TY - JOUR
T1 - Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile
AU - DePaolis, Jessica M.
AU - Dura, Tina
AU - MacInnes, Breanyn
AU - Ely, Lisa L.
AU - CISTERNAS VEGA, MARCO ANTONIO
AU - Carvajal, Matías
AU - Tang, Hui
AU - Fritz, Hermann M.
AU - Mizobe, Cyntia
AU - Wesson, Robert L.
AU - Figueroa, Gino
AU - Brennan, Nicole
AU - Horton, Benjamin P.
AU - Pilarczyk, Jessica E.
AU - Corbett, D. Reide
AU - Gill, Benjamin C.
AU - Weiss, Robert
N1 - Funding Information:
We would like to extend our thanks to Trent Adams for his assistance with sample collection during fieldwork. T.D. was supported by National Science Foundation (NSF) grants EAR-1624795 and EAR-1624533 , and L.E. and B.M. were supported by NSF award EAR-1624542 . M.C., C.M, G.F., and M.Ca. were supported by the FONDECYT -Chile, project N° 1190258 and by the Millennium Scientific Initiative of the Chilean government through grant NC160025 “Millennium Nucleus CYCLO The Seismic Cycle Along Subduction Zones”. M.Ca acknowledges the support from FONDECYT -Chile, project N° 1181479 . This work was supported by the Canadian Foundation for Innovation (CFI-JELF) , Canada Research Chair Program, and an NSERC Discovery grant to JP. This is a contribution to the PALSEA (Palaeo-Constraints on Sea-Level Rise), a working group of the International Union for Quaternary Sciences (INQUA) and Past Global Changes (PAGES), and International Geoscience Program (IGCP) International Geoscience Programme (IGCP) Project 725 “Forecasting Coastal Change”. BPH is supported by the Singapore Ministry of Education Academic Research Fund MOE2019-T3-1-004 and MOE2018-T2-1-030 , and the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative. This work comprises EOS contribution number 374. We would also like to thank Alan Nelson, Rob Witter, and an anonymous reviewer for their constructive critiques that helped improve this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Funding Information:
We would like to extend our thanks to Trent Adams for his assistance with sample collection during fieldwork. T.D. was supported by National Science Foundation (NSF) grants EAR-1624795 and EAR-1624533, and L.E. and B.M. were supported by NSF award EAR-1624542. M.C. C.M, G.F. and M.Ca. were supported by the FONDECYT-Chile, project N? 1190258 and by the Millennium Scientific Initiative of the Chilean government through grant NC160025 ?Millennium Nucleus CYCLO The Seismic Cycle Along Subduction Zones?. M.Ca acknowledges the support from FONDECYT-Chile, project N? 1181479. This work was supported by the Canadian Foundation for Innovation (CFI-JELF), Canada Research Chair Program, and an NSERC Discovery grant to JP. This is a contribution to the PALSEA (Palaeo-Constraints on Sea-Level Rise), a working group of the International Union for Quaternary Sciences (INQUA) and Past Global Changes (PAGES), and International Geoscience Program (IGCP) International Geoscience Programme (IGCP) Project 725 ?Forecasting Coastal Change?. BPH is supported by the Singapore Ministry of Education Academic Research Fund MOE2019-T3-1-004 and MOE2018-T2-1-030, and the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative. This work comprises EOS contribution number 374. We would also like to thank Alan Nelson, Rob Witter, and an anonymous reviewer for their constructive critiques that helped improve this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Publisher Copyright:
© 2021 The Authors
PY - 2021/8/15
Y1 - 2021/8/15
N2 - On September 16, 2015, a Mw 8.3 earthquake struck the north-central Chile coast, triggering a tsunami observed along 500 km of coastline, between Huasco (28.5°S) and San Antonio (33.5°S). This tsunami provided a unique opportunity to examine the nature of tsunami deposits in a semi-arid, siliciclastic environment where stratigraphic and sedimentological records of past tsunamis are difficult to distinguish. To improve our ability to identify such evidence, we targeted one of the few low-energy, organic-rich depositional environments in north-central Chile: Pachingo marsh in Tongoy Bay (30.3°S). We found sedimentary evidence of the 2015 and one previous tsunami as tabular sand sheets. Both deposits are composed of poorly to moderately sorted, gray-brown, fine-to medium-grained sand and are distinct from underlying and overlying organic-rich silt. Both sand beds thin (from ∼20 cm to <1 cm) and fine landward, and show normal grading. The older sand bed is thicker and extends over 125 m further inland than the 2015 tsunami deposit. To model the relative size of the tsunamis that deposited each sand bed, we employed tsunami flow inversion. Our results show that the older sand bed was produced by higher flow speeds and depths than those in 2015. Anthropogenic evidence along with 137Cs and 210Pb dating constrains the age of the older tsunami to the last ∼110 years. We suggest that the older sand bed was deposited by the large tsunami in 1922 CE sourced to the north of our study site. This deposit represents the first geologic evidence of a pre-2015 tsunami along the semi-arid north-central Chile coast and highlights the current and continuing tsunami hazard in the region.
AB - On September 16, 2015, a Mw 8.3 earthquake struck the north-central Chile coast, triggering a tsunami observed along 500 km of coastline, between Huasco (28.5°S) and San Antonio (33.5°S). This tsunami provided a unique opportunity to examine the nature of tsunami deposits in a semi-arid, siliciclastic environment where stratigraphic and sedimentological records of past tsunamis are difficult to distinguish. To improve our ability to identify such evidence, we targeted one of the few low-energy, organic-rich depositional environments in north-central Chile: Pachingo marsh in Tongoy Bay (30.3°S). We found sedimentary evidence of the 2015 and one previous tsunami as tabular sand sheets. Both deposits are composed of poorly to moderately sorted, gray-brown, fine-to medium-grained sand and are distinct from underlying and overlying organic-rich silt. Both sand beds thin (from ∼20 cm to <1 cm) and fine landward, and show normal grading. The older sand bed is thicker and extends over 125 m further inland than the 2015 tsunami deposit. To model the relative size of the tsunamis that deposited each sand bed, we employed tsunami flow inversion. Our results show that the older sand bed was produced by higher flow speeds and depths than those in 2015. Anthropogenic evidence along with 137Cs and 210Pb dating constrains the age of the older tsunami to the last ∼110 years. We suggest that the older sand bed was deposited by the large tsunami in 1922 CE sourced to the north of our study site. This deposit represents the first geologic evidence of a pre-2015 tsunami along the semi-arid north-central Chile coast and highlights the current and continuing tsunami hazard in the region.
KW - Coastal hazards
KW - Earthquakes
KW - North-central Chile
KW - Paleotsunamis
KW - Tsunami inundation
UR - http://www.scopus.com/inward/record.url?scp=85110570262&partnerID=8YFLogxK
U2 - 10.1016/j.quascirev.2021.107052
DO - 10.1016/j.quascirev.2021.107052
M3 - Article
AN - SCOPUS:85110570262
VL - 266
JO - Quaternary Science Reviews
JF - Quaternary Science Reviews
SN - 0277-3791
M1 - 107052
ER -