Browsing by Author "Cisternas, Marco"

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    Decadal coastal evolution spanning the 2010 Maule earthquake at Isla Santa Maria, Chile: Framing Darwin's accounts of uplift over a seismic cycle
    (2023) Aedo, Diego; Cisternas, Marco; Melnick, Daniel; Esparza, Cesar; Winckler, Patricio; Saldana, Bladimir
    Charles Darwin and Robert FitzRoy documented coseismic coastal uplift associated with the great 1835 Chile earthquake (M > 8.5) at Isla Santa Maria. 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 similar to 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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    Historical records of San Rafael glacier advances (North Patagonian Icefield): another clue to 'Little Ice Age' timing in southern Chile?
    (2007) Araneda, Alberto; Torrejon, Fernando; Aguayo, Mauricio; Torres, Laura; Cruces, Fabiola; Cisternas, Marco; Urrutia, Roberto
    Past ice lobe behaviour at Laguna San Rafael is described in documents provided by Spanish and then Chilean explorers from the late seventeenth to the early twentieth centuries. These records begin in AD 1675, when temperate conditions, probably similar to those at present, prevailed. At that point, the glacier was confined within its valley, not penetrating the Laguna. The glacier advanced noticeably during the nineteenth century and probably reached a maximum position for the 'Little Ice Age' around AD 1875. The historical sources suggest a slight retreat in AD 1904 in relation to the conditions prevailing 29 years earlier. The historical data show that the eighteenth to nineteenth century cooling period at San Rafael glacier was within the temporal window of the European 'Little Ice Age'. This work provides independent, direct historical evidence for the occurrence of this event in southern Chile.
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    The 1730 Great Metropolitan Chile Earthquake and Tsunami Commemoration: Joint Efforts to Increase the Country's Awareness
    (2020) Zamora, Natalia; Gubler, Alejandra; Orellana, Victor; Leon, Jorge; Urrutia, Alejandro; Carvajal, Matias; Cisternas, Marco; Catalan, Patricio; Winckler, Patricio; Cienfuegos, Rodrigo; Karich, Cristobal; Vogel, Stefan; Galaz, Jose; Pereira, Sebastian; Bertin, Celeste
    On 8 July 1730, a great earthquake struck metropolitan Chile, causing extensive damage 1000 km along the country and focused in Valparaiso. Due to the date of occurrence of this event, large uncertainties about the earthquake's magnitude have been discussed among the scientific community, and the earthquake and tsunami have remained unknown for most of the population. The purpose of this paper is to describe joint efforts undertaken by organizations, academia, and authorities to rescue the forgotten memory of an event that occurred almost three centuries ago and that may be repeated in the near future. In line with the Sendai Framework, we focus on one of the four priorities for action, which is to understand disaster risk, with the premise that the memory activation and raising awareness can save lives in the future. We designed outreach strategies to communicate this knowledge to the community in a participatory way. The latter involves scientific talks, earthquake simulators, tsunami projection mapping on relief scaled models (mock-up), and a public debate including the participation of academia, politicians, authorities, and the local community. The emulation of such activities and the constant work of regional and national authorities, academia, and non-governmental organizations dealing with risk mitigation encourage involving the community to build safer cities against the tsunami hazard.