Comprendiendo el ciclo sísmico en la costa de Chile central y su complejo registro geológico.
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Fecha
2025
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Universidad de Concepción
Resumen
Las costas adyacentes a zonas de subducción son continuamente amenazadas por grandes terremotos y tsunamis, cuyos efectos generan significativos impactos ambientales y sociales. En este contexto, los registros geológicos completos de eventos pasados constituyen una herramienta clave para evaluar apropiadamente la amenaza futura. Sin embargo, en Chile central, donde reside la mayor población costera del país, estos registros son fragmentarios y discontinuos, producto de la interacción entre factores tectónicos, climáticos y antrópicos que dificultan tanto su formación como su preservación a lo largo del tiempo.
Esta tesis doctoral tuvo como objetivo general evaluar cómo dichos factores condicionan el registro geológico de terremotos y tsunamis, y determinar en qué medida un enfoque multidisciplinario, basado en la integración de evidencias satelitales, estratigráficas, paleoecológicas, históricas e instrumentales, puede mejorar la reconstrucción de la deformación costera y la distribución espacial de los depósitos de tsunami. Las principales preguntas de investigación se centraron en identificar qué factores explican el escaso registro paleosismológico en Chile central, cómo ha variado la deformación vertical costera durante el último siglo, y cuál es el potencial de la percepción remota en la detección de modernos depósitos de tsunami. Estas interrogantes fueron abordadas en dos áreas clave: la costa del Maule, entre Lipimávida y la desembocadura del Río Mataquito, y el humedal de Campiche en la Bahía de Quintero.
Los resultados identificaron tres factores principales que limitan el registro paleosismológico en Chile central: (i) el alzamiento tectónico sostenido, que reduce el espacio de acomodación y favorece la erosión; (ii) el clima mediterráneo semiárido, que restringe la preservación del registro geológico y limita la formación de ambientes de baja energía y (iii) la intervención antrópica, que ha modificado o destruido numerosos sitios con potencial paleosismológico.
A pesar de estas limitaciones, la aplicación de percepción remota permitió identificar y mapear el depósito de tsunami del 2010, demostrando el potencial de técnicas satelitales en la asistencia de trabajos de campo. Asimismo, el análisis de diatomeas, apoyado por mediciones mareográficas y geodésicas, permitió reconstruir la deformación vertical de la costa de Chile central durante todo el siglo XX, sugiriendo que terremotos con fuente profunda en la zona de subducción podrían estar contribuyendo a la construcción de topografía a largo plazo.
En conjunto, se concluye que la integración de enfoques metodológicos multidisciplinarios resulta esencial para asistir en la reconstrucción de patrones de deformación vertical costera y áreas de inundación de tsunamis en este segmento altamente vulnerable del margen chileno. Los hallazgos y enfoques desarrollados en este estudio pueden servir como referencia para otros segmentos del margen de subducción chileno, donde el registro geológico también presenta desafíos significativos para su identificación y comprensión.
Coasts adjacent to subduction zones are continuously threatened by large earthquakes and tsunamis, whose effects cause significant environmental and social impacts. In this context, complete geological records of past events represent a key tool to properly assess future hazards. However, in central Chile, where most of the country’s coastal population resides, these records are fragmentary and discontinuous, as a result of the interplay between tectonic, climatic, and anthropogenic factors that hinder both their formation and long-term preservation. This doctoral thesis aimed to evaluate how these factors condition the geological record of earthquakes and tsunamis, and to determine to what extent a multidisciplinary approach, based on the integration of satellite, stratigraphic, paleoecological, historical, and instrumental evidence, can improve the reconstruction of coastal deformation and the spatial distribution of tsunami deposits. The main research questions focused on identifying the factors that explain the scarce paleoseismological record in central Chile, assessing how coastal vertical deformation has varied over the last century, and evaluating the potential of remote sensing in detecting modern tsunami deposits. These questions were addressed in two key areas: the Maule coast, between Lipimávida and the mouth of the Mataquito River, and the Campiche wetland in Quintero Bay. The results identified three main factors that limit the paleoseismological record in central Chile: (i) sustained tectonic uplift, which reduces accommodation space and enhances erosion; (ii) the semi-arid Mediterranean climate, which restricts geological preservation and limits the development of low-energy depositional environments; and (iii) anthropogenic disturbance, which has modified or destroyed numerous sites with paleoseismological potential. Despite these limitations, the application of remote sensing techniques allowed the identification and mapping of the 2010 tsunami deposit, demonstrating the potential of satellite-based methods to support fieldwork. Likewise, diatom analysis, supported by tide-gauge and geodetic measurements, enabled the reconstruction of vertical coastal deformation throughout the 20th century, suggesting that deep-source earthquakes along the subduction interface may contribute to long-term coastal uplift and landscape building. Overall, this study concludes that the integration of multidisciplinary methodological approaches is essential to assist in the reconstruction of coastal vertical deformation patterns and tsunami inundation areas in this highly vulnerable segment of the Chilean margin. The findings and approaches developed here may serve as a reference for other sectors of the Chilean subduction margin, where geological records also pose significant challenges for their identification and interpretation.
Coasts adjacent to subduction zones are continuously threatened by large earthquakes and tsunamis, whose effects cause significant environmental and social impacts. In this context, complete geological records of past events represent a key tool to properly assess future hazards. However, in central Chile, where most of the country’s coastal population resides, these records are fragmentary and discontinuous, as a result of the interplay between tectonic, climatic, and anthropogenic factors that hinder both their formation and long-term preservation. This doctoral thesis aimed to evaluate how these factors condition the geological record of earthquakes and tsunamis, and to determine to what extent a multidisciplinary approach, based on the integration of satellite, stratigraphic, paleoecological, historical, and instrumental evidence, can improve the reconstruction of coastal deformation and the spatial distribution of tsunami deposits. The main research questions focused on identifying the factors that explain the scarce paleoseismological record in central Chile, assessing how coastal vertical deformation has varied over the last century, and evaluating the potential of remote sensing in detecting modern tsunami deposits. These questions were addressed in two key areas: the Maule coast, between Lipimávida and the mouth of the Mataquito River, and the Campiche wetland in Quintero Bay. The results identified three main factors that limit the paleoseismological record in central Chile: (i) sustained tectonic uplift, which reduces accommodation space and enhances erosion; (ii) the semi-arid Mediterranean climate, which restricts geological preservation and limits the development of low-energy depositional environments; and (iii) anthropogenic disturbance, which has modified or destroyed numerous sites with paleoseismological potential. Despite these limitations, the application of remote sensing techniques allowed the identification and mapping of the 2010 tsunami deposit, demonstrating the potential of satellite-based methods to support fieldwork. Likewise, diatom analysis, supported by tide-gauge and geodetic measurements, enabled the reconstruction of vertical coastal deformation throughout the 20th century, suggesting that deep-source earthquakes along the subduction interface may contribute to long-term coastal uplift and landscape building. Overall, this study concludes that the integration of multidisciplinary methodological approaches is essential to assist in the reconstruction of coastal vertical deformation patterns and tsunami inundation areas in this highly vulnerable segment of the Chilean margin. The findings and approaches developed here may serve as a reference for other sectors of the Chilean subduction margin, where geological records also pose significant challenges for their identification and interpretation.
Descripción
Tesis presentada para optar al grado de Doctor en Ciencias Geológicas.
Palabras clave
Geodinámica, Terremotos, Movimientos tectónicos