availability for tsunami deposit formation in 1960; and/or (3) the possibility that the 1960 tsunami was significantly larger at this particular location than other tsunamis in the past >4500 years. Our research illustrates the complexities of reconstructing a complete stratigraphic record of past tsunamis from a single site for tsunami hazard assessment. ; Puget Sound Energy Graduate Fellowship at Central Washington University; Earthquake Hazards Program of the U.S. Geological Survey; Chilean National Fund for Development of Science and Technology (FONDECYT)Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)CONICYT FONDECYT [1190258, 1181479]; Millennium Scientific Initiative (ICM) of the Chilean government [NC160025]; National Science Foundation (NSF)National Science Foundation (NSF)National Research Foundation of Korea [EAR-1624533, EAR-1624542]; ANID PIA Anillo [ACT192169] ; Published version ; Puget Sound Energy Graduate Fellowship at Central Washington University; Earthquake Hazards Program of the U.S. Geological Survey; Chilean National Fund for Development of Science and Technology (FONDECYT), Grant/Award Numbers: 1190258, 1181479; Millennium Scientific Initiative (ICM) of the Chilean government, Grant/Award Number: NC160025; National Science Foundation (NSF), Grant/Award Numbers: EAR-1624533, EAR-1624542; ANID PIA Anillo, Grant/Award Number: ACT192169 ; Public domain authored by a U.S. government employee