Coastal erosion in sandy beaches along a tectonically active coast: The Chile study case

Martı́nez, Carolina; Winckler, Patricio; Martín, Roberto Agredano; Acuña, César; Torres, Iván; Contreras-López, Manuel

doi:10.1177/03091333211057194

Cited by 22 publications

(29 citation statements)

References 87 publications

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“…Duan et al [89], on the coasts of China, clustered their coastal erosion and sedimentation results into rocky, beachy, muddy, and anthropic coasts. Martinez et al [90] carried out multi-temporal analyses for different beaches in Chile; their results are attributed to processes derived from local regional conditions, such as the different effects of seismic tectonics, e.g., tsunamis, the up-lift, and subsidence. Godwyn-Paulson et al [91] analyzed the effects on the coastline produced by the sea swell event, where new local conditions, such as geomorphology and bathymetry, are the predominant factors in the results.…”

Section: Discussionmentioning

confidence: 99%

Regional Patterns of Coastal Erosion and Sedimentation Derived from Spatial Autocorrelation Analysis: Pacific and Colombian Caribbean

Coca

Ricaurte-Villota

2022

Coasts

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Coastal erosion is a common phenomenon along the world’s coasts. Studying it is complex because such studies must cover large portions of land, and it is necessary to understand the multiple processes that interact in each area, so it is important to recognize regional patterns that allow for defining representativeness in relation to the surrounding dynamics. Spatial statistics can be used in coastal geomorphology to identify and quantify trends in coastal morphodynamics. This study analyzes and interprets the spatio-temporal patterns present in the changes in a shoreline, that is, the processes of erosion and coastal sedimentation in the Pacific and the Colombian Caribbean. The results are derived from the detection of significant changes in the coastline via satellite images. For this study, the shoreline of Colombia was digitized for the years 1986 and 2016, thus obtaining changes in the shoreline at a medium temporal scale. The Global Moran’s Index, Local Moran’s Index and Getis–Ord Index were used to explain the spatial statistics. The Global I Moran values for the Pacific were I = 0.190, z = 31.063 and p = 0.01, and for the Caribbean I = 0.624, z = 74.545 and p = 0.01, which suggests good grouping in the Caribbean and very low grouping for the Pacific. The local indices (Moran’s and Getis–Ord) allowed us to visualize and spatialize the significant points of coastal erosion and sedimentation. According to the results, three conceptual models are herein proposed that relate the indices with the geomorphological characteristics: (a) the greater the geomorphological heterogeneity, the greater the grouping; (b) the greater the geomorphological homogeneity, the lower the degree of clustering; (c) the greater the geomorphological complexity, the lower the degree of clustering. Finally, it is confirmed that coastal erosion and sedimentation processes predominate along low coasts.

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Section: Discussionmentioning

confidence: 99%

Regional Patterns of Coastal Erosion and Sedimentation Derived from Spatial Autocorrelation Analysis: Pacific and Colombian Caribbean

Coca

Ricaurte-Villota

2022

Coasts

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“…Th were affected by two large earthquakes and their coseismic effects 6.9 (M which caused significant changes in the seafloor that could partially explai in the coastline and its dynamics. These changes, coseismic uplift/subside from post-tsunami studies, and source inversions, are detailed for these ear their effects on the coastal areas of Navidad and Pichilemu [71][72][73][74], wh changes can be highly variable in space and determined by changes in th addition, coseismic subsidence in combination with sea level rise en erosion, and coastal subsidence can induce accretion [75].…”

Section: Urban Areasmentioning

confidence: 99%

“…These changes, coseismic uplift/subsidence obtained from post-tsunami studies, and source inversions, are detailed for these earthquakes and their effects on the coastal areas of Navidad and Pichilemu [71][72][73][74], where coseismic changes can be highly variable in space and determined by changes in the coastline. In addition, coseismic subsidence in combination with sea level rise enhances beach erosion, and coastal subsidence can induce accretion [75].…”

Section: Urban Areasmentioning

confidence: 99%

“…This is of particular importance for the potential reactivation of crustal structures during and after the occurrence of large subduction earthquakes, and is therefore also critical for seismic hazard assessment [78]. The evolution of the coastline is also strongly associated with erosion caused by large earthquakes and tsunamis; however, it was quickly rebuilt as a result of favorable sedimentary input [75]. This positive evolution has not been observed in the Pichilemu area, although it could be comparable to Navidad since both sectors are very close and have cove morphology; the differences can be understood more by coseismic subsidence, and less by sedimentary contribution.…”

Section: Navidad and Pichilemumentioning

confidence: 99%

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Measuring Coastal Subsidence after Recent Earthquakes in Chile Central Using SAR Interferometry and GNSS Data

et al. 2022

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Coastal areas concentrate a large portion of the country’s population around urban areas, which in subduction zones commonly are affected by drastic tectonic processes, such as the damage earthquakes have registered in recent decades. The seismic cycle of large earthquakes primarily controls changes in the coastal surface level in these zones. Therefore, quantifying temporal and spatial variations in land level after recent earthquakes is essential to understand shoreline variations better, and to assess their impacts on coastal urban areas. Here, we measure the coastal subsidence in central Chile using a multi-temporal differential interferometric synthetic aperture radar (MT-InSAR). This geographic zone corresponds to the northern limit of the 2010 Maule earthquake (Mw 8.8) rupture, an area affected by an aftershock of magnitude Mw 6.8 in 2019. The study is based on the exploitation of big data from SAR images of Sentinel-1 for comparison with data from continuous GNSS stations. We analyzed a coastline of ~300 km by SAR interferometry that provided high-resolution ground motion rates from between 2018 and 2021. Our results showed a wide range of subsidence rates at different scales, of analyses on a regional scale, and identified the area of subsidence on an urban scale. We identified an anomalous zone of subsidence of ~50 km, with a displacement <−20 mm/year. We discuss these results in the context of the impact of recent earthquakes and analyze the consequences of coastal subsidence. Our results allow us to identify stability in urban areas and quantify the vertical movement of the coast along the entire seismic cycle, in addition to the vertical movement of coast lands. Our results have implications for the planning of coastal infrastructure along subduction coasts in Chile.

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“…Rapid coastal changes after coseismic subsidence were observed after the 2010 Chile (Martínez et al, 2015(Martínez et al, , 2021, 2011 Tohoku (e.g., Tappin et al, 2012) and 2004 Sumatra-Andaman (e.g., Choowong et al, 2009;Liew et al, 2010;Monecke et al, 2015Monecke et al, , 2017 great earthquakes. These studies showed that, after coseismic subsidence, the shoreline typically receded by tens to hundreds of metres.…”

mentioning

confidence: 99%

Decadal coastal evolution spanning the 2010 Maule earthquake at Isla Santa Maria, Chile: Framing Darwin's accounts of uplift over a seismic cycle

Aedo

Cisternas

Melnick

et al. 2023

Earth Surf Processes Landf

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Charles Darwin and Robert FitzRoy documented coseismic coastal uplift associated with the great 1835 Chile earthquake (M > 8.5) at Isla Santa María. In 2010, another similar earthquake (Mw 8.8) uplifted the island, ending the seismic cycle. The 2‐m uplift in 2010 caused major geomorphic and sedimentologic changes to the island's sandy beaches. Understanding the processes governing these changes requires pre‐ and post‐earthquake measurements to differentiate the effects of abrupt coseismic uplift from seasonal, annual, and decadal‐scale signals. Here, we combine spatial analysis of aerial imagery, field geophysics, wind and wave models to quantify geomorphic changes between 1941 and 2021 along the main beach. During the late interseismic phase (1941–2010), a ridge‐runnel system was formed and then buried by a frontal dune. Because of uplift in 2010, the shoreline prograded ~20 m, the uplifted berm was abandoned, and a new seaward berm was built. In the following decade, the abandoned berm was eroded by widening of the backshore as the shoreline and dune advanced seaward. Over the surveyed eight decades, the shoreline prograded continuously, increasing from <1 m/year to up to 3–5 m/year after the earthquake. We infer that these changes were caused by a sedimentary disequilibrium driven by variations in relative sea level, moving formerly passive sands from eroding cliffs and marine depths into the coastal sedimentary system, thus promoting long and cross‐shore sediment transport and, utterly, accretion. Our results have implications for studying beach evolution along tectonically‐active coasts associated with drastic changes in relative sea level.

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Coastal erosion in sandy beaches along a tectonically active coast: The Chile study case

Cited by 22 publications

References 87 publications

Regional Patterns of Coastal Erosion and Sedimentation Derived from Spatial Autocorrelation Analysis: Pacific and Colombian Caribbean

Regional Patterns of Coastal Erosion and Sedimentation Derived from Spatial Autocorrelation Analysis: Pacific and Colombian Caribbean

Measuring Coastal Subsidence after Recent Earthquakes in Chile Central Using SAR Interferometry and GNSS Data

Decadal coastal evolution spanning the 2010 Maule earthquake at Isla Santa Maria, Chile: Framing Darwin's accounts of uplift over a seismic cycle

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