Recent history of natural hazards in Chile Imprints of earthquakes and volcanic events in lacustrine and marine sediments Recente geschiedenis van natuurlijke risico’s in Chili Sporen van aardbevingen en vulkanische activiteit in lacustriene en mariene sedimenten Maarten Van Daele 2012 Dissertation submitted for the degree of Doctor of Science: Geology Supervisor: Prof. Dr. Marc De Batist Research funded by FWO - Vlaanderen Members of the reading committee: Prof. Dr. M. Pino (Universidad Austral de Chile, Valdivia, Chile) Prof. Dr. D. Ariztegui (University of Geneva, Switzerland) Prof. Dr. N. Davies (Ghent University, Belgium) Members of the examination committee: Prof. Dr. J. Verniers (Ghent University, Belgium): chair Prof. Dr. M. De Batist (Ghent University, Belgium): supervisor, secretary Prof. Dr. M. Pino (Universidad Austral de Chile, Valdivia, Chile) Prof. Dr. D. Ariztegui (University of Geneva, Switzerland) Prof. Dr. A. Hubert-Ferrari (Université de Liège, Belgium) Prof. Dr. D. Verschuren (Ghent University, Belgium) Prof. Dr. N. Davies (Ghent University, Belgium) Prof. Dr. D. Van Rooij (Ghent University, Belgium) Cover illustration: picture of Llaima Volcano erupting on January 1, 2008, taken from the shores of Lake Villarrica (K. Heirman). Maarten Van Daele carried out the research with financial support of the Research Foundation – Flanders (FWO – Vlaanderen). This research project was conducted at the Renard Centre of Marine Geology, Ghent University (Ghent, Belgium) To refer to this thesis: Van Daele, M., 2011. Recent history of natural hazards in Chile: Imprints of earthquakes and volcanic events in lacustrine and marine sediments. PhD thesis, Ghent University, Ghent, Belgium. The author and the supervisor give the authorization to consult and copy parts of this work for personal use only. Every other use is subjected to copyright laws. Permission to reproduce any material contained in this work should be obtained from the author. Table of contents List of figures ................................................................................................................................ 7 List of tables ............................................................................................................................... 11 List of abbreviations ................................................................................................................... 13 Acknowledgements - dankwoord ................................................................................................ 15 Summary ................................................................................................................................... 17 Samenvatting ............................................................................................................................. 21 1. Introduction .......................................................................................................................... 27 1.1 Recent catastrophic natural events ................................................................................. 28 1.2 The necessity of geological records ................................................................................. 29 1.3 Research questions ......................................................................................................... 30 1.4 Dissertation outline ........................................................................................................ 32 References ............................................................................................................................. 33 2. Methodology ......................................................................................................................... 37 2.1 Multibeam bathymetry ................................................................................................... 38 2.2 High-resolution seismic profiling ..................................................................................... 38 2.3 Core acquisition .............................................................................................................. 39 2.4 Core analysis .................................................................................................................. 39 2.4.1 Image acquisition .............................................................................................................. 39 2.4.2 Image analysis ................................................................................................................... 40 2.4.3 Impregnation .................................................................................................................... 40 2.4.4 High-resolution magnetic-susceptibility (MS) .................................................................. 40 2.4.5 Grain-size analysis ............................................................................................................. 40 2.4.6 Loss-on-ignition (LOI) ........................................................................................................ 41 2.4.7 X-ray diffraction (XRD) ...................................................................................................... 41 2.4.8 Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and electron microprobe .................................................................................................................................... 41 2.4.9 X-ray fluorescence (XRF) ................................................................................................... 42 2.4.10 X-ray computed tomography (CT) .................................................................................... 42 2.4.11 Varve counting .................................................................................................................. 43 2.4.12 Radionuclide dating .......................................................................................................... 43 References ............................................................................................................................. 43 3. Multi-proxy analysis of annually laminated sediments from three neighboring lakes in South- Central Chile: a continuous record of regional volcanic activity for the past 600 years ................. 47 3.1 Introduction ................................................................................................................... 48 3.2 Regional setting .............................................................................................................. 49 3.2.1 Site description ................................................................................................................. 49 3.2.2 Geology and eruptive history ........................................................................................... 51 3.2.3 Tectonic and seismic history ............................................................................................. 51 3.3 Methodology .................................................................................................................. 52 Recent history of natural hazards in Chile 3.3.1 Bathymetry and seismic data acquisition ......................................................................... 52 3.3.2 Sedimentology, geochemistry and chronology ................................................................ 52 3.4 Results and discussion .................................................................................................... 53 3.4.1 Bathymetry and core location .......................................................................................... 53 3.4.2 Sedimentology and geochemistry .................................................................................... 56 3.4.3 Event deposit classification and formation ...................................................................... 57 3.4.4 Varve formation and chronology ...................................................................................... 63 3.4.5 Event deposit chronology ................................................................................................. 67 3.4.6 The eruptive record of Villarrica Volcano ......................................................................... 74 3.4.7 Probability of a future eruption ........................................................................................ 75 3.5 Conclusions .................................................................................................................... 77 Acknowledgements ................................................................................................................ 78 References ............................................................................................................................. 78 4. Sedimentary imprint of the giant 1960 and 2010 Chilean earthquakes in variable lacustrine environments ............................................................................................................................. 85 4.1 Introduction ................................................................................................................... 86 4.2 Setting ........................................................................................................................... 87 4.2.1 Geomorphologic, tectonic and geologic setting ............................................................... 87 4.2.2 Lake settings ....................................................................................................................