Examinando por Autor "Winckler, Patricio"

Mostrando 1 - 5 de 5
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    Extreme sea levels at Rapa Nui (Easter Island) during intense atmospheric rivers
    (Springer, 2021) Carvajal, Matías; Winckler, Patricio; Garreaud, René; Igualt,Felipe; Contreras‐López, Manuel; Averil, Pamela; Cisternas, Marco; Gubler, Alejandra; Breuer, Wolfgang A.
    In addition to the tsunami hazard posed by distant great earthquakes, Rapa Nui (Easter Island), in the Southeast Pacific Ocean, is exposed to frequent and intense coastal storms. Here, we use sea-level records and field surveys guided by video and photographic footage to show that extreme sea levels at Rapa Nui occur much more frequent than previously thought and thus constitute an unrecognized hazard to the inland’s maritime supply chain. We found that extreme sea-level events, including the two most extreme (March 5th and May 5th, 2020) in our 17-month-long analyzed period (from January 1st, 2019, to May 31st, 2020), resulted from constructive superpositions of seiches on the shelf, storm surges and high tides. By further analyzing time series of atmospheric and wind-generated wave data, we conclude that these extreme sea levels are ultimately driven by the breaking of large waves near the coastline (i.e., wave setup), with lesser contribution of barometric setup and even less of wind setup. We also propose that these large waves were mainly generated from strong, long-lasting, NW winds associated with intense atmospheric rivers (long, narrow regions in the atmosphere that transport abundant water vapor) passing over Rapa Nui. Given that the intensity of atmospheric rivers and sea level are thought to increase as climate changes, a deeper understanding of the relation between meteorological and oceanographic processes at Rapa Nui is strongly needed.
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    Is Rhodamine a good tracer to predict coal transport in water?
    (Universidad Católica De La Santísima Concepción, 2021) Winckler, Patricio; Molteni, Francisco; Reyes, Mauricio; Gubler, Alejandra; Sandoval, Jorge; Aleixo, Rui
    A simple and low-cost experimental procedure to compare the mixing and transport of two substances in water is presented in this paper, aiming to investigate if rhodamine can predict the fate of coal transport in water. The procedure is based on acoustic Doppler techniques to characterize the flow and imaging techniques to measure the transport of substances discharged from an instantaneous point source near the free surface. To validate this procedure, several tests are carried out for rhodamine and two subsamples of coal (defined by a fine and coarse granulometry) in a flume under currents. The results show that the mixing of rhodamine resembles the finest fraction of coal that is transported as a suspended material, but fails to characterize the larger coal grains that experience sedimentation. The procedure here proposed can be expanded to characterize the mixing of substances in a body of water under other conditions, such as waves or wind driven currents.
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    Non-Stationary Probabilistic Tsunami Hazard Assessments Incorporating Climate-Change- Driven Sea Level Rise
    (AGU, 2021) Sepúlveda, Ignacio; Haase, Jennifer S.; Liu, Philip L.-F.; Grigoriu, Mircea; Winckler, Patricio
    We face a new era in the assessment of multiple natural hazards whose statistics are becoming alarmingly non-stationary due to ubiquitous long-term changes in climate. One particular case is tsunami hazard affected by climate-change-driven sea level rise (SLR). A traditional tsunami hazard assessment approach where SLR is omitted or included as a constant sea-level offset in a probabilistic calculation may misrepresent the impacts of climate-change. In this paper, a general method called non-stationary probabilistic tsunami hazard assessment (nPTHA), is developed to include the long-term time-varying changes in mean sea level. The nPTHA is based on a non-stationary Poisson process model, which takes advantage of the independence of arrivals within non-overlapping time-intervals to specify a temporally varying hazard mean recurrence rate, affected by SLR. The nPTHA is applied to the South China Sea (SCS) for tsunamis generated by earthquakes in the Manila Subduction Zone. The method provides unique and comprehensive results for inundation hazard, combining tsunami and SLR at a specific location over a given exposure time. The results show that in the SCS, SLR has a significant impact when its amplitude is comparable to that of tsunamis with moderate probability of exceedance. The SLR and its associated uncertainty produce an impact on nPTHA results comparable to that caused by the uncertainty in the earthquake recurrence model. These findings are site-specific and must be analyzed for different regions. The proposed methodology, however, is sufficiently general to include other non-stationary phenomena and can be exploited for other hazards affected by SLR.
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    Tsunami impact and resilience cycle in an insular town: The case of Robinson Crusoe island, Chile
    (Elsevier, 2021) Breuer, Wolfgang Alejandro; Igualt, Felipe; Contreras-Lopez, Manuel; Winckler, Patricio; Zambra, Cristopher
    This paper analyzes the resilience cycle in San Juan Bautista (SJB), a town in Robinson Crusoe Island which has been severely affected by four tsunamis since it was first occupied in 1591. Technical reports, press archives and zoning plans are classified according to the stages of preparation, response, recovery and adaptation, and then used to explain the factors that delay the resilience cycle following the 2010 Chile tsunami. We conclude that before this event, SJB was not prepared due to the location of critical infrastructure in the flooding zone and the lack of risk principles in land use planning. Additionally, the failure of the Chilean tsunami warning system resulted in 16 casualties. As for recovery, nearly a decade after the tsunami, SJB is the only town countrywide that has not reached pre-tsunami performance levels. The relocation of housing in highlands and the use of emergency infrastructure to guarantee continuity of basic services are partial outcomes of the process. Adaptation has shown little advance since recovery is still ongoing. The analysis suggests that a contextualized urban planning policy, taking advantage of the local conditions, expertise and building materials, as well as the involvement of the community and local government, should be adopted in island territories exposed to tsunamis.
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    Unexpected effects of coastal storms on trophic ecology of two rocky reef fish species
    (Springer, 2021) Polanco‐Pérez, Javier; Search, Francesca V.; Winckler, Patricio; Ochoa‐Muñoz, María José; Landaeta, Mauricio F.
    Coastal storm risks have been increasing over the last couple of decades, affecting both marine infrastructure and human security. Nevertheless, the ecological impact on intertidal marine fishes has not been addressed yet. We carried out a field experiment during austral summer 2018, using statistical wave parameters, characterizing coastal storms as a factor, and the gut content of two sympatric intertidal triplefins, Helcogrammoides chilensis and Helcogrammoides cunninghami, as a proxy for trophic interactions. Three locations were sampled before and after the arrival of three consecutive summer coastal storm events. From all gut contents, a total of 16,597 prey items were found. Both species are micro-carnivorous, predating mostly on harpacticoid copepods, amphipods and chironomid larvae, without significant differences in prey composition with the passing of the summer coastal storms. However, after coastal storms, heavier-at-length fish (0.05–0.5 g weight gain) were found in the intertidal. Indeed, after the impact of the coastal storms, H. chilensis increased their ingestion of larger prey (amphipods, chironomid larvae), while H. cunninghami decreased the number of prey ingested. When compared between species, the feeding success after the passing of coastal storms was greater for H. chilensis than H. cunninghami. Finally, trophic overlap between species was high, but after the coastal storms passed, it decreased noticeably due to small changes in proportion of large chironomid and gammarid amphipods in the diet. Therefore, summer coastal storms affected the foraging behavior, increasing the weight of two recurrent cryptobenthic rocky reef fish from central Chile. In a broader ecological context, the shift from pelagic (i.e., copepods) to benthic prey (i.e., amphipods, polychaetes) may change the relative contribution and the subsidy production in nearshore habitats via pelagic-benthic coupling.