The Evolution of the Bío Bío Delta and the Coastal Plains of the Arauco Gulf, Bío Bío Region: the Holocene Sea-Level Curve of Chile

Isla, Federico Ignacio; Flory, Jorge Quezada; Martı́nez, Carolina; Fernández, Alfonso; Castillo, Edilia Jaque

doi:10.2112/jcoastres-d-10-00035.1

Cited by 16 publications

(22 citation statements)

References 31 publications

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“…The timing of this marine transgression, however, displays a large regional variability. In the Coronel and Carampangue areas (∼36°S), coastal plains formed at a maximum elevation not higher than 5 m over the present mean sea level between 6.0 and 5.0 cal ka BP (Isla et al ., ). Stefer et al .…”

Section: Discussionmentioning

confidence: 99%

“…In coastal areas, local sea-level changes during the past millennia have responded to both tectonic factors (uplift and subsidence) and eustatic changes (Stefer et al, 2010;Jara-Muñoz et al, 2015). Today, climate and geological hazards have significant social and economic impacts (Stefer et al, 2010;Wilson et al, 2011;Isla et al, 2012;Jaramillo et al, 2012;Ruggieri et al, 2012;Dura et al, 2015) but few records explore their long-term dynamics and implications for recent and future environmental changes.…”

Section: Introductionmentioning

confidence: 99%

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A 7000‐year high‐resolution lake sediment record from coastal central Chile (Lago Vichuquén, 34°S): implications for past sea level and environmental variability

Frugone-Álvarez

Latorre

Giralt

et al. 2017

J Quaternary Science

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We present a 7‐ka environmental reconstruction based on sedimentological and geochemical data from Lago Vichuquén, a coastal eutrophic lake in central Chile (34°48′S, 72°03′ W, 4 m a.s.l.). A relatively shallow and restricted marine environment with low productivity, high detrital input and dominant anoxic conditions in the Vichuquén Basin occurred from 7.0 to 6.5 cal ka BP. Rapid onset of a Holocene marine transgression at 6.5 cal ka BP favoured deeper and more biologically productive environments that existed until 2.8 cal ka BP. Bioproductivity changes during the mid‐Holocene (6.5–4.2 cal ka BP) were related to upwelling dynamics controlled by the intensity of the South‐east Pacific Anticyclone (SPA). Periods with lower organic productivity and dominant anoxic conditions reflect an increased intensity of SPA (increased upwelling) and decreased precipitation. A shift at ∼4.0 cal ka BP reflects the onset of modern Southern Westerly Winds and El Niño‐Southern Oscillation patterns. Tectonic uplifting and geormorphological activity (dune advancement) are possible reasons behind the Vichuquén Basin closure at ∼1.2 cal ka BP, leading to a low bioproductivity lacustrine environment which has developed until the present. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A 7000‐year high‐resolution lake sediment record from coastal central Chile (Lago Vichuquén, 34°S): implications for past sea level and environmental variability

Frugone-Álvarez

Latorre

Giralt

et al. 2017

J Quaternary Science

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“…Patterns of uplifted Holocene strandlines and marine terraces based on Jara‐Muñoz and Melnick [], Jara‐Muñoz et al . [], Kaizuka, et al [], Melnick et al [], Bookhagen et al [], and Isla et al []. Relocated microseismicity from the ISSA2000 experiment and processed in this study, color coded by depth.…”

Section: Seismotectonic and Geomorphic Settingmentioning

confidence: 99%

“…The MIS 1 is represented by sequences of parallel Holocene strandlines surrounding the Arauco Bay (Figure ). Some of these strandlines were dated at SMI and Coronel using optically stimulated luminescence and radiocarbon dating, to between 1.8 and 4.3 ka [ Bookhagen et al , ; Isla et al , ]. Bookhagen et al [] proposed that strandlines at SMI have emerged as a result of recurrent coseismic uplift during megathrust earthquakes at a mean uplift rate of 2.3 ± 0.2 m/ka, which is slightly higher than the 1.5 ± 0.3 m/ka uplift rate estimated from MIS 3 deposits [e.g., Jara‐Muñoz and Melnick , ].…”

Section: Seismotectonic and Geomorphic Settingmentioning

confidence: 99%

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Quantifying offshore fore‐arc deformation and splay‐fault slip using drowned Pleistocene shorelines, Arauco Bay, Chile

et al. 2017

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Most of the deformation associated with the seismic cycle in subduction zones occurs offshore and has been therefore difficult to quantify with direct observations at millennial timescales. Here we study millennial deformation associated with an active splay‐fault system in the Arauco Bay area off south central Chile. We describe hitherto unrecognized drowned shorelines using high‐resolution multibeam bathymetry, geomorphic, sedimentologic, and paleontologic observations and quantify uplift rates using a Landscape Evolution Model. Along a margin‐normal profile, uplift rates are 1.3 m/ka near the edge of the continental shelf, 1.5 m/ka at the emerged Santa María Island, −0.1 m/ka at the center of the Arauco Bay, and 0.3 m/ka in the mainland. The bathymetry images a complex pattern of folds and faults representing the surface expression of the crustal‐scale Santa María splay‐fault system. We modeled surface deformation using two different structural scenarios: deep‐reaching normal faults and deep‐reaching reverse faults with shallow extensional structures. Our preferred model comprises a blind reverse fault extending from 3 km depth down to the plate interface at 16 km that slips at a rate between 3.0 and 3.7 m/ka. If all the splay‐fault slip occurs during every great megathrust earthquake, with a recurrence of ~150–200 years, the fault would slip ~0.5 m per event, equivalent to a magnitude ~6.4 earthquake. However, if the splay‐fault slips only with a megathrust earthquake every ~1000 years, the fault would slip ~3.7 m per event, equivalent to a magnitude ~7.5 earthquake.

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A paleo‐hydro‐geomorphological perspective on urban flood risk assessment

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Brox‐Escudero

González

et al. 2019

Hydrological Processes

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Comprehensive flood risk assessment requires enhanced understanding of the coevolution of the river and its floodplain occupation. Paleoflood analysis to determine flood prone areas in combination with numerical simulations to estimate flood hazard and a historical analysis of urban development to consider the evolution of exposure to floods is a possible way forward. The well-documented 2006 extreme flood in the Biobío River system and the impacted metropolitan area of Concepción, Chile (~1 million inhabitants) was used as a complex scenario to test the reliability of the proposed method. Results showed that flood prone areas determined with hydro-geomorphological methods are consistent with those computed with numerical models based on detailed digital elevation models. The flood generation via superficial flow pathways resulting in inundated areas could explain that rivers tend to reactivate paleochannels in extreme conditions. Urban development progressively increased the city's exposure to floods from 0 ha in 1,751 to 1,363 ha in 2006 evidencing a lack of appropriate flood risk management. The 100-year peak discharge resulted in a high flood risk for about 5% of the total urbanized area of Concepción, and higher discharges are likely to reactivate a paleochannel that crosses the current city centre. We conclude that the proposed paleo hydro-geomorphology, hydraulic, and urban planning multimethod approach is a necessary tool to enhance understanding of flood risk in complex scenarios to improve flood risk management. K E Y W O R D SBiobío River, flood risk management, hydro-geomorphological approach, numerical modelling, paleoflood

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The Evolution of the Bío Bío Delta and the Coastal Plains of the Arauco Gulf, Bío Bío Region: the Holocene Sea-Level Curve of Chile

Cited by 16 publications

References 31 publications

A 7000‐year high‐resolution lake sediment record from coastal central Chile (Lago Vichuquén, 34°S): implications for past sea level and environmental variability

A 7000‐year high‐resolution lake sediment record from coastal central Chile (Lago Vichuquén, 34°S): implications for past sea level and environmental variability

Quantifying offshore fore‐arc deformation and splay‐fault slip using drowned Pleistocene shorelines, Arauco Bay, Chile

A paleo‐hydro‐geomorphological perspective on urban flood risk assessment

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